Bell's palsy

Last reviewed: 2 Jan 2023

Last updated: 07 Jun 2022

Bell’s palsy is an acute, sudden-onset, unilateral facial palsy of probable viral etiology.

Clinical diagnosis of exclusion.

High-dose corticosteroids should be administered in all patients in the absence of significant contraindications.

Other treatment options include concomitant antiviral agents, physical therapy, and, in severe cases, surgical decompression.

Eye protection should always be considered.

Failure to demonstrate any return of hemi-facial tone or movement within 4 to 6 months suggests an alternative diagnosis.

Definition

Bell's palsy is an acute unilateral peripheral facial nerve palsy in patients for whom physical examination and history are otherwise unremarkable. It consists of deficits affecting all facial zones equally that fully evolve within 72 hours. To date, it remains a clinical diagnosis of exclusion. Complete recovery to normal facial function occurs in approximately 70% of cases, with permanently impaired facial function occurring to a minor degree in 13% and to a major degree in 16% of cases.[1][2][3][4] However, recovery rate is lower in patients with recurrent Bell's palsy.[2] Onset of clinical recovery is nearly always demonstrated within 4 to 6 months of symptom onset; absence of any return of hemi-facial tone or movement by this time is highly suggestive of an alternative diagnosis.[1] Facial palsy of an otherwise known etiology (e.g., Lyme disease-associated facial palsy), or facial palsy that is progressive, waxing and waning, or affects facial zones in an uneven fashion, is not Bell's palsy.

History and exam

Key diagnostic factors

single episode
unilateral
absence of constitutional symptoms
involvement of all nerve branches
keratoconjunctivitis sicca
pain
synkinesis

More key diagnostic factors

Other diagnostic factors

any age
hyperacusis
dysgeusia

Other diagnostic factors

Risk factors

intranasal influenza vaccination
pregnancy
upper respiratory tract infection
arid/cold climate
hypertension
family history of Bell's palsy
diabetes
dental procedures

More risk factors

Diagnostic investigations

1st investigations to order

clinical diagnosis
electroneuronography (ENoG) (evoked electromyography - eEMG)
needle electromyography (EMG)
serology for Borrelia burgdorferi

More 1st investigations to order

Investigations to consider

pure-tone audiometry
tympanometry and stapedius reflex
MRI (gadolinium-enhanced fine-cut of facial nerve course)
CT (fine-cut, non-enhanced)

More investigations to consider

Treatment algorithm

ACUTE

all patients

Contributors

Authors

Matthew Q. Miller, MD

Assistant Professor Otolaryngology-Head and Neck Surgery

Director UNC Facial Nerve Center

University of North Carolina-Chapel Hill

Chapel Hill

Disclosures

MQM declares that he has no competing interests.

Liliana Ein, MD

Assistant Professor Otolaryngology-Head and Neck Surgery

Division of Facial Plastic and Reconstructive Surgery

University of Miami

Miami

Disclosures

LE declares that she has no competing interests.

Acknowledgements

Dr Matthew Q. Miller and Dr Liliana Ein would like to gratefully acknowledge Dr Tessa Hadlock, Dr Nathan Jowett, Dr Vishnu Madhok, Dr Iain Swan, Dr Pauline Lockhart, Dr Michael Norbury, and Dr John Gail Neely, previous contributors to this topic.

Disclosures

TH, VM, IS, PL, MN, and JGN declare that they have no competing interests. NJ holds a patent on the methods and systems for functional electrical stimulation of the paralyzed face (WO2017124019A1).

Peer reviewers

Giles Elrington, MBBS (Hons), MD, FRCP

Consultant Neurologist

Barts Health NHS Trust

London

Disclosures

GE is involved in a number of clinical trials on multiple sclerosis sponsored by Genzyme, Roche, Teva, Novartis, Biogen, as well as one funded by the MRC. He is also involved in clinical trials sponsored by Allergan, NMT Medical, GlaxoSmithKline (GSK), Bristol-Myers, the UK's Parkinson's Disease Research Group, and Pharmacia. In addition, he has attended lectures, conferences and symposia with the following companies - GSK, Astra Zeneca, MSD, Almirall, Pfizer, Menarini, Allergan, Biogen, Teva, Conference Plus, Infomed, BMJ.

Patrick Grogan, MD

Major

US Air Force

MC Program Director

Department of Neurology

MMCN

Wilford Hall Medical Center

Lackland Air Force Base

Disclosures

PG declares that he has no competing interests.

Venkat Srinivasan, MBBS, DLO, FRCS (Ed), FRCS (ORL)

Consultant in ENT/Thyroid Surgery

Arrowe Park Hospital

Upton

Wirral

Disclosures

VS declares that he has no competing interests.

Differentials
- Herpes zoster oticus (Ramsay Hunt syndrome)
- Lyme disease
- Benign facial nerve tumor (e.g., facial nerve schwannoma)
More Differentials
Guidelines
- ACR appropriateness criteria: cranial neuropathy
- Facial palsy (Bell's palsy)
More Guidelines
Patient leaflets
Bell palsy
More Patient leaflets
Log in or subscribe to access all of BMJ Best Practice

Use of this content is subject to our disclaimer

Bell's palsy

Summary

Definition

History and exam

Key diagnostic factors

Other diagnostic factors

Risk factors

Diagnostic investigations

1st investigations to order

Investigations to consider

Treatment algorithm

all patients

Contributors

Authors

Matthew Q. Miller, MD

Disclosures

Liliana Ein, MD

Disclosures

Acknowledgements

Disclosures

Peer reviewers

Giles Elrington, MBBS (Hons), MD, FRCP

Disclosures

Patrick Grogan, MD

Disclosures

Venkat Srinivasan, MBBS, DLO, FRCS (Ed), FRCS (ORL)

Disclosures

Differentials

Guidelines

Patient leaflets

Log in or subscribe to access all of BMJ Best Practice

Log in or subscribe to access all of BMJ Best Practice

Log in to access all of BMJ Best Practice