Herpes simplex encephalitis: an autopsy case with isolation of type 1 herpes simplex virus

Herpes simplex virus antigen detection in human acute encephalitis: an immunohistochemical study using avidin-biotin-peroxidase complex method

Autopsy specimens from six patients with clinically diagnosed herpes simplex virus (HSV) encephalitis were studied. Since immunocytochemistry has been reported to be a more reliable and successful method to identify HSV as the etiologic agent, antitype 1 HSV (HSV1) and antitype 2 HSV (HSV2) and the avidin-biotin-peroxidase complex (ABC) method were applied to brain paraffin sections. Positive immunostaining was observed in front-orbital, mediobasal temporal lobes, cingulate gyrus, and insula. The staining was bilateral but predominant on one side. In neurons, the cytoplasmic staining was prominent in perikarya and processes, less often observed in nuclei, rarely seen in nuclear inclusions. The positive staining was intense in oligodendrocytes and macrophages, in both nuclei and cytoplasm. In two cases astrocytic processes were stained strongly. Perivascular lymphocytes were always negative. Positive reactions were obtained with both anti-HSV1 and anti-HSV2 but weaker with anti-HSV2. This results suggests that, because of its high sensitivity, ABC method permits viral antigen detection not feasible with other methods. However, this method lacks of accuracy for HSV typing mainly because of probable antigens changes resulting from tissue processing.

Necropsy study of the olfactory portal of entry in herpes simplex encephalitis

Two fatal cases of sporadic herpes simplex virus (HSV) encephalitis were seen and diagnosed at the Sir Charles Gairdner Hospital, Perth, between 1979 and 1981. Necropsy studies were directed to the possible portal of entry of HSV into the central nervous system. Viruses were present in the left olfactory nerve in one patient. No viruses were found in the Gasserian ganglia of either patient. The finding of HSV within an olfactory nerve provides further evidence of an olfactory portal of entry to the central nervous system in sporadic human HSV encephalitis.

Herpes simplex type 2 encephalitis concurrent with known cerebral metastases

A 62-year-old woman developed neurologic deficits 7 months after pulmonary lobectomy for alveolar cell carcinoma of the lung. CT scan of the head demonstrated two metastases with marked peritumoral edema. Administration of Decadron, chemotherapy and 3,000 rad cranial radiation resulted in dramatic improvement of dysphasia and right hand paresis. Almost 2 months later, rhythmic, involuntary movements of the left hand developed. There was progression to multifocal seizures, grand mal seizures, postictal depression, status epilepticus, and coma, with death 9 days after onset of the movement disorder. Bronchoalveolar carcinoma was widely disseminated in lungs and bones, and as three metastases in brain. Bland "ischemic" necrosis in a pseudolaminar pattern was present in the neocortex. Innumerable Cowdry type A intranuclear inclusion bodies were seen in neurons, astrocytes, and oligodenodroglia. Immunofluorescence demonstrated Herpes simplex virus type 2 antigen and electron microscopy revealed virions with the morphology of the Herpes group. The case is significant for (1) the concurrence of intracranial metastases and Herpes simplex encephalitis, and (2) the causal agent, Herpes simplex virus type 2. The implication for the clinical neurocientist is the potential in a patient with systemic cancer, for the causation of neurologic complications by more than one factor or mechanism.