Ulnar neuropathy (cubital tunnel syndrome and Guyon canal)
Ulnar neuropathy is compression of the ulnar nerve (C8-T1), most often at the elbow in the cubital tunnel and less often at the wrist in Guyon canal, causing numbness of the fourth and fifth fingers and, when severe, intrinsic hand weakness, hypothenar atrophy, and an ulnar claw. Diagnosis is clinical with nerve conduction studies and EMG for confirmation, and treatment is avoidance of pressure, splinting, and short-term NSAIDs, with surgical decompression for progressive weakness or persistent symptoms.
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What this article covers
- Overview
Ulnar neuropathy is a compressive mononeuropathy of the ulnar nerve (C8-T1), the second most common upper extremity entrapment after median neuropathy at the wrist.
- Epidemiology
Second most frequent upper extremity nerve compression: median, ulnar, and radial nerve compressions occur in that order of frequency.
- Risk factors
Prolonged or habitual elbow leaning, such as resting the elbow on a desk, the most common cause at the elbow.
- Pathophysiology
Course at the elbow: the nerve runs posterior to the medial epicondyle through the cubital tunnel, whose roof is the cubital tunnel retinaculum (Osborne ligament) between the medial epicondyle and…
- Clinical features
Hallmark: paresthesia and numbness of the little finger and ulnar half of the ring finger.
- Differential diagnosis
Pancoast (superior sulcus) tumor: shoulder and arm pain in the C8-T2 distribution with hand weakness and ipsilateral Horner syndrome; obtain chest imaging (see lung cancer).
- Diagnosis
The diagnosis is established clinically and confirmed by electrodiagnosis: sensory loss confined to the little finger and ulnar half of the ring finger, with or without ulnar-innervated weakness and…
- Management
First, remove the compression: stop leaning on the elbow, pad the elbow, avoid prolonged elbow flexion, and for Guyon canal syndrome pad handlebars, change grip often, and limit constant hand-tool use.
- Complications
Permanent intrinsic hand weakness and hypothenar atrophy, with loss of grip and fine motor control, when compression continues.
- Prognosis
Severity at presentation sets the course: paresthesia alone reflects milder disease, whereas weakness and atrophy of intrinsic hand muscles mark severe disease and the threshold for decompression.
- Prevention
Avoid sustained elbow pressure and flexion: no leaning on the elbow at a desk or in a vehicle, and keep the elbow from sustained flexion during sleep.
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