Toxic/Metabolic/Nutritional Disease Flashcards
What are the key features of central pontine myelinolysis (CPM)?
- 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
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
central pontine myelinolysis (CPM)
What is the classic triad of thiamine deficiency?
- confusion
- opthalmoplegia (nystagmus)
- ataxia
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
Hepatic Encephalopathy
Vitamin B12 deficiency is a treatable cause of _____.
dementia
What vitamin is deficient in thiamine deficiency?
vitamin B1
What are the s/s of cobalamin deficiency?
- 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
Who is at risk for cobalamin deficiency?
- very strict vegetarians
- those starving
What are the s/s of degeneration of the superior cerebellar vermis?
- truncal instability
- leg ataxia
- wide based gait
What are the key features of Wilsons disease?
- 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
What vitamin is lacking in cobalamin deficiency?
vitamin B12
What brain changes are seen in chronic thiamine deficiency?
- loss of myelin
- microglia and mac influx
- fibrous gliosis
- neuronal loss
- hemosiderin and mammillary body atrophy
What is thiamine deficiency especially associated with?
chronic alcoholism
Most often vitamin B12 deficiency results from _____.
pernicious anemia
What can cause thiamine deficiency?
- 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
What are the key features of Hepatic Encephalopathy?
- 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
Name the possible toxin candidates in hepatic encephalopathy.
- ammonia
- mercaptans
- short chain fatty acids
- benzodiazepine-like substances
- GABA-like substances
- impaired glutamate neurotransmission
What causes paresthesias and ataxia in cobalamin deficiency?
swelling of myelin in the dorsal and lateral white matter of the spinal cord
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
Wilsons disease
Name 2 enzymes that require vitamin B12.
- methionine synthetase
- methylmalonyl CoA mutase
What areas of the brain are damaged in thiamine deficiency?
- mammillary bodies
- periaqueductal tissue
- inferior colliculi
- floor of the 4th ventricle
- thalamus
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
cobalamin (vitamin B12) deficiency
What brain changes are seen in acute thiamine deficiency?
- macro and microscopic petechial hemorrhage
- prominence and dilation of capillaries
How does EtOH affect the brain?
- 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
