This presentation is about the entrapment syndrome of upper limb giving an insight regarding diagnosis clinically as well as electrophysiologically and its management.

1. ENTRAPMENT NEUROPATHIES IN UPPER LIMB
Presenter: Dr. Kshitij Bansal
Senior Resident
Department of Neurology
Government Medical College, Kota

2. INTRODUCTION
 Entrapment neuropathy is a condition in which a nerve becomes compressed, or entrapped, between
two other structures in the body.
 Result of mechanical dynamic compression of a short nerve segment.
 Passes through a specific site- fibro-osseous tunnel or an opening in fibrous or muscular tissue.
 Symptoms usually begin insidiously and progress slowly.
 Sensory loss, localised pain and/or motor weakness.
 Diagnosis-combination of history, examination, electrodiagnostic studies.
 MRI and high-resolution ultrasonography (US) increasingly being used-provide valuable spatial
information.

3. Upper Limb
Median Nerve
CTS
Pronater
Syndrome
AIN Syndrome
Ulnar Nerve
Cubital Tunnel
Syndrome
Guyon's Canal
Radical Nerve
PIN Syndrome
Wartenberg
Syndrome

5. TYPES OF NERVE INJURY
 Neuropraxia (1st Degree): Brief or mild compression on the nerve that distorts the myelin, resulting in
segmental demyelination but leaving the axons intact.
 Axonotmesis: Axonal damage that results in Wallerian degeneration; distal to the injury, the axons and
their investing myelin sheath degenerate.
 2nd Degree: Axonal loss is associated with intact endoneurial tubes as well as intact perineurium and epineurium.
 3rd Degree: Axons and endoneurium are damaged while leaving the perineurium and epineurium intact.
 4th Degree: Axons, endoneurium and perineurium are disrupted, but the epineurium is intact.
 Neurotmesis (5th Degree): Complete disruption of the nerve and all the supporting structures.

6. PATHOGENESIS
 Repeated compression leads to ischemia, edema formation in the subendoneurial space and the
synovium and eventually fibrosis.
 Tethering of the nerve due to scar tissue leads to reduced nerve gliding and ischemia.
 Localised mechanical pressure and structures cause of local nerve damage.

7. CARPEL TUNNEL SYNDROME
 Median nerve entrapment at the wrist is the most common of all entrapment neuropathies.
 One of the most frequent reasons for referral for an EDX study.
 The usual site of compression is in the carpel tunnel.

8. ANATOMY

11. ETIOLOGY

12. SYMPTOMS
 Numbness and tingling in the median nerve distribution.
 Nocturnal numbness
 Weakness and/or atrophy of the thenar musculature (Opponens Pollicis, Abductor Pollicis Brevis and
Superficial head of Flexor Pollicis Brevis)
 Weakness of first and second Lumbricals.
 Tinel sign
 Phalen’s test

15. CLINICAL GRADING OF SEVERITY
 Mild: Numbness, tingling or discomfort but no sensory loss or weakness, no sleep disruption and no
difficulty with hand function or interference with ADLs.
 Moderate: Sensory loss, nocturnal symptoms occasionally disrupt sleep. Symptoms may interfere slightly,
but the patient should be able to perform all ADLs.
 Severe: Weakness present, symptoms are disabling and prevent the patient from carrying out one or
more ADLS. Nocturnal symptoms routinely disrupt sleep.

16. ELECTRODIAGNOSTIC STUDIES
 Typical CTS: Median distal motor and sensory latencies and minimum F wave latencies- moderately to
markedly prolonged.
 Routine studies are normal (10-25% of CTS patients)
 Median versus ulnar palm-to-wrist mixed nerve latencies.
 Median versus ulnar wrist-to-digit 4 sensory latencies
 Median (second lumbrical) versus ulnar (interossei [INT]) distal motor latencies.
 Inching across the wrist and palmer stimulation.
 Median versus radial digit 1 sensory latencies.

17. PALMER MIXED COMPARISON STUDY

18. DIGIT 4 COMPARISON STUDY

19. LUMBRICAL INTEROSSEI COMPARISON STUDY

20. INCHING ACROSS THE WRIST

21. MEDIAN RADIAL SENSORY COMPARISON

22. RECOMMENDED EMG PROTOCOL FOR CTS
 Abductor pollicis brevis (APB)
 At least two C6–C7-innervated muscles (e.g., pronator teres, flexor carpi radialis, triceps brachii) to
exclude a cervical radiculopathy
If APB is abnormal, the following additional muscles should be sampled:
 At least one proximal median-innervated muscle (e.g., flexor carpi radialis, pronator teres, flexor pollicis
longus) to exclude a proximal median neuropathy.
 At least two other non-median, lower trunk/C8–T1- innervated muscles (e.g., first dorsal interosseous) to
exclude a lower trunk brachial plexopathy, polyneuropathy, or C8–T1 radiculopathy.

23. ELECTRODIAGNOSTIC GRADING
 Mild: Prolonged (relative to absolute) sensory latencies with normal motor studies. No
evidence of axon loss.
 Moderate: Abnormal median sensory latencies and relative or absolute prolongation of
median motor distal latency. No evidence of axon loss.
 Severe: Evidence of axon loss
 Needle EMG: Denervation potentials

24. ULTRASOUND FEATURES
 Significant increase in the area of the median nerve at the level of the pisiform (Cut off value
> 12 mm2)
 Flattening of the nerve at the level of the hook of the hamate.
 Significant palmar bowing of the flexor retinaculum.
 Hypoechoic change of the median nerve and the altered fascicular pattern caused by neutral
edema.

26. TREATMENT
Non-surgical treatment is an option for early-stage CTS.
 Initial treatment-symptomatic includes rest, avoidance of vibratory tools or repetitive activity.
 Changing work-profile.
 Drug therapy-combination of NSAIDs and oral as well as local steroids.
 Splinting is recommended prior to treatment with surgery.

27. SURGICAL OPTIONS
 Surgery is an option when there is evidence of median nerve denervation.
 Carpal Tunnel Release (Level 1 evidence).

28. EDX STUDIES AFTER CARPAL TUNNEL RELEASE
 Patients will either have recently undergone surgery with no clinical improvement.
 Patients may develop recurrent symptoms for a long period of time after successful carpal tunnel
decompression.
 Median motor and distal sensory latencies may improve.
 But, median sensory amplitudes may or may not improve.
 Sensitive internal comparison studies remain abnormal indefinitely showing some slowing of median
conduction across carpal tunnel.
 May take many weeks to months and improvement continues up to a year after surgery.

29. Possible areas of median nerve compression
proximal to the carpal tunnel
 Proximal entrapment of the median nerve at
the ligament of Struthers.
 Median nerve entrapment more distally, either
beneath the lacertus fibrosus, in the substance
of the PT, or beneath the sublimis bridge
 The latter three entrapment sites usually are
referred to collectively as the pronator
syndrome.

30. PRONATOR SYNDROME
 Compression of the median nerve as it passes between
the two heads of the pronator teres muscle or under the
proximal edge of the proximal FDS arch.
 Presenting Symptoms
 Arching pain in the proximal, volar forearm
 Paresthesias radiating into the median innervated fingers.
 Worsened by repetitive prono-supination movements.

31. PRONATOR SYNDROME VS CTS
 Loss of sensation over palmar cutaneous branch territory.
 No Tinel’s on the wrist.
 No nocturnal disturbance.
 Pain on resisted pronation from a neutral position, especially as the elbow is extended.

32. ELECTRODIAGNOSTIC STUDIES
 Reduced median CMAP and / or SNAP amplitudes with distal latencies that are either normal
or only slightly prolonged.
 Either conduction block / temporal dispersion or marked conduction velocity slowing
between the wrist and antecubital fossa.
 No significant slowing of the median palm-to-wrist latency compared with the ulnar.
 EMG: FPL and FDP to digits 2 and 3, less often in the FDS and APB.
 USG: Any mass or hematoma.
Not easy to make diagnosis as fibrous bands or scar tissue may be too small to visualise with US.

33. MANAGEMENT
 Surgery is usually not necessary.
 Conservative therapy should be tried. (Rest, avoid precipitating activity, steroid orally)
 Surgery is indicated after an adequately long trial, if neoplasm is suspected or
electrophysiology shows gross affection.

34. ANTERIOR INTEROSSEOUS NERVE SYNDROME
 Entrapment of the nerve in the proximal forearm.
 Compressed by fibrous bands, most commonly originating
from the deep head of the PT, FDS and brachialis fascia.
 Cause-direct nerve trauma or compression from a
hematoma or mass.
 Pain may be present in the forearm along the course of the
nerve.
 FPL, FDP to digits 2 and 3, and PQ are affected.
 Inability to make an “OK” sign.

35. RECOMMENDED NCS PROTOCOL FOR PROXIMAL MEDIAN
NEUROPATHY
Routine studies:
 Median motor study recording abductor pollicis brevis, stimulating wrist, antecubital fossa,
and axilla
 Ulnar motor study recording abductor digiti minimi, stimulating wrist, below groove, and
above groove
 Median and ulnar F responses
 Median sensory response, recording digit 2 or 3, stimulating wrist (bilateral studies
suggested)
 Ulnar sensory response, recording digit 5, stimulating wrist
 Median and ulnar palm-to-wrist mixed nerve studies using identical distances of 8 cm

36. NCS IN POSSIBLE PROXIMAL MEDIAN NEUROPATHY
 Reduced median CMAP and/or SNAP with distal latencies that are either normal or only
slightly prolonged (never in the demyelinating range) and no significant slowing of the
median palm-to-wrist latency compared with the ulnar.
 Either conduction block/temporal dispersion or marked conduction velocity slowing between
the wrist and antecubital fossa, with normal or only slightly prolonged distal latencies on
median motor studies
 Prolonged median F responses despite a relatively normal CMAP and distal latency.

37.  Needle EMG-denervation in muscles FPL, pronator quadratus, and FDP (index and middle
finger).
 MR imaging-signal intensity changes related muscles denervation in FDL, FPL and pronator
quadratus muscles.
 US-limited for the evaluation because of the small size of the nerve and relatively deep
location.

38. MANAGEMENT
 Treatment is initially conservative with rest, splinting and observation.
 Spontaneous recovery usually occurs within 3 to 12 months.
 Surgery may not be necessary unless penetrating injury, fracture or progressive deterioration
and weakness are detected.

39. POTENTIAL ULNAR NERVE ENTRAPMENT
 The medial intermuscular septum.
 The medial epicondyle.
 The cubital tunnel.
 The deep flexor pronator aponeurosis.
Ulnar Neuropathy at Elbow
(most common site)

40. ULNAR NEUROPATHY AT ELBOW
Etiology (Medial epicondyle)
 Chronic mechanical compression or stretch.
 Tardy ulnar nerve palsy
 Rare causes ganglia, tumours, fibrous bands
 Immobilisation because of surgery or who sustained compression during anaesthesia or
coma.
Etiology (Cubital Tunnel)
 Compression of ulnar nerve under the humeral-ulnar anoneurocis (HUA).

42. SYMPTOMS
 Numbness and paresthesia in the ring and little finger.
 Difficulty in gripping: intrinsic weakness.
 Pain and tenderness over the elbow region medially
particularly over the ulnar nerve.
Provocative Tests
 Tinel’s test along the course of the ulnar nerve.
 Elbow flexion test.
 Pressure provocation test (where direct pressure is applied
to the cubital tunnel for 60s).
 Combined elbow flexion-pressure test.

48. ELECTRODIAGNOSTIC STUDIES
 Low ulnar SNAP.
 Normal or low amplitude ulnar CMAP with normal of slightly prolonged distal latency.
 Unequivocal evidence of demyelination at elbow (conduction block and/or slowing >10-11
m/s across elbow compared with the forearm segment (flexed elbow position).
 EMG-Useful muscles- FDI, FDP (to digit 4 or 5), and FCU.

51. ULTRASOUND FINDINGS
 Enlargement of the ulnar nerve at the level of the cubital tunnel.
 Area > 8-11mm2 at the elbow-focal compression.
 Comparing the ulnar nerve area at the level of the cubital tunnel with that proximal to the
cubital tunnel (ratio 1.5:1).
 Area of the ulnar nerve at the epicondyle level (8.3-mm2)- 100% sensitivity.
 Ulnar nerve-hypoechoic in US because of neural edema.

53. TREATMENT
Mild Symptoms, less severe Edx findings
 Three months of conservative treatment (use of elbow pads and avoidance of prolonged
elbow flexion).
 50% have a resolution
Surgical management
 Conservative measures fail
 Who have evidence of significant axonal loss on initial Edx studies.
 Simple decompression through excision of the arcuate ligament.
 Medical epicondylectomy
 Ulnar nerve transposition

54. ULNAR NEUROPATHY AT WRIST: GUYON’S CANAL
 Guyon’s Canal is an oblique fibro-osseous tunnel
with a length of about 4 cm between the hook of
the hamate and the pisiform.
Etiology
 Direct trauma and laceration.
 Ganglion cyst.
 Repeated external pressure by hand tools, bicycle
handlebars.
 Degenerative wrist joint changes

55. SYMPTOMS
 Painless unilateral hypothenar and interossei weakness or atrophy.
 Sensory loss-palmar surface of the ulnar-innervated fingers, distal hypothenar region.
 Compression at the distal portion of the Guyon canal
 Selective involvement of the deep motor branch.
 Interossei weakness and atrophy.
 Complete or relative sparing of the hypothenar muscles as well as sensation.

56. ELECTRODIAGNOSTIC
 Low amplitude (with or without prolonged distal motor latencies) to the FDI or ADM muscles
or both.
 Ulnar SNAP may or may not be abnormal.
 Denervation of the ulnar-innervated hand muscles.
EDX (inconsistent with an ulnar neuropathy at the wrist)
 Low amplitude or absent dorsal ulnar SNAP.
 Focal slowing or conduction block across the elbow.
 Denervation of the FCU or FDP (ulnar portion).

57.  Plain radiograph of the wrist-fracture of the pisiform or hook of the hamate bone.
 MRI or ultrasound demonstrate a structural lesion such as ganglion cyst.
Treatment
 Sources of occupational or recreational trauma should be eliminated.
 Surgical intervention fractures, ganglia or mass lesion.
 The prognosis is usually good after surgical decompression with effective reinnervation.

58. PIN SYNDROME
 Compressive neuropathy of the deep branch of the radial
nerve in the region of the supinator muscle.
Etiology
 Thickened proximal tendinous edge of the supinator muscle
(Arcade of Frohse)- Most Common.
 The thickened leading edge of the ECRB.
 The distal ligamentous margin of the supinator muscle.
 Space occupying lesion (tumor / ganglion)
 Prominent recurrent radial vessels.
 Systematic diseases (diabetes, rheumatoid arthritis)

59. Presentation
 Palsy of the exterior muscles of the forearm. (Inability to extend fingers and thumb).
 ECRL function intact- the wrist extends and radially deviates.
Edx Studies
 Normal radial SNAP.
 Denervation of the muscles supplied by the PIN, with sparing of more proximal radial-
innervated muscles-brachioradialis, extensor carpi radialis, anconeus and triceps muscles.

60. Ultrasound
 Enlargement of the PIN at the proximal portion of the compression site.
 Cut-off value of the PIN diameter 15-mm
 Space occupying lesions can be found.
 USG-echo difference of the dorsal extensor muscles caused by denervation, as compared to
the contralateral side.
MRI Findings
 Direct visualisation of nerve thickening with increased T2 signal and muscle signal alterations.
 Detection of compressive lesions or abnormal structures.

62. TREATMENT
 Anti-inflammatory medications, rest, and corticosteroid injections (1st Line)
 If the syndrome is progressive, surgical exploration is indicated.
 Surgical release of the superficial head of the supinator muscle may be performed.

63. WARTENBERG’S SYNDROME
 Entrapment neuropathy of the superficial branch of
the radial nerve as it exists beneath the
brachioradialis at the level of the distal forearm.
Etiology
 Trauma
 Placement of fixator pins due to Colles fractures.
 Cephalic vein cannulation.
 Presentation
 The patient presents with pain numbness and
paraesthesia in the radial-side wrist and thumb.

64.  Edx Studies
 Nerve conduction study often shows a low-amplitude or absent dorsal radial SNAP.
 Needle EMG-Normal including all radial innervated muscles.
 Treatment
 Benign self-limiting condition.

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