🔥 Chapter 60: Acute Febrile Encephalopathy

Fever + altered sensorium ± seizures · Bacterial vs viral vs tubercular meningitis · Herpes simplex encephalitis (HSV) · CSF interpretation · Empiric antibiotics + acyclovir · Steroids in meningitis · Cerebral malaria · ADEM · Tubercular meningitis (TBM) stages & treatment

🔍 Core Concepts: Acute Febrile Encephalopathy

📌 Definition
Fever, seizures, and/or altered consciousness. Common in tropical countries. Aetiologies: meningitis (bacterial, viral, TB), encephalitis (HSV, Japanese B), cerebral malaria, ADEM, systemic infections with encephalopathy.
🦠 Bacterial Meningitis (ABM)
CSF: PMN pleocytosis (100-1000), low glucose (<50% blood), high protein (>100). Empiric: ceftriaxone + vancomycin (if pneumococcal resistance). Dexamethasone 0.15 mg/kg Q6H x 2-4 days (if H.influenzae or pneumococcus).
🧬 Viral Encephalitis (HSV)
CSF: lymphocytic pleocytosis, normal glucose, elevated protein. Temporal lobe involvement on MRI. HSV PCR gold standard. Treatment: IV acyclovir 10 mg/kg Q8H x 14-21 days.
🦠 Tubercular Meningitis (TBM)
Insidious onset, CSF: lymphocytes (10-500), low glucose, protein 150-200 (cobweb). Basal enhancement on CT/MRI. Treatment: 4-drug ATT (HRZE) + steroids (dexamethasone).
🦟 Cerebral Malaria
P. falciparum, unarousable coma >6h after seizure correction, peripheral smear positive. Treatment: IV artesunate (2.4 mg/kg at 0,12,24h then daily). Avoid quinine if artesunate available.
🧠 ADEM (Acute Disseminated Encephalomyelitis)
Post-infectious (2-30 days), altered sensorium, multifocal deficits. MRI: ill-defined white matter lesions. Treatment: methylprednisolone 10-30 mg/kg/day x 3-5 days, then oral taper.

🩺 Stepwise Approach: Acute Febrile Encephalopathy

1
Emergency stabilisation (ABCDE)
Airway: GCS <8 → intubate. Breathing: O2, monitor EtCO2. Circulation: IV access, fluid bolus if shock, vasopressors. Check bedside glucose (correct hypoglycaemia). Control seizures (benzodiazepines).
2
Assess for signs of raised ICP / herniation
Papilloedema, unequal pupils, Cushing triad (hypertension, bradycardia, irregular breathing). If present, give mannitol 0.5-1 g/kg, hyperventilate (PaCO2 30-35), elevate head, urgent CT.
3
Lumbar puncture (if no contraindications)
Contraindications: signs of ↑ICP, shock, coagulopathy, local infection. CSF: cell count (PMN vs lymph), glucose, protein, Gram stain, culture, PCR (HSV, enterovirus), India ink (cryptococcus), AFB.
4
Empiric antimicrobial therapy (do not delay)
If LP deferred: ceftriaxone (100 mg/kg) + vancomycin (60 mg/kg/day) + acyclovir (10 mg/kg Q8H) for suspected HSV encephalitis (focal signs, temporal lobe). Add dexamethasone if bacterial meningitis suspected.
5
Specific therapies based on diagnosis
Bacterial: target antibiotics, dexamethasone for 2-4 days. HSV: acyclovir 14-21 days. TBM: 4-drug ATT + steroids. Cerebral malaria: IV artesunate. ADEM: methylprednisolone pulse.
6
Supportive care & monitoring
ICP monitoring if severe. Seizure control (levetiracetam, phenytoin). Maintain normothermia, normoglycaemia, euvolemia. Treat hyponatraemia (SIADH) with fluid restriction. Monitor for complications.