Nerve Compression & Entrapment

Nerves become entrapped where they pass through anatomically narrow spaces — fibro-osseous tunnels, under ligaments, or around bony prominences. 

Contributing factors include:

• Repetitive movements — occupational or recreational activities involving repetitive wrist, elbow, or knee motion
• Sustained postures — prolonged elbow flexion, leg crossing, kneeling, or squatting
• Direct compression — leaning on an elbow, tight clothing or braces, or prolonged pressure from immobilisation
• Anatomical variation — some individuals have naturally narrower tunnels or anomalous muscles
• Systemic conditions — diabetes, hypothyroidism, rheumatoid arthritis, obesity, and pregnancy increase susceptibility to entrapment
• Trauma — fractures, dislocations, or lacerations near the nerve
• Space-occupying lesions — ganglion cysts, lipomas, or other masses within the tunnel

Symptoms depend on the nerve affected and whether the nerve is purely sensory, mixed sensory-motor, or predominantly motor:

Sensory Symptoms

• Numbness — reduced or absent sensation in the nerve's territory
• Tingling (paraesthesia) — pins and needles, often worse at night or with activity
• Burning or electric pain — a characteristic neuropathic quality
• Hypersensitivity (allodynia) — pain from normally non-painful stimuli such as light touch

Motor Symptoms

• Weakness — difficulty with specific movements depending on the nerve affected
• Muscle wasting — visible atrophy of muscles supplied by the nerve in longstanding or severe cases
• Clumsiness or loss of fine motor control

Symptoms are typically confined to the nerve's specific territory — a key diagnostic feature that allows localisation of the entrapment site.

Diagnosis is based on clinical history and examination, with confirmation by nerve conduction studies:

• Clinical examination — detailed neurological assessment of sensation, motor strength, and reflexes in the nerve's territory; provocative tests (Tinel's sign, Phalen's test, elbow flexion test) help localise the entrapment site
• Nerve conduction studies (NCS) and electromyography (EMG) — the gold standard diagnostic tool; objectively confirms nerve compression, localises the level of entrapment, assesses severity, and guides surgical planning; performed by a neurologist or neurophysiologist
• Ultrasound — high-resolution nerve ultrasound demonstrates nerve enlargement at the entrapment site and identifies structural causes such as ganglion cysts or accessory muscles; increasingly used as a first-line adjunct to NCS
• MRI — assesses soft tissue and bony anatomy in detail

It is important to distinguish peripheral nerve entrapment from nerve root compression (radiculopathy from lumbar spine or cervical spine disc disease) and from systemic peripheral neuropathy — conditions that can produce similar symptoms but require entirely different treatment.

Common Nerve Entrapment Syndromes — Treated at One Brain and Spine

One Brain and Spine's Melbourne neurosurgeons assess and treat the full range of peripheral nerve entrapment syndromes, including:

• Carpal tunnel syndrome — median nerve at the wrist; the most common nerve entrapment; causes thumb, index, and middle finger numbness and hand weakness
• Cubital tunnel syndrome (ulnar neuropathy) — ulnar nerve at the elbow; causes ring and little finger numbness and intrinsic hand weakness
• Meralgia paraesthetica — lateral femoral cutaneous nerve at the inguinal ligament; causes outer thigh burning and numbness
• Common peroneal nerve entrapment — common peroneal nerve at the fibular head; causes foot drop and lateral leg numbness
• Thoracic outlet syndrome — brachial plexus compression between the clavicle and first rib; causes arm pain, numbness, and weakness

Treatment Approach

Conservative Management

Many nerve entrapments respond to conservative measures: splinting to rest the nerve, activity modification, treatment of contributing systemic conditions, physiotherapy, and anti-inflammatory medications. These are always trialled first for mild to moderate entrapments.

Corticosteroid Injection

Injection of local anaesthetic and corticosteroid at the entrapment site provides both diagnostic confirmation (immediate symptom relief) and therapeutic benefit, with effects typically lasting weeks to months.

Surgical Decompression

When conservative measures fail, surgical decompression is highly effective. The entrapping structure — ligament, fibrous band, or abnormal tissue — is divided to release the nerve. One Brain and Spine's neurosurgeons offer both endoscopic (minimally invasive) and open decompression techniques depending on the specific nerve and entrapment site. Surgery provides durable, long-term relief in most patients.

Outcomes are best when surgery is performed before significant muscle wasting or permanent nerve injury has occurred — early assessment is important.