Summary Ulnar Tunnel Syndrome is a compressive neuropathy of the ulnar nerve at the level of the wrist (Guyon's canal), most commonly due to a ganglion cyst. Diagnosis can be made clinically with paresthesias of the small and ring finger with intrinsic weakness with a Tinel's sign over Guyon's canal. Treatment involves a course of conservative management with splinting, and surgical decompression in the presence of a compressive lesion (i.e ganglion) or continued symptoms. Epidemology Incidence less common than cubital tunnel syndrome Risk factors cyclists (also known as handlebar palsy) Etiology 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 Radial border Hook of hamate Zones of Guyon's canal Zone Location 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 3 and 4) 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 Cubital tunnel syndrome compared to ulnar 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 Diagnosis Clinical and EMG/NCS diagnosis confirmed with history, physical exam and EMG/NCS MRI studies used to confirm presense of compressive lesion (i.e ganglion) 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 6 1 2 3 4 5 6 Previous Next Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK Sorry, this question is for PEAK Premium Subscribers only Upgrade to PEAK (OBQ18.119) A 55-year-old patient presents with numbness and tingling in the right small and ring fingers and associated hand weakness. On examination, there is decreased sensation on the volar, ulnar and radial aspect of the small finger and the volar, and ulnar aspect of the ring finger, but the sensation on the dorsum of the hand is preserved. Symptoms are reproduced with pressure over the wrist during flexion. There is weakness of finger adduction and grip strength, but flexor digitorum profundus strength of the ring and small finger remains preserved. The patient denies any previous trauma to the right hand or wrist. What study would most likely identify the causative lesion? QID: 213015 Type & Select Correct Answer 1 MRI of the cervical spine 2% (30/1826) 2 EMG/NCV of the upper extremity 28% (520/1826) 3 MRI of the wrist 64% (1164/1826) 4 Carpal tunnel view radiographs 3% (57/1826) 5 CT and MRI of the elbow 2% (32/1826) L 2 Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 3 Review Tested Concept Review Full Topic (SBQ17SE.6) A 26-year-old male construction worker presents with a six-month history of paresthesias in the small and ring fingers. Physical examination reveals weakness of the first dorsal interosseous muscle. An MRI is demonstrated in Figure A. Which additional finding is characteristic of this pathology? QID: 211171 FIGURES: A Type & Select Correct Answer 1 Abnormal sensation over the dorsal ulnar hand 18% (309/1751) 2 Wartenberg syndrome 17% (293/1751) 3 Inability to flex the thumb interphalangeal joint (IPJ) without flexing the distal IPJ joint of the index finger 4% (73/1751) 4 Thumb and index finger IPJ flexion when attempting to pinch a piece of paper 58% (1024/1751) 5 Inability to flex both the thumb IPJ and index finger IPJ 2% (33/1751) L 4 Question Complexity A Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic (OBQ16.256) A 38-year-old female presents with 8 months of gradual weakness of her right hand. She denies paresthesias, numbness, and pain in the right upper extremity. She has compensatory thumb interphalangeal flexion during key pinch and intact two point discrimination. She has a negative Tinel's sign at the wrist and elbow. Electromyography (EMG) shows normal sensory conduction velocities but delayed motor conduction to the first dorsal interosseous muscle. Figure A and B show MRI images of pre and post contrast, respectively. Ultrasound is shown in Figure C. What is the next best step? QID: 9018 FIGURES: A B C Type & Select Correct Answer 1 Biopsy of the mass 12% (410/3502) 2 Cyst excision 84% (2934/3502) 3 MRI of cervical spine 1% (49/3502) 4 Excision of the hook of hamate 1% (49/3502) 5 Cubital tunnel release 1% (35/3502) L 2 Question Complexity B Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 2 Review Tested Concept Review Full Topic (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? QID: 3225 FIGURES: A Type & Select Correct Answer 1 Accessory head of the FPL 5% (194/3655) 2 Flexor carpi ulnaris 12% (426/3655) 3 Osborne's ligament 19% (699/3655) 4 Ganglion within Guyon's canal 61% (2233/3655) 5 Anconeus epitrochlearis 2% (79/3655) L 3 Question Complexity B Question Importance Select Answer to see Preferred Response SUBMIT RESPONSE 4 Review Tested Concept Review Full Topic
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