Original Editor - Wendy Walker
- 1 Introduction
- 2 Epidemiology
- 3 Mechanism of Injury / Pathological Process
- 4 Clinical Presentation
- 5 Diagnostic Procedures
- 6 Medical Management
- 7 Physiotherapy Interventions
- 8 Differential Diagnosis
- 9 Resources
- 10 References
Bell's Palsy, or Bell Palsy, is facial paralysis which is caused by dysfunction of Cranial Nerve VII, the Facial Nerve.
Also known as Idiopathic Facial Palsy. It is named after Sir Charles Bell [1774 to 1842], who was a Scottish surgeon, neurologist and anatomist.
It results in inability or reduced ability, to move the muscles on the affected side of the face ie. Facial Palsy.
Bell's Palsy is an idiopathic condition, i.e. no specific cause has been conclusively established. It is a diagnosis of exclusion: once other causes of facial palsy have been eliminated, the patient is said to have Bell's Palsy.
Population studies show an average incidence of 15 to 30 cases per 100,00 population.
It is the most common cause of acute unilateral facial paralysis, thought to cause between 60 and 75% of all unilateral facial palsy cases.
Mechanism of Injury / Pathological Process
The facial nerve is damaged by inflammation within the nerve causing it to become enlarged, at the point where the nerve exits the skull through the stylomastoid foramen.
Ischemia occurs as the nerve swells in its bony canal, blocking neural blood supply.
Having said that Bell's Palsy is a diagnosis of exclusion, and that we are not certain what causes the nerve inflammation, there is some evidence to suggest that in the majority of cases it is likely to be linked to Herpes Simplex infection.
For more information on the course of Cranial Nerve VII, please see the Facial Nerve page.
Loss of control of the muscles on one side of the face is the main physical presentation.
Some patients also report general malaise in the first few days on onset, as well as some pain in the region of the ipsilateral mastoid (known as otalgia), but many of patients have no otalgia or malaise.
At onset the paralysis may be complete, or partial (paresis) and although it frequently affects all branches of the facial nerve on the affected side, resulting in loss of control of that side of the mouth and the ipsilateral eye, in a few cases only one or two branches of the facial nerve are affected.
For a more detailed description of the clinical presentation, please see the Facial Palsy page.
Bell's Palsy is essentially a diagnosis of exclusion, so once other causes of facial palsy have been eliminated, we call an isolated facial palsy Bell's Palsy, or Idiopathic Facial Palsy.
Corticosteroids and antiviral medication are generally considered to be the 1st line treatment for Bell's Palsy, providing the best results when treatment starts within 72 hours of onset of symptoms. There are a number of studies showing benefit for steroids given within this time-frame.
However, many studies do not demonstrate any advantage of using antiviral medication combined with corticosteroids over corticosteroids along.
- In 2012 the Guideline Development Subcommittee of the American Academy of Neurology published a review Evidence-based guideline update: steroids and antivirals for Bell palsy, looking specifically at studies published since 2000. This consisted of 9 studies, 2 of which were rated Class 1 (high methodological quality).
The conclusions & recommendations were: For patients with new-onset Bell's palsy, steroids are highly likely to be effective and should be offered to increase the probability of recovery of facial nerve function [this conclusion was based on 2 Class 1 studies, Level A, && the risk difference was 12.8%-15%]. They concluded that for new-onset Bell's Palsy, antiviral agents in combination with steroids do not increase the probability of facial functional recovery by >7%, but "because of the possibility of a modest increase in recovery, patients might be offered antivirals (in addition to steroids" [Level C evidence]. They also remark "patients offered antivirals should be counselled that a benefit from antivirals has not been established, and, if there is a benefit, it is likely that it is modest at best".
- The Cochrane review "Antiviral treatment for Bell's palsy" Idiopathic facial paralysi,s concludes:"Moderate-quality evidence from randomised controlled trials showed no additional benefit from the combination of antivirals with corticosteroids compared to corticosteroids alone for the treatment of Bell's palsy of various degrees of severity. Moderate-quality evidence showed a small but just significant benefit of combination therapy compared with corticosteroids alone in severe Bell's palsy."
Physiotherapy treatment modalities include:
Massage improves blood flow, decreases the edema and improves the oxygenation of the hypoxic tissue
Massage manipulation techniques include: effleurage, finger or thumb kneading, stroking, wringing, tapping and hacking.
- Laser therapy
Laser therapy improves the nerve function as it decreases pain and inflammation. Also, it improves nerve regeneration and decreases never degeneration. It increases the never micro-circulation and activates angiogenesis.
A study by Banu Ordahan and Ali yavuz Karahan found that combining low-level laser therapy with facial muscles exercises produced better outcomes than only facial muscles exercise.
- Galvanic current
Interrupted galvanic current produces fast muscle twitches with no risk of muscles contractures.
- Faradic current
Faradic current produces tetanic muscle contraction of the facial muscles which could lead to muscles contractures.
- Shortwave diathermy
Shortwave diathermy could help improve bell's palsy as it decreases pain, increases metabolic function, improve microcirculation and prevents contractures. 
- EMG biofeedback
EMG provides the patient with sensory feedback to improve the recovery.
- Neuromuscular electrical stimulation (NMES)
NMES uses small electrical current to stimulate nerve supplying the paralyzed facial muscles to improve facial muscles strength and delay muscle atrophy in the chronic stage.
Infrared may improve the recovery by increasing the blood flow and decreasing the inflammation but there is low evidence to support use of infrared in treatment of bell's palsy.
Exercise of facial muscles in acute stage decreases the recovery time and in chronic stage improves facial functions.
Kabat Technique is based on Proprioceptive Neuromuscular Facilitation. The muscle is stretched bilaterally as a whole then resistance is given to the muscle. The patient is motivated by manual contact and verbal input.
It provides individualized therapy program aiming to eliminate the undesired movements and uses sensory feedback, concentrated and coordinated movements to improve facial muscles control.
Sensory feedback could be provided by EMG biofeedback or mirror exercises.
Mime therapy improves facial synergy and synkinesis through exercises that focus on coordination between the 2 sides of the face, eye and lip closure exercise, increase awareness of one's mouth through word exercises and facial expression exercises.
Kinesio TapingKinesio Taping can have positive effect through decreasing pain and edema but mre studies are needed to study its use in bell's palsy.
It is also important to provide information on care of the eye in order to prevent formation of corneal ulcer: see advice page on Dry Eye. Referral to an opthalmologist should be considered.
A number of people with Bell's Palsy suffer from Xerostomia, or Dry Mouth. This occurs because two of the three main salivary glands receive their parasympathetic nerve supply from the facial nerve: the sublingual and glossopharyngeal glands. (The parotid gland is not innervated by the facial nerve, so is unaffected.) See the advice page on Dry Mouth.
Bell's Palsy patients with long term facial paralysis may also start to experience dental problems: see advice page on Dental Issues in Facial Palsy.
The following conditions also result in facial palsy:
- Ramsay Hunt Syndrome - caused by Herpes Zoster infection (AKA Shingles), generally the patient will have vesicles and involvement of other cranial nerves
- Acoustic Neuroma - MRI scan should be used to exclude this
- Facial Schwannoma - caused by a tumour of the facial nerve; MRI scanning (with contrast) will show this
- Neurological (consider Multiple Sclerosis, and Guillain-Barre Syndrome )
- Infections, such as acute otitis media, cholesteatoma, viral infections including Epstein-Barr Virus
- Neoplasm, particularly parotid malignancy
- Upper Motor Neurone [UMN] facial palsy, generally caused by Stroke - note, the forehead will not suffer from paralysis in UMN causes.
The charity Facial Palsy UK has a page on Bell's Palsy.
- Katusic SK; Beard CM; Wiederholt WC; Bergstralh EJ; Kurland LT Incidence, clinical features, and prognosis in Bell's palsy, Rochester, Minnesota, 1968-1982. Ann Neurol. 1986; 20(5):622-7
- Peiterson,E. Bell's Palsy; the spontaneous course of 2,500 peripheral facial nerve palsies of different etiologies. Acta Oto-Laryngologica. Supplementum 2002;549:4-30
- Holland NJ, Weiner GM. Recent developments in Bell's Palsy. BMJ 2004; 329(7465):553-7
- Ahmed A. When is facial paralysis Bell palsy? Current diagnosis and treatment. Cleve Clin J Med. 2005 May;72(5):398-401, 405
- Hato N, Murakami S, Gyo K. Steroid and antiviral treatment for Bell's palsy. Lancet 2008; 371: 1818–20
- Engstrom M, Berg T, Stjernquist-Desatnik A, Axelsson S, Pitkaranta A, Hultcrantz M, et al. Prednisolone and valaciclovir in Bell's palsy: a randomised, double-blind, placebo-controlled, multicentre trial. Lancet Neurol. 2008 Nov. 7(11):993-1000
- Sullivan FM, Swan IR, Donnan PT, Morrison JM, Smith BH, McKinstry B, et al. Early treatment with prednisolone or acyclovir in Bell's palsy. N Engl J Med. 2007 Oct 18. 357(16):1598-607
- Axelsson S, Berg T, Jonsson L, Engström M, Kanerva M, Stjernquist-Desatnik A. Bell's palsy - the effect of prednisolone and/or valaciclovir versus placebo in relation to baseline severity in a randomised controlled trial. Clin Otolaryngol. 2012 Aug. 37(4):283-90
- Berg T, Bylund N, Marsk E, Jonsson L, Kanerva M, Hultcrantz M, et al. The effect of prednisolone on sequelae in Bell's palsy. Arch Otolaryngol Head Neck Surg. 2012 May. 138(5):445-9
- Gagyor I1, Madhok VB, Daly F, Somasundara D, Sullivan M, Gammie F, Sullivan F. Antiviral treatment for Bell's palsy (idiopathic facial paralysis). Cochrane Database Syst Rev. 2015 Jul 1;(7):CD001869.
- Ordahan B, yavuz Karahan A. Role of low-level laser therapy added to facial expression exercises in patients with idiopathic facial (Bell’s) palsy. Lasers in medical science. 2017 May 1;32(4):931-6.
- Kaur A. Physiotherapy For Facial Palsy: The Facial Rehabilitation Guide. FSP Media Publications; 2018 Apr 27.
- Marotta N, Demeco A, Inzitari MT, Caruso MG, Ammendolia A. Neuromuscular electrical stimulation and shortwave diathermy in unrecovered Bell palsy: A randomized controlled study. Medicine. 2020 Feb;99(8).
- Banu HB, Rahman S, Hossain S, Khan EH, Mahmood K, Rahman DL, Ahmed M. Effect of Infrared Radiation (IRR) on Patients with Bell’s Palsy. Bangladesh Medical Journal. 2017 Nov 21;46(1):1-6.
- Kumar C, Bagga TK. Comparison between proprioceptive neuromuscular facilitation and neuromuscular re-education for reducing facial disability and synkinesis in patients with Bell’s palsy: A randomized clinical trial. Int J Phys Med Rehabil. 2015;3(4):1-8.
- Maristella Rangel. Kabat - fisioterapia. Available from: https://www.youtube.com/watch?v=grc138ae8II[last accessed 8/4/2020]
- Beurskens CH, Devriese PP, Van Heiningen I, Oostendorp RA. The use of mime therapy as a rehabilitation method for patients with facial nerve paresis. International Journal of Therapy and Rehabilitation. 2004 May;11(5):206-10.
- Alptekin DÖ. Acupuncture and Kinesio Taping for the acute management of Bell’s palsy: A case report. Complementary therapies in medicine. 2017 Dec 1;35:1-5.
- AskDoctorJo. Bell's Palsy Exercises - Ask Doctor Jo. Available from: https://www.youtube.com/watch?v=8PcHtClQWyI[last accessed 7/4/2020]