Cubital Tunnel Syndrome is a condition defined by the compression or irritation of the ulnar nerve as it passes through a narrow passageway on the inside of the elbow. This nerve is commonly known as the “funny bone” because of the tingling sensation felt when it is bumped. Diagnosis confirms the location of the nerve entrapment and differentiates it from other issues, such as a pinched nerve in the neck or compression at the wrist. The ulnar nerve travels down the arm, supplying sensation to part of the hand and controlling several small hand muscles. When compressed at the elbow, the nerve’s function is disrupted, leading to uncomfortable symptoms that signal the need for professional evaluation.
Symptoms That Prompt Professional Evaluation
Sensory changes are the most common initial symptoms of ulnar nerve compression at the elbow. These manifest as numbness and tingling, often described as “pins and needles,” specifically in the little finger and the adjacent half of the ring finger. These sensations are often intermittent, frequently occurring when the elbow is bent for extended periods, such as while sleeping, driving, or holding a phone.
Aching pain is usually felt on the inside of the elbow, but motor symptoms in the hand may develop as the condition progresses. This can lead to decreased grip strength, difficulty coordinating fine finger movements, and a general feeling of clumsiness. In severe cases, a doctor may observe visible muscle wasting, or atrophy, in the small muscles of the hand, particularly between the thumb and index finger, signaling advanced nerve damage.
Clinical Physical Examination Procedures
The clinician begins with a physical examination to pinpoint the location of the compression. One common initial test is the Tinel’s sign, where the doctor lightly taps the ulnar nerve directly over the cubital tunnel on the inside of the elbow. A positive result occurs if this tapping reproduces the patient’s characteristic tingling or a shock-like sensation radiating down into the ring and little fingers.
Another provocative test is the Elbow Flexion Test, which involves asking the patient to fully bend the elbow and maintain this position for up to 60 seconds. This maneuver temporarily narrows the space around the ulnar nerve; if the patient reports increased numbness and tingling, the test is positive. The doctor also performs a detailed sensory assessment, checking for reduced sensation within the ulnar nerve’s distribution in the hand. Muscle strength is manually tested, focusing on the grip and the ability to spread and pinch the fingers, as weakness indicates nerve impairment.
Specialized Diagnostic Testing Methods
If the clinical examination suggests cubital tunnel syndrome, specialized electrodiagnostic tests are ordered to confirm the diagnosis and determine the severity of nerve damage. The Nerve Conduction Velocity (NCV) study measures how quickly electrical signals travel along the ulnar nerve. Electrodes are placed along the arm, and a small electrical impulse is sent through the nerve.
A significant slowing of the nerve signal’s speed as it crosses the elbow, often below 50 meters per second, indicates compression at the cubital tunnel. Comparing the conduction speed across the elbow segment with the forearm segment precisely localizes the area of entrapment. Electromyography (EMG) often accompanies the NCV study and involves inserting a fine needle electrode into the muscles supplied by the ulnar nerve to assess electrical activity.
The EMG helps identify chronic nerve damage by revealing abnormal spontaneous activity or reduced recruitment of motor units, signifying the muscle is not receiving proper signals. Imaging studies like X-rays or Magnetic Resonance Imaging (MRI) may also be used, though less frequently, to rule out other causes of compression. An X-ray can show bony abnormalities, such as bone spurs or arthritis, while an MRI or ultrasound can visualize soft tissue masses or nerve swelling.
Interpreting Results and Next Steps
The results from the clinical examination and specialized tests determine the nerve’s health and the extent of compression. Cubital tunnel syndrome is categorized by severity—mild, moderate, or severe—based on electrodiagnostic findings and motor weakness. For example, a motor nerve conduction velocity greater than 40 meters per second across the elbow is typically considered a mild case.
For patients with mild symptoms and minimal nerve slowing, the initial recommendation is non-surgical, or conservative, management. This includes activity modification, avoiding prolonged elbow flexion, using a brace or splint at night, and taking anti-inflammatory medications. If testing confirms moderate to severe compression, or if conservative treatments fail to improve symptoms over several months, surgical intervention may be considered. Surgery aims to relieve pressure on the ulnar nerve, either by releasing tight tissues or by physically moving the nerve to a less constricted location.