Intoxications and infections of the NS Flashcards
how does tetanospasmin (the tetanus toxin) affect the nervous system
binds to cortical, brain stem, and spinal interneurons, preventing the release of the inhibitory neurotransmitters glycine and GABA
what symptoms does tetanus cause
Severe, prolonged, painful muscle spasms (may be localized or diffuse), if the toxin enters the blood stream there are generalized convulsive seizures. Trismus or lockjaw, grimacing smile (risus sardonicus) and arching back (opisthotonus)
how is tetanus treated
ICU care with mechanical ventilation, sedation, pharmacological neuromuscular blockade and anticonvulsants. human tetanus immune globulin may neutralize any remaining tetanospasmin
where do patients commonly get botulism from
improperly canned or contaminated food (destroyed with proper cooking)
how does the botulism toxin affect the nervous system
the exotoxin binds to presynaptic nerve terminals and prevents the release of ACh from LMNs and parasympathetic nerves. Resulting in paralysis of skeletal muscle, bowel, bladder and salivary glands. Severity depends on how much toxin in consumed
what are the symptoms seen with botulism toxin
ptosis, diplopia, and pupillary paralysis, followed by dysphagia, facial and limb weakness, and possibly respiratory paralysis
what antitoxin is available for botulism toxin
guanidine to help facilitate ACh release
what is the prognosis for botulism toxin
gradual spontaneous recovery after days to weeks given good supportive care
how does lead poisoning present in adults
peripheral neuropathy often with prominent focal neuropathies like wrist drop
how does lead poisoning present in children
encephalopathy and abdominal pain
how is lead poisoning treated
chelating agents
what does organic solvent exposures cause
peripheral neuropathy or encephalitis
what are some environmental exposures to consider when a patient presents with peripheral neuropathies
lead poisoning, organic solvents, carbon monoxide
what are early symptoms of CO poisoning
headache, vomiting, and blurry vision that can progress to coma, seixures and cardiopulmonary arrest
how do you treat CO poisoning
100% oxygen or a hyperbaric chamber
what may happen after a CO poisoning (lasting effects)
memory or cognition deficits and a few may get parkinsonism symptoms after a few weeks (basil ganglion is very sensitive to CO)
what should be a consideration when stroke symptoms are seen in a young, otherwise healthy patient
drug induced vasoconstiction or hypertension leading to ischemic infarction or brain hemorrhage – cocaine is the most common culprit
what are symptoms of an alcohol withdrawal syndrome
initially hypersympathic stage - tremulousness, sweating, tachycardia and jitteriness, cluster of generalized tonic-clonic seizures
what kind of seizure should raise suspicion for a focal brain lesion in a patient undergoing alcohol withdrawal
any aura or partial seizure since seizures due to withdrawal should be generalized and diffuse
when are delirium tremors seen in an alcoholic patient
3-4 days after alcohol cessation
what are delirium tremors
fluctuating motor and autonomic activity, confusion, and hallucinaitons - must be treated or may become fatal
what drug may be given to a patient undergoing alcohol withdrawal for seizure control
benzodiazepines - provide sedation and seizure control
what causes Wernicke-Korsakoff syndrome
Thiamine (B1) deficiency - common in alcoholic
what does Wernicke’s encephalopathy refer to
acute phase of the Wernicke-Korsakoff syndrome consisting of nystagmus, ophthalmoplegia, gait ataxia, and confusion - resolves with thiamine administration
what causes Korsakoff’s psychosis
persistant, severe, or recurrent thiamine deficiency
how does Korsakoff’s psychosis present
chronic memory deficit or amnestic syndrome with frequent confabulation (story telling- to fill in memory gaps)
what is seen pathologically in Korsakoff’s psychosis
petechial hemorrhages and gliosis in the vicinity of the third and fourth ventricles and connecting aqueduct - involving the mammillary bodies, fornix and dorsomedial thalamus
what structure does Alcoholic Cerebellar degeneration affect
anterior-superior vermis
what symptoms does Alcoholic Cerebellar degneration
ataxic gait and dysmetria of the lower limbs
who gets central pontine myelinolysis
occurs in alcoholics and patients who undergo an overly rapid correction of severe hyponatremia (low to high the pons will die)
what is central pontine myelinolysis
demyelination of the corticospinal and corticobulbar tracts in the pons
how can menengitis spread
either from the blood stream or directly from an otitis or sinusitis
what are symptoms of acute menengitis
fever, headache, stiff neck, malaise, lethargy, nausea, and vomiting = medical emergency
what are the signs seen in meningitis due to nuchal rigidity
Kernig or Brudzinski
what kind of meningitis is associated with a petechial rash
N. meningitidis - meningococcal
what is common initial antibiotics used for meningitis
newer cephalosporin such as ceftriaxone plus vancomycin for any pneumococci resistant to pcn + ampicillin for elderly or neonates to cover listeria
what can be given with antibiotics to reduce neurological complications
IV dexamethasone (reduces complications of deafness and cognitive deficits and lowers mortality)
what are complications of bacterial meningitis
hydrocephalus due to pus obstructing the CSF pathways. inflammation and edema of the cortex itself, or infarction of the brain due to inflammation of superficial blood vessels
what are common causes of meningitis in a neonate
Group B strep
E. coli
listeria
what are common causes of meningitis in children
N. meningitidis
S. pneumo
what are common causes of meningitis in adults
S. pneumo
N. meningitis
E. coli
when should a lumbar puncture be postponed
if the patient has elevated ICP (unconscous state, papilledema) or an intracranial mass with edema
what is the typical CSF profile for bacterial meningitis
Predominantly PMN WBS, low CSF glucose and high protein
what is the typical CSF profile for viral meningitis
lymphocytes, normal protein, normal glucose
what is the typical CSF profile for fungal meningitis
lymphocytes, high protein, low glucose
who is at risk for chronic meningitis
the elderly, malnourished or immunocompromised
what is encephalitis
when the brain (not the subarchnoid space) is the primary site of infection and inflammation
what is the usual cause of encephalitis
viruses
what is the onset and symptoms associated with encephalitis
symptoms evolve over hours to days and involve fever and headache, seizures, focal neurological deficits, behavioral changes and impairment of consciousness
what happens pathologically in encephalitis
patchy demyelination, edema and tiny, petechial hemorrhages
what can be seen microscopically in encephalitis
neuronal destruction by microglia, perivascular lymphocytes and viral inclusions within neurons or glia
what does the CSF show in encephalitis
it looks similar to viral meningitis with lymphocytes and normal or slightly decreased glucose
what should you look for in a patient with encephalitis
antibody titres to suspected viruses and HSV-1 via PCR
what is the treatment for encephalitis
acyclovir if due to herpes virus. treat the increased ICP, anticonvulsants and sedatives
where does HSV-1 usually infect
frontal and medial temporal lobes - often bilaterally and symmetrically
what signs and symptoms are indicative of herpes simplex encephalitis
aphasia, behavioral changes, and memory deficits
what treatment is important when there is suspicion for herpes simplex encephalitis
Acyclovoir (decreases mortality from > 40% to 20%)
what is unique to west nile encephalitis
causes significant weakness by affecting peripheral nerves or anterior horn cells
what areas does polio affect
viral invasion and destruction of anterior horn cells and brain stem motor nuclei
what does the varicella-zoster virus cause
shingles
how does shingles present
eruption of a vesicular rash with severe neuralgic pain on one or two adjacent dermatomes or on the torso or limbs
what treatment can be given for shingles
acyclovoir
what is destroyed by the HIV-1 virus
T4 helper cells
what kind of brain tumor is most commonly associated with AIDS patents
Primary cerebral lymphoma
what opportunistic infections of the CNS are most often associated with AIDS patients
cerebral toxoplamosis, cryptococcal meningitis and CMV retinitis or encephalitis, PML
in addition to bacterial infections causing abscesses in the immunocompromised what else do you need to consider
fungal and parasitic
what symptoms are seen with abscess
headache and fever the patient may be severely ill from a systemic infection. a cerebral abscess may cause seizures and focal neurological signs dependent on its location or it could cause brain edema with mass effect and increased ICP
what results when a brain abscess ruptures
it can produces meningitis
how do prions cause disease
they are misfolded proteins that induce other proteins to convert into a misfolded state as well
what is unique about how prions cause disease
they don’t have nucleic acid and they don’t invoke an inflammatory response
what is the most common prion disease
Creutzfeldt-Jakob dementia (CJD)
what is Creutzfeldt-Jakob dementia
a very rapidly progressive dementia with cerebellar, corticospinal, lower motor neuron, or extrapyramidal signs and symptoms
what is the prognosis of Creutzfeldt-Jakob dementia
it progressives to death within weeks to months and has no cure
what is seen on biopsy of someone with Creutzfeldt-Jakob dementia
spongiform changes which are cytoplasmic vacuoles in neurons and astrocytes and neuronal loss without inflammation.
what may be detected on an EEG of someone with Creutzfeldt-Jakob dementia
periodic sharp wave discharges
what is the variant of Creutzfeldt-Jakob dementia that causes a slower progressing disease with more psychiatric and behavioral symptoms
Mad Cow disease
