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Bell's palsy
Background
Overview
Definition
Bell's palsy, also known as idiopathic facial paralysis, is an acute-onset, isolated, unilateral, lower motor neurone facial weakness/paralysis.
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Pathophysiology
The exact cause of Bell's palsy is unknown; however, reactivation of herpes virus at the geniculate ganglion of the facial nerve has been postulated.
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Disease course
The likely vascular distension, inflammation, and edema with ischemia of the facial nerve results in Bell's palsy, which presents with clinical manifestations of unilateral weakness/paralysis of upper and lower facial muscles, drooping of ipsilateral eyelids, dry eye due to inability to close eyes completely, epiphora, drooping of the corner of the mouth, ipsilateral impaired/loss of taste sensation, difficulty in eating, dribbling of saliva, altered sensation on the affected side of the face, pain in or behind the ear, hyperacusis on the affected side if stapedius muscle is involved. Spontaneous complete recovery occurs in 70-75% of untreated patients.
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Prognosis and risk of recurrence
Bell's palsy is not associated with an increased risk of mortality.
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Guidelines
Key sources
The following summarized guidelines for the evaluation and management of Bell's palsy are prepared by our editorial team based on guidelines from the Japan Society of Facial Nerve Research (JSFNR 2024), the French Society of Otorhinolaryngology (SFORL 2020), the American Academy of Otolaryngology-Head and Neck Surgery Foundation (AAO-HNSF 2013), and the American Academy of Neurology (AAN 2012).
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Screening and diagnosis
Differential diagnosis
As per SFORL 2020 guidelines:
Question the diagnosis of Bell's palsy and screen for tumoral causes in patients with peripheral facial palsy progressing beyond 72 hours after onset or showing fluctuation or recurrence or bilateral involvement.
A
Question the diagnosis of Bell's palsy in patients with peripheral facial palsy associated with abnormal otoscopy or parotid or cervical lymph node palpation or ipsilateral hearing loss, dizziness or other neurological signs.
B
Classification and risk stratification
Severity assessment: as per SFORL 2020 guidelines, assess the severity of facial involvement on a standardized grading system (House-Brackmann classification) for inclusion in the medical file during the initial work-up of patients with Bell's palsy.
B
House-Brackmann facial paralysis scale
Patients characteristics
Normal facial function in all areas
Slight weakness on close inspection; mouth: slight asymmetry, forehead: moderate to good function; eye: complete closure with minimum effort; normal symmetry and tone at rest
Obvious but not disfiguring weakness between 2 sides, noticeable but not severe synkinesis, contracture, and/or hemifacial spasm; mouth: slightly weak with maximum effort, forehead: slight to moderate movement, eye: complete closure with effort; normal symmetry and tone at rest
Obvious and disfiguring asymmetry; mouth: asymmetric with maximum effort, forehead: no motion, eye: incomplete closure; normal symmetry and tone at rest
Barely perceptible motion on contraction; mouth: slight movement, forehead: no motion, eye: incomplete closure; asymmetry at rest
Complete absence of any facial movement
Please make a selection
Diagnostic investigations
History and physical examination
As per SFORL 2020 guidelines:
Perform a clinical examination to confirm the peripheral nature of the facial palsy.
B
Perform a complete clinical neurological and ear, nose and throat examination with otoscopy and parotid and cervical palpation in patients presenting for peripheral facial palsy. Screen for involvement of the superior and inferior facial areas and absence of autonomic-voluntary dissociation to confirm peripheral status. Attempt to rule out involvement of the somatosensory and motor central pathways and other cranial nerves by neurological examination.
B
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Laboratory studies
Diagnostic imaging
Electrodiagnostic testing
Audiometry
Tympanometry
Medical management
Corticosteroids
As per JSFNR 2024 guidelines:
Administer systemic standard-dose corticosteroids (such as prednisolone 60 mg) in patients with Bell's palsy in the acute phase.
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Consider administering systemic high-dose corticosteroids (such as prednisolone 120 mg) over standard-dose corticosteroids in patients with severe Bell's palsy in the acute phase.
C
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Antiviral therapy
Nonpharmacologic interventions
Physical therapy: as per JSFNR 2024 guidelines, consider offering physical therapy in patients with Bell's palsy.
C
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Eye care
Acupuncture
Therapeutic procedures
Intratympanic corticosteroids: as per JSFNR 2024 guidelines, consider offering intratympanic corticosteroid injection in addition to systemic standard-dose corticosteroids in patients with severe Bell's palsy in the acute phase.
C
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Hyperbaric oxygen therapy
Surgical interventions
Specific circumstances
Follow-up and surveillance
Indications for specialist referral: as per AAO-HNSF 2013 guidelines, reassess or refer to a facial nerve specialist patients with Bell's palsy who meet any of the following criteria:
new or worsening neurologic findings at any point
ocular symptoms developing at any point
incomplete facial recovery 3 months after initial symptom onset.
B
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Follow-up surveillance
Recovery interventions