CNS INFECTIONS Flashcards
types of infections?
bacterial
tuberculosis/fungal
viral
rickettsial
what is this?
Becoming less common in the developed world because of
vaccines against common types
In the U.S., main risks are in children, the elderly, and the
immunosuppressed
Clinical presentation is typically acute onset of fever, headache, and meningismus
Diagnosis confirmed by lumbar puncture, usually done after brain imaging
Bacterial Meningitis
what is this?
• Organism enters brain via hematogenous spread and
nasopharynx/cribriform plate
• May occasionally appear in epidemics
• Chills, fever, headache, nausea, emesis, stiff neck,
prostration
• Irritability at onset, then confusion, and sometimes coma
Petechial rash on skin
CSF findings
Elevated protein, reduced glucose
Gram-negative diplococci
treated with Ceftriaxone or cefotaxime are appropriate first choices and can be given IM or IV
Meningococcal Meningitis (Neisseria meningitidis), Acute Bacterial Meningitis
what is this?
Most cases in childhood (90% of cases prior to age of 5)
In adults it is most common after acute sinusitis, otitis media, skull fracture
Prognosis: fatal in 90% of infants if untreated, spontaneous recovery in adults
CSF and serum isolation of organisms
***Ampicillin, or 3rd-generation cephalosporin
Hemophilus Influenzae Meningitis
what is this?
Usually a complication of otitis media, mastoiditis, sinusitis, skull fracture, or upper respiratory infection
Alcoholics, asplenism, and sickle cell disease predispose to this
CSF: Gram-positive diplococci
penicillin, 3rd generation cephalosporin, chloramphenicol for penicillin-allergic
Streptococcus pneumoniae
what is this?
Infrequent cause of meningitis
Presentation is similar to other types of meningitis
Complication of cavernous sinus thrombosis, epidural/
subdural abscess, bacterial endocarditis, or penetrating
head trauma
Treatment is with 3rd generation cephalosporin
Staphylococcus meningitis
Focal pockets of pus caused by extension and entrapment of
focal infection, usually bacterial
Most often from sinusitis, penetrating trauma, neurosurgery, osteomyelitis of skull
abscess and subdural empyema
subacute/chronic meningitis is more common in the?
immunocompromised
what are the two types of subacute/chronic meningitis?
Pachymeningeal
Leptomeningeal
what is this, Pachymeningeal or
Leptomeningeal?
• Infection (meningitis, mycobacterium, syphilis, Lyme, viral meningitis, cryptococcus or coccidioidal meningitis, amebic
meningitis)
- Autoimmune conditions (sarcoidosis, RA, Sjogren’s
- Neoplasm/carcinomatous meningitis
- Iagrogenic (LP)
- Spontaneous intracranial hypotension
- Subarachnoid hemorrhage
Pachymeningeal
what is this, Pachymeningeal or Leptomeningeal?
- Infection
- If mostly basilar: TB, listeriosis, fungi, amebic
- Autoimmune (sarcoidosis, Behcet diseast, histiocytosis
• Neoplasm (carcinomatous meningitis or leptomeningeal
glioneuronal tumor)
Leptomeningeal
most common fungal meningitis worldwide
Common in areas in which HIV is endemic, Mortality rate 25%
More rapidly progressive in HIV patients, slower in others
Treatment: Induction with amphotericin B + flucytosine for
two weeks, then consolidation with fluconazole for 8 weeks,
then maintenance with low-dose fluconazole for 1 year
Cryptococcal meningitis
Prolonged course
Always secondary to TB elsewhere in the body, usually
lungs
Thickened meninges, particularly at the base of the brain
Subacute onset with headache, emesis, fever, irritability, insomnia, anorexia
Prodrome is 2-12 weeks
early stages, signs of mild meningeal infection, Later, papilledema
Diagnosis: CSF
Slightly cloudy (“ground-glass” appearance)
Death in 6-8 weeks
Early is better
Tuberculous meningitis
name this viral CNS infection?
Self-limited illness with signs of meningeal irritation
Viral (aseptic meningitis)
name this viral CNS infection?
Self-limited illness with signs of brain tissue involvement
such as seizures, confusion, and focal neurologic
abnormalities
Viral encephalitis
name this viral CNS infection?
both of above present
Meningoencephalitis
name this viral CNS infection?
Involves any part of spinal cord with infection of neurons, or demyelination of axons
Myelitis
diagnosis of viral CNS infection is done how?
Virus cultures, PCR (polymerase chain reaction), elevated protein and WBCs, normal glucose
Most important cause of fatal encephalitis in the USA
PCR (polymerase chain reaction) verifies diagnosis
- Acylovir 500 mg 5x/dy for ten days
- Seizure control with antiepileptic
- If cerebral edema: consider steroids
Herpes Simplex Encephalitis
Destruction of anterior horn cells by polio virus, a picornavirus
Poliomyelitis
Treatment is supportive
this alone, or via opportunistic infections, can cause
neurologic pathology and symptoms
Associated immunosuppression can lead to infection with
viruses (CMV, HSV, VZV, EBV, HBV), parasites (Toxoplasmosis), fungi (Cryptococcus), or rickettsial (syphilis)
HIV
Treponema pallidum is a corkscrew-shaped bacterium
Primary syphilis with painless chancre
Secondary syphilis appears within a month, usually with a
diffuse maculopapular rash
Diagnosis of neurosyphilis made with lumbar puncture
Definitive diagnosis requires 1) positive serum treponemal
test results, 2) positive CSF VDR or FTA-ABS, and 3) clinical
symptoms
Neurosyphilis
what is this neurosyphilis classification?
No symptoms, CSF abnormal
Asymptomatic
what is this neurosyphilis classification?
Signs and symptoms of increased intracranial pressure and focal neurologic signs; if spinal, may have paresthesias, weakness, and atrophy in affected myotomes/dermatomes.
CSF abnormal
Meningovascular
what is this neurosyphilis classification?
Best example is tabes dorsalis, with paresthesias/ dysesthesias, ataxia, impaired proprioception (due to leptomeningitis); paretic type, with personality changes,
convulsions, and dementia; and optic atrophy with loss of
vision
Parenchymatous
