Introduction HSE is estimated to occur in approximately 1 in 250,000 to 1 in 500, 000 individuals per year, with approximately one third of cases occurring in children and adolescents. Poorer prognosis and neurological sequelae are associated with delayed treatment of HSE.

We retrospectively reviewed all cases of HSV meningoencephalitis admitted to our centre over a ten year period from Jan 2008 to Jan 2018. Four cases were identified based on PCR confirmation of HSV 1 or 2 in cerebrospinal fluid samples. Here we discuss the clinical presentation, as well as electroencelphalogram, neuroimaging and clinical outcomes, to highlight the importance of early recognition and timely treatment of such cases.

Case series Case 1: Nineteen month old male infant presented with prolonged focal febrile seizure, on a preceding history of pyrexia and lethargy for one day, and cough for one week. EEG showed excess slowing over both posterior regions, more marked on the left posterior region, consistent with bilateral cerebral dysfunction without epileptiform discharges. MRI brain demonstrated deep white matter changes in the left parietal and posterior parietal/occipital regions and adjacent grey matter and two small punctate haemorrhages in the left midparietal region.

Case 2: Four week old male infant presented with recurrent focal seizures. No pyrexia or preceding symptoms were documented. EEG recorded two seizures with origin near the right midline with spread to right motor cortex and right hemisphere. MRI brain showed right deep white matter changes and left subcortical lesion.

Case 3: Eleven week old female infant admitted with pyrexia and lethargy. She had 6 episodes of febrile generalised tonic seizures over 48 hours, each less than 5 minutes in duration. EEG demonstrated some asymmetry and excess slow activities over right temporal region in sleep, with no epileptiform features. MRI brain was normal.

Case 4: Thirteen month old female presented with febrile status epilepticus, on a background history of pyrexia and diarrhoea for 3 days. EEG showed three epileptic spasms with background continuous epileptiform discharges, which were multifocal; predominantly right posterior and some frontal discharges were seen in sleep. MRI brain showed subtle high signal white matter changes in the frontal lobes bilaterally and multiple high signal areas throughout corpus callosum.

Discussion This case series demonstrates that HSV encephalitis should be considered in children with atypical febrile seizures which are prolonged, focal or recurrent. Timely recognition of HSE is essential to minimise patient morbidity and mortality.