Cubital Tunnel Syndrome

History: numbness and tingling in the ring and little fingers (ulnar 1.5 digits), often intermittent initially. Worse with elbow flexion - sleeping with elbows bent (the most common aggravator), prolonged phone use, driving, resting elbows on the desk. The hand may feel as though it has fallen asleep at night (distinguish from carpal tunnel, which affects thumb, index, and middle). Grip weakness or dropping objects indicates motor involvement. Difficulty with fine motor tasks (buttons, keys, opening jars) indicates intrinsic hand weakness. In advanced cases, visible wasting of hand muscles. Ask about previous elbow injury, OA symptoms, and coexisting medial epicondylalgia.

Examination:

Sensory: reduced sensation in the ulnar 1.5 digits. The DORSUM of the hand is also affected in cubital tunnel - this distinguishes it from Guyon canal compression where the dorsal cutaneous branch is spared. If medial forearm sensation is also reduced, the lesion is at C8/T1 root or brachial plexus.

Motor: weakness of finger abduction (dorsal interossei) and adduction (palmar interossei), weakness of little finger abduction, positive Froment sign (compensatory thumb IP flexion when gripping paper indicates adductor pollicis weakness), positive Wartenberg sign (little finger abducted at rest indicates weak third palmar interosseous). In advanced cases: visible wasting of first dorsal interosseous and hypothenar, and clawing of the ring and little fingers.

Ulnar claw hand: hyperextension at MCP joints with flexion at IP joints of ring and little fingers. The ulnar paradox: clawing is MORE pronounced in DISTAL lesions (Guyon canal) than proximal (cubital tunnel) because in proximal lesions FDP to the ring and little fingers is also paralysed, preventing IP flexion.

Provocative tests: Tinel test (tapping posterior to the medial epicondyle reproduces tingling into ring and little fingers), elbow flexion test (maximal flexion for 60 seconds; more sensitive than Tinel alone), combined elbow flexion plus compression test (most sensitive combination), scratch collapse test (increasingly used in specialist clinics). Palpate the ulnar nerve during flexion-extension to detect subluxation.

Always assess the cervical spine (C8/T1 radiculopathy can mimic or coexist).

Differentials: C8/T1 cervical radiculopathy; ulnar nerve compression at the wrist (Guyon canal - similar hand symptoms but dorsal hand sensation preserved); thoracic outlet syndrome; medial epicondylalgia (commonly coexists); carpal tunnel syndrome (median nerve distribution, thenar wasting); motor neurone disease (progressive widespread weakness with upper and lower motor neurone signs, no sensory loss - rare but must not be missed).

• •Nerve conduction studies (NCS) and EMG: the main confirmatory test when the diagnosis is uncertain, severity needs quantifying, or surgery is being considered. NCS can be NORMAL in clinically convincing mild cases - a normal study does not exclude the diagnosis
• •Plain radiographs: if there is previous trauma, suspected OA, cubitus valgus, or a bony cause of compression
• •Ultrasound: can show nerve enlargement and dynamic subluxation; increasingly used in UK MSK pathways
• •MRI: not routinely required. For suspected space-occupying lesion or complex surgical planning
• •Bloods: HbA1c (diabetes, double crush), B12 and folate if bilateral or atypical, inflammatory markers if inflammatory arthritis is suspected

Management is driven by McGowan grade.

Grade I (intermittent paraesthesia, no weakness or wasting) - conservative first-line:

• •Education: explain the mechanism (nerve compressed during elbow flexion and direct pressure) and modify aggravating activities
• •Activity modification: avoid prolonged elbow flexion, avoid direct pressure on the medial elbow, modify desk and work tasks
• •Night splinting: an elbow extension splint or rolled-towel wrap to limit prolonged elbow flexion during sleep. A simple rolled towel secured around the elbow is effective and well tolerated. Continue for 3-6 months
• •Neuropathic pain: manage per NICE CG173 if pain is significant. Simple analgesics for any associated medial epicondylalgia

Grade II (measurable weakness without wasting) - trial of conservative management with a lower threshold for referral:

• •As per Grade I. Persistent symptoms despite reasonable conservative trial, especially with progressive motor weakness, should prompt specialist referral. NCS should be arranged

Grade III (intrinsic wasting) - usually requires specialist referral:

• •Established intrinsic wasting represents advanced axonal damage. Conservative management alone is unlikely to reverse it
• •Refer promptly. Surgery aims to halt deterioration; motor recovery may be incomplete

Surgical options (awareness):

• •In situ decompression: release of the cubital tunnel roof. Good outcomes for primary compression without subluxation
• •Anterior transposition (subcutaneous, intramuscular, or submuscular): used when the nerve subluxes, there is bony deformity, or for revision surgery
• •Medial epicondylectomy: less commonly performed
• •No clear superiority of one technique over another for primary cubital tunnel syndrome

Referral:

• •Refer if symptoms persist despite conservative management, especially with motor weakness, any Grade III presentation, or diagnostic uncertainty
• •EXPEDITE if motor weakness is progressing - delayed decompression worsens outcome and intrinsic wasting does not reliably reverse

Activity modification: avoid sustained elbow flexion beyond 90 degrees and direct pressure on the medial elbow. Ergonomic assessment for desk workers.

Night splinting: elbow held in approximately 30 degrees of flexion during sleep. Continue for 3-6 months.

Nerve gliding exercises: gentle ulnar nerve mobilisation (slider and tensioner techniques). Symptom-guided - mild tingling is acceptable but the exercises should not exacerbate.

Strengthening: if intrinsic weakness is present, targeted grip and pinch strengthening once symptoms are improving.

Address coexisting medial epicondylalgia with progressive flexor-pronator loading.

Post-operative: early ROM, nerve gliding from 1-2 weeks, progressive strengthening from 4-6 weeks, return to manual work at 6-12 weeks. Motor recovery may continue for 12-18 months.

Realistic expectations: Grade I usually responds to conservative management. Grade II may require surgery. Grade III motor recovery is often slow and incomplete even after surgery.

• •McGowan classification (modified) - The standard severity framework: Grade I (paraesthesia only), Grade II (weakness without wasting), Grade III (intrinsic wasting). Drives the conservative-vs-surgical threshold.
• •BSSH guidance - Conservative measures first-line for Grades I-II; expedite referral for Grade III or progressive motor signs. UK practice anchor for primary care.
• •NICE CG173 Neuropathic pain - Governs pharmacological management of neuropathic symptoms (amitriptyline, duloxetine, gabapentin, pregabalin) where conservative measures alone are insufficient.
• •Decompression technique trials - Multiple RCTs and meta-analyses have failed to show clear superiority of anterior transposition over simple in situ decompression for primary cubital tunnel syndrome. In situ decompression is favoured for most primary cases.
• •Tardy ulnar nerve palsy - Delayed neuropathy years after a childhood lateral condylar fracture with resulting cubitus valgus. Recognised clinical entity that prompts the previous-elbow-injury history question.

• •Dorsal hand sensation distinguishes cubital tunnel from Guyon canal. The dorsal cutaneous branch arises proximal to the wrist, so dorsum is affected at the elbow but SPARED at the wrist. The single most tested localisation fact. If medial forearm sensation is also reduced, think C8/T1 root or brachial plexus.
• •The ulnar paradox: clawing is WORSE in distal lesions (Guyon canal) than proximal (cubital tunnel) because FDP to the ring and little fingers is also paralysed in proximal lesions, preventing the IP flexion that produces the claw.
• •Froment sign (compensatory thumb IP flexion when gripping paper) = adductor pollicis weakness = ulnar nerve. Wartenberg sign (little finger abducted at rest) = weak third palmar interosseous. Both commonly tested bedside signs.
• •Tardy ulnar nerve palsy describes delayed neuropathy years after a childhood elbow fracture. Always ask about previous elbow injury.
• •Motor neurone disease is the must-not-miss differential - progressive motor wasting WITHOUT sensory loss. A stem describing pure motor signs without sensory deficit should redirect you to MND, not cubital tunnel.
• •McGowan Grade III (intrinsic wasting) signals axonal loss that does not reliably reverse with decompression. Prompt referral when wasting appears is the highest-impact management decision.