🧠 Encephalitis
Inflammation of the brain tissue itself — not just its lining. Why altered mental status dominates, and how it differs from meningitis.
🧬 What it is
Meningitis inflames the coverings. Encephalitis inflames the brain itself.
So meningitis gives you a stiff neck; encephalitis gives you altered thinking, seizures and focal deficits.
| Meningitis | Encephalitis | |
|---|---|---|
| Inflamed | Meninges — the covering | Brain tissue |
| Dominant sign | Nuchal rigidity, headache, fever | Altered mental status, confusion, personality change |
| Seizures | Possible | Common |
| Focal deficits | Uncommon | Common — weakness, speech, behavior |
| Commonest cause | Bacterial or viral | Viral — especially HSV-1 |
Herpes simplex encephalitis is the one that must not be missed. It targets the temporal lobe, so it presents with bizarre behavior, personality change, memory loss and smell/taste hallucinations — and it is treatable with IV aciclovir.
Aciclovir is started on suspicion, before confirmation. Waiting for the PCR result costs brain tissue.
👀 Recognizing it
- Fever + headache — the infectious base
- Altered mental status — confusion, disorientation, personality or behavior change
- Seizures
- Focal neurological signs — weakness, aphasia, cranial nerve palsies
- Photophobia, nausea and vomiting
- May progress to decreasing level of consciousness and coma
🧪 Diagnosis
| Test | Shows |
|---|---|
| CSF PCR | Confirms the virus — HSV, enterovirus, arbovirus |
| Lumbar puncture | Raised lymphocytes, mildly raised protein, normal glucose (unlike bacterial meningitis) |
| MRI | Temporal lobe changes in HSV |
| EEG | Seizure activity; temporal focus |
| CT before LP | If focal signs or reduced consciousness — rule out raised ICP |
🩺 Nursing care
- Neuro observations frequently — LOC is the sensitive marker
- Seizure precautions from admission: padded rails, suction and oxygen at the bedside
- Quiet, dim room; cluster care and allow rest
- Head of bed 30°, head midline — ICP rises with brain edema
- Fluid balance — watch for SIADH, which is common
- Antipyretics; fever raises cerebral metabolic demand
🚨 Priorities
Airway and safety first. A confused, seizing patient with a falling GCS needs airway protection — GCS ≤ 8 means intubation.
Never leave a confused, agitated encephalitis patient unattended with the rails down.
🛡️ Prevention
Mosquito-borne causes (West Nile, La Crosse, EEE) → repellent, covered skin, avoid dusk exposure, remove standing water.
Vaccine-preventable causes: measles, mumps, varicella, rabies, Japanese encephalitis.
🎯 NCLEX traps
- Altered mental status dominates, not neck stiffness
- Suspected HSV → start aciclovir immediately
- CSF glucose is normal in viral, low in bacterial
- Seizure precautions are set up on admission, not after the first seizure