Nerve entrapment or entrapment neuropathy constitutes a lesion where the peripheral nerve is compressed externally as it passes a bone, around the long muscles and through the structures of fibrous or rigid tissue.
The imprisonment can be the result of a compression performed by agents outside the body as exercised by the use of very tight clothing, a bad position when sleeping, prolonged contact with hard surfaces, the application of tourniquets and excessive muscle growth per exercise.
It is very common to find this type of ailments when there are previous alterations such as diabetic or alcoholic polyneuropathies, renal failure or acromegaly among others.
Both the direct compression on the nerve and the presence of ischemia (decrease or absence of blood flow) show evidence of the lesion on the nerve fibers.
The severity of the nerve injury depends mainly on the degree of compression exerted and the time (length) of the pressure.
Mild-to-moderate compression temporarily leads to abnormal nerve conduction that may become blocked. There are no anatomical modifications to the nerves, however when the compression is more important invaginations of the myelin layers are observed; this means that there will be no nerve conduction in the area and therefore the limb will not respond as usual.
It is characterised by the following symptoms of a neuropathy:
Motor (involves the mobility of the region):
Paresis or paralysis of the involved limb that may have presented after the passage of nerve conduction has been obstructed.
At the beginning it is possible to preserve the muscular build, but when the neuropathy becomes chronic, there may be a decrease or very little amount of muscle fibers, which makes the muscle very weak or almost disappear.
Sensitive (involves what the patient feels):
There may be any type of sensory disturbances including burning pain, a sensation referred to as "needle pricks", paresthesias (tingling sensation in the affected area), hyperesthesia (increased sensitivity), hypoesthesia (decreased sensitivity) and anesthesia (not feel nothing). However, perhaps the most important symptom is pain.
Absence of reflexes or deep muscular reflex:
There is absence or diminution of the natural reflexes when stimulating the area, in neuropathies.
Signs of hyperexcitability or increased muscle stimulation unconsciously.
Among them the presence of cramps and rarely of fasciculations.
Classification of Neuropathies
The neuropathies are divided depending on the nerve and the injured anatomical site.
- Carpal canal syndrome
- Median nerve syndrome in the supracondylar process of the humerus
- Median nerve syndrome in the elbow and forearm
- Syndrome of the anterior interosseous nerve of the radial nerve
- Syndrome of the posterior interosseous nerve of the radial nerve
- Ulnar tunnel syndrome
- Syndrome of compression of the ulnar nerve of the wrist
- Suprascapular entrapment syndrome
- Syndrome of femorocutaneous nerve of the thigh
- Saphenous nerve syndrome
- Tarsal tunnel syndrome
When the affectation has little time, the symptoms are moderate and intermittent and when the symptoms are expected to be reversible (pregnancy, myxedema), one should opt for a conservative treatment based on non-steroidal anti-inflammatories.
In the case of Median Nerve entrapment, it is not recommended to perform blockages, as the nerve could be injured.
The surgical indications are: failure to medical therapy, a picture with abnormal neurophysiological data, loss of sensitivity and atrophy or weakness.
The procedure is the release of the nerve with the section of ligament or structure that is causing the entrapment, in the case of the median nerve would be the carpal transverse ligament. It is carried out with local anesthesia or general depends on the area to be treated.