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 idiopathic 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 all of the interosseous muscles and the 3rd and 4th lumbricals. Innervates the hypothenar muscles, the adductor pollicis, and the medial head (deep) of the flexor pollicis brevis (FPB) Classification Presentation varies based on location of compression within Guyon's canal and may be Motor only Sensory only Mixed Motor & Sensory 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 weakness to intrinsics, ring and small finger digital flexion or thumb adduction 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 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 thrombosis and aneurysm Studies NCS and EMG helpful in establishing diagnosis and prognosis threshold for diagnosis conduction velocity <50 m/sec across elbow low amplitudes of sensory nerve action potentials and compound muscle action potentials 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 Complications Recurrence
QUESTIONS 1 of 2 1 2 Previous Next Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK You have 100% on this question. Just skip this one for now. Take This Question Anyway (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? Review Topic QID: 3225 FIGURES: A Type & Select Correct Answer 1 Accessory head of the FPL 5% (146/2851) 2 Flexor carpi ulnaris 11% (318/2851) 3 Osborne's ligament 19% (549/2851) 4 Ganglion within Guyon's canal 62% (1759/2851) 5 Anconeus epitrochlearis 2% (61/2851) L 3 Select Answer to see Preferred Response SUBMIT RESPONSE 4
All Videos (5) Podcasts (0) Login to View Community Videos Login to View Community Videos 2018 Orthopaedic Summit Evolving Techniques Managing the Ulnar Nerve in Athletes - Mark Baratz (OSET 2018) Mark Baratz Hand - Ulnar Tunnel Syndrome 8/23/2019 163 views Login to View Community Videos Login to View Community Videos 2018 Orthopaedic Summit Evolving Techniques Ulnar Nerve Transposition With Dehydrated Amnion Membrane - Raffy Mirzayan, MD (OSET 2018) Raffy Mirzayan Hand - Ulnar Tunnel Syndrome 8/23/2019 88 views Upgrade to View Premium Videos Upgrade to View Premium Videos Allen Test Daniel Hatch Hand - Ulnar Tunnel Syndrome 2/21/2013 3966 views Upgrade to View Premium Videos Upgrade to View Premium Videos Guyon's Canal and Carpal Tunnel Release - Dr. Susan Mackinnon Hand - Ulnar Tunnel Syndrome 9/6/2012 631 views Upgrade to View Premium Videos Upgrade to View Premium Videos Release of ulnar deep motor branch in Guyon's canal and carpal tunnel release Michael Hughes Hand - Ulnar Tunnel Syndrome 7/2/2012 3902 views See More See Less