Abstract
Introduction
Bell's palsy is characterised by an acute, unilateral, partial or complete paralysis of the face, which may occur with mild pain, numbness, increased sensitivity to sound, and altered taste. Bell's palsy remains idiopathic, but a proportion may be caused by reactivation of herpes viruses from cranial nerve ganglia. Bell's palsy is most common in people aged 15-40 years, affecting 1 in 60 in their lifetime. Most make a spontaneous recovery within 1 month, but up to 30% have delayed or incomplete recovery.
Methods and outcomes
We conducted a systematic review and aimed to answer the following clinical question: What are the effects of treatments in adults and children? We searched: Medline, Embase, The Cochrane Library and other important databases up to February 2006 (BMJ Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).
Results
We found eight systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.
Conclusions
In this systematic review we present information relating to the effectiveness and safety of the following interventions: antiviral treatment, corticosteroids (alone or plus antiviral treatment), facial nerve decompression surgery, and mime therapy.
Key Points
Bell's palsy is characterised by unilateral, acute paresis or acute paralysis of the face, which may occur with mild pain, numbness, increased sensitivity to noise, and altered taste.
Up to 30% of people with acute peripheral facial palsy have other identifiable causes, including stroke, tumours, middle ear disease, or Lyme disease. Severe pain is more consistent with Ramsay Hunt syndrome caused by herpes zoster infection, which has a worse prognosis than Bell's palsy.
Bell's palsy is most common in people aged 15-40 years, and pregnant women may be at higher risk.
Bell's palsy may be caused by reactivation of herpes viruses in the cranial nerve ganglia. Most people make a spontaneous recovery within 3 weeks, but up to 30% may have residual problems.
We don't know whether corticosteroids or antiviral treatment improve recovery of motor function or cosmetically-disabling sequelae compared with placebo or with other treatments.
Combined treatment with aciclovir plus corticosteroids may be more effective than steroids alone.
In pregnant women, antiviral treatments such as aciclovir should only be prescribed under guidance of an obstetrician.
There is some consensus that valaciclovir may be more effective than aciclovir, as it is has improved bioavailability and compliance.
We don't know whether facial nerve decompression surgery is beneficial in Bell's palsy, as no studies of adequate quality have been found.
Mime therapy may improve facial stiffness and lip mobility in Bell's palsy, but the evidence is too weak to draw conclusions.
About this condition
Definition
Bell's palsy is an idiopathic, acute, unilateral paresis or paralysis of the face in a pattern consistent with peripheral facial nerve dysfunction, and may be partial or complete, occurring with equal frequency on the right and left sides of the face. While other possible causes need to be excluded, there is increasing evidence that Bell's palsy is caused by herpes viruses. Additional symptoms of Bell's palsy may include mild pain in or behind the ear, oropharyngeal or facial numbness, impaired tolerance to ordinary levels of noise, and disturbed taste on the anterior part of the tongue. Severe pain is more suggestive of herpes zoster virus infection (shingles) and possible progression to a Ramsay Hunt syndrome, but another cause should be carefully excluded. Up to 30% of people with an acute peripheral facial palsy will not have Bell's palsy; other causes may include stroke, tumour, trauma, middle ear disease, and Lyme disease. Features such as sparing of movement in the upper face (central pattern), or weakness of a specific branch of the facial nerve (segmental pattern), suggest an alternative cause. Bell's palsy is less commonly the cause of facial palsy in children under 10 (under 40%), so an alternative cause should be carefully excluded. The assessment should identify acute suppurative ear disease (including mastoiditis), a parotid mass or Lyme disease in endemic areas.
Incidence/ Prevalence
The incidence is about 20/100,000 people a year, or about 1/60 people in a lifetime. Bell's palsy has a peak incidence between the ages of 15 and 40 years. Men and women are equally affected, although the incidence may be increased in pregnant women.
Aetiology/ Risk factors
The cause of Bell's palsy is unknown, but it is thought that reactivated herpes viruses from the cranial nerve ganglia have a key role in the development of this condition. Herpes simplex virus-1 has been detected in in up to 50% of cases by some researchers and herpes zoster virus in approximately 13% of cases. Herpes zoster associated facial palsy more frequently presents as zoster sine herpete (without vesicles), although 6% of people will subsequently develop vesicles (Ramsay Hunt syndrome). Thus, treatment plans for the management of Bell's palsy should recognise the high incidence of herpes zoster virus, which is associated with worse outcomes. Inflammation of the facial nerve initially results in reversible neuropraxia, but ultimately Wallerian degeneration ensues.
Prognosis
Overall, Bell's palsy has a fair prognosis without treatment. Clinically important improvement occurs within 3 weeks in 85% of people and within 3-5 months in the remaining 15%. People failing to show signs of improvement by 3 weeks may have suffered severe degeneration of the facial nerve, or have an alternative diagnosis that requires identification by specialist examination or investigations, such as computed tomography or magnetic resonance imaging. Overall, 71% of people will fully recover facial muscle function (61% of people with complete palsy, 94% of people with partial palsy). The remaining 29% are left with mild to severe residual facial muscle weakness, 17% with contracture and 16% with hemifacial spasm or synkinesis. Incomplete recovery of facial expression may have a long-term impact on quality of life. The prognosis for children with Bell's palsy is generally good, with a high rate (more than 90%) of spontaneous recovery, in part because of the high frequency of partial paralysis. However, children with complete palsies may suffer poor outcomes as frequently as adults.
Aims of intervention
To prevent progression from partial to complete facial palsies; to maximise the speed of recovery; to increase the proportion of people making a full recovery; to reduce the incidence of motor synkinesis and contracture; to avoid morbidity to the eye, with minimum adverse effects.
Outcomes
Grade of recovery of motor function of the face; presence of sequelae (motor synkinesis, autonomic dysfunction, hemifacial spasm); time to full recovery.
Methods
BMJ Clinical Evidence search and appraisal February 2007. We performed a broad search for RCTs of any type of corticosteroid, antiviral agent, corticosteroid plus antiviral agent, or physical treatments other than electrical or magnetic stimulation for facial retraining in adults and children with Bell′s palsy, and included any RCT of sufficient quality. Trials used different scoring systems for reporting outcomes. The following databases were used to identify studies for this review: Medline 1966 to February 2007, Embase 1980 to February 2007, and The Cochrane Database of Systematic Reviews and Cochrane Central Register of Controlled Clinical Trials 2007, Issue 1. Additional searches were carried out using these websites: NHS Centre for Reviews and Dissemination (CRD) — for Database of Abstracts of Reviews of Effects (DARE) and Health Technology Assessment (HTA), Turning Research into Practice (TRIP), and National Institute for Health and Clinical Excellence (NICE). Abstracts of the studies retrieved from the initial search were assessed by an information specialist. Selected studies were then sent to the author for additional assessment, using predetermined criteria to evaluate relevant studies. Study design criteria for inclusion in this review were: published systematic reviews and RCTs in any language, at least single blinded, and containing more than 20 individuals of whom more than 80% were followed up. There was no minimum length of follow-up required to include studies. We excluded all studies described as "open", "open label", or not blinded unless blinding was impossible. In addition we use a regular surveillance protocol to capture harms alerts from organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA), which are added to the reviews as required. We have performed a GRADE evaluation of the quality of evidence for interventions included in this review (see table ).
Table.
GRADE evaluation of interventions for Bell’s palsy
| Important outcomes | Recovery of motor function of the face, presence of sequelae, time to full recovery, adverse effects | ||||||||
| Number of studies (participants) | Outcome | Comparison | Type of evidence | Quality | Consistency | Directness | Effect size | GRADE | Comment |
| What are the effects of drug treatments for Bell’s palsy in adults and children? | |||||||||
| 3 (117) | Recovery of motor function | Corticosteroids v placebo/no specific treatment | 4 | –2 | –1 | 0 | 0 | Very low | Quality point s deducted for sparse data and incomplete reporting of results. Consistency point deducted for conflicting results |
| 3 (117) | Presence of sequelae | Corticosteroids v placebo/no specific treatment | 4 | –1 | 0 | 0 | 0 | Moderate | Quality point deducted for sparse data |
| 1 (62) | Time to recovery | Corticosteroids v placebo/no specific treatment | 4 | –1 | 0 | 0 | 0 | Moderate | Quality point deducted for sparse data |
| 1 (101) | Recovery of motor function | Antivirals v corticosteroids | 4 | –1 | 0 | –1 | +1 | Moderate | Quality point deducted for sparse data. Directness point deducted for differences in durations of interventions. Effect size point added for RR greater than 2 |
| 1 (101) | Presence of sequelae | Antivirals v corticosteroids | 4 | –1 | 0 | –1 | 0 | Low | Quality point deducted for sparse data. Directness point deducted for differences in durations of interventions |
| 1 (99) | Recovery of motor function | Corticosteroids plus antivirals v corticosteroids | 4 | –1 | 0 | 0 | 0 | Moderate | Quality point deducted for sparse data |
| 1 study (56 people) | Recovery of motor function | Corticosteroids plus antivirals v no treatment | 2 | –1 | 0 | 0 | 0 | Very low | Quality point deducted for sparse data |
| What are the effects of surgical treatments for Bell’s palsy in adults and children? | |||||||||
| 1 study (67 people) | Recovery of motor function | Total facial nerve decompression surgery v no surgery | 2 | –1 | 0 | 0 | 0 | Very low | Quality point deducted for sparse data |
| What are the effects of physical treatments for Bell’s palsy in adults and children? | |||||||||
| 1 (48) | Recovery of motor function | Mime therapy v waiting list control | 4 | –1 | 0 | 0 | 0 | Moderate | Quality point deducted for sparse data |
Type of evidence: 4 = RCT; 2 = Observational; 1 = Non-analytical/expert opinion. Consistency: similarity of results across studies Directness: generaliseability of population or outcomes Effect size: based on relative risk or odds ratio
Glossary
- Autonomic dysfunction
occurs when aberrant regeneration of the facial nerve causes inappropriate autonomic activation with facial motor activity, for example “crocodile tears” — tearing with chewing.
- Hemifacial spasm
is a generalised involuntary mass contracture of the facial muscles.
- Low-quality evidence
Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate.
- Mime therapy
(mime and physiotherapy) aims to improve symmetry of the face, both at rest and during movement (emotional expression and functional movements), and simultaneously control synkinesis. It focuses on improving movement associated with eating, drinking, and speaking, as well as social integration.
- Moderate-quality evidence
Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.
- Motor synkinesis
is caused by aberrant regeneration of the facial nerve which causes synchronous movements of different parts of the face — for example, dimpling of the chin occurring simultaneously with each blink.
- Neuropraxia
is reversible nerve dysfunction without the degeneration or loss of nerve axons.
- Ramsay Hunt syndrome
is characterised by acute facial paralysis with herpetic (herpes zoster virus) blisters of the skin of the ear canal or tongue. Other symptoms may include vertigo, ipsilateral hearing loss, and tinnitus.
- Very low-quality evidence
Any estimate of effect is very uncertain.
- Wallerian degeneration
describes the sequelae of axonal injury and subsequent removal of axonal and myelin debris by Schwann cells and invading macrophages.
Disclaimer
The information contained in this publication is intended for medical professionals. Categories presented in Clinical Evidence indicate a judgement about the strength of the evidence available to our contributors prior to publication and the relevant importance of benefit and harms. We rely on our contributors to confirm the accuracy of the information presented and to adhere to describe accepted practices. Readers should be aware that professionals in the field may have different opinions. Because of this and regular advances in medical research we strongly recommend that readers' independently verify specified treatments and drugs including manufacturers' guidance. Also, the categories do not indicate whether a particular treatment is generally appropriate or whether it is suitable for a particular individual. Ultimately it is the readers' responsibility to make their own professional judgements, so to appropriately advise and treat their patients.To the fullest extent permitted by law, BMJ Publishing Group Limited and its editors are not responsible for any losses, injury or damage caused to any person or property (including under contract, by negligence, products liability or otherwise) whether they be direct or indirect, special, incidental or consequential, resulting from the application of the information in this publication.
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