Management of Bell’s Palsy and Ramsay Hunt Syndrome

Bell’S Palsy

Bell (1774–1842) first described a patient with facial paralysis in 1818; subsequently, all patients with facial palsy of unknown etiology have come to bear his name. The etiology of this “idiopathic” disorder has become much clearer in recent years. Although first proposed in 1972 by McCormick, herpes simplex virus (HSV) has only recently been identified as the disease vector, and an animal model has been designed. Murakami et al. identified HSV type 1 (HSV-1) DNA fragments in the perineural fluid in 11 of 14 patients undergoing facial nerve decompression. In this study, no control subjects had HSV-1 DNA in the perineural fluid. Using polymerase chain reaction to analyze the saliva of patients with Bell’s palsy, Furuta et al. identified HSV-1 DNA in 50% of patients, which was significantly more often than controls, a finding confirmed by other groups. Polymerase chain reaction has also been used to isolate HSV-1 genomic DNA from the geniculate ganglion of a temporal bone in a patient dying during the acute phase of Bell’s palsy.

Sugita et al. proposed an animal model of BP. Six days after the inoculation of HSV-1 into the auricle or tongue of mice, a temporary ipsilateral facial paralysis was identified that recovered spontaneously within 3 to 7 days. Histopathologically, neural edema, vacuolar degeneration, and inflammatory cell infiltration with associated demyelination or axonal degeneration were observed in the affected facial nerve and nucleus. HSV-1 antigens were identified within the facial nerve, geniculate ganglion, and facial nucleus 6 to 20 days after inoculation. Similar pathological findings have been shown in rabbits after HSV-1 inoculation, but without the associated facial paralysis.

The histopathological changes observed in autopsy specimens of patients who died with acute idiopathic facial paralysis have provided some insight into the underlying cellular mechanisms in Bell’s palsy. Reddy et al. found degeneration of the myelin sheath and axons, perivascular inflammation, and a phagocytic cell infiltrate in 10% to 30% of nerve fibers in a patient 17 days after the onset of an acute idiopathic facial paralysis. Fowler found diffuse vascular engorgement throughout the intratemporal facial nerve and evidence of acute hemorrhage within the intracanalicular, labyrinthine, and geniculate portions of the facial nerve in a patient who died shortly after the onset of Bell’s palsy. In examining an autopsy specimen of a patient who died 13 days after the onset of Bell’s palsy, McKeever et al. found diffuse lymphocytic infiltration of the intratemporal facial nerve with ongoing myelin phagocytosis. They later reexamined the same specimen and noted that the most pronounced lymphocytic infiltration of the nerve was at the labyrinthine segment, findings that they believed were most consistent with an ongoing compression-type injury to the facial nerve.

Multiple reports have found that there seems to be evidence of constriction of the nerve at the meatal foramen (MF) in cases of Bell’s palsy. In specimens examined during the acute phase of Bell’s palsy, lymphocytic infiltration, perineural edema, and myelin degeneration have been noted. ^, In a nerve specimen examined 1 year after the diagnosis of Bell’s palsy lymphocytic infiltration, perineural edema and fibrotic changes were noted. Intraoperative biopsy specimens of the greater superficial petrosal nerve from patients undergoing nerve decompression procedures for Bell’s palsy have shown axonal demyelination and degeneration with lymphocytic infiltration. Together, the histopathological findings in Bell’s palsy show demyelination and axonal loss with lymphocytic or phagocytic infiltration, findings that appear more pronounced at the labyrinthine segment of the facial nerve.

Considering this evidence, the pathogenesis of Bell’s palsy becomes more apparent: a virally induced inflammatory response that produces edema within the nerve. Fisch and Felix first proposed that the facial nerve was entrapped at the MF as a result of neural edema. Intraoperative conduction studies have shown an electrophysiological blockage at this site. The constriction imposed produces a conduction block at first; however, with prolonged or increased constriction, ischemia results. Subsequently, Wallerian degeneration occurs, producing axonotmesis, neurotmesis, or both. A spectrum of injury within the nerve from neurapraxia to neurotmesis may occur in Bell’s palsy. ^, The proportion of each of these determines the amount of facial function that returns when the acute phase of the disease subsides.

Bell’s palsy accounts for nearly three-quarters of all acute facial palsies. The incidence of Bell’s palsy is 20 to 30 cases per 100,000 per year. The median age is 40 years, but it can occur at any age. The incidence is highest in patients older than 70 years and lowest in children younger than 10 years. The left and right sides are equally affected. Men and women are equally affected, but there is a higher incidence of Bell’s palsy in pregnant women (45 cases per 100,000).

The clinical presentation of Bell’s palsy is well known; however, the clinician must exclude other causes of facial paralysis based on the history and physical examination findings. Patients describe an acute onset of unilateral paresis that occurs within less than 72 hours. The paresis can progress to complete paralysis over 1 to 7 days. Bilateral involvement, either simultaneously or consecutively, has been described. A history of progression of weakness over weeks to months, recurrent episodes of paralysis, and twitching of the facial muscles should not be considered symptoms of Bell’s palsy. Other associated symptoms of hearing loss, vestibular symptoms, or other cranial nerve neuropathies also exclude the diagnosis of Bell’s palsy.

On physical examination, the patient displays unilateral weakness or flaccid paralysis of all branches of the facial nerve. If the forehead movement is normal and there is strong eye closure and symmetric blinking, a central origin of paralysis should be suspected. The tympanic membrane should have normal color and mobility. Careful bimanual palpation of the parotid gland may reveal a deep lobe parotid neoplasm. Oral cavity examination may show a loss of papillae on the ipsilateral tongue. Cranial nerve (CN) testing is normal with the exception of the involved CN VII. Serial examinations are essential; if some evidence of recovery is not noted within 3 to 6 months, an aggressive search for an underlying neoplasm should be undertaken.

Audiometric evaluation should reveal symmetric function except for an absent ipsilateral acoustic reflex. If unilateral hearing loss or acoustic reflex decay is present, further evaluation for retrocochlear pathology is necessary. If vestibular complaints are present, an electronystagmogram is performed, and a diagnosis of Bell’s palsy should be questioned. If the history and clinical presentation are highly suggestive of Bell’s palsy, magnetic resonance imaging (MRI) and computed tomography (CT) are not performed. High-resolution CT scans and MRIs are obtained if patients have associated symptoms of otorrhea, vestibular complaints, and hearing loss. Planned surgical decompression and persistent dense paralysis after 6 months are also indications for imaging. Serologic tests for Lyme disease (immunoglobulin G or M) are an important part of the work-up for unexplained facial paralysis in endemic areas. Serologic testing for antibodies to HSV or varicella zoster has provided some correlative evidence for a viral etiology in Bell’s palsy, although laboratory investigations in general have not been found to provide clinically relevant data and routine serological testing is not currently recommended.

Electrodiagnostic testing is an important element of the diagnostic evaluation of facial paralysis. Testing can determine the extent of facial nerve injury and provide useful prognostic information for the development of management strategies. The technique of electroneuronography (ENoG), developed by Esslen, can estimate the proportion of nerve fibers that have undergone Wallerian degeneration from those fibers that are temporarily blocked (neurapraxia). ENoG testing is not performed until 3 to 4 days after the development of complete unilateral paralysis because Wallerian degeneration does not become apparent until 48 to 72 hours after an acute injury to the nerve. Electrodiagnostic testing is not performed when the patient exhibits paresis only. The presence of voluntary movement 4 to 5 days after the onset of paresis indicates only minor injury, and complete recovery should be anticipated.

ENoG is most accurate when it is performed within 3 weeks of the acute injury. The test is performed using standard electromyography (EMG) equipment but requires the use of special surface stimulating and recording electrodes. The recording electrodes are placed in a hand-held carrier and manipulated in the nasolabial fold with the Esslen technique. The recording electrodes are not taped to the skin, as has been described by others.

An evoked electric stimulus generates synchronous facial muscle movement that can be recorded from the skin surface [termed the compound muscle action potential (CMAP)]. The amplitude of the biphasic CMAP has been found to correlate with the number of blocked or neurapraxic nerve fibers. As the percentage of degenerated fibers within the nerve increases, the amplitude of the CMAP decreases compared with the normal side of the face. Fisch and Esslen determined that if 90% or more of the fibers within the facial nerve degenerate within the first 14 days of an acute paralysis, a severe injury has occurred and the chances of complete recovery are less than 50%. Patients who do not reach the 90% degeneration level by 3 weeks have a very good prognosis and are likely to regain normal facial motion without synkinesis. The time course of degeneration is also important; the more rapid the degeneration, the more severe the injury. A patient showing greater than 90% degeneration at 5 days would have a worse prognosis than a patient with 90% degeneration at 14 days.

Patients exhibiting 90% to 100% degeneration or no response to electric stimulation, in addition to ENoG, must undergo EMG testing. An EMG needle is placed in the orbicularis oris and oculi muscles, and the patient is asked to make a forceful contraction. Any voluntary motor unit activity indicates deblocking of the conduction block and portends a favorable prognosis. When deblocking occurs, fibers may not discharge at the same rate because of the previous injury, and may fail to generate a surface CMAP, resulting in a false-positive test result on ENoG testing. As movement returns to the face, the surface CMAP may also be absent for the same reason. Voluntary evoked EMG testing is mandatory if a surgical decompression is planned. If a facial paralysis has been slowly progressive over weeks to months, degeneration and regeneration of nerve fibers occur within the nerve, resulting in similar dyssynchronous discharge of evoked impulses and an inaccurate CMAP recording.

Topognostic testing is widely reported to be useful in determining the site of injury in acute facial paralysis; however, intraoperative studies have shown that the Schirmer test is not accurate in diagnosing Bell’s palsy. The Schirmer test may be used to determine the extent of lacrimation and the need for eye protection.

A review of the natural history of Bell’s palsy shows that approximately 85% of patients begin to display some return of facial movement within 3 weeks of the onset of paresis. The remaining 15% begin to improve 3 to 6 months after the onset of the disease. Most patients show a complete return of facial function, but 10% to 15% have residual unilateral weakness and develop the secondary deformities of synkinesis, epiphora, or contracture. Some motion returns in almost all individuals with Bell’s palsy by 6 months. If no movement returns, a vigorous search for another etiology should begin.

The management of patients with Bell’s palsy varies depending on the type of specialist initially seeing the patient and on the training of the individual specialist. Fig. 26.1 presents an overview of our management strategy. Patients presenting within the first week of facial weakness with paresis are placed on steroid therapy (prednisone, 60 to 80 mg/day for 7 days) and an antiviral agent (valacyclovir, 500 mg three times per day for 10 days). If patients are seen 7 to 10 days after onset and motor function is stable or improving, medical treatment is unnecessary. Patients are instructed to return in 1 week for reevaluation to determine if neural degeneration has occurred. Electrodiagnostic testing is unnecessary as long as voluntary facial movement is present. If total paralysis occurs in the interim, the total paralysis protocol of Fig. 26.1 is followed. Stable or improving patients are seen in 1 month.

The use of steroids in Bell’s palsy has been the subject of much debate. Numerous studies of varying designs in adults have shown better outcomes in patients treated with steroids, ^{, ,} especially when initiated early in the course of the disease. Other randomized studies and meta-analyses, including many studies in children, have concluded that steroids did not affect the ultimate facial function outcomes in Bell’s palsy. Grogan and Gronseth, in a comprehensive, evidence-based review, concluded that there appeared to be a beneficial effect from the use of steroids in Bell’s palsy. Ramsey et al. performed a meta-analysis of 47 trials of steroid therapy for Bell’s palsy and concluded that there seemed to be improved odds of recovery in patients treated with steroids (49% to 97%) compared with untreated controls (23% to 64%). We use prednisone in a dose of 1 mg/kg daily for 7 days in all cases in which it is not medically contraindicated, in anticipation of speeding recovery, reducing the number of degenerating axons, and reducing the number of patients needing decompression.

The combination of steroids and antivirals may be superior to either one alone, although this remains a source of controversy in the literature. A double-blind, randomized, controlled trial of acyclovir and prednisone versus prednisone alone in the treatment of Bell’s palsy showed better results with the combination therapy. This study documented poor facial function recovery in 23% of patients in the prednisone-only group compared with 7% in the acyclovir-plus-prednisone group. Interpreting the results of this study, Grogan and Gronseth reported that patients who receive antiviral therapy in addition to steroids were 1.22 times as likely to have a good facial nerve outcome. A multicenter, randomized, placebo-controlled study by Hato et al. comparing treatment of patients with Bell’s palsy with steroids and antivirals with treatment with steroids alone concluded that the addition of valacyclovir improved the recovery rate from 75% to 90% in cases of complete palsy, and from 89% to 96% in all cases of facial palsy. Many other reviews of the topic have made similar conclusions. Conversely, two multicenter, double-blind, placebo-controlled trials found no significant improvement in facial nerve outcomes with the addition of antiviral medications alone or in combination with corticosteroids. ^,

When these studies ^{, , ,} are taken as a whole, the question of whether antiviral medications benefit patients with Bell’s palsy remains a source of contention. Careful analysis of the results from Hato et al. reveals that the benefit of valacyclovir appears to vary with the severity of facial nerve dysfunction with an absolute risk reduction (ARR) of 15.1% for those with complete facial paralysis, 5.7% of those with severe facial palsy, and no ARR for those with moderate facial dysfunction. One explanation for why studies by Sullivan and Engström failed to demonstrate benefit from treatment with antiviral medications could be that in an effort to recruit large numbers of subjects, many patients with mild to moderate facial paresis were included. Patients with mild facial paresis are known to have a high rate of complete recovery and this may have mitigated the effect of the antiviral medications. When comparing the extent of facial palsy, patients enrolled by Hato et al. had more severe facial dysfunction (House-Brackmann grades IV to V) than did those enrolled by Sullivan (House-Brackmann grade 3.6). Integrating the overall results from the aforementioned studies and careful subgroup examination, it seems possible that antiviral medications may offer therapeutic benefit to those with severe facial nerve dysfunction and is of little aid to those with mild to moderate facial paresis.

Other studies have found no significant difference between this combination of drugs and the natural history of the disease. ^, One study found a negative impact of treatment of patients with Bell’s palsy with antivirals alone versus steroids alone. Because of the paucity of potential side effects and good patient tolerance of antiviral medications, the addition of antiviral medications to steroids in the treatment of patients with Bell’s palsy seems prudent, especially in those presenting with complete facial paralysis.

Patients presenting within 1 week of the onset of total unilateral paralysis undergo electrodiagnostic testing (if at least 3 days have passed since the onset of paralysis) and are started on medical therapy. If the patient is seen in the first 3 days after the onset of paralysis, steroid and antiviral therapy are initiated, and follow-up electrodiagnostic studies are arranged. The frequency of follow-up electrodiagnostic examinations is determined by the result of testing and the time interval after paralysis, as suggested by Fisch ( Fig. 26.2 ). Patients exhibiting nearly 90% neural degeneration on ENoG examination, or who are degenerating quickly, undergo frequent electrodiagnostic testing (every 1 or 2 days). If degeneration of greater than 90% is reached, and there are no motor unit potentials on voluntary EMG testing, the patient is considered a candidate for middle cranial fossa decompression. When 90% degeneration is not reached within 2 weeks (14 days) after the onset of paralysis, no further electrodiagnostic studies need to be performed. Patients seen for the first time more than 2 weeks after the onset of paralysis undergo EMG evaluation to determine if regeneration has begun. They are scheduled for a 6-month follow-up to ensure that some motor function has returned. If no movement is evident at 6 months, it must be assumed that Bell’s palsy was an incorrect diagnosis, and a search for another disease process is initiated. The other etiologies of facial nerve paralysis include traumatic, congenital, stroke, neoplasm, metastatic lesion to the facial nerve, metabolic disease, infectious disease (e.g., Lyme disease, zoster), autoimmune (e.g., Guillain–Barré syndrome) and systemic disease (e.g., sarcoidosis). Rare cases of idiopathic recurrent facial nerve paralysis have been reported; the entity affects 4-7% of patients who develop acute, nontraumatic facial nerve paralysis. Clinical presentation shows much heterogeneity, with variable age at presentation, number of facial paralysis episodes, and time interval between facial nerve paralysis episodes. Electrodiagnostic testing is not routinely performed, as patients often present between episodes of recurrent facial nerve paralysis. Sullivan et al. demonstrated that decompression of the facial nerve may be a reliable therapeutic modality to decrease the number of facial nerve paralysis episodes and also to improve facial nerve functional status. In the study ( n =11), the average number of facial palsy episodes was 3.5 preoperatively compared with 0 postoperatively at an average follow-up of 6.5 years. The timing of decompression of this population is different to that of Bell’s palsy in that they usually present after the 3-week window that is followed in Bell’s palsy. The decompression can occur at the time of another episode without ECoG findings or even in a period of quiescence. Unfortunately, with this disorder, recovery worsens following multiple episodes of paralysis.

Ramsay Hunt Syndrome

Herpes zoster oticus refers to a syndrome of acute otalgia accompanied by a herpetic vesicular rash. When accompanied by facial paralysis, the syndrome is known as Ramsay Hunt syndrome. Ramsay Hunt syndrome is the second most common cause of facial paralysis (after Bell’s palsy), and is induced by the reactivation of the varicella zoster virus that remains latent in the geniculate ganglion after primary infection with chickenpox. Classically, patients present with severe otalgia and unilateral facial paralysis. Vesicular eruptions may or may not be present initially, but usually appear within 3 to 5 days of the paralysis. The vesicular lesions can appear on the concha, ear canal, postauricular skin, and tympanic membrane. Occasionally, the oral cavity, neck, and shoulder are also involved. The disease can affect other cranial nerves, including the auditory, vestibular, trigeminal, glossopharyngeal, and vagus nerves, prompting the name herpes zoster cephalicus .

Additionally, in contrast to Bell’s palsy, the symptoms are more severe and the prognosis worse in Ramsay Hunt syndrome. The frequency of complete neural degeneration of the facial nerve is substantially higher than that in Bell’s palsy, and complete recovery of the facial motor function has ranged from 10% to 31% in several studies. Patients with auditory and vestibular dysfunction in addition to facial paralysis generally have a worse prognosis. In addition, patients with diabetes, hypertension, and advanced age have been reported to have a poorer prognosis in Ramsay Hunt syndrome.

The diagnosis of Ramsay Hunt syndrome is based on the history of otalgia, vesicular lesions or eschars, and facial paralysis. MRI typically shows the enhancement of a large portion of the facial nerve, often the vestibular and cochlear nerves, the labyrinth, and the dura lining the internal auditory canal (IAC). Imaging as part of routine evaluation is unnecessary. Electrodiagnostic studies have been unreliable in herpes zoster oticus .

The management of Ramsay Hunt syndrome has changed with the development of antiviral agents. The natural history of the disease was evaluated by Devriese and Moesker, who identified only a 10% rate of complete facial nerve recovery. Many studies have identified a superior recovery rate of 75% using a combination of steroids and antiviral agents. ^, The benefit of early initiation of steroid and antiviral treatment was clearly shown in a study by Murakami et al., in which 75% of patients treated within 3 days of the onset had complete recovery, whereas only 30% of patients treated after 7 days experienced complete recovery. We have experienced similar successful results using intravenous acyclovir (10 mg/kg 3 times daily), oral acyclovir (800 mg, 5 times daily), or oral valacyclovir (500 mg 3 times daily) for 10 days, in combination with a 3-week tapering course of prednisone (60 to 80 mg/kg daily). Patients report a rapid reduction in pain and occasionally experience the return of facial movement during the medical therapy. Because of the presence of “skip” regions and diffuse neuritis of the facial nerve, ^, surgical decompression of Ramsey Hunt syndrome is not recommended.