Infections of brain

Question 1

What causes encaphalitis?

Answer 1

1) Viral infection: HSV 1 and 2 ( most common), VZV, Epstein Barr, CMV, HIV, mumps and measles
2) Non-viral - secondary to bacterial meningitis, TB, toxoplasma, malaria, listeria, Cryptococcus
3) Risk factors: Immunocomprimised patients, and extremes of age
4) Mainly affects frontal and temporal lobes - confusion, ALOC, focal signs. Can lead to permanent brain damage if not treated.

Question 2

Signs/symptoms of encephalitis?

Answer 2

1) Begins with features of viral infection: Fever, fatigue, headache, nausea, myalgia
2) Progresses to: Decreased consciousness/drowsiness and confusion (predominant symptom), behavioural change, focal neurological deficit, seizures, coma.
3) May have signs of meningitis (meningo-encephalitis)

Question 3

Diagnosis and investigations for encephalitis?

Answer 3

1) Lumbar puncture/CSF studies (cultures + PCR studies) - moderate elevation in protein, lymphocytes +/- decreased glucose.
2) FBC and blood film - leucocytosis.
3) Blood cultures, viral PCR, U and E’s, LFT’s, glucose, ESR, CRP, throat swab and stool culture.
4) Contrast-enhanced CT/MRI - exclude space-occupying lesions, stroke, raised ICP (CI for LP). MRI shows oedematous changes in encephalitis.
5) EEG - diffuse abnormal slow wave changes

Question 4

Management of encephalitis?

Answer 4

Depends on cause:

1) If viral - give urgent antiviral treatment - acyclovir high dose IV for 14 days
2) Supportive treatment +/- anti-epileptics
3) If meningitis suspected - emergency IM benzylpenicillin

Question 5

Brief pathophys on meningitis:

Answer 5

Nisseria meningitides transmitted by droplet spread - meningococcal disease and may be meningitis or meningococcal septicaemia (invades into blood and endotoxin leads to inflammatory cascade). Septicaemia presents with petechial rash and signs of sepsis.

Question 6

Aetiology and RF of meningitis?

Answer 6

1) Adults and children: Nisseria meningitides, or Streptococcus Pneumoniae.
Haemophilus Influenzae is less common due to vaccine.
2) Pregnant women/older adults: Listeria monocytogenes
3) Neonates: E.coli, Group B Haemolytic streptococcus
4) Immunocomprimised: CMV, TB, Cryptococcus

Question 7

Signs and symptoms of meningitis?

Answer 7

1) Fever
2) Headache - worst of life lasting minutes to hours (not as sudden as SAH)
3) Meningism - photophobia, neck stiffness (Kernigs and Brudzinski signs)
4) Altered mental state due to cerebral oedema (+/-)
5) Seizures
6) Non-blanching petechial rash

Question 8

Diagnosis of meningitis, what would you find?

Answer 8

1) FBC, blood culture, PCR, swabs from throat and stool, CT scan.
2) Lumbar puncture: send CSF for PCR, culture, microscopy and glucose (Only if no signs on scan or symptoms of ICP)
3) Bacteria CSF: polymorphs/neutrophils present, raised protein, low glucose, turbid colour.
TB CSF: Lot of lymphocytes present, raised protein, low/normal glucose.
Viral CSF: Lymphocytes present, normal protein and glucose.
4) Cryptococcus Neoformans in HIV patients stains with India ink

Question 9

Management of meningitis?

Answer 9

Treatment:
1) IV Cefotaxime (3rd gen cephalosporin)
2) IM Benzylpenicillin if in community
3) If over 50 add Ampicillin to cover Listeria monocytogenes
4) Consider dexamethasone to reduce cerebral oedema.
Prophylaxis: Rifampicin or Ciprofloxacin.