Stroke mimics - A case of viral encephalitis

Published Date: 19th July 2016

Publication Authors: Mavinamane S

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Introduction

Stroke causes significant morbidity and mortality. In the UK it accounts for up to 11% of deaths annually, with over 56,000 deaths occurring in England and Wales in 1999. Stroke typically presents with focal neurological deficits including speech disturbance and limb weakness, consistent with vascular territory involved. However, in some cases, this typical presentation can mimic other life threatening diagnoses; one being viral encephalitis (VE), as discussed here. VE is uncommon although it remains a serious illness with significant risk of morbidity and death. Most commonly caused by Herpes Simplex Virus Type-1 (HSV-1), it can present with fever, headaches, confusion, behavioural changes and focal neurological deficits. Prompt diagnosis and treatment with high-dose Aciclovir is essential. We as clinicians need to have a high index of suspicion when tackling such cases.

The case

A 52 year old lady with known hypertension, presented with expressive dysphasia and intermittent headaches. Primary diagnosis was of a partial anterior circulation stroke. CT-head showed a left MCA (middle cerebral artery) infarct with subsequent MRI-head confirming acute infarct of the left temporal lobe. She was treated with 300 mg Aspirin and stroke risk factor management, then discharged home with stroke clinic follow-up. She presented with increasing lethargy, intermittent drowsiness and ongoing expressive dysphasia two days later. Haemorrhagic transformation of her acute infarct was considered although repeat CT-head showed increasing oedema around the area of infarct. This was thought to be too extensive for an infarct and general consensus was that the scan findings were not typical of stroke but rather to consider a diagnosis of VE. Treatment with high dose intra-venous Aciclovir was commenced. The lumbar puncture performed confirmed active infection with HSV-1 on CSF PCR examination. At three weeks, the virus was still present in her CSF, although there was marked improvement in oedema on repeat MRI scan. Prolonged Aciclovir course was continued with weakly CSF analysis at the regional Infectious Diseases Centre. Clinically the patient made significant improvement.

Conclusion

Stroke mimics can cloud our clinical judgement at times, however it is essential that we consider important diagnoses when the clinical picture is atypical and more importantly when clinical improvement has not occurred following appropriate stroke management. Viral encephalitis is a life-threatening diagnosis not to miss!

Elmamoun, S; Mavinamane, S; Meenakisundaram, S. (2013).  Stroke mimics - A case of viral encephalitis . European Journal of Internal Medicine. 24 (Supp 1), E51

 

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