With prolonged cellular telephone use, people may note the onset of aching, burning, numbness, or tingling in the ulnar forearm and hand. This constellation of symptoms, termed “cell phone elbow” by the lay press, is known medically as cubital tunnel syndrome—the second most common nerve compression syndrome in the upper extremities after carpal tunnel syndrome.
In most cases, treatment consists simply of modifying the activity and avoiding activities that aggravate the symptoms. Switching hands frequently while talking on the phone or using a hands-free headset can help. Other daily activities that produce cubital tunnel syndrome include leaning on an elbow while driving or working, and sitting at a computer workstation that requires elbow flexion greater than 90 degrees. Making ergonomic adjustments to these activities is beneficial.
For patients who have nocturnal symptoms, a simple elbow pad worn anteriorly or a towel wrapped around the elbow to prevent flexion while sleeping can be very efficacious. Occasionally, anti-inflammatory injections can be given to quiet an inflamed ulnar nerve and reduce symptoms.1 Surgical interventions, discussed below, are available for patients with severe, persistent symptoms.
WHAT IS CUBITAL TUNNEL SYNDROME?
Cellular telephone use has increased exponentially, with 3.3 billion service contracts active worldwide—or about one for every two people on the planet. The exact incidence of cell phone elbow is not known, but anecdotal reports and our own clinical experience indicate that its incidence parallels the rise in the use of cell phones and computer workstations.
Cubital tunnel syndrome is caused by compression of the ulnar nerve as it traverses the posterior elbow, wrapping around the medial condyle of the humerus. When people hold their elbow flexed for a prolonged period, such as when speaking on the phone or sleeping at night, the ulnar nerve is placed in tension; the nerve itself can elongate 4.5 to 8 mm with elbow flexion.2 Additionally, flexion of the elbow narrows the space available for the nerve2 and can cause a sevenfold to 20-fold increase in the pressure within the cubital tunnel, depending on muscle contraction.3 This can be compounded by compression on the nerve, either from various fascial bands surrounding the nerve or from extrinsic sources of compression, such as leaning on one’s elbow while driving or talking. This increased pressure on the nerve leads to decreased blood flow and nerve ischemia; this in turn causes increased permeability of the epineurial vessels and nerve edema, enlarging the nerve and continuing the cycle. Less frequently, cubital tunnel symptoms can be caused by the ulnar nerve subluxing in and out of its groove in the posterior elbow, leading to nerve inflammation and swelling from the repetitive friction.
THE CLINICAL PRESENTATION
The clinical picture of cubital tunnel syndrome consists of numbness or paresthesias in the small and ring fingers. Dorsal ulnar hand numbness, which is not present if the ulnar nerve is compressed at Guyon’s canal, helps the clinician differentiate cubital tunnel nerve compression from distal ulnar nerve compression.
If ulnar nerve compression persists, symptoms may progress to hand fatigue and weakness, including difficulty opening bottles or jars. Chronic and severe compression may lead to permanent motor deficits, including an inability to adduct the small finger (Wartenberg sign) and severe clawing of the ring and small fingers (a hand posture of metacarpophalangeal extension and flexion of the proximal and distal interphalangeal joints due to dysfunction of the ulnar-innervated intrinsic hand musculature). Patients may be unable to grasp things in a key-pinch grip, using a fingertip grip instead (Froment sign).