Peripheral nerves carry sensation from the exterior to the brain. They are part of a very efficient foolproof circuit where even a wisp of hair touching the foot can be perceived by the individual in less than a fraction of a second. Damage to any one or more of these nerves occurs in peripheral neuropathy. These nerves can be damaged by various causes, resulting in altered or impaired sensations or loss of sensation.
Altered sensations can be in the form of tingling, sensation of insects crawling, burning pain, cramps, etc. When feet are affected, while walking, one feels as if they are walking on wool. Impaired sensation becomes a source of trauma to the hands and feet as the affected person is not able to feel pain and, hence is not able to withdraw the limb while encountering a sharp object or something hot or harmful.
The site of the problem depends on the nerve or nerves affected. A single nerve may be affected causing loss of sensation and or paralysis. A classic example is while sleeping in a stupor over a chair with an arm hanging over it, the individual may wake up to find one hand paralysed.
Peripheral neuropathy can be due to many reasons. Diabetic patients are very vulnerable to developing it as high blood glucose damages the peripheral nerve fibres. It is one of the main reasons for the development of diabetic foot. Here, due to peripheral neuropathy, a person has repeated trauma and infections that can result in deformities of the feet in severe cases.
Chronic vitamin B. complex deficiency, particularly B1 (thiamine), B6 (pyridoxine), and B12 (cobalamin) results in peripheral neuropathy. Alcohol depletes the vitamin B. complex of the body and is also toxic to the peripheral nerves.
People consuming alcohol can develop features of damage to peripheral nerves which increases in severity as consumption continues. It is one of the manifestations of chronic liver and kidney diseases.
Infectious diseases like herpes zoster, HIV, and leprosy cause inflammation and damage to the peripheral nerves resulting in chronic disability.
Some drugs also cause peripheral neuropathy. Antibiotics like ciprofloxacin, anti-tubercular drugs like isoniazid, metronidazole used for intestinal protozoal infections, etc. are some of the drugs that can cause peripheral neuropathy as adverse effects. Withdrawal of the offending drug helps in the improvement of the symptoms. Radiation therapy and chemotherapy used to treat any malignancy can damage the peripheral nerves along with malignant cells resulting in abnormal or impaired sensations.
Desk workers, people using computers for long hours, become prone to developing peripheral neuropathy.
Exposure to chemicals like mercury, lead, arsenic, and thallium in industrial settings results in peripheral neuropathy in the workers. Insecticides also contain chemicals leading to damage to nerves. Workers dealing with them on a daily basis are the ones who are most affected.
Chemicals toxic to the nerves like mercury and arsenic are also present in certain herbal products. People use these products innocently considering them to be a safe alternative to modern medicine which does produce some secondary effects.
Inadvertently, they suffer from peripheral neuropathy. It is troublesome when one has abnormal or reduced sensations anywhere in the body. Often, sleep is disturbed due to a burning sensation in the hands and or feet. Due to severe paresthesias, a person finds it difficult to work or even walk at times.
Taking a nutritious diet rich in vitamin B. complex helps to prevent neuropathy due to vitamin B. complex deficiency. It also helps to minimise the suffering due to peripheral nerve damage. Such a diet should include whole grains, cereals, nuts, red meat, and more.
Those who suffer from diabetes need to keep blood glucose levels well controlled by means of diet and drugs to avoid peripheral neuropathy. Neuropathy, if treated early, is reversible in diabetic patients. Alcohol and tobacco are best avoided.
Treatment consists of drugs that provide symptomatic relief for troublesome neuropathy. Supplements of vitamin B. complex are also given sometimes.
Whenever a person develops recurrent or persistent altered sensations in the limbs or any part of the body, they should seek medical treatment before the problem is aggravated.
Dr Rachna Pande is a specialist in internal medicine.