Chronic neuropathies include Alcoholic, Nutritional, Leprosy and diabetes.
Chronic alcoholism is important cause of polyneuritis. It occurs in alcoholics whose diet is poor in nutrition and who suffer from impaired absorption of nutrients due to chronic gastritis and chronic alcohol intake. Nerves are also damaged as a result of direct effect of alcohol.
Changes in nervous system are those of degeneration at the peripheral ends and in muscles characteristic of lower motor neurone lesion.
It is a disease of middle aged men who have been addicts to alcohol for a number of years. Sensory disturbances are prominent feature. Patient usually complains of tingling, numbness and paraesthesia in the feet and hands.
Painful cramps in the calf muscles especially at night are distressing and disturb sleep. Sensory loss over the peripheral parts develops and there is weakness of the limbs. Tenderness is maximum in the calf muscles. There is blunting of all types of sensibilities in the periphery of the limbs.
Because of loss of postural sensibility and neuritis, high stepping character of gait develop. Sensory loss which is present in the peripheral parts extends upwards.
Foot drop and wrist drop may result. Tendon reflexes are either diminished or lost (ankle jerks disappearing before knee jerks). Cranial nerves may be involved.
Psychiatric disturbances (Korsakoff’s psychosis) may complicate the picture. Trophic and vasomotor disturbances develop in alcoholic neuropathy of long standing.
Prognosis of alcoholic neuritis shall depend on as to how early treatment is begun.
In severe cases recovery may take several months.
It consists of
(i) Withdrawal of alcohol
(ii) Taking patient away from surroundings
(iii) Institution of good nutritive diet
(iv)Administration of heavy doses of Vit B1, B6 & B12.
Nutritional neuropathies includes cases due to thiamine deficiency (ben-ben), nicotonamide (pellagra) and vitamin B12 deficiency (sub acute combined degeneration of the cord).
These neuropathies generally manifest in chronic form with burning feet, tenderness of calf muscles associated with hyperaresthesia. Both motor and sensory neuropathies occur.
Leprosy caused by Hansen Bacillus is characterized by involvement of cutaneous and peripheral nerves in all forms of the disease. There is a combination of both inflammatory and degenerative changes in large or small nerves. The tuberculoid type of leprosy is characterized by granulomatous changes (leprous module) while in lepromatous form there is non-specific mononuclear response. The infection in nerves usually begins at the periphery and ascends upwards leading to marked irregular thickening. Degenerative and regenerative changes in the axons are observed. Myoneural endings are also effected. Clinically the onset of symptoms is gradual. Irregular patchy anaesthesia due to involvement of fine cutaneous nerve fibres occurs any where in the body.
Sensory nerve involvement may occur selectively in great auricular and long cutaneous nerves. This occurs earlier than motor. In polyneuritic form there is symmetrical anaesthesia of glove and stocking type together with atrophic paralysis of peripheral muscles. Cranial nerve involvement may occur. Mixed nerve trunks (ulnar, median, peroneal, posterior tibial and occasionally radial) involvement may also occur. The nerves are thickened and palpable. Leprous polyneuritis is a progressive illness depending on the pathogenesis of basic disease. It may have to be differentiated from progressive Hypertrophic polyneuritis.