Objectives: To describe an atypical case of Herpes simplex virus encephalitis (HSE) and propose an algorithm to prevent delayed diagnosis and treatment of complex cases.
Methods: We highlight the unusual presentation of a man who developed unilateral HSE seven days after a fall and left petrous temporal bone fracture, resulting in a contusion of the right temporal cortex and subdural haematoma. He later developed left seventh and eighth cranial nerve palsies, for which corticosteroids were commenced. Subsequently he presented with confusion and fever. Cerebrospinal fluid (CSF) analysis was normal, and computed tomography showed resolution of the haemorrhage. However, an electroencephalogram showed severe dysfunction of the left frontotemporal region, and magnetic resonance imaging demonstrated striking unilateral changes involving the left temporal lobe.
Results: Herpes simplex virus (HSV) type 1 polymerase chain reaction was positive and the patient was commenced on aciclovir. He continued to have significant cognitive deficits and required ongoing neurorehabilitation.
Conclusions: Potential explanations for this atypical presentation include the possibility of HSV infection as a result of the head injury, either by direct transmission or reactivation of latent infection. The administration of steroids may have contributed to the lack of pleocytosis of the CSF. A simple algorithm is proposed that involves a battery of questions emphasising cognitive and language function, so that the diagnosis and treatment of less straightforward cases of HSE is not delayed. This should be used in the appropriate context in conjunction with thorough clinical assessment, and has yet to be validated.