[Herpetic vestibular neuronitis: a hypothesis].

Abundant experimental research has shown the potentially damaging effects that the herpes simplex virus (HSV) may have on peripheral or central nervous pathways. Fifty subjects (ages 20-45) with labial herpes virus (HSV-1) and 15 (ages 25-35) with genital herpes virus (HSV-2) were studied through recording spontaneous and optokinetic nystagmus (OKN) and using the eye-tracking-test (ETT) by means of electronystagmography (ENG). Recording was carried out during the first two days after vesicular eruption and seven days later, when cutaneous manifestations had disappeared. Thirty-five of the 50 subjects with HSV-1 showed spontaneous nystagmus, frequently with a vertical component, which in most cases had disappeared by the seventh control day. We recorded qualitative alterations of OKN as well as ETT in 19 patients while in 3 subjects only ETT was abnormal. All the subjects were normal on the seventh control day. At no time did any of the patients with HSV-2 show objective signs involving the peripheral or central vestibular system. Our research shows that HSV infection, especially HSV-1 infection, determines subclinical alterations of the vestibular function, probably due to the involvement of the brainstem. Therefore the virus is to be taken into account in establishing the etiology of "unknown" vertigo.