Surgical operation for Bell's palsy (idiopathic facial paralysis)

Review question

What are the effects of early surgery in the management of Bell's palsy, compared with no treatment, operations performed after three months, other types of surgery, sham (fake) treatment or treatment with medicines?


Bell's palsy is a paralysis of the facial muscles, usually one sided, that has no known underlying cause (idiopathic). The symptoms probably occur when a nerve in the face is trapped and swollen. People with Bell's palsy generally recover, often with help from steroid medication, but there is a small group who do not. Some surgeons have thought that operating as soon as possible (within three months of the onset of paralysis) to free the nerve could improve recovery.

Study characteristics

Cochrane review authors collected and analysed studies to answer the review question. We found two studies to include in our review, which involved 65 people with Bell's palsy. Our main measure of the effects of surgery was the complete recovery of paralysis at 12 months. The first study compared surgery with no treatment and the second study compared early surgery with late surgery and no treatment. Both studies reported no conflicts of interest. One study did not provide funding information, the other reported national and regional science programme and university funding.

Key results and reliability of the evidence

Evidence on the effects of early surgery for Bell's palsy is of very-low reliability because the trials are small and have very serious limitations. We are unable to say whether recovery is better or worse after early surgery (before three months) than with no treatment, or after early surgery compared to later surgery.

One study reported side effects or complications of surgery. The reliability of this evidence was very low. Four participants who had surgery had some hearing loss, and three experienced tinnitus (ringing in the ears). The surgery group showed some loss of control of tear production in the eyes.

We have too little evidence to decide whether an operation would be helpful or harmful for people with early Bell's palsy. There is unlikely to be further research into the role of an operation because Bell's palsy usually recovers without treatment.

The evidence is up-to-date to March 2020.

Authors' conclusions: 

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.

Read the full abstract...

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.

Search strategy: 

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

Selection criteria: 

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.

Data collection and analysis: 

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.

Main results: 

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).