Cns Infection Flashcards
What is bacterial meningitis?
An acute purulent infection within the subarachnoid space, considered a medical emergency.
What are the most common causes of bacterial meningitis in adults?
Streptococcus pneumoniae (50%), Neisseria meningitidis (25%), and Listeria monocytogenes (10%).
What is the classic triad of bacterial meningitis?
Fever, headache, and nuchal rigidity.
What is Kernig’s sign?
A sign of meningeal irritation where the patient experiences pain when the leg is extended at the knee while the hip is flexed.
What is Brudzinski’s sign?
A sign of meningeal irritation where flexion of the neck causes involuntary flexion of the hips and knees.
What is the most common cause of meningitis in neonates?
Group B streptococci and Listeria monocytogenes.
What is the mortality rate of pneumococcal meningitis despite antibiotic therapy?
0.2
What is the role of dexamethasone in bacterial meningitis?
It reduces the rate of hearing loss and neurologic complications when given before or with the first dose of antibiotics.
What is the most common complication of bacterial meningitis?
Increased intracranial pressure (ICP).
What is the most common cause of viral meningitis?
Enteroviruses (e.g., echoviruses, coxsackieviruses).
What is the typical CSF profile in viral meningitis?
Lymphocytic pleocytosis (25-500 cells/μL), normal glucose, and slightly elevated protein.
What is the most common symptom of viral meningitis?
Headache, often frontal or retro-orbital, with photophobia.
What is the treatment for HSV meningitis?
Intravenous acyclovir.
What is the most common cause of encephalitis in immunocompetent adults?
Herpes simplex virus (HSV-1).
What is the diagnostic test of choice for HSV encephalitis?
CSF PCR for HSV DNA.
What is the most common focal finding in HSV encephalitis?
Frontotemporal lobe involvement.
What is the most common cause of brain abscess?
Streptococcus spp. (40%), Enterobacteriaceae (25%), and anaerobes (30%).
What is the most common source of otogenic brain abscess?
Otitis media and mastoiditis, often affecting the temporal lobe.
What is the typical presentation of a brain abscess?
Headache, fever, and focal neurologic deficits.
What is the treatment for brain abscess?
Combination of high-dose antibiotics (e.g., ceftriaxone, metronidazole) and neurosurgical drainage.
What is the most common complication of brain abscess?
Seizures, occurring in 15-35% of patients.
What is the most common cause of fungal meningitis?
Cryptococcus neoformans.
What is the diagnostic test for cryptococcal meningitis?
CSF cryptococcal antigen test (CrAg).
What is the treatment for cryptococcal meningitis?
Amphotericin B plus flucytosine.
What is the most common cause of tuberculous meningitis?
Mycobacterium tuberculosis.
What is the classic CSF finding in tuberculous meningitis?
Lymphocytic pleocytosis, elevated protein, and decreased glucose.
What is the treatment for tuberculous meningitis?
Anti-TB therapy (e.g., isoniazid, rifampin) for 9-12 months, plus steroids.
What is the most common cause of syphilitic meningitis?
Treponema pallidum.
What is the diagnostic test for neurosyphilis?
Positive CSF VDRL test.
What is the treatment for syphilitic meningitis?
Aqueous penicillin G for 10-14 days.
What is the most common cause of meningitis in immunocompromised patients?
Cryptococcus neoformans and Listeria monocytogenes.
What is the most common symptom of encephalitis?
Altered level of consciousness, often with fever and headache.
What is the most common cause of encephalitis in children?
Enteroviruses and arboviruses (e.g., West Nile virus).
What is the most common cause of encephalitis in the elderly?
Herpes zoster virus (VZV).
What is the most common cause of encephalitis worldwide?
Japanese encephalitis virus.
What is the most common cause of encephalitis in the United States?
West Nile virus.
What is the most common cause of encephalitis in HIV patients?
Cytomegalovirus (CMV).
What is the most common cause of encephalitis in transplant recipients?
Cytomegalovirus (CMV).
What is the most common cause of encephalitis in cancer patients?
Progressive multifocal leukoencephalopathy (PML) caused by JC virus.
What is the most common cause of encephalitis in alcoholics?
Wernicke’s encephalopathy due to thiamine deficiency.
What is the most common cause of encephalitis in drug users?
HIV encephalitis.
What is the most common cause of encephalitis in travelers?
Malaria.
What is the most common cause of encephalitis in campers?
Lyme disease.
What is the most common cause of encephalitis in hunters?
Rabies.
What is the most common cause of encephalitis in farmers?
Listeria monocytogenes.
What is the most common cause of encephalitis in fishermen?
Vibrio vulnificus.
What is the most common cause of encephalitis in veterinarians?
Brucella spp.
What is the most common cause of encephalitis in laboratory workers?
Herpes B virus.
What is the most common cause of encephalitis in soldiers?
Leishmaniasis.
