6/17- Toxic/Metabolic Disorders of the Nervous System Flashcards
Outline/hierarchy of toxic and metabolic disorders
What is the result of Vitamin B12 deficiency (loss of what?)
Combined system degeneration:
- Dorsal columns
- Corticospinal tract (lateral and anterior)
What other conditions look similar to Vitamin B12 deficiency?
- Nitrous oxide toxicity
- Vacuolar myelopathy of HIV
What does this show?
Mammillary body hemorrhage
- Memory disturbances, disrupted short-term memory
- Causes vascular proliferation and atrophy
- Involved in thiamine deficiency/Wernicke’s encephalopathy (?)
Thiamine deficiency results in what?
Wernicke’s encephalopathy
- Mammillary body impaired, causing decreased memory (can still retrieve old, but short-term impaired); confabulation
- Midbrain affected, so change in vertical gaze, nystagmus, ataxia
T/F: Wernicke’s encephalopathy is reversible?
True at first, but if you don’t treat quickly enough it may become irreversible
What is it called when Wernicke’s encephalopathy becomes irreversible?
Korsakoff’s psychosis
What is confabulation?
May not remember information from the past few days and so replacing it with other possessed memories (without realizing)
Vitamin B6 is involved in the synthesis of what? Deficiency results in what?
GABA
- Deficiency results in increased incidence of seizures
What is Wilson’s Disease? Symptoms?
Copper metabolism disorder with deposition in:
- Liver: (normally excretes Cu in bile) cirrhosis
- Brain: movement disorders (Cu tends to go to basal ganglia); chorea, athetosis, psychosis (may look like Huntington’s)
- Eye: Kayser-Fleischer rings around cornea
May present with CNS manifestations, liver manifestations, or both
This is treatable!
- Restrict copper in diet
- Use chelators to bind Cu and prevent absorption or promote clearance from blood
What is hepatic encephalopathy?
- Gross pathology
- Microscopic
Will have increased levels of ammonia, affecting levels of consciousness
Gross pathology: possibly cerebral edema
- Ammonia appears to affect function of astrocytes (trouble sustaining BBB)
Microscopic: Alzheimer type II astrocytosis*
- Enlarged, often paired, pale nuclei with nuclear chromatin peripheralized
*NOT seen in Alzheimer’s disease; not related at all, just same scientist
What is this?
Alzheimer type II astrocytes seen in hepatic encephalopathy
- No cytoplasm (similar to a normal astrocyte)
- Nucleus is very large with peripheralized chromatin; large and pale
__ in __ hospitalizations is alcohol-related, with __% of MVAs involving alcohol consumption
1 in 25 hospitalizations is alcohol-related, with 50% of MVAs involving alcohol consumption
What is this? What could cause this? Symptoms?
Vermal cerebellar atrophy (see much space between folia)
- Could by caused by chronic alcohol consumption
- Would result in trunkal ataxia (wide-based stance when walking, etc.); higher likelihood of falling
What is Marchivava-Bignami syndrome? What causes it?
- Demyelination and necrosis of corpus callosum
- Seen with rapid correction of hyponatremia
- First described in alcoholics
What is this?
Demyelination and necrosis of corpus callosum seen with rapid correction of hyponatremia
What is this? What causes it?
Central pontine myelinolysis
- Also seen with rapid correction of hyponatremia (although not technically part of Marchivava-Bignami syndrome?)
What is the mechanism of methanol intoxication damage? Symptoms?
Converted by liver to formic acid and formaldehyde
- Toxic to retinal ganglia cells -> blindness
- Hemorrhagic necrosis of basal ganglia
- Necrosis of the putamen -> movement disorder
What is this?
Necrosis of the putamen caused by methanol intoxication (bilateral)
What is this?
Bilateral necrosis of the globus pallidum due to carbon monoxide intoxication
What is the mechanism of carbon monoxide intoxication damage? Symptoms? Result of?
- Bilateral globus pallidum necrosis (likely due to binding of iron in this tissue??)
- Depressed levels of consciousness (may go to sleep)
May result from:
- Auto exhaust
- Gasoline engines
- Coal stoves without adequate ventilation
Intoxication with ___ causes necrosis of ____: - Methanol: - Carbon monoxide:
- Methanol: Putamen (1 word-1 word)
- Carbon monoxide: Globus pallidus (2 words-2 words)
What is this? Caused by?
Diffuse cerebral edema from heavy metal (lead) intoxication
What are the most common heavy metal intoxication elements?
- Lead
- Arsenic
- Thallium
What is this? Caused by? Results in?
Vascular necrosis in lead poisoning
- Central area used to be a BV
- Breakdown of BBB -> cerebral edema
- May result in LOC
