Early collection of saliva specimens from Bell's palsy patients: quantitative analysis of HHV-6, HSV-1, and VZV

Bell's palsy is the most common cause of facial paralysis. Although it has been associated with diabetes mellitus, hypertension, pregnancy, and preeclampsia, the etiology of Bell's palsy remains unknown. The reactivation of latent herpes simplex virus (HSV) or varicella-zoster virus (VZV) with subsequent inflammation and entrapment of the facial nerve in the narrow labyrinthine segment has been implicated as a cause of facial paralysis, but the active role of these viruses in Bell's palsy is still discussed. This study quantified HSV-1 DNA, VZV DNA, and HHV-6 DNA in 95 saliva samples collected from patients within 48 hr from the onset of paralysis. HSV-1, VZV, and HHV-6 were detected in 13%, 3%, and 61% of patients, respectively. The detection rate did not differ significantly between patients and a control group of healthy donors. Interestingly, however, the value of HHV-6 DNA copies was significantly higher than that detected in healthy donors. In addition, the mean value of HHV-6 DNA recorded in patients who had at least a one grade improvement of palsy at the first visit was significantly lower than that detected in patients who showed no change in facial palsy grade or an increase of at least one grade. These findings call into question the role of HSV-1 and VZV in the etiology of Bell's palsy, and suggest that HHV-6 may be involved in the development of the disease or that the underlying disease mechanism might predispose patients to HHV-6 reactivation.