Radial nerve entrapment is a condition where the radial nerve becomes compressed or irritated along its course through the upper arm, elbow, or forearm. The radial nerve is responsible for supplying the muscles that extend the wrist and fingers, and also provides sensation to parts of the back of the hand. When the radial nerve is compressed, patients may experience pain, weakness, or altered sensation, which can mimic other musculoskeletal or neurological conditions. Radial nerve entrapment is common among athletes and active individuals, as it can lead to functional limitations, especially in sports that require grip strength, wrist stability, or repetitive arm movements.

Anatomy of the Radial Nerve

The radial nerve is a branch of the brachial plexus that passes on the outside of the arm. The nerve splits into two branches at the elbow joint: the superficial radial branch and the posterior interosseous nerve (PIN) branch. The PIN supplies the triceps, supinator, brachioradialis, and wrist and hand extensor muscles. The radial nerve also supplies the skin over the back of the arm and forearm, and the dorsal thumb, index, and middle fingers.

Trapping can occur at various sites:

  • Humerus: The radial nerve is often injured by humeral shaft fractures. Other causes of compression include tumours, triceps muscle hypertrophy in body builders or fibrosis at the lateral intermuscular septum.

Symptoms of Radial Nerve Entrapment

The symptoms of radial nerve entrapment vary depending on the exact site of compression.

The most common features include forearm pain, particularly on the outer (lateral) side near the elbow. Patients often describe a deep, aching discomfort that may worsen with repetitive use or resisted forearm movements. Weakness in wrist and finger extension is another key feature, which can lead to a characteristic “wrist drop” in severe cases. Sensory changes may occur along the back of the hand and forearm, including numbness, tingling, or burning. However, unlike carpal tunnel syndrome, the palm is not typically affected because the radial nerve does not supply this region.

Clinical Presentation

On clinical examination, patients with radial nerve entrapment often show the following:

  • Tenderness over the supinator muscle or the lateral aspect of the elbow.
  • Resisted supination or extension of the wrist may reproduce pain.
  • In some cases, there is visible weakness in wrist extension, and the fingers may not extend fully against resistance.
  • Sensory testing can reveal decreased sensation over the dorsum of the hand, particularly between the thumb and index finger.
  • Neck movements do not reproduce the symptoms, which helps differentiate radial nerve entrapment from cervical radiculopathy. 
injury to nerves of the hand including superficial branch of radial nerve

Investigations

Generally, investigations are useful for confirming the diagnosis and excluding other causes of pain, weakness, and numbness.

  • Nerve conduction studies and electromyography (EMG) are the gold standard for diagnosing radial nerve entrapment. They demonstrate slowed conduction or denervation in the affected muscles.

  • Ultrasound can visualise the radial nerve and identify sites of compression, swelling, or entrapment within the supinator tunnel.

  • MRI of the elbow and forearm may be used to assess soft-tissue structures, detect scarring, or rule out other causes, such as tumours, ganglion cysts, or muscle hypertrophy compressing the nerve.

  • X-rays are sometimes performed to exclude associated fractures or bony abnormalities following trauma.

Treatment of Radial Nerve Entrapment

Generally, most cases of radial nerve entrapment respond well to non-surgical management. 

Initial treatment focuses on reducing nerve compression and inflammation. Rest and modification of activities that aggravate symptoms are often recommended. Non-steroidal anti-inflammatory drugs (NSAIDs) or nerve medications (amitriptyline or duloxetine) can help reduce pain and swelling. Physiotherapy plays a key role in improving flexibility and correcting biomechanics around the elbow and wrist.

Ultrasound-guided injections of corticosteroid and local anaesthetic around the site of entrapment may relieve pain and reduce inflammation in selected cases. Sometimes, nerve hydrodissection is helpful. If symptoms persist beyond several months despite conservative measures, surgical decompression of the radial nerve may be considered. This involves releasing structures that compress the nerve, such as the supinator muscle in radial tunnel syndrome or scar tissue around the humerus. 

Final Word from Sportdoctorlondon about Radial Nerve Entrapment

Radial nerve entrapment is an uncommon but disabling condition that presents with forearm pain, weakness in wrist and finger extension, and sensory changes over the dorsum of the hand. Clinical assessment, nerve conduction studies, and imaging are all critical for diagnosing the condition. Most cases improve with activity modification, physiotherapy, and, occasionally, a corticosteroid injection, but surgery may be necessary for persistent or severe compression of the radial nerve.

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