Nerve compression syndrome

By: Dr Abdul Haseeb Baktash MS Ortho, Senior consultant OCT 2016

Nerve compression syndromeNerve compression

syndrome or compression neuropathy, also known as entrapment neuropathy, is a medical condition caused by direct pressure on a single nerve. It is known colloquially as a trapped nerve, though this may also refer to nerve root compression (by a herniated disc, for example).

Symptoms Its symptoms include pain, tingling ,

numbness, and muscle weakness. The symptoms affect just one particular part of the body, depending on which nerve is affected. Nerve conduction studies help to confirm the diagnosis. In some cases, surgery may help to relieve the pressure on the nerve, but this does not always relieve all the symptoms.

PathophysiologyExternal pressure reduces flow in the vessels

supplying the nerve with blood (the vasa nervorum). This causes local ischaemia, which has an immediate effect on the ability of the nerve axons to transmit action potentials. As the compression becomes more severe over time, focal demyelination occurs, followed by axonal damage, and finally scarring.

Causes A nerve may be compressed by prolonged or repeated external

force, such as sitting with one's arm over the back of a chair (radial nerve), frequently resting one's elbows on a table (ulnar nerve), or an ill-fitting cast or brace on the leg (peroneal nerve).

Part of the patient's own body can cause the compression, and the term entrapment neuropathy is used particularly in this situation. The offending structure may be a well-defined lesion such as a tumour (for example a lipoma, neurofibroma or metastasis), a ganglion cyst or a haematoma. Alternatively, there may be expansion of the tissues around a nerve in a space where there is little room for this to occur, as is often the case in carpal tunnel syndrome. This may be due to weight gain or peripheral oedema (especially in pregnancy), or to a specific condition such as acromegaly,  hypothyroidism or scleroderma and psoriasis.

Some conditions cause nerves to be particularly susceptible to compression. These include diabetes, in which the blood supply to the nerves is already compromised, rendering the nerve more sensitive to minor degrees of compression.

Diagnosis The symptoms and signs depend on which nerve is affected,

where along its length the nerve is affected, and how severely the nerve is affected. Positive sensory symptoms are usually the earliest to occur, particularly tingling and neuropathic pain, followed or accompanied by reduced sensation or complete numbness. Muscle weakness is usually noticed later, and is often associated with muscle atrophy.

A compression neuropathy can usually be diagnosed confidently on the basis of the symptoms and signs alone. However, nerve conduction studies are helpful in confirming the diagnosis, quantifying the severity, and ruling out involvement of other nerves (suggesting a mononeuritis multiplex or polyneuropathy). A scan is not usually necessary, but may be helpful if a tumour or other local compressive lesion is suspected.

Nerve injury, as a mononeuropathy, may cause similar symptoms to compression neuropathy. This may occasionally cause diagnostic confusion, particularly if the patient does not remember the injury and there are no obvious physical signs to suggest it.

Treatment Conservative splints NSAID, Steroid local steroid injectionsSurgery surgical releases

carpal tunnel syndromeMedian nerve

anterior interosseous syndromeMedian

pronator teres syndromeMedian

ligament of Struthers syndromeMedian

cubital tunnel syndromeUlnar

Guyon's canal syndromeUlnar

radial nerve compressionRadial axilla, spiral groove

posterior interosseous nerve entrapment

Radial posteror interosseous.n

Wartenberg's SyndromeRadial superficial branch

suprascapular nerve entrapmentSuprascapular.n

peroneal nerve compression

Common peroneal.n

tarsal tunnel syndromeTibial.n

meralgia paraestheticalateral cutaneous nerve of thigh

piriformis syndrome sciatic

MORTON’S NEUROMA(INTERDIGITAL NEUROPATHY)

Interdigital.N

THE END