Bell's palsy, also known as acute idiopathic facial paresis, is an idiopathic neuropathy of the facial nerve (cranial nerve VII). It is a rapid onset facial paralysis that is not life-threatening. While acute immune demyelination triggered by a viral infection may be responsible for Bell's palsy, its exact cause is still unclear. Bell's palsy is usually self-limiting with the majority of patients recovering spontaneously without treatment within 6 months of onset of the disorder. However, a recent study by Kanazawa et al (2007) reported that recovery from Bell's palsy in diabetics is delayed, and the facial movement score remains low in comparison with non-diabetics.
The diagnosis of Bell's palsy is primarily one of exclusion, however certain features in the history and physical examination can aid in distinguishing it from facial paralysis as a consequence of other conditions. These clinical features include abrupt onset with complete, unilateral facial weakness at 24 to 72 hours, and, on the affected side, numbness or pain around the ear, a reduction in taste, and hypersensitivity to sounds (Ahmed, 2005).
Blink reflex testing and facial electromyography (EMG) have been used in the diagnosis of patients with Bell's palsy. Hill et al (2001) investigated electrophysiologically a population-based sample of patients with Bell's palsy to help understand the spectrum of abnormalities that can be seen in this setting. A total of 224 patients were surveyed, of whom 91 underwent formal neurological assessment. Of the latter, 44 were studied electrophysiologically using standard techniques. Thirty-two of the 44 patients fulfilled clinical criteria for Bell's palsy. A wide range of electrophysiological changes was observed. Blink responses were the most useful test showing diagnostic sensitivity of 81 % and specificity of 94 % compared to the contralateral control side. Needle EMG was additionally helpful in only 1 of 6 patients with normal conduction studies. The authors concluded that there is a wide spectrum of electrophysiological abnormalities in Bell's palsy. They stated that blink reflex latencies may be under-utilized in the assessment of the facial nerve in Bell's palsy; and facial EMG is generally not useful in routine evaluation. In an analysis of the clinical value of blink reflex, Xu et al (2007) noted that as one convenient test, blink reflex helps locate the lesion of trigeminal nerve or facial nerve and has highly diagnostic value to the lesion of brain stem, even to the subclinical lesion at the early time of some disease without any symptoms.
Transcranial magnetic stimulation (TMS) has been employed in the diagnosis of Bell's palsy. Recently, Nowak and colleagues (2005) noted that earlier investigations have suggested that isolated conduction block of the facial nerve to TMS early in the disorder represents a very sensitive and potentially specific finding in Bell's palsy differentiating the disease from other etiologies. These researchers examined the diagnostic relevance of TMS and electrical stimulation (ES) of the facial nerve in the management of facial/Bell's palsy. Stimulation of the facial nerve was performed electrically at the stylomastoid foramen and magnetically at the labyrinthine segment of the Fallopian channel within 3 days from symptom onset in 65 patients with Bell's palsy, 5 patients with Zoster oticus, 1 patient with neuroborreliosis, and 1 patient with nuclear facial nerve palsy due to multiple sclerosis. Absence or decreased amplitudes of muscle responses to early TMS was not specific for Bell's palsy, but also evident in all cases of Zoster oticus and in the case of neuroborreliosis. Amplitudes of electrically evoked muscle responses were more markedly reduced in Zoster oticus as compared to Bell's palsy, most likely due to a more severe degree of axonal degeneration. The degree of amplitude reduction of the muscle response to ES reliably correlated with the severity of facial palsy. The authors concluded that TMS in the early diagnosis of Bell's palsy is less specific than previously thought.
Bell's palsy has a generally favorable prognosis. Jabor and Gianoli (1996) stated that 84 % of patients reported satisfactory recovery without any treatment, however 16 % suffered moderate to severe sequelae. Prognosis was influenced by degree of paresis, age of patient, and time until first signs of recovery. On the other hand, in a study that assessed the prognostic factors in patients with Bell's palsy (n = 55) and Ramsay Hunt syndrome (n = 26), Yeo et al (2007) reported that there was no prognostic factor found in the Bell's palsy patients; while prognostic factors of Ramsay Hunt syndrome were age, diabetes mellitus, essential hypertension as well as vertigo.
Treatment of Bell's palsy is still not well-defined. Conservative approaches entail physiotherapies such as facial exercises, massage, and muscle relaxation, which may support rehabilitation and possibly reduce the production of pathological synkinesia. Medical treatments include anti-viral agents, botulinum toxin type A (Botox), cortisone and possibly antibiotics. However, the effectiveness of some of these therapies has not been established. The American Academy of Neurology's practice parameters on Bell's palsy (Grogan and Gronseth, 2001) stated that for patients with Bell's palsy, a benefit from steroids, acyclovir, or facial nerve decompression has not been definitively established. However, available evidence suggests that steroids are probably effective and acyclovir (combined with prednisone) is possibly effective in improving facial functional outcomes.
The American Academy of Neurology practice parameters on Bell's palsy (Grogan and Gronseth, 2001) found insufficient evidence to make recommendations regarding surgical facial nerve decompression for Bell's palsy. The guidelines stated that well-designed studies of the effectiveness of treatments for Bell's palsy are still needed. A systematic evidence review in BMJ Clinical Evidence concluded that the effect of facial nerve decompression in adults and children with Bell's palsy is unknown (Holland, 2007).
Chepeha and associates (2001) found that in patients with facial paralysis, gold weight eyelid implants provided significant reduction in lagophthalmos and significant improvement in corneal coverage. This is in agreement with the findings of Abell et al (1998) as well as Choi et al (1999). Abell and colleagues (1998) noted that deficient eyelid closure is a major visual threat to patients with unresolved facial nerve palsy. Gold weight implants aided eyelid closure in patients with paresis of the orbicularis oculi, ameliorating patient complaints of dry eye, excessive tearing, and corneal epithelial breakdown. Choi and co-workers (1999) reported that in patients with complete facial nerve palsy, implantation of gold weight resulted in dynamic closure of the eyelid as well as excellent protection and cosmesis. These researchers also noted that lagophthalmos and exposure keratitis resolved in treated patients; and visual acuity significantly improved without complications.
Acupuncture, ES, and hyperbaric oxygen therapy have also been used in treating Bell's palsy. However, the effectiveness of these modalities has not been established. Although a recent study (Liang et al, 2006) reported that acupuncture and moxibustion may exert therapeutic effects on Bell's palsy, better than that of the basic treatment group (i.e., prednisone, vitamin B1, vitamin B12, and dibazol) or the basic treatment plus acupuncture-moxibustion group, a Cochrane review (He et al, 2007) stated that more evidence is needed to show whether acupuncture is beneficial for Bell's palsy. Zhou and colleagues (2009) examined the effectiveness of acupuncture in hastening recovery and reducing long-term morbidity from Bell's palsy. These investigators concluded that the quality of the included trials was inadequate to allow any conclusion regarding the effectiveness of acupuncture. They stated that further investigation with high-quality trials is needed.
Adour (1991) noted that facial nerve decompression and electrotherapy are not advised for the management of patients with Bell's palsy. This is in agreement with Wolf (1998) who stated that ES should not be used in the treatment of Bell's palsy. Diels (2000) stated that ES should not be used at any time in facial rehabilitation. There is evidence that it may be contraindicated, and it is unnecessary. Buttress and Herren (2002) reviewed the medical literature to ascertain whether ES had any advantages over facial exercises in promoting recovery after Bell's palsy. Of the 270 papers found using the reported search, only 1 presented the best evidence to answer the clinical question. The authors stated that there is no evidence to suggest that either facial exercises or ES is beneficial to patients with acute Bell's palsy. However, evidence does exist to justify the use of ES in patients with chronic Bell's palsy, although the study design was not rigorous. An evidence review conducted by the Alberta Heritage Foundation for Medical Research (Hailey, 2003) concluded that use of hyperbaric oxygen therapy is not supported for a number of conditions including Bell's palsy.
It has been suggested that some patients with Bell's palsy may benefit from a special form of physical therapy called facial retraining, which entails a specific program designed to retrain facial muscles for movement and expression following facial nerve paralysis. The objectives of facial retraining therapy are: (i) to normalize movement of facial muscles, (ii) to increase symmetrical movement patterns of the face, (iii) to increase volitional movements of the face, (iv) to inhibit undesired movements and synkinesis, and (v) to normalize muscular tone. Facial retraining involves a thorough evaluation of facial movements through observation, dual channel EMG and sensation. This regimen includes active self training by patients (e.g., specific functional facial exercises), EMG training by means of sensory, visual and auditory feedback as well as supervised sessions that incorporate the use of modalities such as ES, heat/cold and massage.
Brach et al (1997) described the outcome of facial neuromuscular retraining for oral synkinesis in individuals with facial nerve disorders (n = 14). These researchers concluded that brow to oral as well as ocular to oral synkineses associated with partial recovery from facial paralysis were reduced with facial neuromuscular retraining. Diels (2000) stated that patients with facial paralysis resulting from viral causes, post-surgical tumor resection, traumatic injury, or congenital paresis may be candidates for treatment. Typical patients present with flaccid paralysis acutely and may develop abnormal movement patterns (synkinesis) as recovery progresses. Neuromuscular retraining provides specific strategies that inhibit synkinesis based on individual function and unique facial nerve and muscle properties. Cronin et al (2003) found that neuromuscular facial retraining exercises and EMG are effective for improving facial movements (n = 24). While there is preliminary evidence that facial retraining may be effective for patients with facial paralysis, it must be noted that these studies were small and none of them was a controlled trial. The value of facial retraining for patients with Bell's palsy awaits findings from randomized controlled studies.
Cederwall et al (2006) evaluated a physiotherapeutic treatment intervention in Bell's palsy. A consecutive series of 9 patients with Bell's palsy participated in the study. Participants were enrolled 4 to 21 weeks after the onset of facial paralysis. The study had a single subject experimental design with a baseline period of 2 to 6 weeks and a treatment period of 26 to 42 weeks. Subjects were evaluated using a facial grading score, a paresis index and a written questionnaire created for this study. Every patient was taught to perform an exercise program twice-daily, including movements of the muscles surrounding the mouth, nose, eyes and forehead. All patients improved in terms of symmetry at rest, movement and function. The authors concluded that patients with remaining symptoms of Bell's palsy appear to experience positive effects from a specific training program. Moreover, these investigators noted that a larger study is needed to fully evaluate the treatment.
Cardoso et al (2008) examined the effects of facial exercises associated either with mirror or EMG biofeedback with respect to complications of delayed recovery in Bell's palsy. Patients with unilateral idiopathic facial palsy were included in this review. Main outcome measures were report of facial symmetry, synkinesis, lip mobility, and physical and social aspects. Four studies met the eligibility criteria. The studies described mime therapy versus control (n = 50), mirror biofeedback exercise versus control (n = 27), "small" mirror movements versus conventional neuromuscular retraining (n = 10), and EMG biofeedback plus mirror training versus mirror training alone. The duration of treatment varied from 1 to 12 months. The authors concluded that because of the small number of randomized controlled trials (RCTs), it was impossible to analyze if facial exercises, associated either with mirror or EMG biofeedback, were effective. They stated that the available evidence is not yet strong enough to allow facial exercises (with mirror or EMG biofeedback) to be integrated into clinical practice.
Osteopathic and chiropractic manipulation has also been used to treat Bell's palsy (Alcantara et al, 2003; Lancaster and Crow, 2006). However, there is insufficient scientific evidence to support their effectiveness for this indication.
Although corticosteroids and anti-viral therapy given within 10 days of onset have been reported to help, there is still controversy regarding these therapies.
A Cochrane review (Salinas et al, 2004) stated that available evidence from RCTs does not demonstrate significant benefit of corticosteroids in treating patients with Bell's palsy. These investigators further stated that more RCTs with a greater number of patients are needed to determine reliably whether there is real benefit (or harm) from the use of corticosteroid therapy in patients with Bell's palsy. Another Cochrane review (Allen and Dunn, 2004) concluded that more data are needed from a large multi-center randomized controlled and blinded trial with at least 12 months' follow-up before a definitive recommendation can be made regarding the effectiveness of acyclovir or valacyclovir on Bell's palsy. Furthermore, Gilden (2004) noted that large randomized double-blind studies are needed to better ascertain the effectiveness of glucocorticoids, anti-viral agents, or both as compared with placebo, as well as to evaluate the benefit of surgical decompression among patients considered to be at high risk for permanent paralysis. In particular, studies are needed to determine the time after which medical therapy or surgery is of no value. Additionally, more investigation is needed to examine if a combination of anti-viral and corticosteroid therapy is more effective than treatment with corticosteroids alone. In a review of treatment of Bell's palsy using anti-viral agents, Alberton and Zed (2006) stated that the use of acyclovir remains controversial. These investigators noted that additional, adequately powered, randomized, placebo-controlled studies are needed to definitively support its use. For the time being, the authors favor the combination of acyclovir and prednisone only if treatment is commenced within the first 72 hours of symptom onset.
Turk-Boru et al (2005) stated that although corticosteroid therapy is widely used in patients with idiopathic facial nerve paralysis, its effectiveness has not been clearly demonstrated. In an open, randomized, prospective controlled study (n = 56), these researchers assessed the role of steroids in idiopathic facial nerve paralysis. Within the first three days after the onset of symptoms, the patients were randomly assigned to two groups to receive either steroids or other medications for the prevention of ocular complications or to provide pain relief. The severity of facial paralysis was evaluated using the House-Brackmann classification before and after 3 and 6 weeks of the treatment. Regression to stage 1 or 2 disease was regarded as a successful response. Although the initial response to steroid therapy seemed to be better, the results at the end of 3 and 6 weeks of the treatment were not statistically different from those of patients receiving other supportive treatments (p > 0.05). The authors concluded that more studies with large patient series are needed to clarify the use of steroids in the treatment of idiopathic facial nerve paralysis. Atzema and Goldman (2006) stated that the best available evidence shows no benefit from steroids in the treatment of children with Bell's palsy; they noted that until a large, randomized, controlled study can prove otherwise, these patients should not be treated with steroids. Rahman and Sadiq (2007) stated that the use of steroids has been suggested as a means of limiting facial nerve damage in the acute phase of facial nerve palsy. Unfortunately, no single randomized control trial has achieved an unquestionable benefit with the use of oral steroid therapy; thus its use remains controversial.
In a multi-center, randomized placebo-controlled study, Hato et al (2007) examined the effects of valacyclovir and prednisolone in comparison with those of placebo and prednisolone for the treatment of Bell's palsy, excluding zoster sine herpete. A total of 221 patients with Bell's palsy were treated within 7 days of the onset. Serological and polymerase chain reaction examinations were performed to distinguish Bell's palsy from zoster sine herpete. Patients were treated with either valacyclovir (dosage, 1,000 mg/d for 5 days) plus prednisolone (VP [n = 114]) or placebo plus prednisolone (PP [n = 107]) administered orally. Recovery from Bell's palsy was defined as a score higher than 36 using Yanagihara 40-point scoring system without facial contracture or synkinesis. Patients were followed-up until complete recovery occurred or for more than 6 months in cases with a poor prognosis. The overall rate of patient recovery among those treated with VP (96.5 %) was significantly better (p < 0.05) than the rate among those treated with PP (89.7 %). The rate of patient recovery was also analyzed by classifying the initial severity of facial palsy. In cases of complete or severe palsy, the rates of patients treated with VP and PP who recovered were 95.7 % (n = 92) and 86.6 % (n = 82), respectively; the recovery rate for treatment with VP was significantly better than that with PP (p < 0.05). The authors concluded that the valacyclovir and prednisolone therapy was more effective in treating Bell's palsy, excluding zoster sine herpete, than the conventional prednisolone therapy. Although treatment with valacyclovir and prednisolone was found to be significantly (statistically) better than prednisolone alone (97 % versus 90 %), it is unclear whether this difference is clinically significant. These findings need to be validated by further investigation.
The Health Technology Assessment Program of the National Institute for Health Research commissioned an independent academic group to determine if prednisolone or acyclovir used early in the course of Bell's palsy improves the chances of recovery. Sullivan et al (2007) performed a double-blind, placebo-controlled, randomized, factorial study involving patients with Bell's palsy who were recruited within 72 hours after the onset of symptoms. Patients were randomly assigned to receive 10 days of treatment with prednisolone, acyclovir, both agents, or placebo. The primary outcome was recovery of facial function, as rated on the House–Brackmann scale; secondary outcomes included quality of life, appearance, and pain. Final outcomes were assessed for 496 of 551 patients who underwent randomization. At 3 months, the proportions of patients who had recovered facial function were 83.0 % in the prednisolone group as compared with 63.6 % among patients who did not receive prednisolone (p < 0.001) and 71.2 % in the acyclovir group as compared with 75.7 % among patients who did not receive acyclovir (adjusted p = 0.50). After 9 months, these proportions were 94.4 % for prednisolone and 81.6 % for no prednisolone (p < 0.001) and 85.4 % for acyclovir and 90.8 % for no acyclovir (adjusted p = 0.10). For patients treated with both drugs, the proportions were 79.7 % at 3 months (p < 0.001) and 92.7 % at 9 months (p < 0.001). There were no clinically significant differences between the treatment groups in secondary outcomes. There were no serious adverse events in any group. The authors concluded that in patients with Bell's palsy, early treatment with prednisolone significantly improves the chances of complete recovery at 3 and 9 months. There is no evidence of a benefit of acyclovir given alone or an additional benefit of acyclovir in combination with prednisolone.
While the study by Hato et al (2007) suggested that valacyclovir may be a useful addition to prednisolone, it was smaller than the afore-mentioned study by Sullivan and colleagues. Furthermore, as pointed out by Sullivan et al, patients in the study by Hato et al were treated in tertiary centers, and the outcome assessors were aware of the study-group assignments. Thus, the results of that study should be interpreted with caution.
de Almeida and colleagues (2009) estimated the association of corticosteroids and anti-viral agents with the risk of unsatisfactory facial recovery in patients with Bell palsy. Eligible studies were RCTs comparing treatment with either corticosteroids or anti-viral agents with a control and measuring at least 1 of the following outcomes: unsatisfactory facial recovery (greater than or equal to 4 months), unsatisfactory short-term recovery (6 weeks to less than 4 months), synkinesis and autonomic dysfunction, or adverse effects. Two reviewers extracted data on study characteristics, methods, and outcomes. Disagreement was resolved by consensus. A total of 18 trials involving 2786 patients were eligible. Regression analysis identified a synergistic effect when corticosteroids and anti-viral agents were administered in combination compared with alone (odds ratio for interaction term, 0.54 [95 % confidence interval (CI): 0.35 to 0.83]; p = 0.004). Meta-analysis using a random-effects model showed corticosteroids alone were associated with a reduced risk of unsatisfactory recovery (relative risk [RR], 0.69 [95 % CI: 0.55 to 0.87]; p = 0.001) (number needed to treat to benefit 1 person, 11 [95 % CI: 8 to 25]), a reduced risk of synkinesis and autonomic dysfunction (RR, 0.48 [95 % CI: 0.36 to 0.65]; p < 0.001) (number needed to treat to benefit 1 person, 7 [95 % CI: 6 to 10]), and no increase in adverse effects. Anti-viral agents alone were not associated with a reduced risk of unsatisfactory recovery (RR, 1.14 [95 % CI: 0.80 to 1.62]; p = 0.48). When combined with anti-viral agents, corticosteroids were associated with greater benefit (RR, 0.48 [95 % CI: 0.29 to 0.79]; p = 0.004) than anti-viral agents alone. When combined with corticosteroids, anti-viral agents were associated with greater risk reduction of borderline significance compared with corticosteroids alone (RR, 0.75 [95 % CI: 0.56 to 1.00]; p = 0.05). The authors concluded that in Bell palsy, corticosteroids are associated with a reduced risk of unsatisfactory recovery. Anti-viral agents, when administered with corticosteroids, may be associated with additional benefit.
On the other hand, in a systematic review and meta-analysis of corticosteroids versus corticosteroids plus anti-viral agents in the treatment of Bell palsy, Goudakos and Markou (2009) found that the addition of an anti-viral agent to corticosteroids for the treatment of Bell palsy is not associated with an increase in the complete recovery rate of the facial motor function. Prospective RCTs on the treatment of patients with Bell palsy were selected for this analysis. Odds ratios (ORs), 95 % CIs, and tests for heterogeneity were reported. A total of 5 studies were eventually identified and systematically reviewed. Meta-analysis was performed for 4 studies. Regarding the complete recovery rate of facial nerve paralysis 3 months after initiation of therapy, the current systematic review and meta-analysis suggests that the addition of an anti-viral agent does not provide any benefit (OR, 1.03 [95 % CI: 0.74 to 1.42]; p = 0.88). The same conclusion emerged at posterior (4th, 6th, and 9th) months of assessment. Subgroup analysis, conducted on the basis of time point of therapy initiation, type of anti-viral agent, and blindness of assessments did not change the results obtained. The occurrence rate of adverse effects attributable to therapy choice was not significantly different between patients receiving corticosteroids and those following combined treatment. A systematic evidence review by Quant et al (2009) reached similar conclusions about the lack of proven benefit of antiviral agents in Bell's palsy. The authors concluded that combined treatment using steroids and antivirals compared with steroids alone provided no additional benefit in achieving at least partial facial muscle recovery in patients with Bell's palsy.
In a Cochrane review, Lockhart and colleagues (2009) examined the effect of anti-viral therapy on Bell's palsy. These investigators updated the search of the Cochrane Neuromuscular Disease Group Trials Register (December 2008), MEDLINE (from January 1966 to December 8 2008), EMBASE (from January 1980 to December 8 2008) and LILACS (from January 1982 to December 2008). Randomized trials of anti-virals with and without corticosteroids versus control therapies for the treatment of Bell's palsy. A total of 23 papers were selected for consideration -- 7 trials including 1,987 participants met the inclusion criteria, adding 5 studies to the 2 in the previous review. There was no significant benefit in the rate of incomplete recovery from anti-virals compared with placebo (n = 1,886, RR 0.88, 95 % CI: 0.65 to 1.18). In meta-analyses with some unexplained heterogeneity, the outcome with anti-virals was significantly worse than with corticosteroids (n = 768, RR 2.82, 95 % CI: 1.09 to 7.32) and the outcome with anti-virals plus corticosteroids was significantly better than with placebo (n = 658, RR 0.56, 95 % CI: 0.41 to 0.76). In single trials, there was no significant difference in long-term sequelae comparing anti-virals and corticosteroids with corticosteroids alone (n = 99, RR 0.39, 95 % CI: 0.14 to 1.07) or anti-virals with corticosteroids (n = 101, RR 1.03, 95 % CI: 0.51 to 2.07). There was no significant difference in rates of adverse events between anti-virals and placebo (n = 1544, RR 1.06, 95 % CI: 0.81 to 1.38), between anti-virals and corticosteroids (n = 667, RR 0.96, 95 % CI: 0.65 to 1.41) or between the anti-viral/corticosteroid combination and placebo (n = 658, RR 1.15, 95 % CI: 0.79 to 1.66). The authors concluded that high quality evidence showed no significant benefit from anti-herpes simplex anti-virals compared with placebo in producing complete recovery from Bell's palsy. Moderate quality evidence showed that anti-virals were significantly less likely than corticosteroids to produce complete recovery.
It is also interesting to note that in an economic evaluation of early administration of prednisolone and/or aciclovir for the treatment of Bell's palsy, Hernandez and colleagues (2009) concluded that treatment with prednisolone is likely to be considered cost-effective, while treatment with acyclovir is highly unlikely to be considered cost- effective. They stated that further data on costs and utilities would be useful to confirm these findings.
Alakram and Puckree (2010) examined the safety and potential effectiveness of applying electrical stimulation to the facial muscles during the early phase of Bells palsy. A pre-test post-test control versus experimental groups design composed of 16 patients with Bell's palsy of less than 30 days' duration. Adult patients with clinical diagnosis of Bell's palsy were systematically (every second patient) allocated to the control and experimental groups. Each group (n = 8) was pre-tested and post-tested using the House-Brackmann index. Both groups were treated with exercises, heat, massage, and a home program. The experimental group also received electrical stimulation. The House-Brackmann Scale of the control group improved between 17 % and 50 % with a mean of 30 %. The scores of the experimental group ranged between 17 % and 75 % with a mean of 37 %. The difference between the groups was not statistically significant (2-tailed p = 0.36). Electrical stimulation as used in this study during the acute phase of Bell's palsy is safe but may not have added value over spontaneous recovery and multi-modal physiotherapy. The authors stated that a larger sample size or longer stimulation time or both should be investigated.
In a Cochrane review, McAllister and colleagues (2011) evaluated the effectiveness of surgery in the management of Bell's palsy and compared this to outcomes of medical management. These investigators searched the Cochrane Neuromuscular Disease Group Specialized Register (November 23, 2010). They also searched the Cochrane Central Register of Controlled Trials (CENTRAL) (November 23 in The Cochrane Library, Issue 4, 2010). They adapted this strategy to search MEDLINE (January 1966 to November 2010) and EMBASE (January 1980 to November 2010). These researchers included all randomized or quasi-randomized controlled trials involving any surgical intervention for Bell's palsy. Two review authors independently assessed whether trials identified from the search strategy were eligible for inclusion. Two review authors assessed trial quality and extracted data independently. Two trials with a total of 69 participants met the inclusion criteria. The first study considered the treatment of 403 patients but only included 44 in their surgical study. These were randomized into a surgical and non-surgical group. The second study had 25 participants which they randomly allocated into surgical or control groups. The nerves of all the surgical group participants in both studies were decompressed using a retro-auricular approach. The primary outcome was recovery of facial palsy at 12 months. The first study showed that both the operated and non-operated groups had comparable facial nerve recovery at 9 months. This study did not statistically compare the groups but the scores and size of the groups suggested that statistically significant differences are unlikely. The second study reported no statistically significant differences between their operated and control groups. One operated patient in the first study had 20 dB sensorineural hearing loss and persistent vertigo. The authors concluded that there is only very low quality evidence from randomized controlled trials and this is insufficient to decide whether surgical intervention is beneficial or harmful in the management of Bell's palsy. They stated that further research into the role of surgical intervention is unlikely to be performed because spontaneous recovery occurs in most cases.
Teixeira et al (2011) evaluated physical therapies for Bell's palsy. These investigators searched the Cochrane Database of Systematic Reviews and the Cochrane Central Register of Controlled Trials (The Cochrane Library, Issue 1, 2011), MEDLINE (January 1966 to February 2011), EMBASE (January 1946 to February 2011), LILACS (January 1982 to February 2011), PEDro (from 1929 to February 2011), and CINAHL (January 1982 to February 2011). They included searches in clinical trials register databases until February 2011. They selected RCTs or quasi-RCTs involving any physical therapy, and included participants of any age with a diagnosis of Bell's palsy and all degrees of severity. The outcome measures were: incomplete recovery 6 months after randomization, motor synkinesis, crocodile tears or facial spasm 6 months after onset, incomplete recovery after 1 year and adverse effects attributable to the intervention. Two authors independently scrutinized titles and abstracts identified from the search results. Two authors independently carried out risk of bias assessments, which , took into account secure methods of randomization, allocation concealment, observer blinding, patient blinding, incomplete outcome data, selective outcome reporting and other bias. Two authors independently extracted data using a specially constructed data extraction form. They undertook separate subgroup analyses of participants with more and less severe disability. For this update to the original review, the search identified 65 potentially relevant articles; and 12 studies met the inclusion criteria (872 participants) -- 4 trials studied the efficacy of electrical stimulation (313 participants), 3 trials studied exercises (199 participants), and 5 studies compared or combined some form of physical therapy with acupuncture (360 participants). For most outcomes these researchers were unable to perform meta-analysis because the interventions and outcomes were not comparable. For the primary outcome of incomplete recovery after 6 months, electro-stimulation produced no benefit over placebo (moderate quality evidence from 1 study with 86 participants). Low-quality comparisons of electro-stimulation with prednisolone (an active treatment)(149 participants), or the addition of electro-stimulation to hot packs, massage and facial exercises (22 participants), reported no significant differences. Similarly a meta-analysis from 2 studies, one of 3 months and the other of 6 months duration, (142 participants) found no statistically significant difference in synkinesis, a complication of Bell's palsy, between participants receiving electro-stimulation and controls. A single low- quality study (56 participants), which reported at 3 months, found worse functional recovery with electro-stimulation (mean difference (MD) 12.00 points (scale of 0 to 100) 95 % CI: 1.26 to 22.74). Two trials of facial exercises, both at high-risk of bias, found no difference in incomplete recovery at 6 months when exercises were compared to waiting list controls or conventional therapy. There is evidence from a single small study (34 participants) of moderate-quality that exercises are beneficial on measures of facial disability to people with chronic facial palsy when compared with controls (MD 20.40 points (scale of 0 to 100), 95 % CI 8.76 to 32.04) and from another single low-quality study with 145 people with acute cases treated for 3 months where significantly fewer participants developed facial motor synkinesis after exercise (risk ratio 0.24, 95 % CI 0.08 to 0.69). The same study showed statistically significant reduction in time for complete recovery, mainly in more severe cases (47 participants, MD -2.10 weeks, 95 % CI: -3.15 to -1.05) but this was not a pre-specified outcome in this meta-analysis. Acupuncture studies did not provide useful data as all were short and at high-risk of bias. None of the studies included adverse events as an outcome. The authors concluded that there is no-high quality evidence to support significant benefit or harm from any physical therapy for idiopathic facial paralysis. There is low-quality evidence that tailored facial exercises can help to improve facial function, mainly for people with moderate paralysis and chronic cases. There is low-quality evidence that facial exercise reduces sequelae in acute cases. The suggested effects of tailored facial exercises need to be confirmed with good quality RCTs.