median nerve injury

1. MEDIAN NERVE INJURIES
Dr SAURABH AGRAWAL
Assiatant professor
Deptt of orthopedics, AIIMS bedwas

2. Median nerve introduction
The median nerve is derived from both the lateral and
medial cords of the brachial plexus, with the lateral cord
providing mostly sensory axons from C6 and C7, and the
medial cord providing motor axons from C8 and T1.
it is the only nerve that passes through the carpal
tunnel. Carpal tunnel syndrome is the disability that
results from the median nerve being pressed in the
carpal tunnel.
Also called labourer’s nerve.

4. Motor Functions
The median nerve innervates the majority of the muscles in the anterior forearm,and
some intrinsic hand muscles.
The Anterior Forearm
Inthe forearm, the median nerve directly innervates muscles in the superficial and
intermediate layers:
Superficial layer: Pronator teres, flexor carpi radialis and palmarislongus.
Intermediate layer:Flexor digitormsuperficialis.
The median nerve also gives rise to the anterior interosseous nerve, which suppliesthe
deep flexors:
Deep layer: Flexor pollicis longus, pronator quadratus, and the lateral half of the
flexor digitorum profundus (the medial half of the muscle is innervated by the ulnar
nerve).
Ingeneral these muscles perform pronation of the forearm, flexion of the wrist and
flexion of the digits of the hand.

7. HAND
innervates some of the muscles in the hand via two branches.
The recurrent branch of the median nerve innervates the thenar muscles –
muscles associated with movements of the thumb.
The palmar digital branch innervates the lateral twolumbricals – these muscles
perform flexion at the metacarpophalangeal joints of the index and middle
fingers

11. Sensory innervation:
The median nerve is responsible for the cutaneous
innervation of part of the hand. This is achieved via two
branches:
Palmar cutaneous branch –Arises in the forearm and
travels into the hand. It innervates the lateral aspect of
the palm. This nerve does not pass through the carpal
tunnel, and is spared in carpal tunnel syndrome.
Palmar digital cutaneous branch –Arises in the
hand. Innervates the palmar surface and fingertips of the
lateral three and half digits.

12. Course of median nerve
Anterior compartment of arm
anterior compartment (anteromedial to humerus)
runs with brachial artery (lateral in upper arm / medial at elbow)
no branches in thearm
Forearm
enters the forearm between the pronatorteres and biceps tendon
travels between flexor digitorum superficialis (FDS)and flexor digitorum
profundus (FDP)
then emerges between the FDSand flexor pollicis longus (FPL)

14. Hand
the nerve then enters the hand via the carpal tunnel, along with the tendons of the
FDS,FDPand FPL
Terminal branches
anterior interosseous branch (AIN)
innervates the deep volar compartment of forearm except the ulnar half ofthe FDP
palmar cutaneous branch
supplies sensory innervation to lateral palm
recurrent branch (to thenar compartment)
digital cutaneous branches
supply the radial 3 1/2 digits (palmar)
can also supply the index, long, and ring fingers dorsally

15. Clinical findings:
1. Injury at the Elbow: Supracondylar fracture of the humerus.
Motor functions: The flexors and pronators in the forearm are paralysed, with the
exception of the flexor carpi ulnaris and medial half of flexor digitorum profundus.
The forearm constantly supinated, and flexion is weak (often accompanied by
adduction, because of the pull of the flexor carpi ulnaris). Flexion at the thumb is also
prevented, as both the longus and brevis muscles are paralysed.
The lateral two lumbrical muscles are paralysed, and the patient will not be able to
flex at the MCP joints or extend at IPjoints of the index and middle fingers.
Sensory functions: Lack of sensation over the areas that the median nerve
innervates.
Characteristic signs: The thenar eminence is wasted, due to atrophy of the thenar
muscles. If patient tries to make a fist, only the little and ring fingers can flex
completely. This results in a characteristic shape of the hand, known as hand of
benediction.

17. 2.Injury at the Wrist:
How it commonly occurs: Lacerations just proximal to
the flexor reticaculum.
Motor functions: Thenar muscles paralysed, as are the
lateral two lumbricals. This affects opposition of the
thumb and flexion of the index and middle fingers.
Sensory functions: Same as an injury at the elbow.

18. Median nerve clinical assessment:
1. Pronator teres (C6, C7) assessment: The patient’s forearm is extended and fully
pronated. The patient is then instructed to resist supination of the forearm by the
examiner.

19. 2. Flexor carpi radialis (C6, C7) assessment: The patient flexes the wrist
along the trajectory of the forearm. Wrist deviates ulnarly.

20. 3. Flexor digitorum superficialis (C8,
T1) assessment: To test proximal
interphalangeal joint flexion, the
supinated forearm and hand are
placed straight. This maneuver
places the finger to be tested
in mild flexion at the metacarpal–
phalangeal (knuckle) joint, and
stabilizes the remaining fingers in
extension, a position that allows
isolation of the flexor digitorum
superficialis. Ask the patient to flex
PIPjt againstresistance.

21. 4. Flexor digitorum profundus (C8,T1) assessment: To assessthe median
innervation of the flexor digitorum profundus one should concentrate on the
index finger. To do so, hold the metacarpal-phalangeal and proximal
interphalangeal joints immobile, and have the patient flex the distal phalanx
against your resistance.

22. The Thenar Group
5. Flexor pollicis longus (C8, T1)assessment:Immobilize the thumb, except the
interphalangeal joint, and then ask the patient to flex the distal phalanx against
resistance.

23. 6. Okay” or “circle” sign with anterior interosseous
nerve weakness.
A quick way to assessthe flexor digitorum
profundus and flexor pollicis longus innervation
from the anterior interosseous nerve is to ask the
patient to make an okay sign by touching the tips
of the thumb and index finger together.
With weakness in these muscles, the distal
phalanges cannot flex, and instead of the
fingertips touching, the volar surfaces of each
distal phalanx make contact.

24. 8.Abductor pollicis brevis (C8,T1) assessment: Resist movement of the thumb
away from the plane of the palm (palmar abduction), while stabilizing the
metacarpals of the
remaining fingers.

25. 9. Flexor pollicis brevis (C8, T1)
assessment
The patient flexes the thumb at the metacarpal-
phalangeal joint against resistance placed over
both the proximal and distal phalanges.
Make certain the distal interphalangeal joint does
not flex because in allowing this, substitution by
the flexor pollicis longus occurs.
Use your other hand to immobilize the first
metacarpal to reduce substitution by the
opponens pollicis.
Because of its dual innervation, even with
complete thenar motor branch palsies some
thumb flexion still occurs.

26. 10: Opponens pollicis (C8, T1)
assessment:
Have the patient forcibly maintain
contact between the volar pads of the
distal thumb and fifth digit, while you try
to pull the distal first metacarpal away
from the fifth digit. Although thumb
opposition is only innervated by the
median nerve, a combination of thumb
adduction (adductor pollicis, ulnar nerve)
and thumb flexion (flexor pollicis brevis,
deep head, ulnar nerve) may mimic
thumb opposition even when there is
complete median nerve palsy present.

27. 11. Lumbrical of second digit (C8,
T1) assessment:
Stabilize the patient’s index finger
in a hyper-extended position at
the metacarpal-phalangeal joint
and then provide resistance as
the patient extends the finger at
the MCP joint.

28. Sensory system
examination
Modality test – pain,touch,temperature ,pressure
and vibration
Functional tests –two point discrimination
Objective test –
(a) sweat test (iodinestarch test)-
dusting extremities with quinizarine powder
In denervated area powder remain dry and light gray
In normal sweating area it become deep purple
colour

29. (b)Skin resistance test
Richter dermometer is used
Absence of sweating demonstrate
increased resistance to passage of
electric current
(c)wrinkle test
denervated skin do not wrinkle on
exposure to water for prolonged period (
4*C for 30 min.)

30. • (d) Tinel’s sign-
– tested by gentle percussion along course of nerve
from distal to proximal direction.
– Tingling sensation felt by patient in distribution of
nerve.
– Tingling should persist for several seconds
• Importance of Tinel’s sign
– Whether Nerve interrupted
– Whether in Process of regeneration
– Rate of regeneration
– Success of nerve repair

31. Electrophysiological
study
Electromyography
Around 3 wks after denervation, the
muscle fibres will twitch rhythmically and
involuntarily
These fibrillations cannot be seen clinically
but can be measured by EMG
Fibrillations are called denervation
fibrillation

32. • Nerve conduction test
– First calculate threshold by stimulating on sound side
– If twice the threshold fails to produce muscle contraction
nerve conduction is absent
– Slow rate of conduction suggest damage to nerve
• Compound muscle action potential can be recorded from both
proximal and distal Forearm extensor muscles

33. CLASSIFICATIONOFNERVEINJURIES
SEDDON’S CLASSIFICATION
Neuropraxia – temporary paralysis of a nerve
caused by lack of blood flow or by pressure
on the affected nerve with no loss of structural
continuity.
Axonotmesis – neural tube is intact but axons
are disrupted. Nerves are likely to recover.
Neurotmesis – neural tube is severed. Injuries
are likely to be permanent without repair.

34. SUNDERLAND’S CLASSIFICATION

35. Median nerve Compression Syndromes
CarpalTunnel
Pronator Teres
Anterior Interosseous

36. Carpal Tunnel Syndrome
Compressive neuropathy as the nerve passes through the Carpal Tunnel
Causes:
- Idiopathic :Most common
- Inflammatory :Rheumatoid Arthritis
:Wrist osteoarthritis
- Post traumatic :Bone thickening
: Myxoedema
:Acromegaly
- Endocrine
- Pregnancy
- Gout
- Repetitive wrist movts: Typists & Computer users

37. Carpal Tunnel

38. Symptoms
Hand and wrist Pain
Paraesthesia
Hypoaesthsia
Sparing of Palmar cutaneous branch supply
Patient wakes at night with burning or aching pain and shakes the hand to
obtain relief and restore sensation
Aggravated by elevation of hand
Thenar atrophy and weakness of thumb opposition and abduction may
develop late

39. Diagnosis
History
Clinical examination:
- Thenar wasting
- Phalen’s sign
- Tinel’s sign
- Carpal compression test
Electro Diagnostic Studies:
- Very reliable for evaluation
- Atypical casesmay be present

40. Thenar atrophy

42. Tinel’s Sign

43. Carpal Compression test/ Durkan’s test

44. Management
• Splinting – prevents wrist flexion
• Corticosteroid/anesthetic injection
• Surgical decompression:Division of the transverse carpal ligament
- Open
- Endoscopic

48. Complications
Injury to palmar cutaneous/recurrent motor branch of the mediannerve
Hypertrophic scarring
Hematoma/Arterial injury

49. Pronator teres syndrome
• High Compression neuropathy
• It is rare compared to CTSandAIS
• Misnomer  Proximal forearm median nerve compression

50. Symptoms & signs
Symptoms are similar to those of carpal tunnel syndrome
Sensory disturbances
- Thumb & Index > Middle finger
Night pain is unusual and forearm pain is more common
Hand numbness on gripping
Phalen’s test negative
Symptoms provoked by resisted elbow flexion with forearm
supinated ( tightening of bicipital aponeurosis )
By resisted forearm pronation with the elbow extended
( pronator tension )

51. Management
No relief with steroids
Surgical decompression

52. Anterior Interosseous Syndrome
Damage to the Anterior Interosseous Nerve
Pain in the forearm
Weakness of the gripping movement of the thumb and indexfinger(
unable to make ok sign )
Causes:
- Injury to elbow
- Injury during open/closed reduction

53. Management
Corticosteroids
Surgery:
- Resection/detachment of deep head of PT

54. Tendon transfer in median nerve injuries
Median nerve palsy is perhaps the most devastating single nerve injury of the
upper extremity. Not only is there a loss of fine motor control and opposition,
but sensibility is lost over the area of the hand used for precision movements
and prehensile functioning.
Tendon transfer procedures to restore movement may be ineffective if
sensibility cannot be restored.
High median nerve palsy is defined as an injury proximal to the innervation of
the forearm muscles. Although PTand FCRfunctions are lost, forearm pronation
and wrist flexion are compensated for by other muscles, and do not need to be
restored.

55. Although the FDSto all four fingers is lost, flexion is maintained in the ring
and small fingers by the functioning ulnar-innervated FDPmuscle bellies.
However, even though ring and small finger flexion is preserved, grip strength
is diminished.
More importantly, there is a loss of thumb IPJflexion and index and middle
finger DIPJflexion due to loss of the AIN innervated muscles. This results in a
lack of fine motor control of the hand, which is normally provided by precise
movements of the IPJof the thumb and the IPJ’sof the index and middle
fingers.
In addition to these deficits, crucial thumb opposition is lost.
Low median nerve palsy, on the other hand, results in loss of thumb
opposition and sensory loss only. The fact that some degree of sensory
reinnervation is likely when a low median nerve injury has been repaired
makes this a potentially less devastating injury than high median nerve palsy.

56. General indications of
surgery
In sharp injury exploration for diagnostic as
well as theurapeutic purpose .Nerorrhaphy
can be done at time of exploration or
delayed
In avulsion or blast injury –to identify and
suture of nerve ends for delayed repair
No improvement since last 12 weeks
following close injury

57. Time of
surgery
Primary repair within 6-8 hours gives
best results
Delayed primary repair – between 7- 18
days
Secondary repair - 3 to 6 weeks later
.preferable in crushed
,avulsed,contaminated wounds where
patients life is seriously endangerd

58. Surgical
techniques Coaptation
Approximatingthe cut ends of nerve
in such a way that motor fasiculi
meets another motor fasiculi and
sensory to sensory
Conventionally done by 8-0 to 10-0
nylon suture
Sutureless methods includes fibrin
clots, adhesive tapes ,collagen

59. Neurolysi
s Neurolysis is dissection to free nerve
fibers
Exo Neurolysis-
removal of neuroma or binding
cicatrix
Endo Neurolysis-
seperation of of each of fasciculi
from surrounding non fascicular
tissue

60. Neurorrhaph
yNeurorrhaphy is end to end suturing of
nerve
Types
Partial Neurorrhaphy
Epineural Neurorrhaphy
Perineural (fascicular) Neurorrhaphy
Epiperineural Neurorrhaphy
Interfascicular nerve grafting

61. Epineural
neurorrhaphy

62. Perineural
neurorrhaphy

63. Epiperineural
neurorrhaphy

64. Inter fascicular nerve
grafting

65. Nerve
grafting
A gap between cut ends more than 2.5-4
cm is indication of nerve graft
Types of grafts
Trunk graft
Cable graft
Pedicle nerve graft
Inter fascicular nerve graft
Pre vascularised nerve graft

66. Critical Limit of Delay of Suture
Return of motor function should not be
expected when suture has been delayed for
more than 15 months.

67. Reconstructive
procedure
1 Tendon transfer
2 Arthrodesis
When neighboring tendons are intact and if all
criteria for tendon transfer met ,then tendon transfer
is treatment of choice
Tendon transfer should be delayed for 6 months

68. Criteria for tendon
transfer
– Muscle power grade 5 (preferably),if not atleast grade 4
– Should have its own nerve and blood supply
– Synergistic group are chosen because of easier rehabilitation
– Age should be more than 5 years
– Disease should not progress and infection to be controlled
– Prior to transfer joint stiffness,contracture and malunion are
corrected
– Tendon transferred should not be at an acute angle

69. COMPLICATIONS:
Tendon adhesions,
transfer rupture,
Transfer weakness
Infection
Neuro vascular injuries

70. Thank
you