Immunologic aspects of facial nerve paralysis induced by herpes simplex virus infection in mice

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.

Valacyclovir and prednisolone treatment for Bell's palsy: a multicenter, randomized, placebo-controlled study

OBJECTIVE

To investigate the effects of valacyclovir and prednisolone in comparison with those of placebo and prednisolone for the treatment of Bell's palsy, excluding zoster sine herpete.

STUDY DESIGN

Prospective, multicenter, randomized placebo-controlled study.

SETTING

Six academic tertiary referral centers.

PATIENTS

Ultimately, 221 patients with Bell's palsy who were treated within 7 days of the onset. Serological and polymerase chain reaction examinations were performed to distinguish Bell's palsy from zoster sine herpete.

INTERVENTION

The patients were treated with either valacyclovir (dosage, 1,000 mg/d for 5 days) plus prednisolone (VP [n = 114]) or placebo plus prednisolone (PP [n = 107]) administered orally.

MAIN OUTCOME MEASURE

Recovery from the palsy was defined as a score higher than 36 using Yanagihara 40-point scoring system without facial contracture or synkinesis. The patients were followed up until complete recovery occurred or for more than 6 months in cases with a poor prognosis.

RESULTS

The overall rate of patient recovery among those treated with VP (96.5%) was significantly better (p < 0.05) than the rate among those treated with PP (89.7%). The rate of patient recovery was also analyzed by classifying the initial severity of facial palsy. In cases of complete or severe palsy, the rates of patients treated with VP and PP who recovered were 95.7% (n = 92) and 86.6% (n = 82), respectively; the recovery rate for treatment with VP was significantly better than that with PP (p < 0.05).

CONCLUSION

The valacyclovir and prednisolone therapy was more effective in treating Bell's palsy, excluding zoster sine herpete, than the conventional prednisolone therapy. To our knowledge, this is the first controlled study of an antiviral agent in the treatment of a sufficient number of Bell's palsy cases based on an etiologic background.

The role of viruses in idiopathic peripheral facial palsy and cellular immune response

PURPOSE

The purpose of this study is to investigate the role of viruses on the idiopathic peripheral facial palsy and show the interaction of immune system.

MATERIALS AND METHODS

The levels of immunoglobulin (Ig) G and IgM antibodies against to varicella-zoster virus (VZV), herpes simplex virus (HSV), cytomegalovirus (CMV), Ebstein-Barr virus (EBV), and mumps virus in venous blood taken from patients in the amount of 10 mL have been investigated by enzyme-linked immunosorbent assay method. Tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), and transforming growth factor-beta (TGF-beta) were also examined. Of lymphocyte subpopulation, antibodies of CD3(+), CD4(+), CD8(+), CD19(+), and CD16(+) plus 56(+) were analyzed.

RESULTS

Ten of the patients had HSV-1 IgG; 1 of the patients IgM, 5 of the patients EBV IgG, 6 of the patients VZV IgG, 1 of the patients IgM, 9 of the patients mumps IgG, 1 of the patients IgM, and finally in 7 of the patients CMV IgG antibodies were obtained. It was found that CD4(+) cell and ratio of CD4(+)/CD8(+) lower and the percentage of the CD8(+) and CD16(+) plus 56(+) cells higher compared with the control group (P < .05). The levels of TNF-alpha were lower, whereas IFN-gamma and TGF-beta1 were higher.

CONCLUSION

It may be concluded from these results that VZV, HSV-1, CMV, EBV, and mumps virus play a significant role in the etiology of idiopathic peripheral facial palsy and activate the cellular immunity.

Efficacy of Early Treatment of Bell's Palsy With Oral Acyclovir and Prednisolone

OBJECTIVE

To investigate the therapeutic effects of acyclovir and prednisolone in relation to the timing of treatment in Bell's palsy.

STUDY DESIGN

This was a retrospective study of 480 Bell's palsy patients who were treated with oral acyclovir and prednisolone (94 cases) or prednisolone alone (386 cases).

PATIENTS

Patients met the after criteria: (1) severe or complete Bell's palsy with a score lower than 20 on the 40-point Yanagihara facial score and (2) treatment started within 7 days after onset. The patients were treated with oral prednisolone (60-40 mg/day) with or without oral acyclovir (2,000 mg/day).

MAIN OUTCOME MEASURE

Rate of recovery, which was defined as a facial score of 36 or more, and the absence of contracture with synkinesis.

RESULTS

The overall recovery rate of patients treated with acyclovir and prednisolone was 95.7 percent, which was better than that of patients treated with prednisolone alone (88.6%). The recovery rate in patients who began the combined therapy within 3 days of the onset of palsy was 100 percent and early treatment resulted in early remission. In contrast, the recovery rate in patients who started the combined therapy more than 4 days after onset was 86.2 percent.

CONCLUSION

These results suggest that early diagnosis and treatment within 3 days of the onset of paralysis are necessary for maximal efficacy of combined acyclovir and prednisolone therapy for Bell's palsy.