Peripheral neuritis, alcohol

Thiamin deficiency can result in three distinct syndromes a chronic peripheral neuritis, beriberi, which may or may not be associated with heart ilure and edema acute pernicious (fulminating) beriberi (shoshin beriberi), in which heart failure and metabolic abnormalities predominate, without peripheral neuritis and Wernicke s encephalopathy with KorsakofPs psychosis, which is associated especially with alcohol and dmg abuse. The central role of thiamin diphosphate in... 

Classic beri-beri, rarely seen in the United States and Europe, except in alcoholism (P4), is endemic in the Far East because of the prevalent diet of decorticated rice (F6). It occurs in two forms wet beri-beri, characterized by edema and cardiovascular symptoms (G6), and dry beri-beri with peripheral neuritis, paralysis, and atrophy of the muscles. Conditions which may predispose to deficiency by increasing thiamine requirements are pregnancy (see section 2.4), and lactation, hyperthyroidism, malignant disease, febrile conditions, increased muscular activity, high carbohydrate diets, and parenteral administration of glucose solutions. A constant supply of thiamine is required for optimal nutrition because storage in the liver and elsewhere is limited. Thiamine is synthesized by bacteria in the intestinal tract of various animals, but this is not a dependable source for man. 

Disulfiram is used as an adjunct in the management of alcohol dependence. It is contraindicated in patients with a history of cerebrovascular accident, cardiac failure, coronary artery disease, hypertension and psychosis. Side-effects that may be present include initial drowsiness and fatigue, nausea, vomiting, halitosis, reduced libido, psychotic reactions, allergic dermatitis, peripheral neuritis and hepatic cell damage. 

A. Ethambutol is associated with retrobulbar neuritis, resulting in loss of central vision and impaired red-green discrimination. Ethionamide (B) is an analogue of isonicotinic acid and is associated with GI intolerance and peripheral neuropathy, but not the optic neuritis or color vision discrimination problems. Aminosalicylic acid (C) can cause GI irritation and bleeding problems, so caution is required in peptic ulcer patients. It has no neurological side effects. Rifampin (D) is associated with red-orange discoloration of saliva, tears, and urine but not the color vision problems. Isoniazid (E) is associated with peripheral neuritis in chronic alcoholics and malnourished individuals and requires pyridoxine supplements. It is not associated with optic neuritis. 

B (thiamine) Treats peripheral neuritis from alcoholism or beriberi... 

While peripheral neuritis and acute cardiac beriberi with lactic acidosis occur in thiamin deficiency associated with alcohol abuse, the more usual presentation is as the Wernicke—Korsakoff syndrome, due to central nervous system lesions. Initially there is a confused state, Korsakoff s psychosis, which is characterized by confabulation and loss of recent memory, although memory for past events may be unimpaired. Later, clear neurological signs develop — Wernicke s encephalopathy. This is characterized by nystagmus and extraocular palsy. Post-mortem examination shows characteristic brain lesions. 

In its more severe forms thiamine deficiency can present as (1) wet beri-beri with generalized oedema 2md tendency to heart failure, (2) dry beri-beri, a chronic polyneuropathy with degenerative changes in the peripheral nerves, (3) infantile beri-beri, a chronic marasmic state also frequently associated with sudden heart failure, and (4) Wernicke s encephalopathy, which may be seen in chronic alcoholics and may be regarded as a cerebral beri-beri . Less severe states of thiamine deficiency usually manifest themselves as a chronic polyneuropathy. Problems of differential diagnosis from other forms of peripheral neuritis therefore arise, and it is in this connection that studies of pyruvate metabolism may be of help. 

Adverse reactions may include acneiform eruptions allergic dermatitis arthropathy multiple cases of cholestatic and fulminant hepatitis drowsiness fatigue headache hepatotoxicity resembling viral or alcoholic hepatitis impotence metallic or garlic-like aftertaste peripheral neuropathy polyneuritis optic or retrobulbar neuritis restlessness occasional skin eruptions. 

Isoniazid is a structural analogue of pyridoxine and accelerates its excretion, the principal result of which is peripheral neuropathy with numbness and tingling of the feet, motor involvement being less common. Neuropathy is more frequent in slow acetylators, malnourished people, the elderly and those with HIV infection, liver disease and alcoholism. Such patients should receive pyridoxine lOmg/d by mouth, which prevents neuropathy and does not interfere with the therapeutic effect some prefer simply to give pyridoxine to all patients. Other adverse effects include mental disturbances, incoordination, optic neuritis and convulsions. 

In the functioning of peripheral nerves— Thiamin is involved in the functioning of the peripheral nerves. In this role, it has value in the treatment of alcoholic neuritis, the neuritis of pregnancy, and beriberi. 

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