Imaging recommendation · Neuro · Head & Neck

Suspected encephalitis

Q: What's the alternative imaging for suspected encephalitis when mri contraindicated?

CT — CT Head with contrast (less sensitive) (iv contrast).

Q: What's the alternative imaging for suspected encephalitis when autoimmune encephalitis suspected?

MRI — MRI Brain + LP for antibody panel + EEG (iv contrast).

Recommended: MRI Brain with and without contrast (including FLAIR and DWI) is the preferred imaging study for suspected encephalitis. Temporal lobe involvement is classic for HSV.

Recommended study

MRI Brain with and without contrast (including FLAIR and DWI)

MRI IV contrast Preferred Neuro · Head & Neck EmergencyAcute inpatient Reviewed 2026-05

Temporal lobe involvement is classic for HSV. Limbic encephalitis pattern suggests autoimmune.

If the default doesn't apply

MRI contraindicated

CT CT Head with contrast (less sensitive) IV contrast

Autoimmune encephalitis suspected

MRI MRI Brain + LP for antibody panel + EEG IV contrast

Watch-outs

Empiric acyclovir

Start within 6 hours of suspected HSV encephalitis — better outcomes; do not wait for imaging or LP.

Status epilepticus

Encephalitis can present with non-convulsive status — add EEG if persistent altered mental status.

Pearls

HSV encephalitis: bilateral (often asymmetric) medial temporal + insular involvement with sparing of basal ganglia.
Anti-NMDA receptor encephalitis: young patient with neuropsychiatric symptoms, autonomic instability, dyskinesias.
Viral encephalitis usually preserves basal ganglia; consider Eastern equine, West Nile, JE in geographic context.