Upper extremity neuropathy is commonly encountered in the orthopaedic clinic. In the upper extremity, cubital tunnel syndrome is second in incidence only to carpal tunnel syndrome and is largely dependent upon physical examination for an accurate diagnosis(1). Patients early in presentation often complain of numbness and paresthesia’s in the ring and small finger of the affected extremity. Without treatment, symptoms can progress to atrophy of muscles innervated by the Ulnar Nerve and diminished function of the extremity. This video demonstrates the physical examination of ulnar neuropathy.
Well defined signs of ulnar neuropathy can be evaluated with a thorough history and physical examination and have been well detailed by Goldfarb and Stern et al(3). The most common and readily identifiable signs and tests for Ulnar Neuropathy include: Froment’s Sign, Jeanne’s Sign, Duchenne’s Sign, Wartenberg’s Sign, and First Dorsal Interossei atrophy. High versus low ulnar neuropathy can be also differentiated with physical examination.
The dorsal sensory cutaneous branch of the Ulnar Nerve branches approximately seven centimeters proximal to the wrist crease. Intact sensibility within its distribution confirms a low Ulnar Nerve neuropathy. A high Ulnar Neuropathy must also be differentiated from a C8-T1 radiculopathy with evaluation of dermatomal dysesthesias. Sensory evaluation is completed with evaluation of light moving touch, vibration threshold, pressure threshold with a Semmes-Weinstein monofilament, and with two-point discrimination.
Goldfarb et al. describes asynchronous flexion of the digits as a result of interossei paralysis(3). During digital flexion, the lack of interossei requires the Flexor Digitorum Profundus and Superficialis to supply flexion of the metacarpophalangeal joint. During grip, the digits will flex at the interphalangeal joints before initiating metacarpophalangeal joint flexion resulting in an intrinsic minus deformity. This is responsible for patients difficulty with buttoning shirts and picking up small objects. Grip strength is reported to decrease 50-75% and pinch strength to decrease up to 20% with ulnar neuropathy(3). The following are readily identifiable physical examination findings with ulnar neuropathy:
First Dorsal Interossei Atrophy – This is often the first identifiable indicator of ulnar neuropathy upon initial inspection of an affected hand with marked atrophy of the dorsal first web space.
Froment Sign – Compensatory thumb interphalangeal flexion during attempted thumb adduction. Patients compensate for the loss of the Adductor Pollicis with contraction of the Flexor Pollicis Longus.
Duchenne Sign – Small and ring finger metacarpophalangeal joint hyperextension with proximal and distal interphalangeal joint flexion. Although all interossei muscles are denervated, this posture results from the loss of only the third and fourth lumbricals causing an intrinsic minus posture of the small and ring fingers.
Wartenberg Sign – Small finger abduction with attempted extension. This posture results from and imbalance in adduction and abduction forces on the small finger. The Abductor Digiti Minimi no longer has an opposing force due to loss of the third volar interossei.
References:
Green, David P, and Scott W. Wolfe. Green's Operative Hand Surgery. Philadelphia: Elsevier/Churchill Livingstone, 2011. Print.
Elhassan, B; Steinmann, S. Entrapment Neuropathy of the Ulnar Nerve. J Am Acad Orthop Surg. 2007;15: 672-681.
Goldfarb, C; Stern, P. Low Ulnar Nerve Palsy. J Am Soc Surg Hand. Vol.3;No.1;Feb 2003.
Submitted by: Stephen Hiatt, M.D. and David Carl, D.O. Department of Hand and Upper Extremity Surgery University at Buffalo – State University of New York
