Encephalitis Nursing Guide

Encephalitis Overview

Encephalitis is inflammation of the brain parenchyma, causing altered consciousness, personality change, seizures or focal neurological deficits. It is distinct from meningitis (meninges only) but may coexist (meningoencephalitis).

Classic Presentation

Fever — usually present (absent in autoimmune encephalitis)
Altered consciousness/behaviour — confusion, personality change, psychosis — key differentiator from meningitis
Seizures — focal or generalised; often refractory
Focal neurological deficits — depending on brain regions affected
Headache — may be present
Movement disorders — in autoimmune encephalitis (chorea, orofacial dyskinesias)

Encephalitis vs meningitis: Meningitis affects meninges only — headache, neck stiffness, photophobia, normal cognition. Encephalitis involves brain parenchyma — altered cognition, personality, seizures are hallmarks.

Causes

Category	Examples
Viral (most common)	HSV-1 (most common sporadic encephalitis), HSV-2, VZV, EBV, CMV, Enterovirus, West Nile, Japanese B, Rabies
Autoimmune/Anti-NMDAR	Anti-NMDAR encephalitis, LGI1, CASPR2, GABA-B, AMPAR antibodies
Bacterial (rare parenchymal)	Listeria, Mycobacterium TB, Brucella, Rickettsia
Parasitic	Cerebral malaria (Plasmodium falciparum), neurocysticercosis, toxoplasma (immunocompromised)
Other	Cryptococcal (HIV/immunocompromised), ADEM (post-infectious), paraneoplastic

Diagnostic Approach

Empirical aciclovir MUST be started immediately in any patient with suspected encephalitis — before LP results. Delay in HSV encephalitis treatment increases mortality dramatically.

Investigations

Investigation	Findings in Encephalitis
CT head (before LP)	Usually normal initially; may show temporal lobe involvement in HSV; exclude mass lesion before LP
MRI brain (with gadolinium)	Best imaging — temporal lobe T2/FLAIR hyperintensity in HSV; limbic system in autoimmune
Lumbar puncture (CSF)	Lymphocytic pleocytosis (>5 WBCs), elevated protein, normal/slightly low glucose; red cells in HSV
CSF PCR — HSV-1, HSV-2, VZV, EBV, CMV, Enterovirus	Gold standard for viral encephalitis; HSV PCR sensitivity 98%
EEG	Temporal lobe focus in HSV; periodic lateralising epileptiform discharges (PLEDs); non-convulsive status check
Autoimmune antibody panel (serum + CSF)	Anti-NMDAR, LGI1, CASPR2 antibodies in autoimmune encephalitis
Blood cultures + FBC, CRP, procalcitonin	Exclude bacterial meningitis; elevated inflammatory markers

CSF Interpretation

Parameter	Normal	Viral Encephalitis	Bacterial Meningitis
Appearance	Clear, colourless	Clear or slightly turbid	Turbid, purulent
WBC	<5/μL	10–1000 (lymphocytes predominantly)	>1000 (neutrophils predominantly)
Protein	<0.45 g/L	Mildly elevated (0.5–1.0)	Markedly elevated (>1.0)
Glucose (CSF:serum ratio)	>0.6	Normal or slightly low	Low (<0.4)
Red cells	None	Present in HSV (haemorrhagic)	Absent (unless traumatic)

Treatment

Aciclovir — HSV Encephalitis Treatment

Parameter	Detail
Drug	Aciclovir (Acyclovir) IV
Dose (adult)	10 mg/kg IV every 8 hours (adjusted for renal function)
Duration	14–21 days (minimum 14 days; 21 days in confirmed HSV)
Infusion time	Over 60 minutes (crystals form in kidneys with rapid infusion — flush well)
Renal monitoring	Creatinine/eGFR every 48 hrs; crystalline nephropathy — ensure adequate hydration
Start timing	IMMEDIATELY on suspicion — do not wait for LP/CSF results
Continue even if PCR negative	Yes — HSV PCR can be false negative in first 24–72 hrs; continue 14 days unless alternative diagnosis confirmed

Empirical Treatment Protocol

Aciclovir 10 mg/kg IV TDS — covers HSV and VZV
Ceftriaxone 2 g IV BD — covers bacterial meningitis (cannot be excluded until CSF results)
Dexamethasone 0.15 mg/kg QDS × 4 days — if bacterial meningitis suspected (reduces inflammation and deafness)
Seizure management: Levetiracetam or phenytoin IV for acute seizures; EEG monitoring for non-convulsive status
Antipyretics: Paracetamol for fever control — fever worsens cerebral metabolism
Cerebral oedema: Mannitol IV if raised ICP suspected; head of bed 30°

Nursing Care Priorities

Neurological observations every 30–60 mins (GCS, pupils, focal deficits)
Seizure precautions: padded cot sides, suction available, rescue benzodiazepine prescribed
Swallowing assessment — encephalitis patients frequently have dysphagia; NBM until assessed
Skin integrity — immobile/confused patients at pressure injury risk; reposition 2-hourly
Isolation: respiratory precautions if viral aetiology suspected (droplet); standard precautions otherwise
Fluid monitoring: aciclovir hydration requirements; target urine output ≥0.5 mL/kg/hr to prevent crystalline nephropathy

Autoimmune Encephalitis

Anti-NMDAR Encephalitis

The most common autoimmune encephalitis — especially in young women. Caused by antibodies against NMDA (N-methyl-D-aspartate) receptor.

Typical course: Prodromal fever/flu → psychiatric symptoms (psychosis, aggression, hallucinations) → seizures → movement disorders (orofacial dyskinesias, choreoathetosis) → decreased consciousness → autonomic instability → coma
Key feature: Often misdiagnosed as psychiatric illness initially
Associated tumour: Ovarian teratoma in ~50% of female patients — must be screened (pelvic ultrasound/CT)
Treatment: IV methylprednisolone 1 g/day × 5 days + IVIG 0.4 g/kg/day × 5 days; tumour removal; second-line: rituximab, cyclophosphamide
Fever: Often ABSENT — helps distinguish from viral encephalitis

GCC-Specific Context

Encephalitis in GCC

West Nile Virus: Endemic in parts of Middle East and Africa — causes West Nile encephalitis in immunocompromised and elderly. Transmitted by Culex mosquitoes. No specific antiviral treatment; supportive care. GCC cases reported particularly after summer flooding events
MERS-CoV: Middle East Respiratory Syndrome coronavirus can cause neurological complications including encephalitis in severe cases — sporadic cases in Saudi Arabia, UAE, Qatar since 2012. Contact precautions essential
Rabies: Cases imported from endemic countries (India, Africa, Pakistan) to GCC. Key for healthcare workers — post-exposure prophylaxis protocol exists at all GCC major hospitals. Encephalitic (furious) rabies — fatal without post-exposure treatment
Cerebral malaria: In patients from endemic areas (Africa, South Asia) visiting/working in GCC — Plasmodium falciparum causes cerebral malaria with encephalitis-like presentation. Urgent blood film and rapid malaria antigen test required
Neurocysticercosis: Taenia solium larvae in brain — common in patients from pork-eating endemic countries (Latin America, South/Southeast Asia) working in GCC. CT/MRI shows ring-enhancing lesions

Exam Tips

HSV encephalitis = start aciclovir IMMEDIATELY — do not wait for LP results
Aciclovir dose: 10 mg/kg IV every 8 hours × 14–21 days
Temporal lobe involvement on MRI = HSV encephalitis
Anti-NMDAR encephalitis: young woman + psychiatric symptoms + orofacial dyskinesias + ovarian teratoma
CSF in viral encephalitis: lymphocytic pleocytosis, slightly elevated protein, normal glucose
Aciclovir crystalline nephropathy prevention: ensure adequate hydration

Exam MCQs — DHA / SCFHS / QCHP

Q1. A 35-year-old presents with fever, confusion and temporal lobe seizures. MRI shows right temporal lobe T2 signal changes. CT is normal. What is the PRIORITY treatment before LP results are available?

A) Wait for CSF PCR results — do not treat until diagnosis confirmed B) Start aciclovir 10 mg/kg IV TDS immediately — do not wait for LP results C) Start oral valaciclovir — equivalent to IV and less nephrotoxic D) Corticosteroids first to reduce cerebral inflammation

✅ B — Suspected HSV encephalitis is a neurological emergency. Aciclovir must be started IMMEDIATELY on clinical suspicion — delay significantly increases mortality and disability. HSV PCR can be negative in the first 24–72 hours. Aciclovir is safe to give empirically. Never delay for diagnostic results.

Q2. A 22-year-old woman is admitted with 2 weeks of increasingly bizarre behaviour, visual hallucinations and new onset seizures. She has no fever. Pelvic ultrasound shows a left ovarian mass. What is the MOST LIKELY diagnosis?

A) HSV encephalitis — most common viral encephalitis B) Anti-NMDAR receptor encephalitis — autoimmune encephalitis associated with ovarian teratoma C) First episode schizophrenia — psychiatric illness D) Herpes simplex virus 2 encephalitis

✅ B — Classic anti-NMDAR encephalitis presentation: young woman + subacute psychiatric symptoms + seizures + movement disorders + NO fever + ovarian teratoma. Check anti-NMDAR antibodies in serum and CSF. Treatment: immunotherapy + tumour removal. Initial misdiagnosis as psychiatric illness is common.

Q3. A nurse is administering aciclovir IV. The patient's urine output falls to 15 mL/hr. Creatinine has risen from 65 to 145 μmol/L. What complication is occurring?

A) SIADH from viral encephalitis B) Aciclovir-induced crystalline nephropathy — stop or reduce dose, increase IV fluids C) Pre-renal AKI from inadequate fluid intake — increase oral fluid intake D) Expected diuresis from fever management

✅ B — Aciclovir can precipitate in renal tubules causing crystalline nephropathy (obstructive AKI). Risk factors: rapid infusion, dehydration, high doses. Prevention and treatment: infuse over 60 minutes, ensure good hydration (urine output >75 mL/hr), reduce dose per eGFR. Withhold if severe AKI and notify medical team.

Q4. CSF analysis shows: 180 WBCs/μL (90% lymphocytes), protein 0.8 g/L, glucose 3.2 mmol/L (serum 5.8 mmol/L), red cells 50/μL. What do these results suggest?

A) Bacterial meningitis — high protein and neutrophilic pleocytosis B) HSV encephalitis — lymphocytic pleocytosis with red cells (haemorrhagic) and elevated protein, normal glucose C) Normal CSF — white cell count within normal range D) Traumatic tap — red cells from needle trauma only

✅ B — This CSF pattern is classic for HSV encephalitis: lymphocytic pleocytosis (lymphocytes predominant), mildly elevated protein, normal glucose (CSF:serum ratio 3.2/5.8 = 0.55 — borderline low), and red cells (haemorrhagic component typical of HSV temporal lobe necrosis). Continue aciclovir. Traumatic tap would show decreasing red cells from tube 1 to tube 3 — constant = true blood.

🦠 Encephalitis