Most patients with Bell's palsy recover completely within 6 weeks, regardless of eventual treatment received. In some cases full recovery ensues after 9 months or even longer, but often with residual damage and development of sequelae.
Patients who show signs of recovery within 3 weeks upon onset of symptoms are most likely to undergo a complete recovery. A general rule is as follows: the sooner the recovery begins, the less chance there is that permanent sequelae will develop. The recurrence rate of Bell’s palsy is between 4-14%, with 36% of such patients re-experiencing paralysis on the same side of the face.
Severity of the nerve inflammation and the degree of facial paralysis are important prognostic factors, thus full restoration usually occurs in patients with partial facial palsy. Age is also an important prognostic factor, with younger patients recovering more swiftly. Risk factors associated with a bad outcome in affected individuals include age greater than 60 years, complete paralysis, as well as decreased salivary flow or taste on the side of paralysis. Other factors related with less favorable outcomes are decreased lacrimation and pain in the posterior area of the ear.
Because the exact cause of Bell's palsy remains elusive, there is no specific prevention or cure available. Attempts of treatment are geared toward improving facial nerve function, reducing neuronal inflammation and preventing complications stemming from corneal exposure. The cornea of affected individuals is particularly at risk of drying due to an improper lid closure and decreased production of tears; therefore prescription of eye ointments and lubricating eye drops is recommended. Adequate psychological support should also be provided in the early stages of the disease.
The use of oral corticosteroids to reduce facial nerve inflammation in patients with Bell's palsy is supported by evidence, and prednisone remains the single best treatment for this condition. Antiviral medications (acyclovir, valacyclovir or famciclovir) can be added to the treatment regimen, although studies have been inconclusive whether they provide an additional benefit. Given the safety profile of the aforementioned drugs, patients with no specific contraindications and presenting within three days of the onset of symptoms should be offered a combination therapy. In cases of complete facial nerve paralysis the rate of spontaneous recovery is significantly lower, therefore such patients may be more likely to benefit from this treatment.
Surgical facial nerve decompression within three weeks of onset is sometimes recommended for patients with persistent loss of function (i.e. loss greater than 90 percent shown on electroneurography). The most frequent complication of such approach is a postoperative hearing loss, affecting up to 15% of patients. As other risks are also imminent, this specific surgery should be considered only in refractory cases, given the paucity of data and lack of consensus on the topic. Physical therapy may hasten the recovery process and reduce sequelae, but additional randomized controlled trials are needed. Electrical nerve stimulation is a suggested method of accelerating the recovery of patients via invoked muscle stimulation.