Aetiology

Paralysis of facial nerve (VII cranial nerve)
This Clinical Management Guideline addresses Bell’s Palsy (idiopathic lower motor neurone facial nerve dysfunction), which constitutes 72% of all facial palsy:

• annual incidence 20-30 per 100,000, especially between 15 & 45 yrs with a possible second peak in the over-70s
• sudden onset, unilateral
• M = F (except in pregnancy, see below)
• cause unknown, but sometimes associated with latent virus infection (HSV type 1, Herpes zoster)
• fair prognosis without treatment
  • however, up to 30% of treated patients do not recover completely
• better prognosis with systemic steroid therapy
• most improvement occurs within three weeks

Other causes of paralysis of the facial nerve, which are not addressed in this Clinical Management Guideline, include:

• infection, e.g. otitis media
• trauma, e.g. temporal bone fracture
• tumour compressing the facial nerve, e.g. acoustic neuroma
• sarcoidosis
• Guillain-Barré syndrome
• cerebrovascular accident (stroke)

Predisposing factors

Bell’s Palsy is more common in:

• pregnancy (annual incidence increases to 45 per 100,000)
• diabetes
• HIV

Although there have been case reports of isolated facial paralysis after viral vaccination (including mRNA COVID-19 vaccines), more detailed pharmacoepidemiological studies have not found an association.

Symptoms of facial palsy (Bell’s palsy)

Distressing cosmetic change due to loss of muscle tone on one side of face
Watering of eye (epiphora)
Ocular exposure causes:

• redness, discomfort, pain, photophobia, reduced vision

Signs of facial palsy (Bell’s palsy)

Unilateral facial weakness including orbicularis oculi

• incomplete blink leads to corneal drying
• incomplete closure at night (lagophthalmos) causes prolonged corneal exposure
• loss of lacrimal pump mechanism produces pooling and epiphora

Conjunctival hyperaemia, oedema, staining
Corneal desiccation ranges from mild superficial punctate erosions to frank ulceration (usually inferior)

Differential diagnosis

Other causes of facial nerve palsy:

• as part of a stroke (cerebro-vascular accident with hemiplegia), in which forehead muscle function is preserved
• infection (e.g. otitis media, Lyme disease)
• trauma (e.g. cranial fracture, facial laceration)
• tumour (e.g. acoustic neuroma: damage to nerve by tumour or secondary to surgical trauma; also perineural invasion by a squamous cell carcinoma)

Ectropion or Entropion (see appropriate Clinical Management Guidelines)
Other causes of lagophthalmos

• orbital (thyroid eye disease – assess by exophthalmometry)
• mechanical (cicatricial – look for lid scarring)
• physiological (patient’s partner to check for full lid closure at night)

Management by optometrist

Practitioners should recognise their limitations and where necessary seek further advice or refer the patient elsewhere

GRADE* Level of evidence and strength of recommendation always relates to the statement(s) immediately above

Tape lids closed at night (and during day if corneal desiccation is marked)
(GRADE*: Level of evidence=low, Strength of recommendation=strong)

Sunglasses for photophobia and general protection
(GRADE*: Level of evidence=low, Strength of recommendation=strong)

Therapeutic contact lens (if unresponsive to frequent use of ocular lubricants)

• silicone hydrogel should be considered as first choice (however, scleral lens gives maximum protection)

NB therapeutic contact lens fitting is contraindicated in cases of neurotrophic keratitis with loss of corneal sensation (cranial nerve V). Such patents are at high risk of infection, which may be further increased by contact lens wear
(GRADE*: Level of evidence=low, Strength of recommendation=weak)

Tear supplements / lubricants by day, unmedicated ointment at night
(GRADE*: Level of evidence=low, Strength of recommendation=strong)

Management category

New cases, and where there is loss of corneal sensation:
A2: first aid measures and emergency (same day) referral to GP or hospital A&E department
Improved prognosis in moderate/severe cases of Bell’s palsy if treated
with systemic corticosteroid within 72 hours of onset
Combination therapy with anti-virals provides no additional benefit to
rates of complete recovery but probably reduces rates of late sequelae
compared to corticosteroids alone
NB: corneal ulceration due to exposure is potentially sight threatening and may justify emergency referral

Recovering and established cases:
B2: alleviation/palliation; no referral

If cannot be managed easily, then:
B1: prescription of drugs; routine referral

Possible management by ophthalmologist

Urgent medical treatment for new cases:

• systemic steroid ± anti-viral

Temporary tarsorrhaphy

Upper lid lowering with botulinum toxin injection of levator muscle

Eyelid surgery for permanently unrecovered cases:

• tarsorrhaphy (permanent)
• upper lid lowering (surgery, gold weight)
• surgical sling to raise lower lid
• there is insufficient evidence on the value of surgical decompression of the
  facial nerve

Evidence base

*GRADE: Grading of Recommendations Assessment, Development and Evaluation (www.gradeworkinggroup.org)
 

Sources of evidence

Baugh R, Basura G, Ishii L, et al. Clinical practice guideline: Bell’s palsy. Otolaryngol Head Neck Surg. 2013;149(3)(suppl):S1-S27

de Almeida JR, Guyatt GH, Sud S, Dorion J, Hill MD, Kolber MR, Lea J, Reg SL, Somogyi BK, Westerberg BD, White C, Chen JM; Bell Palsy Working Group, Canadian Society of Otolaryngology. Management of Bell Palsy: clinical practice guideline. Head and Neck Surgery and Canadian Neurological Sciences Federation. CMAJ. 2014;186(12):917- 22

Gagyor I, Madhok VB, Daly F, Sullivan F. Antiviral treatment for Bell's palsy (idiopathic facial paralysis). Cochrane Database Syst Rev. 2019;9:CD001869

Madhok VB, Gagyor I, Daly F, Somasundara D, Sullivan M, Gammie F, Sullivan F. Corticosteroids for Bell's palsy (idiopathic facial paralysis). Cochrane Database Syst Rev. 2016;7:CD001942

Menchetti I, McAllister K, Walker D, Donnan PT. Surgical interventions for the early management of Bell's palsy. Cochrane Database Syst Rev. 2021;1(1):CD007468.

Renoud L, Khouri C, Revol B, Lepelley M, Perez J, Roustit M, Cracowski JL. Association of facial paralysis with mRNA COVID-19 vaccines: a disproportionality analysis using the World Health Organization Pharmacovigilance Database. JAMA Intern Med. 2021;181(9):1243-1245.

Facial Palsy (Bell’s Palsy)
Version 14
Date of search 21.02.22
Date of revision 11.03.22
Date of publication 22.11.22
Date for review 20.02.24
© College of Optometrists