Bell's palsy is an acute peripheral facial palsy of unknown cause. However, the terms "Bell's palsy" and "idiopathic facial paralysis" may no longer be considered synonymous, as herpes simplex virus activation is the likely cause of Bell's palsy in most cases. A peripheral facial palsy is a clinical syndrome of many causes, and evaluation requires more than a superficial examination.
ACUTE TREATMENT — The mainstay of pharmacologic therapy for acute idiopathic facial nerve palsy (Bell's palsy) or facial nerve palsy of suspected viral etiology is early short-term oral glucocorticoid treatment. In severe acute cases, combining antiviral therapy with glucocorticoids may improve outcomes. Eye care is important for patients with incomplete eye closure .
Glucocorticoid and antiviral therapy — We recommend early treatment with oral glucocorticoids for all patients with idiopathic facial nerve palsy (Bell's palsy) or facial nerve palsy of suspected viral etiology, consistent with current guidelines .Treatment should preferably begin within three days of symptom onset. Suggested regimen is prednisone (60 to 80 mg/day) for one week.
The suspicion that Bell's palsy is caused by herpes simplex virus in most patients led to trials of antiviral therapy. Compared with placebo, these trials found no benefit for antiviral therapy alone. However, it is possible, but not proven, that the addition of antivirals to glucocorticoids is beneficial, particularly for the subgroup of patients with severe facial palsy, defined as House-Brackmann grade IV or higher . Until certainty is reached, we suggest early combined therapy with prednisone (60 to 80 mg per day) plus valacyclovir (1000 mg three times daily) for one week for patients with severe facial palsy at presentation, defined as House-Brackmann grade IV or higher .
●The largest trial studied 829 adults with Bell's palsy who were randomly assigned within 72 hours of onset to one of four treatment groups :
•Placebo plus placebo.
•Prednisolone (60 mg daily for five days, then tapered by 10 mg daily, for a total treatment length of 10 days) plus placebo.
•Valacyclovir (1000 mg three times daily for seven days) plus placebo.
•Prednisolone (10 days) plus valacyclovir (seven days).
•At one-year follow-up, the time to complete recovery of facial function was significantly shorter for patients treated with prednisolone compared with those not treated with prednisolone. By contrast, time to recovery was no different for patients treated or not treated with valacyclovir. Furthermore, time to recovery with the addition of valacyclovir to prednisolone was no better than with prednisolone alone.
Eye care — In severe cases of Bell's palsy, the cornea may be at risk because of poor eyelid closure and reduced tearing.Artificial tears Protective glasses or goggles should be prescribed. Patches can be used at night, but tape should not be placed directly on the eyelid since the patch could slip and abrade the cornea. Rarely, tarsorrhaphy or temporary implantation of a gold weight into the upper lid is required.
Other interventions — There is a lack of high-quality evidence to support interventions such as physical therapies or surgical facial nerve decompression for the treatment of Bell's palsy. Nevertheless, physical therapy is often incorporated into multimodal interventions for patients with incomplete recovery. (See 'Management of incomplete recovery' below.)
Physical therapy — Physical therapy encompasses a host of different interventions for Bell's palsy, including but not limited to exercises, mime therapy, massage, electrical stimulation, acupuncture, heat therapy, biofeedback, and combinations. The methodologic quality of the trials ranged from low to moderate; none were high. The following observations were reported:
●Facial exercises did not reduce the proportion of patients with incomplete recovery at six months. One low-quality trial reported that facial exercises reduced the rate of synkinesis (ie, involuntary movement of the ipsilateral face during volitional movement of another area of the face, which is caused by aberrant regeneration of facial nerve fibers) at three months. Another low-quality trial of 34 subjects with persistent facial palsy that lasted more than nine months found that exercises (mime therapy) led to some improvement in facial function at one year.
●No significant benefit or harm was found from electrical stimulation or acupuncture.
Surgical decompression — The issue of surgical decompression of the facial nerve is mentioned only for discussion, as it is not a currently recommended treatment.
Permanent unilateral hearing loss is the most common serious side effect among patients undergoing facial nerve decompression
PROGNOSIS — The prognosis of Bell's palsy is related to the severity of the lesion .
The prognosis is favorable if some recovery is seen within the first 21 days of onset . A diagnosis of Bell's palsy is doubtful if some facial function, however small, has not returned within three to four months.
In severe lesions that recover, the outgrowth of new axons from the injury site is not discretely directed but is disorganized and misdirected; on volitional activation of the facial nerve, a mass action of facial musculature or synkinesis ensues. Thus, on blinking there is twitching of the angle of the mouth, and on smiling the eye may close or wink. Similarly, with misdirected autonomic fibers, a salivary stimulus may result in excess lacrimation, the syndrome of "crocodile tears."
Recurrence — Recurrent attacks of idiopathic facial palsy on either the ipsilateral or contralateral side have been observed in 7 to 15 percent of patients
●The recurrence rate was 7 percent, and the mean time to recurrence was approximately 10 years.
●A third or fourth attack was unusual, occurring in 3 and 1.5 percent of cases, respectively.
●Recurrence did not portend a worse prognosis for recovery.
Pregnancy may be a risk factor for recurrence of Bell's palsy.
MANAGEMENT OF INCOMPLETE RECOVERY Specific interventions include the following:
●Botulinum toxin injections may benefit patients with synkinesis, facial spasm, or hyperlacrimation ("crocodile tears") .
●Brow ptosis correction may enhance facial symmetry and cosmetic appearance .
●Weight insertion into the upper eyelid and suspension of the lower eyelid or tarsorrhaphy can improve eye closure .
Cosmetic and functional improvement may be possible with facial reanimation surgery, although it is rarely done .
DR ATUL CHOWDHURY