🧠 Acute encephalitis constitutes a neurological emergency. Treatment must be started promptly on the basis of the likely diagnosis. Can occur at any age and HSV can even mimic a Deep MCA stroke. Consider LP and early MRI if considered. Aciclovir should be started if reasonable suspicion until diagnosis excluded when it can be stopped. Aciclovir is not benign and can rarely cause AKI and its use must be balanced with risks and benefits. Always take expert neurology advice.

🧠🚨 Initial Encephalitis Management Summary
🫁 Stabilise ABCs → Admit, consider ITU; give O₂ if hypoxic. 💉 Investigations: Bloods (FBC, U&E, LFT, cultures, glucose) + CSF if safe. 🖼️ CT head first if ↑ ICP or mass suspected. 💊 IV Aciclovir 10 mg/kg TDS immediately if HSV encephalitis suspected. 🧲 MRI Brain for supportive diagnosis. ⚡ EEG if available. 🧪 IV Cefotaxime (or Ceftriaxone) if meningitis cannot be excluded while awaiting results. 📞 Urgent Neurology / Infectious Disease consult.

🧠🚨 Initial Encephalitis Management Summary

🫁 Stabilise ABCs → Admit, consider ITU; give O₂ if hypoxic.
💉 Investigations: Bloods (FBC, U&E, LFT, cultures, glucose) + CSF if safe.
🖼️ CT head first if ↑ ICP or mass suspected.
💊 IV Aciclovir 10 mg/kg TDS immediately if HSV encephalitis suspected.
🧲 MRI Brain for supportive diagnosis. ⚡ EEG if available.
🧪 IV Cefotaxime (or Ceftriaxone) if meningitis cannot be excluded while awaiting results.
📞 Urgent Neurology / Infectious Disease consult.

📖 About

Encephalitis = inflammation of brain parenchyma, usually viral but can be autoimmune, bacterial, or fungal.
HSV encephalitis is the most common and most treatable → early Aciclovir improves survival & outcomes.
Prognosis depends on pathogen and immune status.

🦠 Causes & Features

Cause	Clinical Features	Investigations	Treatment
Viral (HSV, VZV, enterovirus)	Fever, headache, confusion, seizures, focal neurology (e.g. aphasia, hemiparesis)	CSF lymphocytosis + PCR, MRI: temporal lobe hyperintensity, EEG: temporal activity	IV Aciclovir + supportive care, anticonvulsants
Autoimmune (Anti-NMDA-R)	Psychiatric features, memory loss, seizures, dyskinesias, autonomic instability	CSF oligoclonal bands, serum/CSF antibodies, MRI often normal, EEG diffuse slowing	Steroids, IVIG, plasma exchange ± Rituximab/Cyclophosphamide, treat underlying tumour
Bacterial (e.g. Listeria, Mycoplasma)	Fever, headache, confusion, seizures, focal deficits	CSF neutrophils, high protein, low glucose, Gram stain & culture; MRI ± abscess	IV antibiotics (e.g. Ampicillin for Listeria), manage ICP
Fungal (Cryptococcus, Aspergillus)	Subacute headache, meningism, cranial nerve palsies	CSF antigen/India ink, MRI nodules or abscesses	Amphotericin B + Flucytosine → Fluconazole maintenance

🧠 Clinical Presentation (esp. HSV)

Fever, headache, altered mental status.
Seizures (temporal lobe), aphasia, hemiparesis.
Specific signs: rigidity/chorea in Japanese encephalitis; rash with HHV6/Zoster.

🔬 Investigations

FBC/CRP → raised WCC/CRP.
U&E → check renal function before Aciclovir.
CSF: lymphocytic pleocytosis, raised protein, viral PCR.
MRI: temporal lobe hyperintensity (classic for HSV).
EEG: temporal lobe epileptiform activity.

💊 Management

Aciclovir 10 mg/kg IV q8h for 14–21 days (dose adjust in renal impairment).
Anticonvulsants for seizures (e.g. Levetiracetam, Phenytoin).
Supportive care: hydration, antipyretics, ITU if severe.
Raised ICP → consider Mannitol, hyperventilation, ITU care.

⚠️ Poor Prognostic Features

Age > 30 years
Coma at presentation
Bilateral EEG abnormalities
High CNS viral load
Delay > 4 days to treatment
Abnormal CT findings

⏳ Late Complications

Memory impairment, cognitive decline.
Mood and personality changes (irritability, depression).

📚 References

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Acute Encephalitis