Lecture 17: CNS Infections Flashcards
+ Kernigs and +Brudzinski’s sign *also see neck stiffness and fever
specific for meningitis
Physical exam ‘can’t miss’ in CNS infections
1) DO NOT MISS MENINGEAL IRRITATION • Nuchal (neck) rigidity (moderate sensitivity; moderate specificity) • Kernig/Brudzinski sign (low sensitivity; high specificity) • Jolt accentuatation (high sensitivity; low specificity) 2) DO NOT MISS INTRACRANIAL HYPERTENSION SIGN • Fundoscopic examination • Bulging of anterior fontanelle (infant) 3) DO NOT MISS FOCAL NEUROLOGIC SIGN • Check level of consciousness (alertness and orientations) • At minimum, examine cranial nerves and motor/sensory of extremities
What is the single most important diagnostic test for meningitis?
LUMBAR PUNCTURE! -MUST do diagnostic procedure anytime you suspect meningitis or encephalitis CONTRAINDICATIONS: 1) intracranial mass lesion 2) intracranial hypertension 3) severe thrombocytopenia or coagulopathy 4) agitated patient
When should you obtain CT scan before lumbar puncture procedure?
1) Possible Intracranial Mass • Any focal neurologic sign • Any known intracranial pathology • Immunocompromised host 2) Possible Elevated ICP • Presence of papilledema 3) Both • Altered mental status *Attempts to safely perform lumbar puncture procedure should NEVER delay the administration of antibiotics for possible bacterial meningitis!!!!!! try to initiate antibiotic therapy ASAP
ER order for lumbar puncture
What neuroimaging am I describing?
1) “Quick evaluation” of intracranial process
2) Very good for bleeding and bony abnormality (e.g. skull base fracture)
3) Lower resolution of image
4) Can provide adequate informatoion for the safety of LP
5) NOT diagnostic for meningitis, just use it to decide can we do Lumbar Puncture or not?
6) better for ER cuz quicker
CT
What neuroimaging am I describing?
1) Can provide higher resolution of image
2) Can demonstrate most CNS pathology earlier
3) Longer time for study/care interruption -takes too damn long
4) great for encephalitis or brain abscess
MRI
Symptoms of Meningitis
1) fever-90%
2) nuchal rigidity-90%
3) altered mental status-80%
4) vomiting-40%
5) headache-90%
*classic triad: fever/nuchal rigidity/altered mental status 30-45%
at least 2 of classic triad>95%
When do you do brain/meningeal biopsy?
1) LAST RESORT diagnostic procedure
2) Indications
- microbiologic diagnosis of brain abscess
- differentiation of chronic infection vs tumor
- diagnosis of chronic meningitis
Neonatal Meningitis Signs/Symptoms
1) Clinically indistinguishable from other sepsis syndromes
2) Consider meningitis for any febrile illness in newborn
- Body temperature alteration (hypothermia more common)
- Seizure
- Bulging fontanelle (uncommon)
- Nuchal rigidity (uncommon)
- Poor feeding
What is an adjunctive therapy to give in bacterial meningitis?
Steroids!
- suppress severe inflammatory reaction in CSF is beneficial, practically indicated for all suspected bacterial meningitis
- give at same time as antibiotics in Strep. pneumo and H. influenzae
- Mycobacterium TB-slow tapering over 8 weeks
- wanna give Ampicillin, Vancomycin, 3rd generation Cephalosporin as main therapies
What causes Encephalitis?
1) >80% of Encephalitis is Idiopathic-unknown etiology
2) 2 tasks in ER are to recognize clinical syndrome and suspect encephalitis and NOT miss less common treatable causes (HSV, bacterial)
3) Bacterial-usually as meningoencephalitis-Neisseria meningitidis
4) Bacterial-purely as encephalitis-Listeria
5) Parasitic-Amoebea
6) VIRAL-most common-HSV, VZV, HHV, Arbovirus
Brain/Parenchymal Involvement
1) Focal Neuro signs-character/personality change
2) Altered Mental Status-coma/obtundation is more common and early stage
Meningeal Irritation
1) neck stiffness is less common
2) headache may/may not be present
other clues-outdoor exposure (west nile, ricketessia), animal exposure, travel history
Encephalitis!
*suspect encephalitis for any unexplained brain parenchymal lesion especially when NOT consistent with neurovascular anatomy
• One of few “treatable” cause
What disease am I describing and how are you going to DIAGNOSE it and TREAT it?
1) Typically involves temporal lobe
- T2 high intensity on MRI
- Low density on CT
2) Classical presentation:
1) Fever and personality change-almost uniformly present
2) Seizure
3) Aphagia
4) Motor deficit
1) DISEASE: HSV Encephalitis (elevated RBCs)
2) DIAGNOSIS: HSV PCR on Cerebrospinal fluid is the gold standard for HSV encephalitis diagnosis
3) TREATMENT: high dose Acyclovir
TAKE HOME POINTS
- any patient with encephalitis needs to be considered to have HSV until otherwise proven
- Acyclovir should be started immediately ofr suspected encephalitis patients without waiting for test results
What imaging/treatment should you do for brain abscess?
IMAGING
1) Gadolinium-enhanced T1
2) Diffusion-weighted image
3) CT is poor test unless enhanced by IV contrast!
TREATMENT
1) Ceftriaxone
2) Metronidazole
3) Vancomycin
