The management of peripheral facial nerve palsy: "paresis" versus "paralysis" and sources of ambiguity in study designs

Abstract

Objective: Conservative management of idiopathic or herpetic acute peripheral facial palsy (herpes zoster oticus, HZO) often leads to a favorable outcome. However, recent multicenter studies have challenged the necessity of antivirals. Whereas large numbers of patients are required to reveal statistical differences in a disease with an overall positive outcome, surprisingly few studies differentiate between patients with paresis and paralysis. Analyzing our own prospective cohort of patients and reviewing the current literature on conservative treatment of Bell's palsy and HZO, we reveal the importance of initial baseline assessment of the disease course to predict the outcome and to validate the impact of medical treatment options. STUDY DESIGN AND DATA SOURCE: Prospective analysis of consecutive patients referred to 2 tertiary referral centers and research on the Cochrane Library for current updates of their previous reviews and search of MEDLINE (1976-2009) for randomized trials on conservative treatment of acute facial palsy were conducted.

Methods: One hundred ninety-six patients with Bell's palsy or HZO were followed up prospectively until complete recovery or at least for 12 months. The numeric Fisch score (FS) was used to classify facial function, and patients were separated between incomplete palsy (=paresis) and complete paralysis. Electroneuronography (ENoG) was used to further subdivide patients with paralysis. The treatment protocol was independent of the ongoing investigation including prednisone and valacyclovir in most patients. A total of 250 previous studies on facial palsy outcome were evaluated regarding their distinction between different severity scores at baseline and its impact on treatment outcome. Trials not making the distinction between paresis and paralysis at baseline and with an insufficient follow-up of less than 12 months were excluded.

Results: In the Bell's and HZO paresis group, all except 1 patient recovered completely, most of them within 3 months, independent of the treatment regimen. In the Bell's paralysis group, 38 patients (70%) recovered completely after 1 year, including 94% of patients with a denervation by ENoG of less than 90%. Thirty percent of Bell's paralysis patients recovered incompletely, revealing the worst outcome in patients with a 100% denervation on ENoG. None of the 4 patients with HZO and ENoG denervation of more than 90% recovered to normal facial function. We found a highly significant difference regarding the time course and final outcome in patients with incomplete palsies versus total paralysis; however, only 3 of 250 studies make this distinction.

Conclusion: The time course for improvement and the extent of recovery is significantly different in patients presenting with an incomplete facial nerve paresis compared with patients with a total paralysis. Whereas the term "palsy" includes both entities, the term "paralysis" should only be used to describe total loss of nerve function. Patients with incomplete acute Bell's palsy (paresis) should start to improve their facial function early (1-2 wk after onset) and are expected to recover completely within 3 months. These patients do not benefit from antiviral medications and most likely do not profit from systemic steroids. Mixing patients with different severity of palsies will always lead to controversial results.