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.
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.
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.
Key medicines
Prednisolone for adult Bell palsyStart within seventy-two hours: use either prednisolone 50 mg once daily for ten days, or 60 mg once daily for five days followed by a 10 mg daily reduction, according to local guidance.
Preservative-free ocular lubricantsUse lubricating drops frequently while awake and a lubricating ointment at night, with dosing intensified to symptoms and ophthalmic advice while eyelid closure remains incomplete.