Besides causing the common oral lesions, HSV-1 is associated with encephalitis and is the more common cause of adult encephalitis. Pathophysiology of this encephalitis is poorly understood in humans. Animal models suggest that the virus enters the CNS via peripheral nerves. Virus-induced apoptosis may play a role in the molecular pathogenesis of herpes simplex encephalitis (HSE).
The encephalitis affects the temporal lobes of the brain in most cases. Wasay et al (Eur J Neurol 2005;12(6):475-9) report temporal lobe involvement in 60% of patients. Fifty-five percent of patients demonstrated temporal and extratemporal pathology, and 15% of patients demonstrated extratemporal pathology exclusively.
Generally, patients may have a prodrome of malaise, fever, headache and nausea. These are followed by acute or subacute onset of an encephalopathy whose symptoms include lethargy, confusion and delirium. Headaches, seizures, aphasia and other focal deficits also may occur. On neurological examinations, global and focal neurologic findings include encephalopathy, delirium, aphasia, cranial nerve deficits and hemiparesis. Meningeal signs may be present. Unusual presentations occur:
- Ku et al (Pediatr Neurol 1996;15(2):169-71) discussed the unique presentation of HSE in a bilingual patient, who developed global aphasia for 1 language (his most recently learned language) but retained most of his birth language ability.
- McGrath et al (Neurology 1997;49(2):494-7) reported on 4 patients with confirmed HSE, each with an anterior opercular syndrome. The syndrome (ie, paralysis of the masticatory, facial, pharyngeal, and lingual muscles) occurred as the primary manifestation of HSE in 2 patients and as part of the encephalitis picture in the other 2 patients. The authors suggested that unique presentations, such as the anterior opercular syndrome, should alert the clinician to the possibility of HSE.
CT scan or MRI scan show abnormal mass or abnormal signal at temporal lobe.
CASE REPORT
A 58-year-old man, after a brief period of malaise, developed disorientation, difficulty with short-term memory and then aphasia and epileptic seizures. He was hospitalized and was started on antiepileptic therapy. He was also treated with acyclovir for presumed herpes encephalitis, which was confirmed by the MRI scan, that demonstrated altered signal in left medial temporal lobe. Two weeks later, patient’s symptoms were disappeared and he was dismissed from the hospital.
18F-FDG PET scans of this patient are shown below.
18F-FDG PET scan shows an area of increased uptake of FDG in the left hippocampus.
The glucose metabolism in the left hippocampus is significantly greater than in the right hippocampus.
So, this is the case report..
If anyone has suggestions or comments….
Posted by valeberti 
