What is cell phone elbow, and what should we tell our patients?
THE DIAGNOSIS IS USUALLY CLINICAL
The diagnosis of cubital tunnel syndrome is first and foremost a clinical one based on a thorough history, including symptoms, duration, and aggravating activities and factors.
The physical examination should include evaluation of sensibility of the hand, including the Semmes-Weinstein monofilament test and vibratory perception test, which will be affected before the Weber two-point discrimination test. Sensibility of the entire hand should be assessed to differentiate focal ulnar deficits from more widespread peripheral neuropathies.
Motor function can be evaluated by asking the patient to hold the fingers abducted, testing key-pinch grip, or asking the patient to cross the middle finger over the index finger. This crossed-finger test is quite reliable, as it is difficult to “fake out” with other muscles.4
The examination should also evaluate the cervical spine and vascularity. Provocative maneuvers can be performed to elicit symptoms, including the Hoffman-Tinel test (tapping the ulnar nerve in its groove at the posterior medial elbow, eliciting electric shocks or tingling radiating into the small finger). The equivalent of the Phalen maneuver for carpal tunnel syndrome can be performed by having the patient sit with the elbow fully flexed for 30 seconds to see if symptoms are reproduced; this may be positive in 10% of normal individuals. 5 One can combine elbow flexion with compression over the proximal ulnar nerve; this maneuver has good sensitivity and specificity. 6 Early in the disease, these provocative maneuvers may be the only examination findings, since sensation and motor function are usually normal.
Ruling out other entities that can cause numbness in the distribution of the medial hand and forearm is also important. These entities include cervical spine conditions such as herniated disk impinging on the C8 nerve root, or a space-occupying lesion of the cervical spine such as a tumor or syrinx.
The neck should be examined for loss of motion. Also, a Spurling test of the cervical spine checks for foraminal nerve impingement: with the patient seated, the clinician extends the patient’s neck and rotates it toward the involved side, then presses down on the top of the patient’s head and asks if this reproduces or worsens the symptoms in the patient’s arm. Hyperreflexia of the upper extremities or the presence of a Hoffman sign should alert the clinician to a more central process. In unclear cases or in patients with known cervical disease, electromyography should be able to differentiate ulnar neuropathy from a C8 nerveroot impingement or confirm the presence of both conditions (a so-called “double crush” phenomenon).
Other less common entities that can present with hand tingling include an apical lung tumor compressing the lower brachial plexus, thoracic outlet syndrome, or peripheral neuropathy (diabetes, vitamin B12 deficiency, hypothyroidism, alcoholism). Other conditions that can cause medial-sided elbow pain include elbow instability or medial epicondylitis (golfer’s elbow); however, these are not associated with numbness or tingling by themselves.
DIAGNOSTIC TESTS
Advanced diagnostic studies may help in certain cases, although they are not essential if the diagnosis is obvious on clinical examination.
Imaging studies may include plain radiography to look for osteophytes or bone fragments, which may impinge on the ulnar nerve, particularly in an arthritic or previously traumatized elbow. Magnetic resonance imaging is only indicated if a space-occupying lesion is suspected. Electrodiagnostic studies may help when findings are equivocal, when the site of compression is unclear, or when coexisting conditions such as diabetes or cervical spine disease make the diagnosis unclear. Nerve conduction studies may be unreliable early in cubital tunnel syndrome, as nondiseased nerve fibers may be tested, creating a false-negative result. Performing the study with the patient’s elbow flexed may increase the sensitivity of the test. Electromyography generally does not become positive until later in the disease, when more profound changes have occurred.
TREATMENT OF CELL PHONE ELBOW
As mentioned, changing how one uses a cell phone often helps, as does avoiding activities that require the elbow to remain flexed more than 90 degrees for extended periods. But when nonoperative means fail to reduce symptoms, surgery may be warranted.
Operative interventions include simple decompression or transposing the nerve from its usual course around the posterior elbow to a path anterior to the elbow, thus decreasing the tension on the nerve. This can be done either subcutaneously or by embedding the nerve in or under the muscles of the forearm.
In patients with coexisting medial epicondylitis or a subluxing nerve, the medial epicondyle can be excised. Techniques for minimally invasive or endoscopic ulnar nerve decompression have been recently introduced, but the long-term results with these are not yet known.
Overall, treatment for persistent paresthesias is successful even when patients present late, but those who present early have a better chance of full sensory and motor recovery.
