EMReports | All Hand Numbness Isn't Carpal Tunnel

All Hand Numbness Isn't Carpal Tunnel

Larry Mellick, MD, MS, FAAP, FACEP
Professor of Emergency Medicine and Pediatrics
Medical College of Georgia
Augusta

Pearl: Just as the median nerve can become entrapped at the wrist and cause carpal tunnel syndrome, the ulnar nerve can be impinged with associated symptoms.

Presentation: A 30-year-old woman presented to the emergency department complaining of discomfort in her right arm and hand for nine days. She reported numbness on the ulnar aspect of her hand and pain that began in her right elbow. This discomfort was present after waking up one morning. She self-treated with ibuprofen 800 mg three times per day without relief. She worked as a certified nursing assistant. On examination of that extremity, the patient reported numbness over the fourth and fifth fingers of the right hand and pain with palpation over the ulnar nerve canal at the medial elbow. She also demonstrated a positive Tinel's sign with tapping over the ulnar nerve. Her cervical examination was unremarkable.

She was given a referral to sports medicine, continued on high doses of nonsteroidal anti-inflammatory drugs, and instructed to use nocturnal splinting of the elbow.¹

Diagnosis: Cubital tunnel syndrome

Case Two: A 30-year-old woman presented with numbness of her fourth and fifth fingers after being kicked violently on the wrist twice. The patient had redness and discoloration on the ulnar aspect of her left wrist. (See Figure 1.) On further examination, the patient had numbness of the hand in the ulnar nerve distribution with involvement of the fourth and fifth fingers. Tapping over the ulnar nerve at the wrist reproduced tingling in the fingers in the ulnar sensory distribution. Radiographs demonstrated no fractures. Her wrist was splinted, and she was given a prescription for ibuprofen 800 mg to be taken with food three times per day. She also was given a consult to follow up with orthopedics.

Diagnosis: Guyon's tunnel syndrome

Discussion: Both of these patients were experiencing ulnar neuropathy. The cubital tunnel was the location of the ulnar nerve entrapment for the first patient, and the second patient's ulnar nerve compression occurred at Guyon's tunnel.

Ulnar neuropathy at the elbow is very common. In fact, it is the second most common entrapment neuropathy of the upper extremity. The presentation ranges from sensory loss and paresthesias over digits 4 and 5 to interosseous muscle weakness in the hand and noted changes in hand grip. With complete loss of the nerve innervations, one will see clawing of these digits ("benediction sign") and atrophy of the intrinsic muscles. Besides weakness (difficulty opening jars or turning door knobs) and paresthesias, a Tinel's sign may be present and reproduced by tapping over the nerve. While it is tempting to simply attribute symptoms to just entrapment in the cubital tunnel (see Figure 2), one source described five different locations for entrapment.² Even though provocative testing (Tinel's test, flexion compression test, palpating for local ulnar nerve tenderness and nerve thickening) is recommended, the sensitivity and specificity of these tests may be poor. At least one study demonstrated their clinical usefulness to be limited.³

Treatment options include NSAIDs, education concerning resting one's body weight on the elbow, elbow extension splinting, and analysis of workplace ergonomics. For chronic or recurrent pain, anticonvulsants such as gabapentin (Neurontin), pregabalin (Lyrica), and others can be used. Surgical release is indicated if other therapeutic modalities are unsuccessful.

The ulnar nerve travels through a tunnel at the wrist called Guyon's canal. Just as with carpal tunnel syndrome and the median nerve, compression of the ulnar nerve can occur at the wrist. The clinical presentation is very similar to that seen with compression of the ulnar nerve at the elbow. The second patient most likely experienced significant soft-tissue trauma and swelling that caused compression of the ulnar nerve following direct blows to the wrist.

References:

Seror P. Nocturnal orthosis: A new treatment of compression of the ulnar nerve at the elbow. 30 cases. Rev Neurol ( Paris) 1994;150:721-727.
Posner MA. Compressive ulnar neuropathies at the elbow: I. Etiology and diagnosis. J Am Acad Orthop Surg 1998;6:282-288.
Beekman R, Schreuder T, Rozeman S, et al. The diagnostic value of provocative clinical tests in ulnar neuropathy at the elbow is marginal. J Neurol Neurosurg Psychiatry 2009 Jun 23.

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