alcohol and the nervous system

ALCOHOL AND THE NERVOUS SYSTEM

DR M KAKAZA

COMMON COMPLICATIONS

• Nutritional deficiency• Diseases partly nutritional in origin• Direct effects of alcohol• Abnormalities of electrolytes and osmolality• Diseases of uncertain pathogenesis

A. Nutritional Complications

• Wernicke’s Encephalopathy• Korsakoff’s syndrome• Pellagra

1. Wernicke’s Encephalopathy

• Clinical features include:•Confusion•Opthalmoplegia•Ataxia

• MRI features: ( T2, Diffusion-weighted and FLAIR)Signal changes in periaqueductal gray matter, medial thalami and mamillary bodies

Wernicke’s Encephalopathy….

• Treatment:– Thiamine 100mg ivi stat then daily throughout

the acute stageNB alcoholics may have poor intestinal absorption

Wernicke’s Encephalopathy….

• Other causes:– Hyperemesis of pregnancy– Systemic malignancy– GIT surgery– Prolonged iv feeding– Re-feeding after prolonged fast– Anorexia nervosa– Dieting and gastric plication– AIDS

2. Korsakoff’s Syndrome

• Russian Psychiatrist• Wernicke and Korsakoff’s syndrome are

different stages of the same disease process.• Korsakoff’s follows Wernicke’s and tends to

appear as ocular symptoms and encephalopathy improve

Korsakoff’s syndrome….

• Memory is impaired out of proportion to other cognitive functions – Amnestic syndrome

• Have inability to form new memory

Korsakoff’s Syndrome….

•Clinical features:•Memory loss•Confabulation•Alertness, attention, social behavior intact

•Localization of the lesion•Diencephalon•Temporal lobes

3. Pellagra• Due to Nicotinic acid deficiency• From Italian ‘pelle agra’ which means ‘dry

skin’• Nicotinic acid is converted to NAD and NADP • NAD and NADP are coenzymes required in the

metabolism of carbohydrates

Pellagra…..

• Clinical triad:–Dementia–Dermatitis–Diarrhea

Pellagra….

• Communities that depend on corn for their diet can suffer from pellagra.

• Corn lacks tryptophan, a precursor that can be converted to nicotinic acid in the body.

Pellagra….

• Bread is now enriched with niacin• Treatment:–Nicotinic acid ivi 25mg bd or tds

B. Direct Effects of Alcohol

• Acute intoxication• Fetal alcohol syndrome• Alcohol withdrawal seizures• Delirium tremens

Stages of acute alcohol intoxication

BLOOD LEVEL• 0.01 – 0.05• 0.03-0.12• 0.09-0.25• 0.18-0.30• 0.25-0.40• 0.35-0.50• 0.45+

STAGESubclinicalEuphoriaExcitementConfusionStuporComaDeath

C. Abnormalities of Serum Electrolytes and osmolality

• Hyponatremia• Hypocalcemia• Hypomagnesemia• Hypophosphatemia

Central pontine myelinolysis

D. Diseases at least partly nutritional in origin

• Alcoholic neuropathy• Amblyopia

1 Alcoholic Neuropathy

• Most common complication• Distal symmetrical polyneuropathy• Mixed sensory motor disorder• Pathology – Axonal loss• Pathogenesis:– Direct alcohol neurotoxicity– Thiamine deficiency

2. Amblyopia

• Vision loss caused by a selective lesion of the optic nerves

• History – chronic alcoholic, poor dietary intake, loss of weight

• Most likely due to nutritional deficiency• Treatment – Good nutrition , B vitamins• Prognosis – Improves on treatment (despite

continued drinking)

E. Diseases of uncertain pathogenesis

• Alcoholic myopathy• Alcoholic dementia• Cerebellar degeneration• Marchiafava-Bignami Syndrome

1. Cerebellar Degeneration

• Associated with long-standing use of alcohol• Patients often have neuropathy as well• Presentation –Progressive unsteadiness of gait– Trunkal ataxia

Cerebellar Degeneration….

•Pathological changes:•Selective atrophy of the anterior and

superior parts of the vermis

•Histological changes:•Purkinje’s cells most severely affected

4. Marchiafava-Bignami Syndrome

• Italian pathologists • Described in 1903

• Clinical picture difficultMental slowing, Motor slowing, Personality or behaviour changes, Incontinence, Seizures, Dysarthria and hemiparesis

Marchiafava-Bignami Syndrome….

• Patholological changes:– Selective demyelination of the corpus

callosum