A peripheral nerve, or simply nerve is an enclosed, cable-like bundle of many peripheral axons (the long, slender projections of neurons). A nerve provides a common pathway for the electrochemical nerve impulses that are transmitted along each of the axons. Nerves can be damaged due to pressure or trauma, or due to immune attack or toxins or vitamin deficiency (among others).
Below I discuss three common examples of nerve problems. To look at the different causes of numb hands, for example, click here.
To diagnose these nerve problems, nerve conduction studies are the gold standard test.
Different types of peripheral nerve problems include:
Carpal tunnel syndrome
This is a very common disorder, which causes:
- Hand numbness at night– this can include both whole hand numbness or numbness of the outer part of the hand from the thumb to the ring finger
- Tingling or pins and needles of the above area, although radiation the pain as high up as the shoulder is seen
- Worsening of symptoms with gripping activities, such as holding a steering wheel, knitting or holding a telephone
- Wrist pain or discomfort
Diagnosis requires clinical examination as well as nerve conduction studies
Treatment often includes initially a resting hand splint worn at night; else a corticosteroid anti-inflammatory injection into the wrist; else carpal tunnel decompressive surgery.
Ulnar neuropathy
Another type of nerve compression occurs when the ulnar nerve is compressed against the bone of the elbow. This causes numbness, tingling and pain over the little finger and half of the ring finger. More severe injury, which is more common in this than in carpal tunnel syndrome, causes significant weakness and wasting of the muscles of the hand.
The most common cause is direct elbow pressure over hard surfaces, most typically the arms of chairs or cars during driving.
Again, nerve conduction studies are important for diagnosis.
Treatment initially involves strict offloading of the nerve where it is usually compressed against the bone at the elbow.
Peripheral neuropathy
Peripheral neuropathy is a very common condition associated with damage to the peripheral nerves – usually affecting the long nerves in the body, those supplying sensation or movement to the feet. These nerves send an axon (cable that connects the cell body to the feeling) from the spinal column to the feet and are therefore very long and prone to injury, particularly from a toxic or metabolic cause.
The Common symptoms include:
- Numbness and other sensory symptoms (burning, tingling, a painful cold feeling or discomfort), which can start on the feet and ascend upwards. If this becomes severe, then walking or balance can be affected due to insufficient input to the brain of feeling from the feet.
- Weakness of the muscles, particularly of the foot but this can progress
- Autonomic symptoms – changes in skin character making it more prone to crack and be infected
Common causes:
There are numerous causes for a peripheral neuropathy, amongst the most common being:
- Diabetes
- Alcohol
- Numerous other metabolic and hormonal problems, including vitamin deficiencies, abnormal blood proteins et cetera
Diagnosis:
To confirm the presence of a peripheral neuropathy, nerve conduction studies are undertaken to ascertain the degree of nerve damage. It is also demonstrate whether there is damage to the lining of the nerve fibres, called a demyelinating neuropathy which is treated differently.
Treatment:
Apart from addressing the cause, nerve symptoms can be treated with medications, including tricyclic antidepressants and anti-epilepsy medications. These reduce the intensity of nerve pain.
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