19th June 2023

An 18-year-old female presented to A&E with confusion, drowsiness, fever, headache for 3 days

An 18-year-old female presented to A&E with confusion, drowsiness, fever, headache for 3 days with an episode of seizure prior to arrival in A&E. On assessment, temp 37.9, BP 130/80 mm hg, HR 98bpm, O2 saturations 98% on room air. GCS 12/15 (E3 V4 M5). Pupils are equal and reactive to light bilaterally. Neck rigidity is present, but no rashes noted. The remainder of the neurological examination was normal.

Bloods show a mild rise in white blood cells with raised lymphocytes. Blood glucose is 6.

IV ceftriaxone and IV acyclovir were started empirically for a possible CNS infection.

MRI brain was performed, which showed hyperintensity of the frontotemporal region. LP showed raised protein with lymphocytosis. CSF viral PCR is pending.

Of the options below, which is the most likely diagnosis?