Published in Panorama
Who is predisposed to Neuropathy
Two to three weeks after the viral fever had abated, Rajat felt tingling numbness of his lower limbs and also muscle weakness of these limbs. He was diagnosed as having neuropathy, which fortunately was of a temporary nature.
What is neuropathy and who are the individuals affected by it? Neuropathy is a disorder where there is involvement, usually of the peripheral nerves which become inflamed, explains Dr.Sharmila Changkakoti, Physician and Neurologist, Zulekha Hospital, Sharjah. The peripheral nerves consist of the main nerve, the axon and the surrounding myelin sheath, both of which may be involved in neuropathy. Motor, sensory and autonomic nerves may be singly or jointly affected by neuropathy, thus affecting voluntary movements, sensations and involuntary functions, respectively.
Depending on the area or areas of nerve damage, patients may suffer from mononeuropathy or polyneuropathy in addition to suffering from symmetric neuropathy when the disorder occurs in the same places on both sides of the body.
Peripheral neuropathy may be associated with a host of factors amongst which diabetes is a major cause, says Dr.Sharmila. Other predisposing factors to the disorder include nutritional deficiencies, pressure, trauma, leprosy, diseases of the nerves, systemic illnesses, lupus, rheumatoid arthritis, AIDs, penetrating injuries, malignancies, toxins, metabolic disorders, infections, chemotherapeutic agents, hereditary disorders and a certain group of diseases called vasculitis. In some instances of neuropathy, the cause may be unknown.
Whatever the cause, symptoms of neuropathy include weakness, numbness, burning, tickling, pricking or tingling and pain in the arms, hands, legs and feet, explains Dr.Sharmila. The symptoms however, depend on the type of nerves that are affected and on where their location in the body. Typically, when motor nerves are damaged, cramps and muscle weakness are the predominant symptoms. Sometimes, there may also be loss of balance and coordination. On the other hand, sensory nerve damage produce pain, numbness and tingling sensations and the patient may feel as if he or she is wearing some glove or socks and extreme sensitivity to touch.
Abnormal heart rate and blood pressure, intestinal tract disorders with constipation alternating with diarrhoea, involvement of the bladder, impaired sweating, suggest autonomic neuropathy. Usually we get a mixed pattern in which one form of involvement predominates.
Dr.Sharmila adds a word of caution, However, symptoms of numbness, tingling and loss of sensation involving the extremities, need not necessarily imply neuropathy. Neuropathy is like a dying backphenomenon as we call it. That is, it starts from the ends or extremities, at the tips of the fingers, toes and moves upwards.
Neuropathy may sometimes develop secondary to some infection, generally a viral infection, adds Dr.Sharmila. Any simple viral fever could give rise to this form of neuropathy. For instance, an individual may have had some upper respiratory tract infection, cold, cough, et al. Two to three weeks after the infection has gone, the person may have severe neuropathy. The patient cannot move his limbs; he develops tingling numbness and severe muscle weakness of all four limbs to such an extent that even the respiratory muscles are involved and very often we have to put these patients on a respirator. This neuropathy, fortunately, is of a temporary nature and it is self-resolving without the involvement of the respiratory muscles. But where respiratory muscles are involved and the patient requires respiratory support, steps have to be taken immediately to diagnose the condition and give appropriate treatment; else, there is the possibility of losing the patients.
Dr.Sharmila adds, In days when Diphtheria was prevalent, we used to get a lot of this form of neuropathy. Hepatitis B is another infection where we get this form of the disorder.
Sometimes, even after surgery, due to some immunological stress associated with it, we get to see this form of neuropathy. In these instances, neuropathy occurs because of the immunological change that the body undergoes on account of these infections, and not because of the infection-causing organisms themselves.
As regards the progression of neuropathy, Dr.Sharmila reveals that while some neuropathies may develop suddenly, others may progress slowly, even over a number of years. Even the severity of the condition varies among individuals and in the same individual may vary in severity through the day, becoming more severe at night.
One cannot categorise individuals in terms of age as being predisposed to neuropathy since its causes are varying, emphasizes Dr.Sharmila. For example, malignancies and chemo agents are associated with the elderly; metabolic disorders are more common in the middle ages, like hyperthyroidism is a very common cause of neuropathy. Of course, it is sometimes felt that small children and the elderly are more predisposed, but there is no concrete evidence to prove this.
How is neuropathy diagnosed? Clinical examination of the patient is supported by other investigative measures, says Dr.Sharmila. In 80% of cases, I would say clinical examination alone may be sufficient. Clinically, we do muscle testing by flexing and extending the muscles to assess the patients motor power in addition to assessing his reflexes and sensory power. To assess the muscle action potential, Nerve conduction velocity studies are recorded and EMG (Electromyography) is done. Sometimes, in diabetics or patients with hyperthyroidism and other metabolic disorders or vasculitis, the patients may not complain of neuropathy or numbness. But when we do an electro-physiological investigation, we see there is nerve involvement. Also, it is important to determine the cause of neuropathy so as to reduce as quickly as possible, the risk of permanent nerve damage. This may require routine lab tests of blood and urine, EEG, CT Scan and MRI to rule out other disorders or illnesses. When suspect, even a nerve or muscle biopsy may have to be done.
Untreated peripheral neuropathy may result in permanent loss of limbs due to loss of sensation, consequent infection from injury of which the patient is not aware, loss of nerve function, tissue damage, and muscle atrophy, reveals Dr.Sharmila. The patient may become bed-ridden and wheelchair bound.
What is the treatment of neuropathy? Essentially, it is control of risk factors where the cause is known, explains Dr.Sharmila. For instance, if the patient is a diabetic, then control of diabetes is important. Surgery to remove tumor may be the therapy if tumor is the underlying cause. Renal dialysis may improve neuropathy that develops as a result of chronic renal failure. Vitamin supplements, particularly the B Complex group may help in instances of nutritional neuropathy.
To treat the pain from neuropathy, medication in the form of analgesics, anti-depressants and anticonvulsants, injection therapy, and physical therapy may be resorted to. Topical treatment with capsaicin cream may also be used in certain cases, says Dr.Sharmila.
How well a patient responds to treatment for neuropathy, whether the nerve damage can be slowed or reversed, whether the patient recovers fully or partially, depends on how early the condition was diagnosed, the underlying cause, the type of neuropathy and appropriateness of treatment, emphasizes Dr.Sharmila. vessel) deficits. If severely affected, the patient may develop chronic muscular atrophy.
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