Nocturnal onset and development of Bell's palsy.

OBJECTIVE/HYPOTHESIS: To examine the mechanism and pathophysiology of idiopathic peripheral facial palsy (Bell's palsy), the mode of onset of facial palsy was investigated.

STUDY DESIGN

Retrospective case review.

METHODS

We identified the point at which patients with facial palsy first noticed their illness using our medical charts for 648 patients and information from 3,580 facial palsy cases who visited an Internet site; we found that the time of a patient's first awareness of his or her illness was mentioned in 258 (204 Bell's palsy) and 53 cases, respectively. These cases were divided into three periods: morning, afternoon, and night.

RESULTS

The ratio of morning:afternoon:night in the two groups was 141:30:33 and 50:0:3, respectively. These findings indicate that the majority of patients first noticed their palsy in the morning.

CONCLUSION

Because several hours are required for facial palsy to develop before becoming apparent, this suggests that the onset and development of facial palsy occurred during sleep, when circulatory dynamics are reduced. In humans, ischemia is more likely to occur and produce facial palsy than virus reactivation.