Viral infections - Herpes simplex encephalitis

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Viral infections of the nervous system are mainly caused by Herpes simplex virus (HSV) and human immunodeficiency virus (HIV). (Refer to section on viral infections and HIV)

Herpes simplex encephalitis 

Most  of  cases  in  adults  are  caused  by  HSV-1,  a  small  number  are  caused  by  HSV-2  usually  in immunosuppressed states or in neonates. It should be suspected in all patients not responding to  antibiotics/other treatments. 

Clinical presentation

  • Early features are fever, headache & altered consciousness which may develop gradually over days or rapidly over hours
  • The  most  common  manifestations  are  personality  change,  dysphasia,  behavioural disturbance, and occasional psychotic features
  • Focal or generalized seizures

Investigations 

  • Lumbar  puncture — CSF  is  under  increased  pressure  and  may  appear  normal  or  show  a mild-moderate  lymphocytosis,  a  mild-moderate elevated protein  levels  and  normal  or decreased glucose
  • CSF PCR
  • HSV1+HSV2 CSF Rapid test
  • MRI — demonstrate  predominant  involvement  of  the  limbic  system  structures,  medial temporal lobes, and insular cortex

Pharmacological Treatment 

B: acyclovir (IV/PO) 10–15mg/kg 8hourly for 14–21days 

Non pharmacological treatment 

Provide supportive therapy as for unconscious patients