Episode 45: Neurology Clerkship Shelf Review Part 2

Fungal/Tb Meningitis

Bacterial Meningitis

HSV meningitis or HSV encephalitis

#1 cause bacterial meningitis in children through middle-aged adults? Strep pneumo

Pt with Ò meningitidis meningitis becomes profoundly hypotensive + hypoglycemic + hyperkalemic + bleeding from mucosal sites. Dx? → Waterhouse-Friedrichson syndrome

• Pathophys? adrenal hemorrhage → primary adrenal insufficiency
  • Cortisol production impaired → hypoglycemia & hypotension
  • Aldosterone production impaired → hyperkalemia & non-AG metabolic acidosis (can’t excrete H+)
  • Type 4 RTA
• Populations at risk for Neisseria meningitis?
  • Asplenic patients (e.g. sickle cell disease)
  • Terminal complement deficiency or eculizumab use (tx for paroxysmal noctural hematuria)
    • Terminal complement = C5-C9
    • Eculizumab = C5 inhibitor
• 25 yo M having generalized tonic-clonic seizures. Began intranasal desmopressin (ADH analog) 5 days ago after water deprivation test was conducted at local hospital. Dx? → hyponatremic seizures (i.e. due to increased water reabsorption)
  • Pathophys? Desmopressin = ADH analog acts on V2 receptors of principal cells to cause increased water reabsorption → this causes dilutes serum Na+
  • Tx? Hypertonic saline
    • To raise serum Na+ levels
    • Note: cannot increase Na+ levels > 12 mEq over 24 hrs
• What neurological complication results if hyponatremia is corrected too quickly? Osmotic demyelination syndrome aka central pontine myelinolysis aka “locked in” syndrome
• What neurological complication results if hypernatremia is corrected too quickly? Cerebral edema → transtentorial herniation
• In general, do you use a slow or fast general management strategy to manage electrolyte imbalances? SLOW management strategy to correct electrolyte imbalances
• Bizarre dreams on awakening (hypnopompic hallucination) or on falling asleep (hypnagogic hallucination) + history of 3 major accidents from falling asleep while driving + sudden falls from LE weakness (cataplexy). Dx? → Narcolepsy
  • Diagnostic test? Polysomnography (will show decreased sleep latency, i.e. pt goes straight into REM sleep)
  • Tx?
    • Frequent naps
    • Modafinil (stimulant)
    • Sodium oxybate to treat cataplexy
  • CSF findings? Decreased hypocretin/orexin levels
• What drug is given to tx insomnia? Suvorexant
  • MOA? hypocretin receptor antagonist
• Severe headache + multiple extraocular muscle deficits + recent otitis media infection. → cavernous sinus thrombosis
  • Pathophys? CN III, IV, VI, V1, V2 go through cavernous sinus
    • Note: loss of CN VI function occurs first (lateral gaze palsy)
  • Ophthalmic veins anastomose with facial veins & veins that drain sinuses
  • MC organism? Staph aureus
  • Tx? IV abx + heparin

• Severe headache + necrotic sinusitis in patient with blood glucose of 300 + pH of 7.13 + HCO3- of 15. → mucormycosis in context of DKA
  • Tx? Debridement + amphotericin B
• Asymmetric resting tremor + cogwheel rigidity + bradykinesia/festinating gait + postural instability → Parkinson’s disease
  • Associated handwriting finding? Micrographia (small handwriting)
  • Associated BP finding? Orthostatic hypotension
  • Pathophys? Destruction of dopamine-producing cells in substantia nigra pars compacta (part of the midbrain)
  • Gross pathological finding? Loss of pigmentation of substantia nigra
  • Histology of Parkinson disease? Lewy bodies (eosinophilic inclusions made of alpha-synuclein)
  • Tx?
    • Start with:
      • NMDA receptor antagonists (e.g. amantadine; increases dopamine release in CNS)