Surgical interventions for the early management of Bell's palsy

Bell's palsy is an acute unilateral facial paralysis of unknown aetiology and should only be used as a diagnosis in the absence of any other pathology. As the proposed pathophysiology is swelling and entrapment of the nerve, some surgeons suggest surgical decompression of the nerve as a possible management option; this is ideally performed as soon as possible after onset. This is an update of a review first published in 2011, and last updated in 2013. This update includes evidence from one newly identified study.

To assess the effects of surgery in the early management of Bell's palsy.

On 20 March 2020, we searched the Cochrane Neuromuscular Specialised Register, CENTRAL, MEDLINE, Embase, ClinicalTrials.gov and WHO ICTRP. We handsearched selected conference abstracts for the original version of the review.

We included all randomised controlled trials (RCTs) or quasi-RCTs involving any surgical intervention for Bell's palsy. Trials compared surgical interventions to no treatment, later treatment (beyond three months), sham treatment, other surgical treatments or medical treatment.

Three review authors independently assessed trials for inclusion, assessed risk of bias and extracted data. We used standard methodological procedures expected by Cochrane. The primary outcome was complete recovery of facial palsy at 12 months. Secondary outcomes were complete recovery at three and six months, synkinesis and contracture at 12 months, psychosocial outcomes at 12 months, and side effects and complications of treatment.

Two trials with 65 participants met the inclusion criteria; one was newly identified at this update. The first study randomised 25 participants into surgical or non-surgical (no treatment) groups using statistical charts. One participant declined surgery, leaving 24 evaluable participants. The second study quasi-randomised 53 participants; however, only 41 were evaluable as 12 declined the intervention they were allocated. These 41 participants were then divided into early surgery, late surgery or non-surgical (no treatment) groups using alternation. There was no mention on how alternation was decided. Neither study mentioned if there was any attempt to conceal allocation. Neither participants nor outcome assessors were blinded to the interventions in either study. There were no losses to follow-up in the first study. The second study lost three participants to follow-up, and 17 did not contribute to the assessment of secondary outcomes. Both studies were at high risk of bias. Surgeons in both studies used a retro-auricular/transmastoid approach to decompress the facial nerve. For the outcome recovery of facial palsy at 12 months, the evidence was uncertain. The first study reported no differences between the surgical and no treatment groups. The second study fully reported numerical data, but included no statistical comparisons between groups for complete recovery. There was no evidence of a difference for the early surgery versus no treatment comparison (risk ratio (RR) 0.76, 95% confidence interval (CI) 0.05 to 11.11; P = 0.84; 33 participants; very low-certainty evidence) and for the early surgery versus late surgery comparison (RR 0.47, 95% CI 0.03 to 6.60; P = 0.58; 26 participants; very low-certainty evidence). We considered the effects of surgery on facial nerve function at 12 months very uncertain (2 RCTs, 65 participants; very low-certainty evidence). Furthermore, the second study reported adverse effects with a statistically significant decrease in lacrimal control in the surgical group within two to three months of denervation. Four participants in the second study had 35 dB to 50 dB of sensorineural hearing loss at 4000 Hz, and three had tinnitus. Because of the small numbers and trial design we also considered the adverse effects evidence very uncertain (2 RCTs, 65 participants; very low-certainty evidence).

There is very low-certainty evidence from RCTs or quasi-RCTs on surgery for the early management of Bell's palsy, and this is insufficient to decide whether surgical intervention is beneficial or harmful. Further research into the role of surgical intervention is unlikely to be performed because spontaneous or medically supported recovery occurs in most cases.