Peripheral Nerve Blocks
• Advancement in needle delivery devices, safer local anesthetics, and development
of indwelling catheters for postoperative perineural infusion have led to a
transformation in regional anesthesia; the focus has shifted from providing
intraoperative regional anesthesia to providing intraoperative anesthesia and
postoperative regional analgesia.
• Fundamental to the success of regional anesthesia is the correct positioning of the
needle tip in the perineural sheath, prior to injection of local anesthetic.
• In the past, this was accomplished either by eliciting a paresthesia with the needle
tip or, in the case of an axillary nerve block, by using the transarterial approach.
• Either out of fear of persistent paresthesias or arterial injury, or because of
advancement of the specialty and development of newer technologies,
anesthesiologists today commonly employ a nerve stimulator to help define needle
• The use of nerve stimulators is not risk free, as morbidities have been reported
with these devices, leaving providers in search of the optimal tool. Other
technologies that are being studied are ultrasound, Doppler, and sensory nerve
stimulation. Currently the best way to establish needle tip location is based on a
motor response to nerve stimulation; a motor response at approximately 0.5 mA
indicates that the needle is in the appropriate position and local anesthetic can be
• The disadvantages of peripheral nerve blocks, although uncommon,
include the toxicity of local anesthetics, chronic paresthesias and nerve
damage, and, depending on the nerves being anesthetized (interscalene
block, supraclavicular block, etc), respiratory failure due to phrenic nerve
blockade, and seizures due to intraarterial injection
• when performing a block, the anesthesiologist must weigh the toxicity of
the agent to be used and the characteristics of individual local anesthetics
such as time to onset and duration of action, degree of sensory versus
motor block, and the cardiac toxicity of large volumes of local anesthetics
delivered into the perineural sheaths.
Upper Extremity Blocks
• Successful regional anesthesia of the upper extremity requires knowledge of
brachial plexus anatomy from its origin, where the nerves emerge from the
intervertebral foramina, to its termination in the peripheral nerves.
• Also important is an understanding of the side effects and complications of upper
extremity regional techniques, as well as the clinical application of available local
anesthetics for these blocks.
• role of appropriate sedation during placement of the block and during the surgical
procedure should not be underestimated. Many a “perfect” regional anesthetic
technique has been undone by inadequate management of sedation.
Anatomy- brachial plexus is formed by the union of the anterior primary divisions
(ventral rami) of the fifth through the eighth cervical nerves and the first thoracic
nerves . Contributions from C4 and T2 are often minor or absent.
• As the nerve roots leave the intervertebral foramina, they converge, forming
trunks, divisions, cords, and then finally terminal nerves.
• Three distinct trunks are formed between the anterior and middle scalene muscles.
Because they are vertically arranged, they are termed superior, middle, and
• superior trunk is predominantly derived from C5–6, the middle trunk from C7, and
the inferior trunk from C8–T1.
• As the trunks pass over the lateral border of the first rib and under the clavicle,
each trunk divides into anterior and posterior divisions.
• As the brachial plexus emerges below the clavicle, the fibers combine again to
form three cords that are named according to their relationship to the axillary
artery: lateral, medial, and posterior
• lateral cord is the union of the anterior divisions of the superior and middle trunks;
• medial cord is the continuation of the anterior division of the inferior trunk; and
• posterior cord is formed by the posterior division of all three trunks.
• At the lateral border of the pectoralis minor muscle, each cord gives off a large
branch before terminating as a major terminal nerve.
• lateral cord gives off the lateral branch of the median nerve and terminates as the
• medial cord gives off the medial branch of the median nerve and terminates as the
ulnar nerve; and the
• posterior cord gives off the axillary nerve and terminates as the radial nerve.
Techniques for Brachial Plexus Block
• fascial sleeve that is derived from the prevertebral and scalene fascia encloses the
brachial plexus. This sheath extends from the intervertebral foramina to the upper
arm and serves as the anatomic basis for brachial plexus blocks.
• Injection into this sheath at any point allows local anesthetic to spread and block
the C5–T1 nerve roots.
• degree of neural blockade, however, may vary somewhat depending on the level of
injection. interscalene approach is most optimal for procedures on the shoulder,
arm, and forearm.
• Injection at the interscalene level tends to produce a block that is most intense at
the C5–C7 dermatomes and least intense in the C8–T1 dermatomes.
• interscalene approach may therefore not provide optimal surgical anesthesia for
procedures in the ulnar nerve distribution.
• In contrast, the axillary approach to the brachial plexus is most optimal for
procedures from the elbow to the hand. This approach tends to produce the most
intense block in the distribution of C7–T1 (ulnar nerve) but is usually inadequate
for procedures on the shoulder and upper arm (C5–C6).
• The supraclavicular and infraclavicular approaches to the brachial plexus result in a
more even distribution of local anesthetic and can be used for procedures on the
arm, forearm, and hand
Interscalene Brachial Plexus Block
Anatomy-cervical spinal nerves blend into trunks between the anterior and middle
scalene muscles. This interscalene groove lies at the level of the cricoid cartilage
and is a relatively easy place to enter the brachial plexus sheath to elicit a
paresthesia or obtain an evoked motor response with a nerve stimulator.
Technique-Palpation of the interscalene groove is usually accomplished with the
patient supine and the head rotated 30° or less to the contralateral side.
• The external jugular vein often crosses the interscalene groove at the level of the
• The interscalene groove should not be confused with the groove between the
sternocleidomastoid and the anterior scalene muscle, which lies more anterior.
• Having the patient lift and turn the head against resistance often helps delineate
• After injection of a skin wheal with a 25-gauge needle at the level of the cricoid
cartilage, a 22-gauge, 1.5-in B-bevel needle is introduced nearly perpendicular to
the skin and advanced in slightly medial and caudal directions until a paresthesia or
evoked muscle contraction in the arm is elicited.
• If a nerve stimulator is used, activity of the phrenic nerve suggests the needle is too
"anterior," whereas stimulation of the trapezius muscle indicates the needle may
be too "posterior.“
• Motor activity of the arm, wrist, or hand should be elicited, but success has been
reported with a response noted in the deltoid or pectoralis muscles, with
subsequent local anesthetic injection.
• Some clinicians apply proximal pressure on the sheath to favor distal spread of
local anesthetic. A total of 30–40 mL of local anesthetic solution is injected.
• For some surgical procedures such as total shoulder arthroplasty, catheters may be
inserted and kept in place postoperatively for pain control. Such catheters are
placed via an insulated stimulating Tuohy needle.
• Compared to needle insertion for a single-shot block, insertion should begin slightly
more cephalad and advancement of the needle is more medial.
• Interscalene blocks have a multitude of potential side effects.
• The proximity of the stellate ganglion, the phrenic nerve, and the recurrent
laryngeal nerve to this location explains their high rate of incidental blockade.
• The phrenic nerve is commonly blocked, which may lead to respiratory failure in
patients with inadequate pulmonary reserve.
• Patients may display a Horner's syndrome (myosis, ptosis, and anhidrosis),
dyspnea, and hoarseness, respectively.
• The proximity of the vertebral artery to the injection site increases the risk of an
intraarterial injection. Even a very small amount (1–3 mL) of local anesthetic
injected into a vertebral artery can produce a seizure because the entire amount
goes directly to the brain.
• Venous injection and rapid absorption can result in a slower onset of central
nervous system toxicity. Inadvertent epidural, subarachnoid, or subdural injection
can occur because of the close proximity of the cervical neural foramina and the
presence of dural sleeves on nerve roots.
• Advancing the needle too far, particularly in a lateral direction, can result in
puncture of the pleura and a pneumothorax.
Anatomy-At the lateral border of the anterior scalene muscle, the brachial plexus
passes down between the first rib and clavicle to enter the axilla.
• The trunks are tightly oriented vertically on top of the first rib just posterior to the
subclavian artery. Because the plexus is so compacted here, blockade achieves
excellent anesthesia of the entire arm, including the hand.
Technique- patient is placed in a supine position with the head turned away from
the side to be blocked. The far as possible.
• In the classic technique, the midpoint of the clavicle should be identified and
• The posterior border of the sternocleidomastoid can be palpated easily when the
patient raises the head slightly.
• arm to be anesthetized should be adducted, and the hand should be extended
along the side toward the ipsilateral knee as The palpating fingers can then roll
over the belly of the anterior scalene muscle into the interscalene groove, where a
mark should be made approximately 1.5 to 2.0 cm posterior to the midpoint of the
clavicle. Palpation of the subclavian artery at this site confirms the landmark.
• After appropriate preparation and development of a skin wheal, the
anesthesiologist stands at the side of the patient facing the patient's head.
• A 22-gauge, 4-cm needle is directed in a caudad, slightly medial, and posterior
direction until a paresthesia or motor response is elicited or the first rib is
encountered. If a syringe is attached, this orientation causes the needle shaft and
syringe to lie almost parallel to a line joining the skin entry site and the patient's
• If the first rib is encountered without elicitation of a paresthesia, the needle can be
systematically walked anteriorly and posteriorly along the rib until the plexus or the
subclavian artery is located .
• Location of the artery provides a useful landmark; the needle can be withdrawn
and reinserted in a more posterolateral direction, which generally results in a
paresthesia or motor response. On localization of the brachial plexus, aspiration for
blood should be performed before incremental injections of a total volume of 20 to
30 mL of solution.
• The rib is usually contacted at a needle depth of 3 to 4 cm; however, in an obese patient
or in the presence of tissue distortion from hematoma or injection of solution, the
depth may exceed the length of the needle.
• Nonetheless, before the needle is advanced farther, gentle probing in the anterior and
posterior directions should be done at the 2- to 3-cm depth if paresthesias are not
• Multiple injections may improve the quality or may shorten the onset of blockade.
Modified plumb-bob approach uses similar patient positioning, although the needle entry
site is at the point where the lateral border of the sternocleidomastoid muscle inserts
into the clavicle.
1. After preparation and raising of a skin wheal, a 22-gauge, 4-cm needle is inserted
while mimicking a plumb-bob suspended over the needle entry site .
2. Frequently, a paresthesia or motor response is elicited before contacting the first rib
3. If no paresthesia or motor response is elicited, the needle is reinserted while angling
the tip of the needle cephalad and then caudad in small steps until the first rib is
Side Effects and Complications OF Supraclavicular Block
• Although the block is more difficult in obese patients , there does not appear to be
an increased frequency of complications.
• prevalence of pneumothorax after a supraclavicular block is 0.5% to 6% and
diminishes with experience. The onset of symptoms is usually delayed and may
take up to 24 hours. Routine chest radiography after the block is not justified.
• supraclavicular approach is best avoided when the patient is uncooperative or
cannot tolerate any degree of respiratory compromise because of underlying
• Other complications include frequent phrenic nerve block (40% to 60%), Horner's
syndrome, and neuropathy. The presence of phrenic or cervical sympathetic nerve
blockade normally requires only reassurance. Although nerve damage can occur, it
is uncommon and usually self-limited.
• Clinical Applications
• An infraclavicular block provides anesthesia to the arm and hand.
• Blockade occurs at the level of the cords and offers the theoretical
advantages of avoiding pneumothorax while affording block of the
musculocutaneous and axillary nerves. No special arm positioning is
required. A nerve stimulator or ultrasound visualization is required because
there are no palpable vascular landmarks to aid in directing the needle.
• The needle is inserted 2 cm below the midpoint of the inferior clavicular
border and advanced laterally, and a nerve stimulator is used to identify the
• Marking a line between the C6 tubercle and the axillary artery with the arm
abducted is helpful in visualizing the course of the plexus. Incremental
injection of 20 to 30 mL of solution is sufficient after the needle is correctly
placed. The success rate is improved with a distal motor response. However,
more lateral insertion site may result in the absence of blockade of the
musculocutaneous nerve, thus removing the major advantage of this
approach over the simpler axillary block.
• Side Effects and Complications
• Because of the necessarily blind approach to the plexus, the incidence of
intravascular injection may be increased. Exaggerated medial needle
direction may result in pneumothorax. Other rare complications such as
infection and hematoma.
• Clinical Applications
• The axillary approach to the brachial plexus is the most popular because of
its ease, reliability, and safety.
• Blockade occurs at the level of the terminal nerves. Although blockade of
the musculocutaneous nerve is not always produced with this approach, it
can be supplemented at the level of the axilla or at the elbow.
• Indications for axillary block include surgery on the forearm and hand and
elbow procedures .This block is ideally suited for outpatients and is easily
adapted to the pediatric population.
• However, an axillary block is unsuitable for surgical procedures on the
upper part of the arm or the shoulder, and the patient must be able to
abduct the arm to perform the block.
Technique of axillary Block
• Anatomic concepts that should be considered before an axillary block include the
• The neurovascular bundle is multicompartmental .
• The axillary artery is the most important landmark; the nerves maintain a
predictable orientation to the artery.
• The median nerve is found superior to the artery, the ulnar nerve is inferior, and
the radial nerve is posterior and somewhat lateral
• At this level, the musculocutaneous nerve has already left the sheath and lies in
the substance of the coracobrachialis muscle.
• The intercostobrachial nerve, a branch of the T2 intercostal nerve, is usually
blocked by the skin wheal overlying the artery; however, adequate anesthesia for
the tourniquet can be ensured by extending the wheal 1 to 2 cm caudad and
• The patient should be in the supine position with the arm to be blocked placed at a
right angle to the body and the elbow flexed to 90 degrees. The dorsum of the
hand rests on the bed or pillow; hyperabduction of the arm with placement of the
hand beneath the patient's head is not recommended because this position
frequently obliterates the pulse.
• The axillary artery is palpated, and a line is drawn tracing its course from the lower
axilla as far proximally as possible. The artery is then fixed against the patient's
humerus by the index and middle fingers of the left hand, and a skin wheal is raised
directly over the artery at a point in the axilla approximating the skin crease.
Proximal needle placement and maintenance of distal pressure facilitate proximal
spread of the solution.
• Method of Needle Localization
• Several methods of identifying the axillary sheath have been described. Overall,
paresthesias are unnecessary.
• 1. Paresthesias can be sought with a 25-gauge, 2-cm needle, beginning deeply
(i.e., radial nerve) or with the nerves supplying the surgical site. Needles longer
than 2 cm are rarely needed to reach the neurovascular bundle; smaller needles
and a short needle bevel may be associated with a lower incidence of nerve
damage.Each paresthesia is injected with 10 mL of local anesthetic.
• 2. A nerve stimulator can also be used with an insulated needle to locate the
nerves. This technique obviates the need for paresthesias.
• 3. A short-beveled needle can be advanced until the axillary sheath is entered, as
evidenced by a fascial click, after which 40 to 50 mL of solution is injected after
• 4. A transarterial technique can be used whereby the needle pierces the artery
and 40 to 50 mL of solution is injected posterior to the artery; alternatively, half of
the solution can be injected posterior and half injected anterior to the artery. Great
care must be taken to avoid intravascular injection with this technique, particularly
because the pressure of injection within the compartments of the axillary sheath
may move anatomic structures in relation to the immobile needle. Some
practitioners avoid intentional arterial puncture in the belief that it is unnecessarily
• 5. Field block of the brachial plexus with a fanlike injection of 10 to 15 mL of local
anesthetic solution on each side of the artery is a variation of the sheath
technique. Paresthesias, though not sought, are often encountered with this
technique and provide evidence of correct placement.
• Classically, it was recommended that on completion of the injection, the arm
should be adducted and returned to the patient's side to prevent the humeral head
from obstructing proximal flow of the solution. However, a more recent study
reported that maintaining the arm in abduction decreases onset time and prolongs
both sensory and motor blockade.
• Side Effects and Complications
• Nerve injury and systemic toxicity are the most significant complications associated
with the axillary approach.
• Injection of large volumes of local anesthetic, particularly via the transarterial
approach, increases the risk for intravascular injection and systemic toxicity of local
• Hematoma and infection are rare complications.
Median Nerve Block
• Blockade of the median nerve provides anesthesia of the palmar aspects of
the thumb and index finger, the middle finger and radial half of the ring
finger, and the nail beds of the same digits.
• Motor block includes the muscles of the thenar eminence, the lumbrical
muscles of the first and second digits, and in the case of a block at the
elbow, the median-innervated wrist flexor muscles of the forearm.
• Technique at the Elbow
• With the patient's arm placed in the anatomic position (i.e., palm up), a line
is drawn connecting the medial and lateral epicondyles of the humerus.
• The major landmark for this technique is the brachial artery, which is found
medial to the biceps tendon at the intercondylar line. The median nerve lies
medial to the artery, and can be blocked with 3 to 5 mL of solution after
eliciting a paresthesia. If no paresthesia is obtained, the solution can be
injected in a fanlike pattern medial to the palpated artery.
• Technique at the Wrist
• The median nerve is located between the flexor carpi radialis and palmaris
longus tendons and can be blocked at a point 2 to 3 cm proximal to the
wrist crease . (The palmaris longus tendon is congenitally or postsurgically
absent from some patients.) Loss of resistance is felt as the needle passes
through the flexor retinaculum, at which point 2 to 4 mL of solution should
be injected. A superficial palmar branch supplying the skin of the thenar
eminence can be blocked by injecting 0.5 to 1 mL of solution
subcutaneously above the retinaculum. Paresthesias should not be sought
because of confinement of this nerve within the carpal tunnel.
Radial Nerve Block
• Blockade of the radial nerve provides anesthesia to the lateral aspect of the
dorsum of the hand (i.e., thumb side) and the proximal portion of the thumb,
index, middle, and lateral half of the ring finger.
• Technique at the Elbow
• The radial nerve can be blocked at the elbow as it passes over the anterior aspect
of the lateral epicondyle. The intercondylar line and lateral edge of the biceps
tendon are marked. A 22-gauge, 3- to 4-cm needle is inserted at a point 2 cm
lateral to the biceps tendon and advanced until bone is encountered . Three to
5 mL of solution is injected in a fanlike fashion.
• Technique at the Wrist
• The radial nerve block at the wrist is a field block of the multiple peripheral
branches descending along the dorsum and radial side of the wrist. The extensor
pollicis longus tendon can be identified when the patient extends the thumb. The
needle insertion site is over this tendon at the base of the first metacarpal, and the
solution is injected superficial to the tendon. A volume of 2 mL of local anesthetic is
injected proximally along the tendon, and an additional 1 mL is injected as the
needle passes at a right angle across the anatomic snuffbox .
Ulnar Nerve Block
• Blockade of the ulnar nerve provides anesthesia to the ulnar side of the hand, the
little finger, the ring finger, and all the small muscles of the hand, except those of
the thenar eminence and the first and second lumbrical muscles.
• Technique at the Elbow
• ulnar nerve is easily accessible at its subcutaneous position posterior to the medial
epicondyle, blockade at this site is associated with a high incidence of neuritis.
Because the nerve is surrounded by fibrous tissue at this point, intraneural
injection is required for successful blockade.
• Use of a very fine needle along with a small volume of solution (1 mL) diminishes
the risk; however, the nerve can be satisfactorily blocked with 5 to 10 mL of
solution at a site 3 to 5 cm proximal to the elbow. The local anesthetic should be
injected in a fanlike fashion without elicitation of a paresthesia.
• Technique at the Wrist
• ulnar nerve lies beneath the flexor carpi ulnaris tendon between the ulnar artery
and the pisiform bone. Nerve can be approached by directing the needle medially
from the radial side of the tendon or, alternatively, by directing the needle radially
from the ulnar side of the tendon . After eliciting a paresthesia, 3 to 5 mL of
anesthetic solution is injected or spread in a fanlike fashion.
Intravenous Regional Blocks
• Intravenous regional blocks were first described by a German surgeon, August Bier,
in 1908.Early methods involved two tourniquets and the first synthetic local
anesthetic, procaine. The technique lost popularity as reliable methods of blocking
the brachial plexus evolved.
• Clinical Applications
• The Bier block has multiple advantages, including ease of administration, rapidity
of recovery, rapid onset, muscular relaxation, and controllable extent of anesthesia.
It is an excellent technique for short (<90 minutes) open surgical procedures and
for closed reduction of bony fractures.
• An intravenous cannula is placed in the upper extremity to be blocked as far distally
as possible; the patient should also have an intravenous cannula in the
nonoperative upper extremity for administration of fluids and other drugs.
Traditionally, a double tourniquet is placed on the operative side; both cuffs should
have secure closure and reliable pressure gauges.
• After exsanguination of the arm, the proximal cuff is inflated to approximately
150 mm Hg more than systolic pressure, and absence of a radial pulse confirms
adequate tourniquet pressure.
• The total dose of local anesthetic is based on the patient's weight, and it is injected
slowly (3 mg/kg of 0.5% prilocaine or lidocaine, without epinephrine).
• The use of bupivacaine for intravenous regional anesthesia has been associated
with local anesthetic toxicity and death and therefore is not recommended.
However, dilute solutions (0.125% levobupivacaine) of long-acting amides, as well
as the addition of adjuvants (tramadol, ketorolac, clonidine), have been used to
prolong sensory blockade and analgesia after deflation of the tourniquets.
• The onset of anesthesia usually occurs within 5 minutes. When the patient
complains of tourniquet pain, the distal tourniquet, which overlies anesthetized
skin, is inflated, and the proximal tourniquet is released. Use of a single wide cuff
allows lower inflation pressures to be used during intravenous regional anesthesia.
• The postulated advantage is that the lower pressures will decrease the incidence
of neurologic complications related to the high inflation pressures with the narrow
double cuffs. The tourniquet may be safely released after 25 minutes, but the
patient should be closely observed for local anesthetic toxicity for several minutes
after release of the tourniquet. Slow injection of local anesthetic solutions at a
distal site has been shown to lower the risk for toxicity.
• Side Effects and Complications
• Technical problems with this block include tourniquet discomfort, rapidity of
recovery leading to postoperative pain, difficulty providing a bloodless field, and
the necessity of exsanguination in the case of a painful injury.
• Accidental or early deflation of the tourniquet or use of excessive doses of local
anesthetics can result in toxic reactions.
• Cyclic deflation of the tourniquet at 10-second intervals has been shown to
increase the time to peak arterial lidocaine levels and may decrease any potential
• Other rare complications associated with this technique include phlebitis (with 2-
chloroprocaine), the development of a compartment syndrome, and loss of a limb
• Digital Nerves
• These nerve blocks are used for minor operations on the fingers and to supplement
brachial plexus blocks.
• Sensory innervation of each finger is provided by four small digital nerves that
enter each digit at its base in each of the four corners.
• A 23- to 25-gauge needle is inserted at the medial and lateral aspects of the base
of the selected digit. A total of 2–3 mL of local anesthetic without epinephrine is
injected on each side near the periosteum. Addition of a vasoconstrictor
(epinephrine) can seriously compromise blood flow to the digit.
• Nerve injury is the primary risk of a digital block.
Somatic Blockade of the Lower Extremity
The lumbar and the lumbosacral plexi are the major nerve distributions to the lower
extremities. The lumbar plexus is derived from the ventral rami of L1–4, with some
occasional contribution from T12
The lumbar plexus, primarily from L2 to L4, forms three major nerves that innervate
the lower extremity: the lateral femoral cutaneous, femoral, and obturator nerves.
These nerves predominantly supply motor and sensory innervation to the anterior
portion of the lower extremity and the cutaneous sensory portion of the medial lower
leg (saphenous nerve).
The lumbosacral plexus is derived from the nerve roots of L4–5 and S1–3 and primarily
forms the sciatic nerve, which courses posteriorly and supplies both motor and
sensory innervation to the posterior aspect of the lower extremity and foot, largely as
its terminal branches into the tibial and the common peroneal nerves. is a simplified
schematic of the global innervation of the lower extremity. Note that the posterior
cutaneous nerve (S1–3) is highlighted but the sciatic nerve is not; it courses with the
sciatic nerve as it emerges around the piriformis muscle and subsequently it too is
blocked when a proximal sciatic nerve block is performed.
• Spinal and epidural anesthesia are most often employed for regional anesthesia of
the lower extremities. Peripheral nerve blocks in the lower extremity can also
provide excellent surgical anesthesia for some procedures but require multiple
injections and may be technically more challenging in some cases. Ankle block is
the easiest and most commonly used lower extremity block; it is typically used for
• Four major nerves innervate the lower extremities: the femoral (L2–4), obturator
(L2–4), lateral femoral (L1–3), and sciatic nerves (L4–S3). The first three nerves are
part of the lumbar plexus; they lie within the substance of the psoas muscle and
emerge within a common fascial sheath that extends into the proximal thigh. The
common peroneal and tibial nerves are continuations of the sciatic nerve in the
Lumbar Plexus (Psoas) Block
• The lumbar plexus is derived from the ventral rami of the lumbar nerve roots. The
plexus courses via the "psoas compartment" as defined by the fascia of the psoas
muscle (which lies anterior to the plexus) and the fascia of the quadratus laborum
(which lies posterior to the plexus).
• The patient should lie in a lateral decubitus position with the side to be blocked in
the nondependent position. Both iliac crests are identified and a line is drawn
connecting the crests. This line generally crosses the lumbar body of L4. The
posterior superior iliac spine is identified and a line is drawn cephalad, parallel to
the vertebral column. The intersection of the two lines indicates the most lateral
location of the lumbar plexus. Generally, the insertion point is 4 cm from the
midline or two-thirds the distance between the spinous processes of the lumbar
vertebrae and this intersection .
• Psoas block for anesthetizing the lumbar plexus. The site of entry is 4 cm lateral to
the spinous processes on a line drawn between the iliac crests. PSIS, posterior
superior iliac spine.
• A 4-in, 21-gauge insulated stimulating needle is advanced in a perpendicular plane
at this insertion site. When the needle has entered the psoas compartment (70–90
mm), a quadriceps motor response is noted. After reducing the stimulation to < 0.5
mA, witnessing fade of motor activity after injection of 1 mL of local anesthetic and
a negative aspiration of blood, 25–40 mL of local anesthetic is delivered. Early
descriptions of this block employed a "loss of resistance" technique (similar to
epidural placement) when the needle tip entered the psoas compartment
• A psoas block anesthetizes the lateral femoral cutaneous, femoral, and obturator
nerves. This block is useful for procedures involving the knee, anterior thigh, and
hip. Catheter placement and a continuous infusion administered for postoperative
analgesia are common for patients recovering from total hip arthroplasty and
occasionally total knee arthroplasty.
• Local anesthetic toxicity and nerve damage from an intraneural injection or
hematoma have been reported from this block
Femoral Nerve & "Three-in-One" Block
• A femoral nerve block can be used to provide anesthesia for the anterior thigh,
knee, and a small part of the medial foot. It is typically used in conjunction with
other lower extremity blocks. It may also be used for postoperative pain relief
following knee surgery.
• After passing through the psoas compartment, the femoral nerve enters the thigh
lateral to the femoral artery just below the inguinal ligament. Distal to this point,
motor branches to the quadriceps, sartorius, and pectineus muscles arise as well as
numerous sensory branches to the medial and anterior thigh. The nerve is encased
in a sheath that extends from the psoas muscle to just below the inguinal ligament.
• The inguinal ligament should first be identified (by drawing a line connecting the
anterior superior iliac spine and the superior-lateral corner of the pubic tubercle).
The operator approximates the midpoint along this line and palpates for the
femoral pulse. Once the femoral pulse is identified, the insertion point for the
femoral nerve block is located 2 cm lateral to the femoral artery pulse and 2 cm
distal to the inguinal ligament line. With the nerve stimulator technique, a 2-in, 22-
gauge stimulating needle is advanced seeking a quadriceps twitch or "patellar
snap." Once identified, and after reducing the stimulation to < 0.5 mA, witnessing
fade of motor activity after injection of 1 mL of local anesthetic and a negative
aspiration of blood, 20–30 mL of local anesthetic is delivered.
• Femoral nerve block. The insertion site should be 1.5–2.0 cm lateral to the femoral pulse, 2
cm inferior to a line drawn between the pubic symphysis and the anterior superior iliac spine
(which overlies the inguinal ligament).
• A femoral nerve block is very useful in numerous procedures involving the thigh and knee,
such as skin grafting, knee arthroscopy, and patellar surgery, or as an adjunct to procedures
distal to the knee that require anesthesia to the medial aspect of the lower leg (saphenous
distribution). An increasingly common practice in many centers is the insertion of an
indwelling femoral catheter for continuous perineural infusion along with an accompanying
sciatic nerve block for patients recovering from total knee arthroplasty.
• This block is often referred to as Winnie's "3-in-1 block." As first described, placement of
sufficient local anesthetic, directed proximally and with distal compression, blocked not only
the femoral nerve, but the obturator and the lateral femoral cutaneous nerves as well, thus
the "3-in-1." There have been many conflicting reports on the effectiveness of this approach
as a true "3-in-1 block." Many practitioners view this as a femoral nerve only block with little
ability to provide additional nerve coverage.
• Careful aspiration and incremental dosing help avoid intravascular injection and systemic
local anesthetic toxicity.
Fascia Iliaca Block
• A fascia iliaca block takes advantage of the fact that the femoral nerve and, to a
certain degree, the lateral femoral cutaneous, the obturator, and the genitofemoral
nerves course posterior to the fascia iliaca and delivery of local anesthetic behind
the fascia may result in a "compartment" block. The so-called "fascia iliaca
compartment" is a potential space bordered anteriorly by the fascia iliaca (which is
overlaid by the fascia lata) and posteriorly by the iliopsoas muscle.
• In performing this block, the landmarks are similar to those used to identify the
femoral nerve; a line is drawn from the anterior superior iliac spine and connected
to the outer corner of the pubic tubercle. This line is then divided into thirds and
the outer and middle third junction is identified. Two centimeters distal from this
junction is the needle insertion site. In performing the block, it is preferable to use
a B-bevel needle to accentuate the tactile sensation, as this block is not performed
with a nerve stimulator. Commonly a 3.5-in, 22-gauge Whitacre spinal needle may
be used (recognizing that other products are also available). As the needle is
inserted, two "pops" will be felt. The first occurs as the needle passes through the
fascia lata and the second as it passes through the fascia iliaca. Following negative
aspiration of blood, approximately 25–30 mL of local anesthetic is injected.
Fascia iliaca block.
• There has been a recent surge of interest in fascia iliaca blocks.
Because it does not require a nerve stimulator, it can be performed
very quickly, it is not very stimulating, and patients often do not
require sedation. It is useful in procedures involving the hip, thigh,
and knee. A catheter for continuous infusion may be placed for
analgesia in the postoperative period.
• Some anesthesiologists have reservations regarding the block's
consistency, reliability, and adequacy. Complications for this block
are similar to those for other peripheral nerve blocks.
Lateral Femoral Cutaneous Block
• The lateral femoral cutaneous nerve (L2–3) departs from the lumbar plexus,
transverses laterally from the psoas muscle, and courses anterolaterally along the
iliacus muscle. It emerges inferior and medial to the anterior superior iliac spine to
supply the cutaneous sensory innervation of the lateral thigh.
• (Figure 17–24) The block is performed via a field injection technique with 10–12 mL
of local anesthetic at a mark approximately 2 cm distal and 2 cm medial to the
anterior iliac spine. With insertion of a 2-in, 22-gauge needle, a "pop" may be felt
as the needle passes through the fascia lata. This block is accomplished by
repeatedly reinserting the needle while injecting local anesthetic above and below
the fascia in a lateral to medial direction.
• Lateral femoral cutaneous nerve block.
• This nerve may be blocked concurrently with a femoral nerve block or a fascia iliaca
block and certainly is included with a lumbar plexus block. For a skin or muscle
biopsy or a harvest site for a skin graft from the lateral thigh, an isolated block of
this nerve may be performed.
• Complications with this block are few as the amount of local anesthetic injected is
small, and the chance of intraneural injection unlikely, as would be for an
Obturator Nerve Block
• An obturator nerve block provides anesthesia to the medial thigh and muscle
relaxation of the adductor muscles of the hip. It may be used for an adductor
• The obturator nerve exits the pelvis and enters the medial thigh through the
obturator foramen, which lies beneath the superior pubic ramus. It supplies
sensation to the medial thigh and the hip joint and motor innervation to the
adductor muscles of the thigh.
• A 4-in, 21-gauge needle is inserted through a skin wheal 1.5 cm lateral and 1.5 cm
inferior to the pubic tubercle. As the needle is advanced in a posterior direction
toward the superior pubic ramus, small amounts of local anesthetic are injected to
decrease patient discomfort. Upon contacting bone, the needle is redirected in a
lateral and caudal direction another 2–4 cm to enter the obturator foramen. An
adductor motor response should be elicited. Once identified, and after reducing
the stimulation to < 0.5 mA, witnessing fade of motor activity after injection of 1
mL of local anesthetic and a negative aspiration of blood, 15–20 mL of local
anesthetic is administered.
• Obturator nerve block.
• This block is commonly performed as a compliment to
additional blocks performed for knee surgery (eg,
femoral and sciatic nerve blocks). Its role as an isolated
block is limited, although it may be useful in the
diagnosis of hip pain or to treat spasticity of the thigh
• Careful aspiration and incremental dosing help avoid
intravascular injection and systemic local anesthetic
Sciatic Nerve Block
• The sciatic nerve originates from the lumbosacral trunk and is composed of nerve
roots L4–5 and S1–3. It supplies sensory fibers to the posterior hip capsule as well
as the knee. It provides motor activity to the hamstrings and to all the lower
extremity muscles distal to the knee. It also provides all the sensory innervation to
the lower extremity distal to the knee except along the anteromedial aspect, which
is provided by the saphenous nerve.
• Classic or Posterior Approach
• The patient is placed in a lateral decubitus position (Sim's position) with the
operative extremity nondependent. Landmarks are the greater trochanter, the
posterior superior iliac spine, and the sacral hiatus. A line is drawn from the greater
trochanter to the posterior superior iliac spine and a second line is drawn from the
greater trochanter to the sacral hiatus. The midpoint along the line of the greater
trochanter–posterior superior iliac spine is marked and a perpendicular line is
drawn caudad. The intersection of this line and the greater trochanter–sacral hiatus
line (approximately 5 cm) is the insertion point for the block.
• Sciatic nerve block, posterior approach. PSIS, posterior superior iliac spine.
The operator advances a 4-in, 21-gauge insulated stimulating needle in a direction
perpendicular to the skin. After encountering gluteal muscle stimulation, the
needle is inserted further as a motor response is sought in the distal ankle, foot, or
toes. Once identified, and after reducing the stimulation to < 0.5 mA, witnessing
fade of motor activity after injection of 1 mL of local anesthetic and a negative
aspiration of blood, 20–25 mL of local anesthetic is delivered. This approach readily
accommodates placement of a perineural catheter for continuous infusion in the
• Lithotomy Approach
• As the sciatic nerve courses from the pelvis to the leg, it characteristically travels
between the ischial tuberosity and the greater trochanter. Taking advantage of this
consistent course and the nerve's relatively superficial location, the patient is
placed in a supine position with the hip and knee flexed (lithotomy position). In this
position, the midpoint between the ischial tuberosity and the greater trochanter is
identified and marked. A 4-in, 21-gauge insulated stimulating needle is inserted at
the mark and advanced perpendicular to the skin.
• A motor response is sought in the distal ankle, foot, or toes. Once identified,
and after reducing the stimulation to < 0.5 mA, witnessing fade of motor
activity after injection of 1 mL of local anesthetic and a negative aspiration of
blood, 15–20 mL of local anesthetic is delivered.
• Sciatic nerve block, lithotomy approach.
• The sciatic nerve can also be blocked using an anterior thigh approach. This
approach minimizes patient movement, requires less preparation time (as it is
often combined with the same preparation for a femoral block), and therefore
theoretically can be placed more quickly. However, this approach is technically
more challenging. Of all the procedures used to block the sciatic nerve, this
involves the greatest distance the needle must travel to reach its target, thus
making the time needed to perform this block, particularly for the
inexperienced, much longer. To perform this block the patient is placed in a
supine position with the legs in a slight internal rotation (this maneuver rotates
the lesser trochanter posteriorly and out of the line of sight for needle
passage). A common approach begins by identifying landmarks similar to those
used for a femoral nerve block. The inguinal ligament is identified and marked
(drawing a line between the anterior superior iliac spine and the pubic
tubercle). A second line is drawn parallel to the inguinal ligament starting from
the greater trochanter and going medially across the anterior thigh (this line
connects the greater and the lesser trochanter).
• The inguinal ligament line is then divided into thirds. At the junction of the medial
and middle thirds a perpendicular line is drawn that intersects the greater
trochanter line at a right angle. At this point of intersection, a 4-in, 21-gauge
insulated stimulating needle is inserted..
• As the needle is advanced, a motor response is sought in the distal ankle, foot, or
toes. Once identified, and after reducing the stimulation to < 0.5 mA, witnessing
fade of motor activity after injection of 1 mL of local anesthetic and a negative
aspiration of blood, 15–20 mL of local anesthetic is delivered
• Sciatic nerve block, anterior approach.
• Blockade of the sciatic nerve is useful for many surgical procedures involving the
hip, knee, or distal lower extremity. The nerve can be successfully blocked at
numerous sites along its course.
• Partial block due to an injection distal to the branching of the sciatic nerve and
intraneural injection are the most frequent complications
• The sciatic nerve divides into the tibial and common peroneal nerves, high in the popliteal fossa.
The upper popliteal fossa is bounded laterally by the biceps femoris tendon and medially by the
semitendinosus and semimembranosus tendons. Cephalad to the flexion crease of the knee, the
popliteal artery is immediately lateral to the semitendinosus tendon. The popliteal vein is lateral
to the artery, and the tibial and common peroneal nerves (within a sheath) are just lateral to the
vein and medial to the biceps tendon, 4–6 cm deep to the skin. The tibial nerve continues deep
behind the gastrocnemius muscle, whereas the common peroneal nerve leaves the popliteal fossa
by passing between the head and neck of the fibula to supply to the lower leg.
• There are two main approaches for performing this block: the posterior approach and the lateral
• Posterior Approach
• This is the traditional approach used to block the sciatic nerve at this level. The block is
performed after placing the patient in the prone position. The popliteal fossa is identified as a
triangle by outlining the borders of the biceps femoris laterally, the semitendinosus and
semimembranosus medially, and the popliteal crease inferiorly.
• At the midpoint along the popliteal crease, a perpendicular line is drawn cephalad
approximately 8–10 cm in length, bisecting the popliteal triangle. A mark is made 1
cm from the apex and 1 cm lateral for needle insertion. At this mark, a 2-in, 22-
gauge insulated stimulating needle is inserted. As the needle is advanced, a motor
response is sought in the distal ankle, foot, or toes. Once identified, and after
reducing the stimulation to < 0.5 mA, witnessing fade of motor activity after
injection of 1 mL of local anesthetic and a negative aspiration of blood, 30–40 mL
of local anesthetic is delivered.
• Lateral Approach
• An advantage of this approach is that the patient remains supine for the
procedure. The lateral approach is performed by palpating the intertendinous
groove between the vastus lateralis and the biceps femoris muscles approximately
10–12 cm proximal to the superior notch of the patella. With a 4-in, 21-gauge
insulated stimulating needle advanced at 30°, posteriorly angled, a motor response
is sought in the distal ankle, foot, or toes. Once identified, and after reducing the
stimulation to < 0.5 mA, witnessing fade of motor activity after injection of 1 mL of
local anesthetic and a negative aspiration of blood, 30–40 mL of local anesthetic is
• A popliteal nerve block is very useful for foot and ankle surgery and can result in
complete anesthesia of the limb distal to the knee if a separate saphenous nerve
block (terminal nerve of the femoral nerve) is also included. This block can
accommodate placement of a catheter for continuous perineural infusion for
postoperative analgesia and in an increasing number of ambulatory centers
patients may be dismissed home with such infusions.
• Intravascular or intraneural injections are possible
Saphenous Nerve Block
• The saphenous nerve is the terminal extension of the femoral nerve and provides
sensory innervation along the medial aspect of the lower leg between the knee and
the medial malleolus.
• Infiltrate subcutaneously 7–10 mL of local anesthetic starting from the tibial
tuberosity and directed medially, completing the infiltration near the posterior
aspect of the leg.
• Saphenous nerve block.
• This is not commonly performed as an isolated block, but rather in conjunction
with a popliteal block to complete the anesthesia for procedures done below the
• Complications are the same as for other field blocks.
Nerve Blocks at the Ankle
• Four of the five individual nerves that can be blocked at the ankle to provide
anesthesia of the foot are terminal branches of the sciatic nerve: the posterior
tibial, sural, superficial peroneal, and deep peroneal branches. The sciatic nerve
divides at or above the apex of the popliteal fossa to form the common peroneal
and tibial nerves. The common peroneal nerve descends laterally around the head
of the fibula, where it divides into the superficial and deep peroneal nerves.
• The tibial nerve divides into the posterior tibial and sural nerves in the lower part
of the leg. The posterior tibial nerve becomes superficial at the medial border of
the Achilles tendon near the artery of the same name, and the sural nerve emerges
lateral to the Achilles tendon.
• Clinical Applications
• Ankle blocks are simple to perform and offer adequate anesthesia for surgical
procedures on the foot that do not require a tourniquet above the ankle.
• Posterior Tibial Nerve
• The posterior tibial nerve can be blocked with the patient in either the
prone or the supine position. The posterior tibial artery is palpated, and a
25-gauge, 3-cm needle is inserted posterolateral to the artery at the level of
the medial malleolus ( Fig. 52-23A and B ). A paresthesia is often elicited but
is not necessary for a successful block. If a paresthesia occurs, 3 to 5 mL of
local anesthetic should be injected. Otherwise, 7 to 10 mL of solution
should be injected as the needle is slowly withdrawn from the posterior
aspect of the tibia. Blockade of the posterior tibial nerve provides
anesthesia to the heel, plantar portion of the toes, and the sole of the foot,
as well as some motor branches in the same area.
• The sural nerve is located superficially between the lateral malleolus and
the Achilles tendon. A 25-gauge, 3-cm needle is inserted lateral to the
tendon and directed toward the malleolus as 5 to 10 mL of solution is
injected subcutaneously . This block provides anesthesia to the lateral part
of the foot and the lateral proximal aspect of the sole of the foot.
• Deep Peroneal, Superficial Peroneal, and Saphenous Nerves
• The deep peroneal, superficial peroneal, and saphenous nerves can be blocked
through a single needle entry site . A line is drawn across the dorsum of the foot
connecting the malleoli. The extensor hallucis longus tendon is identified by having
the patient dorsiflex the big toe. The anterior tibial artery lies between this
structure and the tendon of the extensor digitorum longus muscle and is palpable
at this level. A skin wheal is raised just lateral to the pulsation between the two
tendons on the intermalleolar line. A 25-gauge, 3-cm needle is advanced
perpendicular to the skin entry site, and 3 to 5 mL of local anesthetic is injected
deep to the extensor retinaculum to block the deep peroneal nerve. This technique
anesthetizes the skin between the first and second toes and the short extensors of
The needle is directed laterally through the same skin wheal while injecting 3 to 5
mL of solution subcutaneously, which blocks the superficial peroneal nerve and
results in anesthesia of the dorsum of the foot, excluding the first interdigital cleft.
The same maneuver can be performed in the medial direction to anesthetize the
saphenous nerve, a terminal branch of the femoral nerve that supplies a strip along
the medial aspect of the foot.
• Side Effects and Complications
• The multiple injections required for some techniques result in
discomfort for the patient. Persisting paresthesias may occur, but
they are self-limited. The presence of edema or induration in the
area of the ankle block can make palpation of landmarks difficult.
Intravascular injection is possible but unlikely if aspiration for blood
is negative. The volume of local anesthetic used is small, thereby
decreasing the risk for local anesthetic toxicity.
Somatic Blockade of the Trunk
• Superficial Cervical Plexus Block
• The superficial cervical plexus block is performed for unilateral procedures on the neck, such
as carotid endarterectomy. This block is also done as an adjunct to an interscalene block
used for shoulder surgery, particularly with very anterior incisions.
• The cervical plexus is formed from the anterior rami of C1–4, which emerge from the
platysma muscle posterior to the sternocleidomastoid muscle. It supplies sensation to the
jaw, neck, the occiput posteriorly, and areas of the chest and shoulder close to the clavicle.
• The patient is positioned supine with the neck slightly turned, and the posterior border of
the sternocleidomastoid muscle is identified. A 22-gauge spinal needle is selected; the
sternocleidomastoid is divided into thirds, and at the junction of the upper and middle
thirds, a skin wheal is raised. The spinal needle is directed cephalad toward the mastoid
along the posterior border of the sternocleidomastoid in a subcutaneous plane and injected
with 2–3 mL of local anesthetic as the needle is withdrawn. Care is taken to avoid entering
the external jugular vein. As the needle reaches the wheal, it is rotated 180° and directed
subcutaneously caudad toward the clavicle along the posterior border of the
sternocleidomastoid. A similar amount of local anesthetic is injected as the needle is
• Rapid systemic absorption and intravascular injection of local anesthetic.
• Intercostal blocks are rarely employed as the sole anesthetic technique for surgery.
commonly used as postoperative analgesia following thoracic and upper abdominal
surgery, and for relief of pain associated with rib fractures, herpes zoster, and
• The intercostal nerves arise from the dorsal and ventral rami of the thoracic spinal
nerves. They exit from the spine at the intervertebral foramen and enter a groove
on the underside of the corresponding rib, running with the intercostal artery and
vein; the nerve is generally the most inferior structure in the neurovascular bundle.
Branches are given off for sensation in the correct dermatome from the midline
dorsally all the way to across the midline ventrally.
• With the patient in the lateral decubitus or supine position, the level of each rib is
palpated and marked in the mid and posterior axillary line. A skin wheal is raised
over the inferior border at the selected ribs, and a 22- to 25-gauge needle is
inserted down to the inferior edge of the rib and "walked-off" until it steps off the
rib inferiorly. The needle is advanced 0.5 cm underneath the rib, and following a
negative aspiration (for blood or air), 3–5 mL of local anesthetic is injected at each
• Intercostal blocks result in the highest blood levels of local anesthetic per
volume injected of any block in the body. Care must be taken to avoid
toxic levels of local anesthetic. Careful aspiration may help prevent
intravascular injection. The risk of pneumothorax is obvious, and any
indication of entering the chest should be investigated with a chest
Celiac Plexus Block
• Clinical Applications
• A celiac plexus block can be combined with an intercostal block to provide
anesthesia for intra-abdominal surgery. Because it results in blockade of
the autonomic nervous system, this block may help reduce stress and
endocrine responses to surgery.
• Anatomy and Technique
• The celiac plexus contains visceral afferent and efferent fibers derived
from T5 to T12 by means of the greater, lesser, and least splanchnic
nerves. The plexus has no somatic fibers and is composed of a number of
ganglia and nerve fibers. It innervates most of the abdominal viscera.
Knowledge of the surrounding structures is important for correct needle
placement. The plexus lies in close relation to the L1 vertebra. The vena
cava lies anteriorly to the right, and on the left anteriorly is the aorta. The
kidneys lie laterally, with the pancreas anterior. The number of ganglia
varies from one to five, and each ganglion is 0.5 to 4.5 cm in diameter.
Left-sided ganglia are usually lower than those on the right.
• Bony surface landmarks can be used reliably for needle placement. With the
patient in the prone position and a pillow beneath the abdomen, lines are drawn
connecting the spine of T12 with points 7 to 8 cm laterally at the lower edges of the
12th ribs. These lines form a flattened isosceles triangle, the equal sides of which
serve as directional guides for the needles ( Fig. 52-33B ). A 20-gauge, 10- to 15-cm
needle is inserted on the left side through a skin wheal at a 45-degree angle toward
the body of T12 or L1. Bone contact should be made at an average depth of 7 to 9
cm. The needle is then withdrawn and reinserted to allow the tip to slide off the
vertebral body anterolaterally. The needle is advanced 1.5 to 2 cm past this point;
aortic pulsations can be felt as they are transmitted along the needle when it is
correctly placed (see Fig. 52-33 ). After this depth is ascertained, the right-sided
needle is inserted in similar fashion to a depth of 1.0 to 1.5 cm farther (see Fig. 52-
33A ). When the needles are in position, observation for leakage of blood, urine, or
cerebrospinal fluid is made before careful aspiration. A 3- to 5-mL test dose of local
anesthetic is given before injection of 20 to 25 mL of solution through each needle.
• Side Effects and Complications
• Side effects associated with celiac plexus blockade include hypotension; spinal,
epidural, or intravascular injection; pneumothorax; puncture of viscera, such as the
kidney, ureter, or gut; and retroperitoneal hematoma.
Paravertebral Nerve Blocks
• Initially described in the early 1900s, paravertebral blocks were popularized in the
1930s as a means to provide analgesia for labor. Although this approach was largely
replaced with more effective alternate treatments for labor, today paravertebral
nerve blocks are being increasingly used as an effective technique for postoperative
analgesia following mastectomy, inguinal hernia repair, and several procedures
involving the chest and body wall.
• Each spinal nerve emerges from the intervertebral foramina and divides into two
rami: a larger anterior ramus, which innervates the muscles and skin over the
anterolateral body wall and limbs, and a smaller posterior ramus, which reflects
posteriorly and innervates the skin and muscles of the back and neck. The thoracic
paravertebral space is defined posteriorly by the superior costotransverse ligament,
anterolaterally by the parietal pleura, medially by the vertebrae and the
intervertebral foramina, and inferiorly and superiorly by the heads of the ribs.
• The paravertebral nerve block is performed first by having the patient placed in a
sitting position, similar to that for a sitting epidural. The spinous processes are
identified, starting with the most obvious lower cervical vertebra in the neck, C7 or
"vertebra prominens." Each process is marked along its superior aspect. From the
midpoint of the superior aspect of each spinolus process, it is necessary to
measure 2.5 cm laterally and mark these points. These are the insertion points for
the blocks and because of the pronounced inferior angulation of the thoracic
spinous processes these marks generally overlie the transverse process of the next
vertebrae below, ie, a mark across from the T4 spinous process overlies the
transverse process of T5.
• At each insertion point a 22-gauge Tuohy needle is advanced in a perpendicular
fashion approximately 3 cm initially, seeking to contact the transverse process. If
bone is encountered (transverse process), the needle is withdrawn and redirected
caudad and advanced an additional 1 cm. A "pop" may be felt as the needle passes
through the costotransverse ligament. Following a negative aspiration, 4 mL of local
anesthetic is delivered. This step is repeated for each level being blocked. If bone is
not encountered with the initial pass, the needle is withdrawn and redirected
caudad and inserted the same distance (ie, 3 cm), again seeking contact with the
transverse process. Failure to contact bone with this pass requires redirection of
the needle in a cephalad angulation, again inserting it the same depth while
searching for bone contact. Failure to contact bone after this three-pass sequence
(midline, caudad, and cephalad at the same depth) necessitates repeating this
sequence at an added depth of 1 cm. This three-pass sequence with the addition of
1 cm in depth may be repeated until contact with bone is achieved. Once bone
contact is made, from that site and depth, the needle is withdrawn and redirected
caudad and advanced an additional 1 cm to enter the paravertebral space.
Subsequent levels are approximately similar in depth, except for the upper
thoracic, which tends to lie deeper. Lumbar paravertebral blocks are performed in a
similar fashion. However, the transverse processes are thinner than their thoracic
counterparts; therefore, after making bone contact and redirecting the needle
caudad, the needle is advanced only an additional 0.5 cm in depth.
• Paravertebral nerve blocks require individual injections delivered at
the various vertebral levels that correspond to the area of body wall
to be anesthetized. For example, a simple mastectomy would
require blocks at levels T3–6; for axillary node dissection, additional
injections should be made at T1 and T2. For inguinal hernia repair,
blocks should be performed at T10 through L1.
• The most common complication of thoracic paravertebral block is
pneumothorax, which is related to the number of levels and the
experience of the operator. If air is aspirated, a chest radiograph is
mandatory. Intravascular injection and failed block are other
Inguinal Nerve Block
• The ilioinguinal and iliohypogastric nerves arise primarily from L1 but may derive
fibers from T12. The iliohypogastric nerve splits into two branches prior to
becoming cutaneous. The lateral branch is sensory to the lateral aspect of the
buttock and hip. The anterior branch becomes superficial just medial to the
anterior superior iliac spine, where it sends off a network of branches that
innervates the lower abdomen. The ilioinguinal nerve follows the same course and
exits the peritoneum to enter the inguinal canal, where it provides sensation to the
scrotum, penis, and medial thigh in the male, or an equivalent area of the labia and
mons pubis in the female. Both nerves pierce the transversalis abdominis and
internal oblique muscles approximately 2 cm medial to the anterior superior iliac
spine. The genitofemoral nerve is derived from L1 and L2. Its femoral branch travels
with the femoral artery to provide cutaneous sensation just below the inguinal
ligament, whereas its genital branch travels in the inguinal canal to supply the
scrotum in men and the labium majus in women.
• A skin wheal is raised 2 cm medial to the upper aspect of the anterior superior iliac
spine, and a 22-gauge, 3.5-in spinal needle is inserted perpendicular to the skin
until it is just under the fascia, and 8–10 mL of anesthetic is injected fanwise to
block both the ilioinguinal and iliohypogastric nerves. The genital branch of the
genitofemoral nerve is blocked with 2–3 mL of local anesthetic injected just lateral
to the pubic tubercle; the femoral branch can be anesthetized with 3–5 mL of local
anesthetic injected subcutaneously just below the inguinal ligament.
• Ilioinguinal and iliohypogastric blocks can be used for inguinal or genital operations,
such as inguinal herniorrhaphy or orchiopexy, or for postoperative pain relief.
Supplementation with a genitofemoral nerve block may be necessary.
• Patient discomfort and persistent paresthesia from intraneural injection are
• Penile Block
• Innervation of the penis is derived from the pudendal nerve, which gives off the
dorsal nerve of the penis bilaterally. It enters the penis deep to Buck's fascia and
divides into dorsal and ventral branches. The genitofemoral and ilioinguinal nerves
may additionally provide sensation to the base of the penis via subcutaneous
• A fan-shaped (triangular) field block with 10–15 mL of local anesthetic injected at
the base of the penis and 2–4 cm lateral to the base on both sides of the penis can
block the sensory nerves without risk of vascular injury. If more profound block is
necessary, or if extensive surgery is planned, the dorsal nerve is blocked just lateral
to the base of the penis bilaterally with a 25-gauge, ¾- to 1-in needle just
penetrating Buck's fascia at the 10:30 and 1:30 o'clock positions; 1 mL of local
anesthetic is injected on each side, with care taken to avoid pressure. Epinephrine
or other vasoconstrictors should be avoided to prevent end artery spasm and
• Penile block is performed for penile surgery or postoperative pain relief
• Careful aspiration is necessary to avoid intravascular injection. Injecting
large volumes of local anesthetic or epinephrine-containing solutions may
compromise blood flow to the penis.
Blocks of the Head and Neck
• Regional anesthesia of the head and neck has become less popular as safer
methods of general anesthesia have been developed.
• Trigeminal Nerve Block
• The trigeminal nerve divides into three main branches in the middle cranial fossa.
These divisions—the ophthalmic, maxillary, and mandibular nerves—provide
sensation to the eye and forehead, midface and upper jaw, and lower jaw,
respectively ( Fig. 52-25A ). With the exception of motor fibers to the muscles of
mastication, carried by the mandibular nerve, these nerves are wholly sensory.
A gasserian ganglion block, approached classically through the foramen ovale, is
infrequently used for producing surgical anesthesia. In the past, it was primarily
applied for the diagnosis and treatment of trigeminal neuralgia; however, the
increasing popularity and safety of thermocoagulation for ablation of the ganglion
have rendered neurolytic blocks obsolete.
• Clinical Applications
• Blockade of the second and third divisions of the trigeminal nerve, as well as
blockade of the peripheral branches, is occasionally useful in the diagnosis and
management of pain syndromes and for discrete surgical procedures in selected
• Technique: Mandibular and Maxillary Nerves
• The mandibular and maxillary nerves, two divisions of the trigeminal nerve, can be blocked through the same needle
entry site (see Fig. 52-25B ). The maxillary nerve (i.e., second division) is blocked as it exits the skull through the
foramen rotundum and crosses the pterygopalatine or infratemporal fossa between the skull and the upper jaw. The
nerve terminates as the infraorbital nerve as it exits through the infraorbital foramen, where it can also be
• The coronoid notch of the mandible is located, and with the patient's mouth closed, a 22-gauge, 8-cm needle is
inserted at the inferior edge of the coronoid notch perpendicular to the skin entry site. The needle contacts the lateral
pterygoid plate at a depth of about 5 cm. It is then withdrawn and redirected anteriorly and superiorly to walk off the
plate and is subsequently advanced approximately 0.5 cm into the pterygopalatine fossa (see Fig. 52-25C ). Between 3
and 5 mL of local anesthetic solution produces anesthesia of the upper jaw and skin of the lower eyelid, cheek, and
• The mandibular nerve (i.e., third division) leaves the cranium through the foramen ovale and innervates the skin of the
lower jaw and the skin anterior and superior to the ear by its posterior division. Peripheral sensory branches of cranial
nerve V3 include the buccal, auriculotemporal, lingual, and inferior alveolar (terminating in the mental nerve) nerves.
The anterior division supplies motor innervation to the muscles of mastication.
• The mandibular nerve is blocked through the same entry site as the maxillary nerve. The needle is advanced along the
inferior margin of the coronoid notch until the bone of the lateral pterygoid plate is contacted (about 5 cm). The
needle is withdrawn and redirected to walk off the posterior border of the pterygoid plate, and it is advanced in an
attempt to elicit a paresthesia. The needle should not be inserted farther than 0.5 cm past the plate (see Fig. 52-25D ).
Injection of 3 to 5 mL of local anesthetic solution at this site is adequate.
• Side Effects and Complications
• Blockade of the maxillary nerve can be associated with hematoma formation and spread of the local anesthetic
solution to the optic nerve, thereby causing temporary blindness. A mandibular nerve block is not associated with
major complications. If the needle is advanced past the pterygoid plate more than the recommended 0.5 cm, the
pharynx may be entered, which increases the risk of contaminating the infratemporal fossa. Rarely, subarachnoid
spread of local anesthetic may occur and result in brainstem anesthesia
• Cervical Plexus Blockade
• The cervical plexus is derived from the C1, C2, C3, and C4 spinal nerves
and supplies branches to the prevertebral muscles, strap muscles of the
neck, and phrenic nerve. The deep cervical plexus supplies the
musculature of the neck segmentally and the cutaneous sensation of the
skin between the trigeminally innervated face and the T2 dermatome of
the trunk. Blockade of the superficial cervical plexus results in anesthesia
of only the cutaneous nerves.
• Clinical Applications
• Blockade of the cervical plexus is easy to perform and provides anesthesia
for surgical procedures in the distribution of C2 to C4, including lymph
node dissection, plastic repair, and carotid endarterectomy. The ability to
monitor the awake patient's neurologic status continuously is an
advantage of this anesthetic technique for the latter procedure and has
resulted in an upsurge in popularity of this technique. Bilateral blocks
can be used for tracheostomy and thyroidectomy.
• Superficial Cervical Plexus
• The superficial cervical plexus is blocked at the midpoint of the posterior border of the
sternocleidomastoid muscle. A skin wheal is raised at this point, and a 22-gauge, 4-cm needle is
advanced while injecting 5 mL of solution along the posterior border and medial surface of the
sternocleidomastoid muscle ( Fig. 52-27 ). It is possible to block the accessory nerve with this
injection, which results in temporary paralysis of the ipsilateral trapezius muscle.
• Deep Cervical Plexus
• The deep cervical plexus block is a paravertebral block of the C2 to C4 spinal nerves as they
emerge from their foramina in the cervical vertebrae ( Fig. 52-28 ). The traditional approach
involves the use of three separate injections at C2, C3, and C4. The patient lies supine with the
neck slightly extended and the head turned away from the side to be blocked. A line is drawn
connecting the tip of the mastoid process and the Chassaignac tubercle (i.e., transverse process
of C6); a second line is drawn 1 cm posterior to the first line. The C2 transverse process lies 1 to 2
cm caudad to the mastoid process, where it can usually be palpated. The C3 and C4 transverse
processes lie at 1.5-cm intervals along the second line. After skin wheals are raised over the
transverse processes of C2, C3, and C4, three 22-gauge, 5-cm needles are advanced perpendicular
to the skin entry site at a slight caudad angulation. The transverse process is contacted at a depth
of 1.5 to 3 cm. If a paresthesia is obtained, 3 to 4 mL of solution is injected after careful aspiration
for blood and cerebrospinal fluid. If no paresthesia is elicited initially, the needle is walked along
the transverse process in the anteroposterior plane until a paresthesia is obtained.
• This block can also be performed with a single injection of 10 to 12
mL at the C4 transverse process. Cephalad spread of the local
anesthetic usually anesthetizes the C2 and C3 nerves. Cervical
plexus anesthesia can also be observed after injection at the
interscalene level for brachial plexus blockade. Maintenance of
distal pressure and a horizontal or slightly head-down position may
facilitate the onset of cervical plexus blockade via the interscalene
• Side Effects and Complications
• Although these blocks are technically straightforward, needle
placement for a deep cervical block allows injection of local
anesthetic in close proximity to a variety of neural and vascular
structures. Reported complications and side effects include
intravascular injection, blockade of the phrenic and superior
laryngeal nerve, and spread of local anesthetic solution into the
epidural and subarachnoid spaces.
• Stellate Ganglion Block
• Clinical Applications
• Blockade of the stellate ganglion is used primarily for the treatment of upper extremity
sympathetic dystrophy and to increase blood flow to this area ( Chapter 58 ).
• The patient lies supine with the neck extended slightly. The most prominent cervical transverse
process—the Chassaignac tubercle (C6)—is palpated between the sternocleidomastoid muscle
and the trachea. The C6 tubercle is palpated between the index and middle fingers and the
carotid artery is pushed laterally. A skin wheal is raised between the fingers over the tubercle,
and a 22-gauge, 4-cm short-beveled needle with a 12-mL syringe attached is inserted in a
perpendicular direction until the tip contacts the C6 transverse process ( Fig. 52-31 ). The needle
is then withdrawn 3 mm and fixed. After careful aspiration, 8 to 12 mL of local anesthetic solution
is injected. Signs of a successful stellate ganglion block include Horner's syndrome, anhidrosis,
injection of the conjunctiva, nasal stuffiness, vasodilation, and increased skin temperature.
• Side Effects and Complications
• Because of the proximity of several major neural and vascular structures to the site of needle
insertion, side effects and complications can occur, including block of the brachial plexus and
recurrent laryngeal nerves, hematoma formation, intravascular injection resulting in convulsions,
and epidural and subarachnoid injection.