Bell’s Palsy is an acute, unilateral facial nerve paralysis of sudden onset, typically involving the 7th cranial nerve (facial nerve). It is one of the most common causes of facial paralysis worldwide and often presents as a frightening condition for patients due to the visible facial asymmetry.
Although it is often temporary, prompt recognition and management are important to improve outcomes.
To aid clinical recall, medical students and healthcare professionals use the mnemonic BELL’S PALSY to remember its characteristic features.
The BELL’S PALSY Mnemonic for Symptoms
- B – Blink reflex abnormal
- E – Earache
- L – Lacrimation (deficient or excessive)
- L – Loss of taste (anterior two-thirds of the tongue)
- S – Sudden onset
- P – Palsy of 7th nerve muscles (facial muscle weakness)
👉 All symptoms are unilateral (one-sided).
Detailed Explanation of Symptoms
1. Blink Reflex Abnormal
Patients often cannot close their eyelids completely on the affected side. This is known as lagophthalmos. The corneal reflex is impaired, predisposing the eye to dryness, irritation, and corneal ulcers.
2. Earache
Many patients complain of pain around or behind the ear. This is due to inflammation of the facial nerve near the stylomastoid foramen. Sometimes, hyperacusis (sensitivity to loud sounds) occurs due to paralysis of the stapedius muscle in the middle ear.
3. Lacrimation Abnormalities
The lacrimal gland receives parasympathetic fibers via the facial nerve. Depending on the site of nerve involvement:
- Reduced tearing (dry eye) may occur.
- Excessive tearing (epiphora) may also happen due to improper eyelid closure.
4. Loss of Taste
The chorda tympani branch of the facial nerve supplies taste sensation to the anterior two-thirds of the tongue. Patients often report altered or complete loss of taste.
5. Sudden Onset
Bell’s Palsy typically presents with an acute onset of symptoms, often noticed on waking up. Patients may find it difficult to smile, close the eye, or raise the eyebrow on one side.
6. Palsy of 7th Nerve Muscles
The hallmark feature is unilateral weakness of facial muscles, including:
- Inability to wrinkle the forehead
- Drooping of the mouth corner
- Inability to blow air or whistle
- Asymmetrical smile
These features distinguish Bell’s Palsy from central causes (like stroke), where forehead wrinkling is preserved due to bilateral cortical innervation.
Causes of Bell’s Palsy
While often idiopathic, possible causes and risk factors include:
- Viral infections (Herpes simplex virus, Varicella zoster)
- Inflammation and swelling of the facial nerve
- Diabetes mellitus
- Pregnancy (third trimester and immediate postpartum)
- Exposure to cold wind
- Hypertension
Diagnosis
Bell’s Palsy is largely a clinical diagnosis, but other causes of facial paralysis must be excluded.
Clinical Evaluation
- Detailed neurological examination
- Rule out stroke (forehead involvement distinguishes Bell’s Palsy from central causes)
- History of infections or systemic illness
Investigations (if atypical or prolonged course)
- MRI/CT to rule out tumors or stroke
- Blood tests for diabetes, Lyme disease, or autoimmune conditions
Treatment of Bell’s Palsy
Most patients recover spontaneously, but early intervention improves prognosis.
1. Medical Treatment
- Corticosteroids (Prednisone) – most effective if started within 72 hours.
- Antivirals (Acyclovir, Valacyclovir) – if herpes virus is suspected.
- Analgesics – for ear pain.
2. Eye Care
- Artificial tears or lubricating ointment to prevent dryness.
- Protective glasses or eye patch, especially during sleep.
3. Physiotherapy
- Facial muscle exercises help prevent contractures.
- Electrical stimulation may be used in some cases.
4. Surgery (Rare)
- Decompression of facial nerve in severe refractory cases.
Prognosis
- 70–85% of patients recover completely within 3–6 months.
- Some may develop residual weakness, contractures, or synkinesis (involuntary facial movements).
- Early steroid therapy greatly improves recovery rates.
Differentiating Bell’s Palsy from Stroke
| Feature | Bell’s Palsy | Stroke |
|---|---|---|
| Onset | Sudden, often overnight | Sudden, often with other neurological deficits |
| Forehead involvement | Yes (cannot wrinkle forehead) | No (forehead movements preserved) |
| Other symptoms | Ear pain, taste loss, lacrimation changes | Limb weakness, speech difficulty, vision loss |
| Recovery | Usually complete in weeks–months | Depends on severity |
Quick Reference – BELL’S PALSY Mnemonic
| Letter | Symptom | Clinical Relevance |
|---|---|---|
| B | Blink reflex abnormal | Eye dryness, risk of corneal ulcer |
| E | Earache | Due to nerve inflammation, hyperacusis possible |
| L | Lacrimation changes | Excessive or reduced tearing |
| L | Loss of taste | Anterior 2/3 tongue |
| S | Sudden onset | Rapid development of symptoms |
| P | Palsy of 7th nerve muscles | Classic facial asymmetry |
Frequently Asked Questions (FAQ)
1. Is Bell’s Palsy the same as stroke?
No. Bell’s Palsy affects only the facial nerve, while stroke affects the brain. Stroke usually spares forehead movements.
2. How long does Bell’s Palsy take to recover?
Most cases resolve in 3–6 months, with or without treatment.
3. Can Bell’s Palsy recur?
Yes, recurrence occurs in about 10% of patients.
4. What are the risk factors?
Diabetes, pregnancy, viral infections, and hypertension increase risk.
5. Can Bell’s Palsy cause permanent paralysis?
In some untreated or severe cases, residual weakness may remain, but most patients recover fully.
