A young male develops fever, followed by headache, confusional state, focal seizures and right hemiparesis. The MRI performed shows bilateral frontotemporal hyper intense lesion. The most likely diagnosis is:

Answer is B (Herpes simplex encephalitis): Focal findings in a patient with encephalitis should always raise the possibility of HSV encephalitis. Since the patient in question is presenting with focal findings, ILSV encephalitis is the most likely clinical diagnosis. The patient in question is presenting with two groups of clinical manifestations Clinical manifestations common to all viral encephalitis Fever Altered level of consciousness/ confusional state Headache Focal findings Focal seizures Right sided hemiparesis Frontoparital hyper intense lesion on MRI According to Harrison 15th / 2476: Harrison 17`h/2631 Focal findings in a patient with encephalitis should always raise the possibility of HSV encephalitis. Examples of focal findings include: MRI - Areas of increased signal intensity in the frontotemporal, cingulate or insular region of brain on MRI (T2 weighted spinecho MRI) CT - Tcmporoparietal areas of low absorption, mass effect and control enhancement EEG - Periodic temporal lobe spikes on a background of slow or low amplitude activity on EEG Since the patient in question is presenting with focal findings, HSV encephalitis is the most likely clinical diagnosis. MRI findings in other options provided in question: Condition Neurocysticercosis Acute pyogenic meningitis Carcinoma meningitis MRI findings Multiple cystic lesions with enhancement on MRI Diffuse meningeal enhancement on MRI Nodular tumor deposits in the meninges or diffuse meningeal enhancement on MRI.