Facial Palsy:
Why Time Matters — and How It Differs from a Stroke

1. What is facial palsy?

In facial palsy, the facial nerve, which controls the muscles of facial expression on one side of the face, is not working properly. If it fails, the affected side droops: the corner of the mouth sags, the eye no longer closes completely and the forehead stays smooth. Because the nerve also supplies taste fibres, the tear and salivary glands and a small muscle in the middle ear that dampens loud sounds, changes in taste, a dry or watery eye and sensitivity to noise are often part of the picture.^¹,²

The most common form is idiopathic facial palsy, also known as Bell’s palsy — “idiopathic” means without an identifiable cause. It is a diagnosis of exclusion: it only stands once stroke, shingles, Lyme disease, ear infections and tumours have been ruled out.^¹ It can occur at any age; people with diabetes and women in the last trimester of pregnancy are affected somewhat more often. The good news first: most people recover fully or largely.

2. Why time matters: ruling out a stroke

A new facial paralysis needs to be checked by a doctor the same day. There are three reasons for this, and their clocks tick at different speeds:^¹,²

• Minutes — ruling out a stroke: A drooping corner of the mouth is a classic sign of stroke. Thrombolysis (dissolving the clot with medication) is only possible within a narrow time window of a few hours.
• Hours to days — starting cortisone in time: For the idiopathic form, the benefit has been proven for treatment started within 72 hours.
• From day one — protecting the eye: If the eyelid does not close, the cornea dries out.

The forehead rule — and its limits

In the emergency department, one of the first checks is whether you can still wrinkle your forehead on the affected side. The upper half of the face receives signals from both halves of the brain, so after a stroke it often stays mobile. In peripheral palsy, the entire half of the face is affected.^¹,³

This table is not a self-test. Small strokes in the brainstem can mimic a peripheral palsy deceptively well. The assessment belongs in medical hands — if in doubt, it is better to go to the emergency department once too often than once too rarely.

3. Symptoms and course

Idiopathic facial palsy usually reaches its full extent within hours to about three days. It is often first noticed in the mirror in the morning — or when brushing your teeth, as water runs out of the corner of your mouth.^¹,³

• Drooping corner of the mouth — smiling and whistling only work on one side, and liquid runs out when you drink.
• Incomplete eyelid closure (lagophthalmos) — the eye stays slightly open, even during sleep; it waters, burns or turns red.
• Smooth forehead — no wrinkling of the forehead on the affected side, and the eyebrow droops.
• Food collecting in the cheek — the paralysed cheek no longer holds food between the teeth.
• Pain behind the ear — often comes before the paralysis or accompanies it.
• Altered taste and sensitivity to noise — reduced or metallic taste on one side of the tongue; everyday sounds seem too loud in one ear.

Many people describe their cheek as “numb”, even though skin sensation is usually intact — a different nerve is responsible for the sense of touch. Doctors become alert if there are blisters in the ear, very severe earache, hearing loss or vertigo, paralysis on both sides, slow progression over weeks, repeated paralysis on the same side or other nerve problems. A specific cause is then looked for.^¹

To tell them apart: lightning-like facial pain without paralysis points to trigeminal neuralgia — a different nerve and a different condition.

4. Causes: idiopathic, shingles, Lyme disease & more

In the idiopathic form, the cause has not been clearly established. The leading theory: reactivated herpes viruses trigger swelling of the nerve, which has no room to give way in its narrow bony canal. This has not been proven — and the fact that antivirals alone do not help argues against a simple viral infection as the sole explanation.^¹

• Shingles of the ear (zoster oticus) — blisters in the ear canal, severe pain, often hearing loss and dizziness. A less favourable outlook; antiviral treatment is needed. More under shingles.
• Lyme disease — after a tick bite, especially in summer and autumn; a comparatively common cause in children, sometimes on both sides.^⁴ See Lyme disease.
• Ear conditions, injuries, operations — for example a middle ear infection, a fracture of the base of the skull or surgery on the parotid gland.
• Tumours — typically causing paralysis that increases slowly.
• Systemic diseases — for example sarcoidosis or Guillain-Barré syndrome (an inflammatory nerve disorder); often on both sides.
• Risk factors — diabetes, high blood pressure, the last trimester of pregnancy and the weeks after giving birth.

And stress or draughts? Both are often blamed, but neither has been proven to be a cause. There is no need to feel guilty about that open window.

5. Diagnosis: what happens in the emergency department and at the practice

The diagnosis is primarily clinical. Technical tests mainly serve to rule out other causes and to estimate the outlook.^¹

• Neurological examination: face, arms, legs, speech, eye movements and the other cranial nerves. If a stroke is suspected, an immediate CT or MRI scan.
• Ear and parotid gland: a look into the ear canal (blisters, inflammation?) and feeling the area in front of the ear.
• Severity: usually graded on the House-Brackmann scale from I (normal) to VI (complete paralysis).
• Blood and cerebrospinal fluid: blood sugar, inflammation markers; if Lyme disease is suspected, antibodies in the blood and often a lumbar puncture — especially in children and with paralysis on both sides.^⁴
• Imaging: not routine with typical Bell’s palsy; useful with an unusual course or if there is no improvement after about three months.
• Electrophysiology: measurements of nerve and muscle activity only become meaningful after a few days and help to estimate the outlook with severe paralysis.

For your appointment, the exact time of onset, any tick bite and your complete medication list are worth more than any amount of online research.

6. Treatment: cortisone in the first 72 hours

For idiopathic facial palsy, the evidence is encouragingly clear: glucocorticoids (cortisone preparations) started within 72 hours increase the proportion of complete recoveries and reduce the risk of lasting faulty nerve rewiring. Large randomised trials support this; the guideline recommends the treatment for adults without contraindications.^¹

To put it honestly: many people recover even without treatment. Cortisone noticeably improves the odds, but it is no guarantee — and according to current evidence, anyone who only seeks help after a week hardly benefits any more.

Children often recover well even without treatment; the evidence on cortisone is considerably thinner for them. During pregnancy, cortisone can be used after weighing up the benefits and risks, and blood pressure is monitored as well, because facial palsy at this stage occurs more often together with pre-eclampsia. Which agents, at what dose and for how long is always decided by the treating practice.

7. Medicines in practice

Cortisone: short, high-dose — and still not trivial

Prednisolone is used in most cases. Over a few days it is usually well tolerated, but the typical pitfalls are well known:^⁶

• Blood sugar: often rises from the very first day, sometimes considerably if you have diabetes. Measure more often and agree any adjustments to insulin or tablets with your practice in advance.
• Stomach and bleeding: Combined with painkillers such as ibuprofen, diclofenac or aspirin, the risk of damage to the stomach lining rises; combined with anticoagulants, the risk of bleeding rises. A stomach-protecting medicine is then often added.
• Blood pressure, sleep, mood: raised blood pressure, restlessness and sleep problems are common — taking the dose in the morning eases the latter.
• Infections: The immune system is dampened; fever should be assessed by a doctor.

How glucocorticoids work and what matters with longer use is explained in the cortisone guide.

Antivirals and antibiotics

Aciclovir and valaciclovir are excreted via the kidneys; with reduced kidney function the dose must be adjusted, otherwise confusion and kidney damage can occur. Doxycycline is not taken at the same time as milk or calcium, magnesium or iron supplements, and it makes the skin sensitive to light.^⁶

8. Eye protection: the underrated part

If the eyelid does not close, the wiping effect of blinking is missing and the cornea dries out. The result can be inflammation or a corneal ulcer — in the worst case with permanent loss of vision.^¹,³

• Artificial tears during the day — regularly, not only once symptoms appear; preservative-free if you use them often. More under dry eyes.
• Gel or ointment and a watch-glass bandage at night — the transparent cover creates a moist chamber. Do not stick a plaster directly onto the open eye, as it can rub against the cornea.
• Glasses with side protection and screen breaks — against wind and dust; we blink less often anyway when we concentrate on looking at something.

If the eye stays open for a longer period, a small gold or platinum weight in the upper eyelid, a temporary botulinum toxin injection into the muscle that lifts the eyelid or, rarely, partially stitching the eyelid margins together can help.

9. Outlook, lasting symptoms and what does not help

The outlook for the idiopathic form is good: the vast majority recover completely or almost completely. First improvements usually appear within about three weeks; full recovery can take months. Less favourable signs are complete paralysis, no improvement in the first weeks, older age, diabetes, high blood pressure and zoster oticus.^¹,³

Possible lasting symptoms are synkinesis (involuntary co-movements: the eye closes when you smile), because regrowing nerve fibres reach the wrong muscle, crocodile tears (tears while eating) and tightness in one half of the face. Targeted botulinum toxin injections, exercise therapy with a mirror or biofeedback and, at specialist facial nerve centres, surgical procedures can help. If there is no recovery at all after a few months, it is worth being seen there — some nerve operations only make sense within a limited time window.

10. Everyday life with facial palsy

• Eating, drinking, teeth — chew on the healthy side, drink through a straw if needed, empty the pocket of your cheek after eating and brush thoroughly: food remnants promote tooth decay.
• An eye routine at fixed times — if you go by how your eye feels, you will usually use drops too rarely.
• Record your progress — regularly take a photo in the same position and make brief notes on eyelid closure, the corner of your mouth and taste.
• All medicines in one place — cortisone, drops and possibly an antiviral are added to your regular medication.
• Take the emotional side seriously — shame and withdrawal are common; talking about it, including with professionals, is not a sign of weakness.

Facial paralysis looks dramatic, and the shock is justified — that is exactly why it needs to be checked straight away. Once a stroke has been ruled out and treatment has started, what you need most is patience: nerves heal slowly, but in the vast majority of cases they do heal.

Cortisone course and eye protection without gaps — with brite

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