Ulnar Tunnel Syndrome

Author: Daniel Hatch

Topic updated on 02/21/13 8:40pm

Introduction

Ulnar nerve compression neuropathy caused by direct compression in Guyon's canal
- also known as handlebar palsy (seen in cyclists)
Pathoanatomy
- causes of compression include
  - ganglion cyst (80% of nontraumatic causes)
  - lipoma
  - repetitive trauma
  - ulnar artery thrombosis or aneurysm
  - hook of hamate fracture or nonunion
  - pisiform dislocation
  - inflammatory arthritis
  - fibrous band, muscle or bony anomaly
  - congenital bands
  - palmaris brevis hypertrophy

Anatomy

Guyon’s canal
- course
  - is approximately 4 cm long
  - begins at the proximal extent of the transverse carpal ligament and ends at the aponeurotic arch of the hypothenar muscles
- contents
  - ulnar nerve bifurcates into the superficial sensory and deep motor branches
- boundaries and zones (see table below)

Boundaries of Guyon's canal
Floor	Transverse carpal ligament, hypothenar muscles
Roof	Volar carpal ligament
Ulnar border	Pisiform and pisohamate ligament, abductor digiti minimi muscle belly
Radial border	Hook of hamate
Zones of Guyon's canal
	Location	Common Causes of Compression	Symptoms
Zone 1	Proximal to bifurcation of the nerve	Ganglia and hook of hamate fractures	Mixed motor and sensory
Zone 2	Surrounds deep motor branch	Ganglia and hook of hamate fractures	Motor only
Zone 3	Surrounds superficial sensory branch	Ulnar artery thrombosis or aneurysm	Sensory only

Deep branch of the ulnar nerve
- innervates the intrinsics (except for radial two lumbricals) and flexor pollicis brevis (FPB)

Presentation

Presentation varies based on location of compression within Guyon's canal and may be
- pure motor
- pure sensory
- mixed motor and sensory
Symptoms
- pain and paresthesias in ulnar 1-1/2 digits
Physical exam
- inspection & palpation
  - clawing of ring and little fingers
    - caused from loss of intrinsics flexing the MCPs and extending the IP joints
  - Allen test
    - helps diagnose ulnar artery thrombosis
- neurovascular exam
  - ulnar nerve palsy results in paralysis of the intrinsic muscles (adductor pollicis, deep head FPB, interossei, and lumbricals 4 and 5)
  - weakened grasp
    - from loss of MP joint flexion power
  - weak pinch
    - from loss of thumb adduction (as much as 70% of pinch strength is lost)
  - Froment sign
    - IP flexion compensating for loss of thumb adduction when attempting to hold a piece of paper
    - loss of MCP flexion and adduction by adductor pollicis (ulnar n.)
    - compensatory IP hyperflexion by FPL (AIN)
  - Jeane's sign
    - a compensatory thumb MCP hyperextension and thumb adduction by EPL (radial n.)
    - compensates for loss of IP extension and thumb adduction by adductor pollicis (ulna n.)
  - Wartenberg sign
    - abduction posturing of the little finger

Imaging

Radiographs and
- useful to evaluate hook of hamate fractures
CT scan
- useful to evaluate hook of hamate fractures
MRI
- useful to evaluate for a ganglion cysts
- a gradient echo MRI will also show an ulnar artery aneurysm
Doppler US or arteriogram
- useful to diagnosis ulnar artery thombosis and aneurysm

Differential

How to differentiate ulnar tunnel syndrome from cubital tunnel syndrome
- cubital tunnel demonstrates
  - less clawing
  - sensory deficit to dorsum of the hand
  - motor deficit to ulnar-innervated extrinsic muscles
  - Tinel sign at the elbow
  - positive elbow flexion test

Treatment

Nonoperative
- activity modification, NSAIDS and splinting
  - indications
    - as a first line of treatment when symptoms are mild
Operative
- local decompression
  - indications
    - severe symptoms that have failed nonoperative treatment
- tendon transfers
  - indications
    - correction of clawed fingers
    - loss of power pinch
    - Wartenberg sign (abduction of small finger)
- carpal tunnel release
  - indications
    - patients diagnosed with both ulnar tunnel syndrome and CTS

Techniques

Local surgical decompression
- release hypothenar muscle origin
- decompress ganglion cysts
- resect hook of hamate
- vascular treatment of ulnar artery thombosis
- explore and release all three zones in Guyon's canal
Tendon transfers
- correct claw fingers
  - possible grafts include ECRL, ECRB, palmaris longus
  - tendons must pass volar to transverse metacarpal ligament in order to flex the proximal phalanx
  - attach with either a two or four-tailed graft to the A2 pulley of the ring and small fingers
- restore power pinch
  - Smith transfer using ECRB or FDS of ring finger
- restore adduction of small finger
  - transfer ulnar insertion of EDM to A1 pulley or radial collateral ligament of the small finger

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Qbank (1 Questions)

TAG

(OBQ10.132) A 72-year-old female complains of progressive weakness with grasp and key pinch in her left hand. Physical exam of the hand is significant for decreased sensation on the volar aspect of the fourth and fifth digits. Dorsal sensation throughout the hand is normal. A clinical photo displaying bilateral key pinch is shown in Figure A. What is the most likely cause of compression? Topic

Review Topic

FIGURES: A

1. Accessory head of the FPL
2. Flexor carpi ulnaris
3. Osborne's ligament
4. Ganglion within Guyon's canal
5. Anconeus epitrochlearis

PREFERRED RESPONSE ▶

DISCUSSION: Compression of the ulnar nerve within Guyon's canal, termed ulnar tunnel syndrome, is most commonly caused by a ganglion cyst. A lack of dorsal ulnar sensory deficit helps differentiate entrapment here from at the elbow because the dorsal ulnar cutaneous nerve branches proximal to Guyon's canal. The clinical photo demonstrates Froment's sign where the FPL is used to substitute for the weakened adductor pollicis resulting in flexion of the thumb at the interphalangeal joint, and MCP joint hyperextension. The AIN can be compressed by the accssory head of the FPL (Gantzer's muscle) which results in loss of FPL, index FDP and PQ motor function and no sensory deficits. Ulnar nerve compression at Osborne's ligament, the two heads of the FCU, or by the anconeus epitrochlearis will classically result in volar and dorsal ulnar sensory loss of the affected hand.

REFERENCES:

1. Omer G Jr. Ulnar nerve palsy. In: Green DP, Hotchkiss RN, eds. Green's Operative Hand Surgery, 3rd ed. Philadelphia, PA: Churchill Livingstone; 1993:1449-1466.

2. Roberts CS, Gleis GE, Seligson D. Treatment of complications. In: Browner BD, Levine AM, Jupiter JB, Trafton PG, Krettek C, eds. Skeletal Trauma: Basic Science, Management, and Reconstruction, 4th ed. Philadelphia, PA: WB Saunders; 2009:545-588.

Question Authors:

Joshua Blomberg MD, Ben Taylor MD,

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Videos

	Allen Test Hand - Physical Exam - Ulnar Tunnel Syndrome Demonstration of Allen test	2/21/2013 209 views 5
	Guyon's Canal and Carpal Tunnel Release - Dr. Susan Mackinnon Hand - Surgical Techniques - Ulnar Tunnel Syndrome The ulnar nerve is decompressed in the wrist through Guyon's canal and in the ha...	9/6/2012 118 views 4
	Release of ulnar deep motor branch in Guyon's canal and carpal tunnel release Hand - Surgical Approaches - Ulnar Tunnel Syndrome Demonstrates ulnar nerve being decompressed in the wrist through Guyon's canal a...	7/2/2012 309 views 5

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Groups

ABOS II: Ulnar Tunnel Syndrome

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7/29/2011

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Evidence & References Show References

Textbooks

Review of Orthopaedics, 6th Edition, Mark D. Miller MD, Stephen R. Thompson MBBS MEd FRCSC, Jennifer Hart MPAS PA-C ATC, an imprint of Elsevier, Philadelphia, Copyright 2012
AAOS Comprehensive Orthopaedic Review, Jay R. Leiberman. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2009
Orthopaedic Knowledge Update 10, John M Flyn. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2011
Hoppenfeld SP. Surgical Exposures in Orthopaedics: The Anatomic Approach. Lipponcott, Williams, and Wilkins, Philadelphia, PA, Copyright 2009
Orthopaedic In-training Examination (OITE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012
Self-Assessment Examination (SAE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012

Undefined

Omer G Jr. Ulnar nerve palsy. In: Green DP, Hotchkiss RN, eds. Green's Operative Hand Surgery, 3rd ed. Philadelphia, PA: Churchill Livingstone; 1993:1449-1466.
Roberts CS, Gleis GE, Seligson D. Treatment of complications. In: Browner BD, Levine AM, Jupiter JB, Trafton PG, Krettek C, eds. Skeletal Trauma: Basic Science, Management, and Reconstruction, 4th ed. Philadelphia, PA: WB Saunders; 2009:545-588.

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