IOWA CITY, Iowa -- How to best treat patients with Bell's palsy who are at high risk of permanent loss of facial muscle control has remained a controversial subject among physicians for decades. However, results of a 15-year study led by University of Iowa Health Care researchers may help to finally settle the debate.
"We hope these findings will help change the attitudes of a lot of different people," said Bruce Gantz, M.D., UI professor and head of otolaryngology.
Timing and strategy are critical when it comes to the subgroup of patients with Bell's palsy who are at the greatest risks for permanent damage. The study results indicate that identifying this patient population and their subsequent surgical treatment must occur within two weeks of the onset of paralysis.
"If we are going to have any impact, the surgery has to come within the first two weeks," Gantz stressed.
Bell's palsy is partial or complete facial muscle paralysis resulting from a certain dysfunctional cranial nerve that is believed to be damaged by the herpes simplex virus type I. The condition affects about 40,000 Americans per year. Although medication will help most individuals fully or almost fully recover from Bell's palsy paralysis, about 10 to 15 percent of patients will not recover unless additional measures are taken.
The study had three related goals, all attempting to answer the primary questions troubling many clinicians treating patients with Bell's palsy. The researchers wanted to determine how to best identify which patients will be left with poor outcomes, establish whether surgical decompression might improve these patients' chances of recovery, and finally, figure out what, if any, impact time had on treatment.
The study results were based on patient outcomes of individuals with Bell's palsy treated at the UI Hospitals and Clinics, the University of Michigan and the Baylor College of Medicine.
Through their investigation, the UI-led team determined that electrical testing was the best method to differentiate a patient with Bell's palsy who has an excellent prognosis from an individual who might have a poor return of facial movement. The testing relies on the use of two strategies. The first, called electroneurography (ENOG), involves stimulating facial nerves and recording their potential to trigger facial movement. Patients with less than 90 percent degeneration in the first two weeks as measured by ENOG recover normal or near-normal facial function. Patients whose tests reveal have higher than 90 percent degeneration subsequently receive electromyography (EMG) testing, which involves inserting a needle electrode in the face and measuring a patient's ability to make forceful contractions. If the patient fails to demonstrate voluntary motor function using EMG, the patient likely has only a 42 percent chance of normal or near-normal recovery. However, if individuals within this subgroup opt for surgical decompression of the facial nerve within two weeks of the onset of paralysis, they increase their chances of recovery to 91 percent.
To perform the decompression procedure, a surgeon first makes a bone "window" by removing a piece of the skull on the side of the head. The region where the facial nerve is tightly encased with bone is exposed using microscopic dissection and a micro-drill. Relieving the constricted portion of the nerve allows earlier recovery and improved outcome.
"Many physicians don't think surgical management is worthwhile because of past controversial results and because it is a very technically demanding procedure," Gantz said. "But we demonstrated that electrical testing can identify a small subgroup that will have residual facial dysfunction, and surgical decompression eliminated poor outcomes in more than 90 percent of this group."
Risks involved in the procedure are minimal, Gantz said. There is less than a 1 percent chance of hearing loss and a 4 to 5 percent chance of temporary cerebral spinal fluid leakage, which can be controlled with a drain.
"Deciding on surgery should be an individual decision, and a physician should at least offer that option to patients if they are potentially going to have a poor outcome," Gantz said. "I would hope that neurologists and family medicine physicians, who are the ones that see most of the facial paralysis, would recognize that there are some test strategies that can differentiate those patients who may have a poor outcome. And then, if they are in that category of poor outcome, the doctors need to send the patients to someone within two weeks, not a month or six months."
Results from the UI-led Bell's palsy investigation appear in a recent issue of The Laryngoscope.
Journal
The Laryngoscope