Metabolic and toxic influences on neurological tissue

Question 1

What is pH is normal blood, acidosis, alkalosis?

Answer 1

Normal: 7.35-7.45

Acidosis: < 7.35

Alkalosis: > 7.45

Question 2

What are the consequences of acidosis, and then of alkalosis?

Answer 2

Acidosis: depression of synaptic transmission -> CNS function depression

Alkalosis: over-excitability in all nerves -> AP formed in minimal stimuli

Question 3

What are the causes of acidosis? and of alkalosis?

Answer 3

Acidosis:
• metabolic - diabetic ketoacidosis, renal failure, diarrhoea
• respiratory - resp failure

Alkalosis:
• metabolic - prolonged vomiting
• respiratory -hyperventilation

Question 4

What are the effects of anaemia on the nervous system? and of pernicious anaemia?

Answer 4

If severe anaemia:
• hypoxia (especially if combined with cerebrovascular disease)

Pernicious: low B12
• progressive degeneration of post. and lat. columns of spinal cord
• maybe degeneration of peripheral nerves (posterolateral sclerosis)

Question 5

What are the effects of polycythaemia vera on the nervous system?

Answer 5

increased blood viscosity -> thrombosis -> ischaemic stroke

Question 6

What are the effects of lymphoma on the nervous system?

Answer 6

Significant neurological complications:
• herpes zoster
• spinal cord compression 
• CN palsies
• peripheral neuropathies
• encephalitic syndromes
• epilepsy
• CNS infections with fungi or yeast

Question 7

What are the effects of leukaemia on the nervous system?

Answer 7

low platelets -> intracranial haemorrhage

Question 8

What are the effects of renal failure on the nervous system?

Answer 8

Uraemic encephalopathy:
• looks like metabolic encephalopathy
• global effect on cerebral dysfunction (concentration difficulties, personality changes, drowsiness, stupor, coma)

Uraemic neuropathy:
• distal neuropathy of sensory and motor nerves
• legs more than arms
• painfull, “burning”

Question 9

What are the effects of chronic liver failure on the nervous system?

Answer 9

Chronic hepatocerebral degeneration -> irreversible hepatic encephalopathy:
• dementia, tremor
• dysarthria
• cerebellar ataxia
• spastic paraparesis
• choreopathetosis

Question 10

What are the effects of acute liver failure on the nervous system?

Answer 10

Severe CNS dysfunction -> coma -> death

Question 11

What are the effects of Wilson’s disease on the nervous system?

Answer 11

• copper deposited in brain, liver, eyes
• hepatolenticular degeneration -> cerebral dysfunction, mvmt disorders, tremor, personality changes
-> Kayser-Fleischer rings in cornea

Question 12

What are the effects of Hyperthyroidism on the nervous system?

Answer 12

• hand tremors
• increased SNS activity -> excess lid retraction -> exophthalmos
• lid lag, widened palpebral fissures
• infrequent blinking
• muscle weakness

Question 13

What are the effects of hypothyroidism on the nervous system?

Answer 13

• weakness
• carpal tunnel -> pains or paraesthesia of hands
• sluggish mental activity
• decreased activity in SNS

Question 14

What are the effects of hyperparathyroidism on the nervous system?

Answer 14

Muscle weakness

Question 15

What are the effects of hypoparathyroidism on the nervous system?

Answer 15

• carpopedal spasm
• convulsions
• numbness of extremities
• cramps of extremities
• Chvostek’s facial sign

Question 16

What are the effects of diabetes mellitus on the nervous system?

Answer 16

• polyneuritis, mononeuritis
• diabetic coma
• cerebrovascular disease

Older diabetics: dehydration leads to hyperosmolar nonketoacidotic coma (seizures)

Question 17

What are the effects of hyperinsulism on the nervous system?

Answer 17

• excess administration of insulin
• paroxysmal: nervousness, anxiety, tremors, automatism, convulsions, coma
• because of hypoglycaemia
• administration of glucose treats it

Question 18

List the effects of alcoholism on the nervous system

Answer 18

• demensia
• peripheral neuropathy
• cerebellum degeneration
• Wernicke-Korsakoff syndrome
• tremulousness (withdrawal)
• Delirium tremens and alcoholic hallucinations

Question 19

What is alcoholic peripheral neuropathy?

Answer 19

• dying back neuropathy
• fro toxic action of alcohol on cell bodies
• primarily sensory

Question 20

What is Wernicke-Korsakoff syndrome?

Answer 20

• due to thiamine deficiency (chronic alcohol abuse)
• Wernicke encephelopathy is acute and reversible
• Korsakoff is chronic -> memory, irreversible

Question 21

What is alcoholic tremulousness?

Answer 21

• part of withdrawal
• exaggeration of normal or physiologic tremor
• develops rapidly over 1h beginning about 8hrs after withdrawal
• slow to disappear
• fine, fast, improves on voluntary movement

Question 22

What is delirium tremens and alcoholic hallucinations?

Answer 22

• most serious withdrawal syndrome
• last 3-7 days or 3wks
• fever, agitation, profuse sweating
• tachycardia, dehydration, hallucinations (maybe + underlying thought disorder)