Toxic/Metabolic/Nutritional Disease

Question 1

What are the key features of central pontine myelinolysis (CPM)?

Answer 1

• focal demyelinating lesions of the ventral pons
• edema mediated myelin damage due to osmotic opening of the BBB
• sparing of axons and neurons
• severe cases = striatum, thalami, lateral geniculate bodies, cerebellum, cerebrum

Question 2

Dx?

• focal demyelinating lesions of the ventral pons
• edema mediated myelin damage due to osmotic opening of the BBB
• sparing of axons and neurons
• severe cases = striatum, thalami, lateral geniculate bodies, cerebellum, cerebrum

Answer 2

central pontine myelinolysis (CPM)

Question 3

What is the classic triad of thiamine deficiency?

Answer 3

• confusion
• opthalmoplegia (nystagmus)
• ataxia

Question 4

Dx?

• long term EtOH abuse
• confusion, forgetfulness, drowsiness, stupor, coma
• flapping tremor of the outstretched arms (asterixis)
• possibly caused by ammonia
• Alzheimer type II astrocytes in deep cerebral cortex, globus pallidus, dentate nucleus of the cerebellum
• astrocytes eventually degenerate

Answer 4

Hepatic Encephalopathy

Question 5

Vitamin B12 deficiency is a treatable cause of _____.

Answer 5

dementia

Question 6

What vitamin is deficient in thiamine deficiency?

Answer 6

vitamin B1

Question 7

What are the s/s of cobalamin deficiency?

Answer 7

• paresthesias
• ataxia
• diminished vibratory sensation and proprioception of lower extremities
• loss of cutaneous sensation
• abnormalities of reflexes
• spasticity
• incontenence
• orthostatic HTN
• psychoses and dementia
• visual changes

Question 8

Who is at risk for cobalamin deficiency?

Answer 8

• very strict vegetarians
• those starving

Question 9

What are the s/s of degeneration of the superior cerebellar vermis?

Answer 9

• truncal instability
• leg ataxia
• wide based gait

Question 10

What are the key features of Wilsons disease?

Answer 10

• auto recessive disorder of copper metabolism
• children or young adults (avg age 12)
• accumulates in lentiform nucleus; putamen and globus pallidus affected most
• causes basal ganglia degeneration and mvmt disorders
• jaundice, dysarthria, limb incoordination, gait disturbances, involuntary mvmts, dystonias, deterioration of intelligence, flapping tremor, spasticity
• tx: chelating agents (penacillamine)
• fatal w/o tx

Question 11

What vitamin is lacking in cobalamin deficiency?

Answer 11

vitamin B12

Question 12

What brain changes are seen in chronic thiamine deficiency?

Answer 12

• loss of myelin
• microglia and mac influx
• fibrous gliosis
• neuronal loss
• hemosiderin and mammillary body atrophy

Question 13

What is thiamine deficiency especially associated with?

Answer 13

chronic alcoholism

Question 14

Most often vitamin B12 deficiency results from _____.

Answer 14

pernicious anemia

Question 15

What can cause thiamine deficiency?

Answer 15

• EtOH abuse
• poor food intake
• reduced absorption/malutilization/increased excretion of vitamin B1
• neoplasms of the GI tract
• prolonged IV therapy
• gastric plications for obesity
• chronic gastritis
• gastric ulcer
• persistent vomiting

Question 16

What are the key features of Hepatic Encephalopathy?

Answer 16

• liver cirrhosis –> encephalopathy confusion, forgetfulness, drowsiness, stupor, coma
• flapping tremor of the outstretched arms (asterixis)
• possibly caused by ammonia Alzheimer type II astrocytes
• in deep cerebral cortex, globus pallidus, dentate nucleus of the cerebellum
• astrocytes eventually degenerate

Question 17

Name the possible toxin candidates in hepatic encephalopathy.

Answer 17

• ammonia
• mercaptans
• short chain fatty acids
• benzodiazepine-like substances
• GABA-like substances
• impaired glutamate neurotransmission

Question 18

What causes paresthesias and ataxia in cobalamin deficiency?

Answer 18

swelling of myelin in the dorsal and lateral white matter of the spinal cord

Question 19

Dx?

• auto recessive disorder of copper metabolism
• children or young adults (avg age 12)
• accumulates in lentiform nucleus; putamen and globus pallidus affected most
• causes basal ganglia degeneration and mvmt disorders
• jaundice, dysarthria, limb incoordination, gait disturbances, involuntary mvmts, dystonias, deterioration of intelligence, flapping tremor, spasticity
• tx: chelating agents (penacillamine)
• fatal w/o tx

Answer 19

Wilsons disease

Question 20

Name 2 enzymes that require vitamin B12.

Answer 20

1. methionine synthetase
2. methylmalonyl CoA mutase

Question 21

What areas of the brain are damaged in thiamine deficiency?

Answer 21

• mammillary bodies
• periaqueductal tissue
• inferior colliculi
• floor of the 4th ventricle
• thalamus

Question 22

Dx?

• paresthesias
• ataxia
• diminished vibratory sensation and proprioception of lower extremities
• loss of cutaneous sensation
• abnormalities of reflexes
• spasticity
• incontenence
• orthostatic HTN
• psychoses and dementia
• visual changes

Answer 22

cobalamin (vitamin B12) deficiency

Question 23

What brain changes are seen in acute thiamine deficiency?

Answer 23

• macro and microscopic petechial hemorrhage
• prominence and dilation of capillaries

Question 24

How does EtOH affect the brain?

Answer 24

• chronic –> brain shrinkage (diffuse loss of white matter, frontal cortex, neuronal cell body, retraction of dendritic arbor, increased neuronal lipofuscin, degeneration of cerebellar vermis)
• acute –> can lead to death from central cardioresp paralysis and cerebral edema