Neuropathy
Neuropathy means a problem with a nerve or nerves, and is usually called peripheral neuropathy because it affects nerves outside the central nervous system. It can affect sensory nerves, producing numbness or tingling (diabetic neuropathy affecting the hands and feet), or motor nerves causing difficulty with movement (Guillain-Barre Syndrome). It may be a problem affecting just one nerve, where the nerve might be trapped (such as the ulnar nerve at the elbow), called a mononeuropathy, or lots of nerves (alcohol abuse), which is a poly neuropathy. The nerve damage may affect the outer sheath, or myelin (some drugs), or the inner part of the fibre, the axon (Vitamin B12 deficiency). Since the peripheral nerves also contain the fibres of the autonomic nervous system this too can be affected, causing symptoms such as postural hypotension (lightheadedness on standing up) and diarrhoea. Since intact nerves are required to maintain the health of muscles, damage to these nerves means that over a period of time the muscles shrink. Any sort of neuropathy may occur in association with an underlying cancer, or as a result of sensitivity to a drug or toxin. The management depends upon the cause. Those neuropathies that are due to underlying disease such as diabetes mellitus may be irreversible. Those due to nerve entrapment may recover if the nerve is freed, but nerve regeneration is a slow process.
There is an inherited neuropathy, called Charcot-Marie-Tooth Disease. Type 1 involves loss of the myelin outer sheath of nerves affecting mainly the muscles of the lower leg, while in Type 2 it’s the middle of the nerves, the axons, which degenerate. Treatment is aimed at preserving function in the lower limb using physiotherapy and appropriate aids.
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