Cubital tunnel syndrome is a condition characterized by the compression or irritation of the ulnar nerve as it passes through a tunnel at the elbow. This nerve, often called the “funny bone,” can become pinched within this narrow passageway. Symptoms commonly include pain, numbness, and tingling, particularly in the ring and little fingers, sometimes radiating up the forearm or into the hand.
The Ulnar Nerve’s Vulnerable Path
The ulnar nerve originates in the neck and extends down the arm, passing through a space at the elbow known as the cubital tunnel. This tunnel is formed by muscle, ligament, and bone, running under a bony prominence on the inner elbow called the medial epicondyle. Its superficial location within this tunnel makes it susceptible to external pressure and irritation. When the elbow bends, the ulnar nerve stretches around the medial epicondyle, which can compress it and reduce its blood supply, contributing to symptoms.
Common Actions and Injuries Leading to Cubital Tunnel Syndrome
Direct causes of cubital tunnel syndrome often involve actions or injuries that put pressure or strain on the ulnar nerve at the elbow. Prolonged or repetitive bending of the elbow can irritate the nerve and hinder its blood flow. This often occurs during activities like extended phone calls, sleeping with bent elbows, or tasks requiring frequent reaching, pulling, or lifting.
Direct pressure on the elbow can also result from leaning on hard surfaces like desks or car armrests. Acute trauma to the elbow, including fractures or dislocations, can damage or compress the ulnar nerve. Sometimes, the ulnar nerve may slide out of its normal position behind the medial epicondyle when the elbow bends, and this repeated movement can irritate the nerve over time.
Underlying Risk Factors and Conditions
Beyond direct actions, predisposing factors and medical conditions can increase an individual’s likelihood of developing cubital tunnel syndrome. Previous elbow injuries, such as fractures or dislocations, can alter the anatomy around the nerve, making it more vulnerable to compression. Similarly, conditions like bone spurs or arthritis in the elbow joint can cause inflammation or structural changes that impinge upon the ulnar nerve.
Swelling or fluid accumulation within the elbow joint can also increase pressure on the nerve. Medical conditions such as diabetes can elevate the risk of nerve problems. Individuals in occupations requiring repetitive elbow movements, like assembly line workers, those performing typing, or baseball pitchers, also face a higher risk due to chronic strain on the ulnar nerve.