Cubital Tunnel Syndrome

Cubital tunnel syndrome is the second most common nerve compression syndrome in the arm, after carpal tunnel syndrome. It occurs when the ulnar nerve is compressed or stretched as it passes behind the medial epicondyle, causing numbness, tingling, and weakness in the hand.

The Ulnar Nerve and Cubital Tunnel

The ulnar nerve travels from the neck, down the inner arm, and passes through a tight fibrous tunnel directly behind the medial epicondyle, the bony inner point of the elbow ('funny bone'). When the elbow is bent, this tunnel narrows by up to 55% and the nerve is stretched up to 8mm, explaining why symptoms are worst at night or when the elbow is held flexed. The ulnar nerve controls sensation in the ring and little fingers and powers many small muscles of the hand.

Sites of Compression

1. Arcade of Struthers

A fascial band approximately 8 cm above the medial epicondyle. An occasional proximal compression point.

2. Cubital tunnel (most common)

The nerve is compressed beneath the cubital tunnel retinaculum as it passes directly behind the medial epicondyle. The most frequent site of compression.

3. FCU Arcade

The fibrous arch between the two heads of flexor carpi ulnaris, just distal to the medial epicondyle. A second common compression point.

Severity Grades (McGowan Classification)

Grade I: Mild

Intermittent tingling in ring and little fingers when elbow is bent. Fully resolves with position change. No weakness or wasting. Normal or mildly slowed NCS.

Grade II: Moderate

Persistent numbness most of the time. Early weakness in grip and pinch. Beginning of intrinsic muscle wasting. Definite slowing on nerve conduction studies.

Grade III: Severe

Constant numbness. Marked weakness. Visible muscle wasting and clawing of ring and little fingers. Positive Froment's sign. Severe changes on NCS/EMG.

Symptoms

  • Numbness and tingling in the ring and little fingers - classic ulnar nerve territory

  • Symptoms worst when sleeping with elbow bent, or holding a phone to the ear

  • Weak grip and pinch - difficulty buttoning shirts, holding keys, fine motor tasks

  • Clawing of the ring and little fingers in severe cases, a sign of intrinsic muscle wasting

⚠ Clawing of the fingers, wasting of the small hand muscles, or a positive Froment's sign indicate advanced compression, seek prompt specialist review. Prolonged severe compression can cause permanent muscle weakness that does not fully recover even after successful surgery.

Treatment

Positional advice and elbow padding

Avoid sustained elbow flexion and direct pressure on the inner elbow. A soft night splint keeping the elbow at ~45° prevents sustained stretch of the nerve during sleep, often produces significant improvement in mild cases within days.

1

Nerve gliding exercises

Gentle ulnar nerve mobilisation exercises improve nerve movement through the cubital tunnel and reduce intraneural adhesions. Performed slowly within comfortable range, vigorous stretching worsens nerve irritation.

2

Surgical decompression of the nerve

Recommended for moderate-to-severe cases, or mild cases failing 3-6 months of conservative management. Two main options: in situ decompression (release of the retinaculum) or anterior transposition (moving the nerve to the front of the elbow).

3

Simple decompression

The roof of the cubital tunnel (retinaculum) is released to relieve pressure. The nerve remains in its original position. Day-case procedure. Preferred when the nerve does not sublux over the epicondyle.

Ulnar nerve transposition

The nerve is moved anterior to the epicondyle (subcutaneous or submuscular). Eliminates stretch with elbow flexion. Used when the nerve is unstable, or in revision surgery.

RECOVERY AFTER SURGERY

  • Small wound dressing. Immediate active elbow movement is encouraged. Most patients experience relief of tingling immediately, though full nerve recovery takes longer.

  • Sutures removed at 2 weeks. Nerve gliding exercises resume. Return to light desk work typically within 2 weeks.

  • Progressive return to manual activity and sport. Grip strength improving. Sensory symptoms continue to resolve at approximately 1mm per day.

  • Full sensory and motor recovery. Patients with severe pre-operative wasting may have incomplete recovery, emphasising the importance of early referral.

The rate of nerve recovery is approximately 1mm per day. From the cubital tunnel to the little fingertip is roughly 500-600mm, meaning full sensory recovery can take 12-18 months even after successful decompression.

FREQUENTLY ASKED QUESTIONS

  • No. Carpal tunnel affects the median nerve at the wrist, numbness in the thumb, index, and middle fingers. Cubital tunnel affects the ulnar nerve at the elbow, numbness in the ring and little fingers. Different nerves, different sites, different treatments.

  • In mild-to-moderate cases, full sensory recovery is expected after successful decompression, though it takes time. In severe cases with significant pre-operative wasting, some permanent deficit may remain. Early intervention before wasting develops produces significantly better outcomes.

  • Most people sleep with their elbows bent, which narrows the cubital tunnel and stretches the ulnar nerve for prolonged periods overnight. A simple elbow splint preventing full flexion can produce significant improvement in night symptoms within days of starting use.

This guide is intended for patient education purposes and does not replace a formal surgical consultation. Treatment decisions are always individualised based on your specific history, examination findings, and imaging. Please discuss your symptoms and management plan directly with your orthopaedic surgeon.