NS66: Toxic or Metabolic Nervous System Disease
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What are the symptoms of Central Pontine Myelinolysis?
Progressive spastic quadriplaresis and lower cranial nerve palsies
What are the histological findings of Central Pontine Myelinolysis?
Discolored area in central basis pons, which is because there is a demyelinated area in the basis pons with preserved axons and pontine neurons.
What causes Central Pontine Myelinolysis?
- too rapid correction of hyponatremia (not enough salt) or serum hypo-osmolality
- often found in alcoholics who are hydrated too quickly in ICU or syndromes of inappropriate ADH levels
What are the symptoms of methanol ingestion?
- intial drukennes
- abdominal pain
- visual loss
How is methanol injestion treated?
infusion with water and ethanol (to compete with methanol molecules at hepatic alcohol dehdrogenase sites). methanol then gets secreted instead of being filtered in the kidney
Why do people who drink methanol have extrapyramidal movement disorders?
because they have injury to the putamen
What happens at the molecular level when methanol is ingested?
- methanol is converted to formic acid and formaldehyde by hepatic alcohol dehydrogenase
- this causes severe metabolic acidosis
What injuries does the brain suffer from methanol ingestion?
- 1.) blindness: formic acid disrupts axoplasmic flow in optic nerve, resulting in optic disc swelling, axonal destruction, and permanent blindness
- 2.) the putamen is injured causing extrapyramidal movement disorders
What is the major constituent of antifreeze?
What are the symptoms of ethylene glycol ingestion?
- initial drunkenness
- generalized convulsions
What are the molecular mechanisms of ethylene glycol poisining?
- the ethylene glycol gets converted to glycolic acid and oxalic acid
- this produces severe acidosis
What are one of the most common causes of kidney stones?
- oxalate crystals from the break down of ethylene glycol
- these stones cause uremia and eventually kidney failure
What organs does ethylene glycol poisining affect?
- Brain: chemical meningitis
- Kidneys: uremia
- both are affected by oxalate crystal deposition
Wernicke-Korsakoff Syndrome is really what?
- 2 diseases: Wernicke disease (an encephalopathy) is an acute disorder
- Korsakoff's pyschosis is the chronic disorder that follows Wernicke disease
What are the symptoms of Wernicke's disease?
- Abrupt onset of nystagmus and lateral rectus palsy progressing to external ophthalmoplegia
- truncal and gait ataxia
- global confusion state
What areas of the brain does the petechial hemorrages, edema, gliosis, and demyelination of Wernicke's disease affect?
- mammillary bodies
- periventricular thalamus
- truncal gait and ataxia:
- periaqueductal gray
- gray beneath 4th ventricle
What are the symptoms of Korsakoff's psychosis?
- anterograde amnesia- inability to form new memories despite intact immediate recall and remote memoryconfabulation- falsifying memories by filling in gaps in memory with information that sounds plausable but has little basis in reality
What is the cause of Korsakoff's Psychosis?
- Bilateral neuronal loss and gliosis of dorsomedial thalamus and mammillary bodies
- for pictures, this means enlarged 3rd ventricle
Why should we always be careful in administering parenteral glucose to alcoholics who have just been admitted?
- b/c they may have low thiamine levels
- thiamine is a cofactor in Kreb's cycle enzymes, which are heavily utilized when metabolizing glucose
- neuronal death is caused by this problem
What are the two enzymes in the Kreb's cycle that utilize thiamine as a co-factor?
- pyruvate dehydrogenase complex
- alpha-ketoglutarate dehydrogenase
What treatment, if administered early in the on-set of Wernicke-Korsakoff Syndrome, can produce rapid improvement?
high-dose parenteral thiamine
What are the symptoms of alcholic cerebellar degeneration?
truncal and gait ataxia; this means that they have a wide-based gait and difficulty ascending stairs
What are the brain findings in an alcoholic cerebellar degeneration?
shrinkage of folia of superior (rostral) vermis and adjacent anterior lobe
What are four classical symptoms seen in adults who have mercury poisining?
- personality disturbance and dementia "mad as a hatter"
- cerebellar ataxia
- intention tremor
- motor neuropathy
What are the symptoms of mercury poisining in children?
- acrodynia: pink disease
- children have swollen, red, cold, moist hands and feet, irritability and insomnia, and anorexiaif recieved mercury in the womb, then child will have mental retardation and cerebral palsy
Mercury poisining would seem uncommon, yet there are plenty of cases of it. What were some we discussed?
- seed sent to middle east coated with mercury as a fungicide
- minamata disease: term used for mercury disease b/c of seaside town in Japan who dumped mercury in the ocean and people suffered effects
What disorder does Vitamin E (Alpha-tocopherol) often present as?
What is Vitamin E (alpha-tocopherol) deficiency often associated with?
chronic malabsorption syndromes such as cystic fibrosis in kids
What are four symptoms seen in Vitamin E (alpha-tocopherol) defiency?
- peripheral polyneuropathy (damage to peripheral nerves)
- opthalmoplegia (extra-occular muscle weakness)
- pigmentary retinopathy
What is the pathogenesis of Vitamin E (alpha-tocopherol) deficiency?
- demyelination of spinal cord posterior columns
- axonal enlargements containing filaments, membranes, abnormal mitochondria, and granular materal
- excessive lipofuscion pigmentation of neurons, astrocytes, and muscle cells
What are the symptoms of Vitamin B12 deficiency?
- loss of posterior column sensation (proprioception: vibratory and position sense) this leads to a positive Romberg Testspasticity with bilateral extensor planter responses and loss of tendon reflexes
- memory disturbance
What three diseases can Vitamin B12 deficiency cause?
- Pernicious anemia
- Subacute combined degeneration of spinal cord
- Combined systems disease
What are some indications of Vitamin B12 deficiency?
- Elevated levels of methylmalonic acid in serum or urine
- Low serum vitamin B12 levels (not a very reliable determinant)
- Anemia (megaloblastic anemia), macrocytosis, or hypersegmented neutrophils
Since this is Neuroscience, what does Vitamin B12 defiency do to the CNS?
- Vacuolation (small cavity found in cytoplasm) and fragmentation of myelin followed by axonal degeneration
- It involves the anterior, posterior, and lateral columns, centered in mid-thoracic spinal cord
What is Sandhoff's Disease?
- It is a GM2 Gangliosidosis
- Deficiency of hexosaminidase A and B
What are the symptoms of Tay-Sachs Disease?
- Initially normal infant
- By 3 months presents: hyperacusis (hypersensitivity to sound), hyperexcitability, psychomotor retardation, hypotonia, macular cherry-red spot
- Progressive decerebrate posturing and opisthotonus
- Macrocrania and seizures
- Die by age 2
What is the pathology of Tay-Sachs Disease?
- Initial brain enlargement followed later by marked cerebral atrophy
- Ballooned neurons containing enlarged lysosomes with granular and lamellar storage material: constipated lysosomes
What are the characteristics of neuronal ceroid lipofuscinosis?
- Autosomal Recessive Inheritance
- Progressive Cognitive Deterioration
- Retinal Abnormalities (pigmentary retinopathy because destruction of sensory retinas)
What are typical findings in Neuronal Ceroid Lipofuscinosis?
- Markedly atrophic brain
- Ceroid lipofuscin in neurons
- Curvilinear bodies
- Autofluorescent material (the actual ceroid lipofuscin) stored in lysosomes of multiple organs
Where is the ceroid lipofuscin stored in Neuronal Ceroid Lipofuscinosis?
- Lysosomes of : Macrophages in spleen, liver, and lymph nodes
- smooth muscle cells of GI tract, arterioles, and arteries
- skeletal and cardiac muscle
- renal glomeruli and tubules
- neurons of brain and retina
What causes Metachromatic Leukodystrophy?
- Accumulation of sulfatide (galactocerebroside sulfate)
- Deficiency of enzyme arylsulfatase A which normally cleaves sulfate from sulfatide
Is metachromatic leukodystrophy more severe as a child or an adult?
What is the affect of Metchromatic Leukodystrophy on adults?
insidious onset in late adolescence or early adulthood of slowly progressive gait disturbance, behavioral problems, spasiticity, and peripheral neuropathy
What are the molecular findings in metachromatic leukodystrophy?
- cavitated white matter (with sparing of U-Fibers)
- loss of oligodendrocytes and Schwann cells and myelin
- Granular masses of accumulated sulfatide in macrophages this accumulated sulfatide stains metachromatically with toluidine blue or cresyl violet
What is the ultimate result of child-onset metachromatic leukodystrophy?
quadrapelises and death
What are the two peroxisomal disorders we learned about?
- Zellweger's Syndrome
What are the characteristics of adrenoleukodystrophy/adrenomyeloneuropathy?
- x-linked inheritance
- single enzyme deficiency
What are the characteristics of Zellweger's Syndrome?
- Autosomal Recessive
- Defective peroxisomal biogenesis resultant multiple enzyme deficiencies
What are the 6 symptoms of Andrenoleukodystrophy/Adrenomyeloneuropathy?
- Spastic paraparesis and sensory loss
- impaired bladder function
- adrenal insufficiency
- low serum testosterone levels
- peripheral neuropathy
- bronzing of the skin
What would you expect to find on a brain with Adrenoleukodystrophy / Adrenomyeloneuropathy?
symmetrical demyelination of cerebral white matter, most severe in occipital regions
What is phenylketonuria?
Accumulation of phenylalanine due to lack of phenylalanine hydroxylase which converts phenylalanine to tyrosine
How is phenylketonuria treated?
involves restricting phenylalanine intake in diet
Why is phenylketonuria not really a problem anymore?
because of newborn screening using the Guthrie test
What do infants present with phenylketonuria?
- severe mental retardation
- defective pigment formation: fair skin, hair, and eyes
What did this man have? What caused it?
- Central Pontine Myelinolysis
- too rapid correction of hyponatremia/serum hypo-osmolarity
What do these brain sections of an autoposied patient suggest was the cause of death?
Which two areas are injured?
- Methanol Ingestion
- putamen and optic nerve
What syndrome is associated with this picture?
What structures are damaged?
How are they damaged?
- Wernicke Disease
- mammillary bodies, hypothalamus, periventricular thalamus, ophthalmoplegia, ataxia, periaqueductal gray, gray beneath the floor of the 4th ventricle
- petechial hemorrhages,edema, gliosis, and demyelination
What is lost here?
What is the resulting syndrome?
- dorsomedial thalamus and mammillary bodies
- Korsakoff's Pyschosis
What is this cerebellum showing us?
What shrank on this?
- Alcoholic Cerebellar Degeneration
What is this presentation called?
What is the Dx?
- Mercury Poisining
Look at this LFP-PAS stain of this spinal cord section, what is wrong?
What is the cause?
- loss of myelin in the anterior, posterior, and lateral columns in the thoracic spinal cord
- Vitamin B12 deficiency
What are the figures in this EM image of a neuron?
What is the diagnosis for this?
- the onion looking things are ballooned lysosomes with granular and lamellar storage material
- Tay-Sachs Disease
This brain is markedly atrophic. What metabolic disorder would do this?
Neuronal Ceroid Lipofuscinosis
This unstained brain is glow'n out of control! What material in the neurons is causing this?
What is the disease?
What else would you find this glow'n material?
- Ceroid Lipofuscin
- Neuronal Ceroid Lipofuscinosis
- Macrophages (spleen, liver, lymph nodes), smooth muscle cells (arteries, arterioles, GI tract), cardiac muscle, skeletal muscle, renal glomeruli, renal tubules
What is this stain indicative of?
What is it called when a color changes in a dye due to binding to certain compounds?
- Metachromatic Leukodystrophy
When you see symmetrical demyelination of cerebral white matter, which high severity in the occipital regions like this, what do you suspect could be a diagnosis?
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