Diabetic mice show an aggravated course of herpes-simplex virus-induced facial nerve paralysis.

HYPOTHESIS: Bell's palsy is highly associated with diabetes mellitus.

BACKGROUND

The cause of Bell's palsy in diabetes mellitus is not completely understood. Diabetic mononeuropathy or reactivation of herpes simplex virus type 1 (HSV-1) may be responsible for the facial paralysis seen in diabetic patients. We previously reported transient and ipsilateral facial paralysis in mice inoculated with HSV-1. In this study, we examined the neuropathogenesis of HSV-1 in diabetic mice to clarify the relationship between Bell's palsy and diabetes mellitus.

METHODS

We compared the incidence and course of facial paralysis after HSV-1 inoculation in diabetic and nondiabetic mice groups. Diabetic mice were prepared by intraperitoneal streptozotocin injection. Facial nerve damage was assessed by electrophysiologic and histopathologic examinations.

RESULTS

Compared with the nondiabetic group, the incidence of facial nerve paralysis was significantly increased in the diabetic mice. Electrophysiologic examinations and histopathologic changes also revealed that the facial nerve damage was more severe in the diabetic group.

CONCLUSION

The aggravated course of HSV-1 infection in diabetes suggests that HSV-1 may be the main causative factor for the increased incidence of facial paralysis in diabetic patients.