Neurological conditions: Radial Neuropathy

Radial Neuropathy means damage, injury or pathologies of the radial nerve.

It is an important nerve in the upper limb. It originates from a structure of the nervous system called as brachial plexus through its posterior cord. Its roots include c5, c6, c7, c8 & T1. It descends downwards from the brachial plexus, passes through arm pit (axilla), winds around the humerus bone then enters the forearm. It supplies the extensor muscles of the arm, forearm & fingers. Posterior interrosseus nerve is an importat motor branch of radial nerve.

Muscles are supplied by radial nerve by itself;

• Triceps
• ECRL (extensor carpi radialis longus)
• ECRB (extensor carpi radialis brevis)
• Anconeus
• Brachioradialis
• Supinator

Muscles are supplied by radial nerve through its posterior interrosseous branch;

• EDM (Extensor digiti minimi)
• Extensor digitorum
• Extensor indicis
• Extensor carpi ulnaris(ECU)
• Abductor pollicis longus & brevis
• Extensr pollicis longus

The sensory branches of radial nerve supply the posterior aspect of arm, forearm and hand along with other nerves.

Varieties of trauma conditions can damage this nerve. Saturday nerve palsy is the name given for people who sleep on their arm for prolonged period in the same position and precipitate this nerve injury. It is called so because some people after a hectic week go to sleep with heavy alcoholic drink and sleep over their arm fr prolonged period but obviously it can occur on other days too. Crutch injury to the axilla, Fracture of humerus (at the arm), hand cuff injury at the wrist level all can cause damage to this nerve or its branches. Rarely growths like tumors, cysts etc can compress this nerve or its branches along their course.

It may be part of mononeuritis multiplex where multiple nerves are involved in an asymmetric fashion and the cause may be rheumatologic/immunological disorders.

Lead toxicity may present as radial mononeuropathy.

If the main trunk of radial nerve is involved then wrist drop & finger drop or both may be seen, if only posterior interrosseous branch is involved then mostly finger drop is seen. With wrist drop patient is unable to bend the hand upwards at the wrist, with finder drop the fingers cannot be lifted upwards. If the nerve damage is of long duration then atrophy (thinning) of the muscles supplied by this nerve and muscle twitching (fasciculaton) mat be seen.

Depending upon where the lesion is some numbness, tingling sensation, loss of sensation etc may be experienced over the radial nerve supplied skin area, especially the back of the arm, firearm, part of the back of the hand etc.

Diagnosis is made based on typical clinical picture, and an EMG/NCS (electromyography and nerve conduction study) may be needed too. Blood tests and radiological investigations are not routinely required but in certain situations like heavy metal toxicity, vasculitic syndromes they are necessary.

The treatment of Radial Neuropathy will involve;

• Symptomatic care using medications to alleviate the pain, numbness, tingling sensations
• Wrist splint
• Physical therapy
• Occupational therapy
• Rarely surgical interventions etc

If conditions like lead toxicity, vaculitis etc is suspected they are treated appropriately.

A neurologist is frequently involved in the care of Radial Neuropathy patients.