Synopsis
Distinguish an acute idiopathic lower motor neurone facial palsy from stroke, Ramsay Hunt syndrome, ear or parotid disease, trauma and progressive facial-nerve lesions while protecting the cornea promptly.
- Bell palsy is an acute idiopathic unilateral lower motor neurone facial-nerve palsy diagnosed after excluding a recognisable alternative; symptoms usually evolve over hours and reach maximum within seventy-two hours.
- Observe eyebrow elevation, gentle and forced eye closure, nasolabial fold and smiling or showing teeth. True peripheral weakness affects upper and lower face on the same side, although effort and baseline asymmetry must be considered.
- Forehead sparing with lower facial weakness suggests a contralateral supranuclear lesion, but this is a localisation clue rather than a stand-alone stroke exclusion rule.
- Ask about exact onset, limb or speech symptoms, diplopia, vertigo, hearing change, dysphagia, severe headache, ear pain or vesicles, rash, tick exposure, trauma, surgery, parotid swelling, cancer and previous episodes.
- Examine all cranial nerves, limbs and coordination, and inspect the external ear, canal, tympanic region, oral cavity, parotid and skin. An isolated facial examination can miss brainstem or skull-base disease.
- Corneal protection begins immediately when closure is incomplete: frequent preservative-free lubricating drops by day, lubricating ointment and eyelid closure at night according to local eye-care advice.
- Oral corticosteroid started within seventy-two hours improves the chance of complete recovery in adults with Bell palsy when contraindications and individual risks are addressed.
- Do not use antiviral treatment alone for Bell palsy. Combined antiviral and steroid treatment is considered selectively through current local guidance, particularly in severe complete palsy or suspected herpetic disease.
- Ramsay Hunt syndrome may cause facial palsy with severe ear pain, vesicles in the canal, pinna or palate, hearing loss or vertigo; vesicles can appear after weakness and absence at first examination does not guarantee Bell palsy.
- Routine imaging or broad blood panels are unnecessary for a classic first isolated Bell palsy, but atypical tempo, recurrence, bilateral disease, other nerves, systemic features or failure to recover warrants specialist investigation.
- Document function and severity with a recognised scale where used locally, photograph only with consent on an approved clinical system and arrange follow-up of eye closure and neurological recovery.
Key red flags
Predominantly lower facial weakness with relatively preserved forehead movement, especially with contralateral limb deficit, aphasia, neglect, gaze or field abnormality, supports an acute cerebral lesion and demands stroke assessment.
Peripheral facial palsy with prominent otalgia, vesicles in or around the ear or palate, hearing loss or vestibular symptoms suggests varicella-zoster reactivation. Early lesions may be subtle or delayed.
An ipsilateral peripheral-pattern facial weakness accompanied by abduction or gaze disturbance, contralateral limb signs, ataxia or altered facial sensation localises to the pons rather than an isolated extracranial nerve.
Slow progression, recurrent same-side weakness, facial pain, multiple branch involvement, a parotid mass, other cranial neuropathies or cancer history suggests neoplastic, infiltrative or compressive disease.
Bilateral palsy is not typical Bell palsy and raises inflammatory neuropathy, sarcoidosis, infection, brainstem disease, malignancy and systemic causes; assess limb reflexes, respiratory and bulbar function urgently.
Incomplete blink or closure with redness, foreign-body sensation, photophobia, pain, epithelial haze or reduced vision indicates corneal surface injury and requires urgent eye-service advice.
Investigation priorities
Confirm the distribution of facial weakness and identify supranuclear, brainstem, multifocal or systemic neurological disease.
Management branches
Unilateral upper and lower facial weakness reaching maximum within seventy-two hours, with no alternative features after examination.
- Confirm onset and exclusion features, examine all cranial nerves and limbs, inspect ear, palate and parotid, and assess corneal closure and symptoms before applying the Bell palsy label.
- Start an appropriate oral corticosteroid within seventy-two hours when safe, institute preservative-free lubrication and night closure measures, and follow local advice on selective antiviral addition.
- Give written eye and neurological safety-netting and arrange follow-up of closure and recovery; refer if progression continues, no improvement begins in the expected interval or function remains incomplete.