Ans. is 'c' i.e., Temporal lobe involvement Pathology of Herpex simplex encephalitis:o Herpes simplex infection has a prediliction for the involvement of Temporal lobe.o The lesions in HSV encephalitis are intense hemorrhagic necrosis of the inferior and medial temporal lobe and the mediorbital part of frontal lobes.o The temporal lobe lesions are usually b/L but not symmetrical.o The distribution of the lesion is so characteristic that the diagnosis can be made by gross inspection or by their location and appearance on imaging studies.o In the acute stages of the disease, intranuclear eosinophilic inclusions are found in neurons and glial cells in addition to the usual microscopic abnormalities of acute encephalitis and hemorrhagic necrosis.C.S.F examination# Increased C.S.F pressure# Pleocytosis, cells are mostly lymphocytes# Red cells sometimes numbering in thousands and xantho chromia are found refecting the hemorrhagic nature of the brain lesions.# Protein content is increased in most cases.# Slight reduction of glucose.o Herpes simplex encephalitis is characterized bv "focal neurological symptoms"o Over 90% patients will have one of the following symptoms offocal neurological deficit, plus fever -# Focal cranial nerve deficits# Hemiparesis# Dysphasia# Aphasia# Ataxia# Focal seizure# Altered mentation and level of consciousnesso Most common area involved in herpes simplex encephalitis is "Temporal lobe"# Temporal lobe abnormalities on brain imaging are considered strong evidence for herpes simplex encephalitis.# Temporal lobe lesions are predominantly unilateral.# Most sensitive and specific investigation for HSV-1 encephalitic is MRI# In contrast, cranial CT scans have only 50% sensitivity and that too early in the disease.EEG findings in HSV-jencephalitis# Focal electroencephalogram (EEG) findings occur in >80% of cases typically showing prominent intermittent high amplitude slow waves (delta and theta slowing) and occasionally continuous "periodic lateralized epileptiform discharges ".