Abstracts

Rationale: Human herpesvirus-7 (HHV-7) is a β-herpesvirus isolated from peripheral blood CD4+ T cells from healthy individual in 1990. Most closely related to HHV-6 and cytomegalovirus, HHV-7 infection is ubiquitous and primary infection occurs during childhood and persistent long time. HHV-7 DNA also has been detected in CSF and normal brain tissue but not detected frequently than HHV-6. Previous studies have provided the evidence that CMV and HHV-6 are responsible for neurological diseases including encephalitis, Guillain-Barre syndrome, multiple sclerosis and seizures etc. A few previous studies reported HHV-7 definition in immunocompetent or allograft patients and showed that HHV-7 might be involved in immunologic or inflammatory process of CNS disease. However, small cases lead litter information is available about intractable epilepsy associated with HHV-7 infection till now. Methods: Brain tissues of 305 consecutive cases with intractable epilepsy from 2009 to 2012 were analyzed for neuropathology and for HHV-7 KR4 antigen by immunohistochemistry. 21 samples as control group were obtained from patients with brain trauma or stroke. Results: The 305 patients included 201 males (65.9%) and 104 females (34.1%). The mean age was 23.88±6.23 years (range 18 to 45). HHV-7 KR4 protein was detected in samples from 27 out of 305 (8.9%) patients with intractable epilepsy and in 0 of 21 control samples. The most prominent etiologic factors for HHV-7 infection were hippocampus sclerois (11 out of 69 cases), scar lesion (8 out of 58 cases) and vascular malformation (4 out of 52 cases). Conclusions: These findings firstly suggest a possible association between HHV-7 positivity and intractable epilepsy especially hippocampus sclerosis. This study will provide us with additional insight to the underlying pathogenesis of intractable epilepsy.