Special tests for ulnar nerve compression include: ● Froment sign : For this test, the patient attempts to hold a piece of paper between the thumb and index finger while the examiner pulls the paper out. The test is positive if the examiner sees compensatory interphalangeal hyperflexion by the flexor pollicis longus (supplied by the anterior interosseous nerve) as a compensation for weakness in the adductor pollicis longus (thumb adductor) (Sharrak & Das, 2023). ● Wartenberg sign : The patient presents with an abduction posturing of the fifth digit due to weakness of the palmar interosseous muscle, which adducts this finger (Sharrak & Das, 2023) Differential diagnosis for ulnar nerve compression includes cubital tunnel syndrome, extensor carpi ulnaris tendonitis, hook of the hamate fracture, and triangular fibrocartilage The radial nerve is a mixed motor and sensory nerve that divides at the elbow into the superficial (sensory) branch and the deep branch (also known as the posterior interosseous nerve [PIN]). In the hand, the superficial (sensory) branch provides sensation to the lateral dorsum of the hand, dorsal thumb, and dorsal proximal aspect of the second to fourth digits. In the hand, the PIN innervates the abductor pollicis longus, extensor pollicis longus, extensor pollicis brevis, and extensor indicis (Sharrak & Das, 2023). Radial nerve compression at the wrist or hand is rare and is referred to as Wartenberg syndrome. It involves the superficial branch of the radial nerve and is caused by trauma to the wrist, such as distal radius fracture or external compression (via handcuffs, bracelets, or a wristwatch). Soft tissue masses, such as lipomas or ganglion cysts, can also compress the radial nerve (Sharrak & Das, 2023). There are no motor deficits with radial nerve compression. Pain is usually the major complaint, although pain, tingling, and/or paresthesias along the dorsolateral aspect of the wrist, hand, and fingers is common. Symptoms are aggravated by repetitive wrist flexion and ulnar deviation. Physical examination should include palpation (for presence of a mass) and sensory testing, including light touch and two-point discrimination of the dorsolateral aspect of the wrist and hand (Sharrak & Das, 2023). Special tests for radial nerve compression include: ● Tinel sign : For this test, the examiner gently taps over the course of the superficial branch of the radial nerve. The test is positive if pain and/or paresthesias are reproduced. ● Dellon test : For this test, the patient actively and forcefully hyperpronates the forearm while flexing and ulnarly deviating the wrist. This test is positive if it reproduces the patient’s pain. Self-Assessment Quiz Question #8 complex tear. Radial nerve Which nerve’s sensory branch provides sensation to the palmar aspect of the medial hand, fifth finger, and medial aspect of the fourth finger? a. Median nerve.
Several special tests can be used to assist in accurately diagnosing carpal tunnel syndrome. ● Tinel sign : For this test, the examiner gently taps on the median nerve at the carpal tunnel. The test is positive if there is a sensation of electrical shock in the median nerve distribution. This test has a sensitivity of 50% and a specificity of 77%. ● Phalen test : For this test, the patient flexes the wrist for 60 seconds. The test is positive if this results in numbness or tingling in the median nerve distribution. This test has a sensitivity of 68% and a specificity of 73%. ● Durkan test or carpal tunnel compression test : For this test, the examiner presses both thumbs over the carpal tunnel and holds pressure there for 30 seconds. This test is positive if it causes onset of pain or numbness and/or tingling in the median nerve distribution. This test has a sensitivity of 87% and a specificity of 90%. ● Flick sign : This sign is a history of awakening with numbness or tingling in the median nerve distribution and shaking the hand to provide relief. At 96% specificity, this test is most specific in the diagnosis of carpal tunnel syndrome. Differential diagnosis for median nerve compression includes anterior interosseous compressive neuropathy, flexor tendonitis, pronator syndrome, and wrist osteoarthritis (Sharrak & Das, 2023). Ulnar nerve The ulnar nerve is a mixed motor and sensory nerve, with the motor branch innervating the hypothenar muscles (abductor digiti minimi, opponens digiti minimi, flexor digiti minimi, palmaris brevis) and the adductor pollicis, the deep head of the flexor pollicis brevis, the two medial lumbricals, and the dorsal and palmar interossei. The sensory branch provides sensation to the palmar aspect of the medial hand, the fifth finger, and the medial aspect of the fourth finger (Sharrak & Das, 2023). Compression of the ulnar nerve (called ulnar tunnel syndrome ) can occur for a variety of reasons. Internal reasons include ganglion formation, lipoma, tumor, and carpal bone fracture. External reasons include use of a screwdriver, bicycle, wheelchair, or walker (Sharrak & Das, 2023). Individuals who perform these activities during their regular occupational activities (e.g., mechanics, construction workers, and bikers) are more at risk. Additionally, the elderly and those who rely on assistive devices for mobility may be at risk as well. Examination for ulnar nerve compression should include the following: ● Inspection for hypothenar or interossei atrophy. ● Inspection for clawing of the fingers. ● Inability to cross the fingers (indicative of weakness in intrinsic hand muscles innervated by the ulnar nerve). ● Palpation of the hand and wrist to determine if there is a mass or tenderness that might indicate a carpal fracture. ● Sensory testing of the palmar fifth digit and ulnar half the fourth digit. ● Motor assessment of distal interphalangeal (DIP) flexion, thumb abduction, and finger extension; grip strength may be diminished from loss of metacarpal–phalangeal flexion strength, and pinch weakness may be present from loss of thumb abduction strength (Sharrak & Das, 2023).
b. Ulnar nerve. c. Radial nerve. d. Musculocutaneous nerve
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