Acute facial palsy: Bell's palsy or something else
- Emergency
Sudden weakness of one side of the face: first decide if it is central (stroke) or peripheral, then look for causes other than Bell's palsy.
What it is
Acute facial weakness has two big groups of causes. A central (upper motor neurone) lesion, such as a stroke, weakens the lower face but spares the forehead, because the forehead receives input from both hemispheres. A peripheral (lower motor neurone) lesion of the facial nerve weakens the whole half of the face, forehead included. Bell's palsy is the most common peripheral cause, but it is a diagnosis of exclusion: the ear, the parotid, the skin and the rest of the neurological exam must be checked first.
How to recognise it
- Ask the patient to raise the eyebrows and close the eyes tightly: forehead movement preserved means central.
- Bell phenomenon: when trying to close the eye, the eyeball rolls up and the white of the eye is seen.
- Ramsay Hunt: ear pain, vesicles in the canal or auricle, and sometimes hearing loss and vertigo.
- Slowly progressive palsy over weeks, or palsy affecting only some branches, suggests a tumour (parotid, temporal bone).
Step-by-step management
- Check the forehead: if it moves normally, treat as a possible stroke and follow the stroke pathway.
- Do a full neurological exam and examine the ear (otoscopy), the parotid, the neck, the skin and the mouth.
- Grade the weakness (for example House–Brackmann) and record the time of onset.
- If Bell's palsy is likely and onset is within 72 hours, start oral corticosteroids; consider adding an antiviral in severe palsy.
- Start eye protection at once: lubricating drops, night ointment and taping; urgent eye review if the eye is red or painful.
- Ramsay Hunt: corticosteroids with an antiviral; otitis media or cholesteatoma: urgent ENT.
- Review within weeks; most Bell's palsy improves within three weeks, and absent recovery needs imaging and ENT.
Central or peripheral, and which peripheral cause
| Finding | Think of | Next step |
|---|---|---|
| Forehead spared, other neurological signs | Stroke (central lesion) | Stroke pathway, urgent brain imaging |
| Whole half face, sudden, otherwise normal exam | Bell's palsy | Corticosteroids within 72 hours, eye care |
| Vesicles in the ear, ear pain, hearing loss | Ramsay Hunt syndrome (herpes zoster) | Corticosteroids plus antivirals, ENT |
| Red bulging eardrum or ear discharge | Otitis media or cholesteatoma | Urgent ENT assessment |
| Gradual onset, parotid mass, branch weakness | Parotid or other tumour | Imaging and ENT referral |
| Head injury, bleeding from the ear | Temporal bone fracture | CT temporal bone, ENT |
Red flags
- Forehead sparing or other neurological deficits (limb weakness, speech, diplopia).
- Bilateral facial palsy (Guillain–Barré syndrome, sarcoidosis, other systemic causes; not Bell's palsy).
- Slowly progressive weakness, a parotid mass or a neck lump.
- Ear pain with vesicles, ear discharge, hearing loss or vertigo.
- No sign of recovery after about three to four months, or recurrence on the same side.
Next step / Initial management
- Typical Bell's palsy needs no routine blood tests or imaging; order them when features are atypical (MRI for progressive, recurrent or non-recovering palsy; CT for trauma or ear disease).
- First-line: oral corticosteroids within 72 hours, eye protection, and an antiviral (acyclovir or valacyclovir) for Ramsay Hunt or as an add-on in severe Bell's palsy.
- Refer as an emergency, the same moment, to the stroke pathway any facial weakness that spares the forehead or comes with other neurological signs.
- Refer to ENT urgently (same day) palsy with ear disease or trauma; refer within weeks palsy with a parotid mass or no recovery after three months.
Test yourself
Think of the answer, then tap the question to see it.
A 68-year-old has sudden right facial droop, but can wrinkle both sides of the forehead. What is the most likely site of the lesion?
A central (upper motor neurone) lesion, such as a left hemisphere stroke. The forehead is spared because it receives input from both hemispheres; activate the stroke pathway.
Which treatment, started within 72 hours, improves recovery in Bell's palsy?
Oral corticosteroids. Eye protection is essential; antivirals may be added in severe palsy but are not effective alone.
A man has left facial palsy, severe ear pain and vesicles in the ear canal. What is the diagnosis?
Ramsay Hunt syndrome (herpes zoster of the geniculate ganglion). It is treated with corticosteroids plus an antiviral and has a worse prognosis than Bell's palsy.
Why is bilateral facial palsy not attributed to Bell's palsy?
Bilateral palsy is rare in Bell's palsy and suggests systemic causes such as Guillain–Barré syndrome or sarcoidosis, which need investigation.
Connections
Educational content; it does not replace a medical assessment and is not a clinical instruction. For a real case, follow current guidelines and specialist advice.
Sources: Bell Palsy (StatPearls) (StatPearls Publishing, NCBI Bookshelf, 2026); Ramsay Hunt Syndrome (StatPearls) (StatPearls Publishing, NCBI Bookshelf, 2026); Facial Nerve Palsy (StatPearls) (StatPearls Publishing, NCBI Bookshelf, 2026).
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Representative model, for educational purposes only.