Dr. YIU Kee Ki, Janet

Resident Medical Officer

Specialist in Family Medicine

Most people will think of having stroke when facial dropping occurs suddenly, but it is not necessarily the case. Facial nerve inflammation can result in this clinical presentation. While the cause of the inflammation remains uncertain, it is postulated that viral infection, such as herpes simplex or herpes zoster, may contribute. These viruses may lie dormant in the nerve roots, and could cause facial nerve inflammation when reactivated. This condition was first described by and thus named after a Scottish doctor named Dr. Charles Bell. While the occurrence of Bell’s palsy is higher in people with diabetes and pregnant women, it could happen to any of us.

What is the Facial Nerve? What are the Symptoms of Bell’s Palsy?

Located on both sides of the face, the facial nerve (the seventh cranial nerve) originates from the brain and branches out via the opening in the bone located near the base of the ear. It controls the facial muscles that help us to make facial expressions (e.g. smiling, raising eyebrows), control eyelid movement and convey taste sensations over the tongue.

Due to the motor weakness on one side, patients with Bell’s palsy could only move one side of face move. It is more noticeable when smiling. Drinks and saliva may leak from the side of the mouth. Other symptoms include slurred speech, tearing and dry eyes (due to the failure to close the eyelids completely), difficulty in raising eyebrows and blowing cheeks. These symptoms may develop rapidly within hours or days, with variable clinical presentations depending on the involvement of affected nerves. While pain over the face is usually absent or mild in most patients, some may feel pain near the ears for days. Increased sensitivity to sound or loss of tongue sensation on the affected side is sometimes reported.

Can Facial Paralysis be Caused by Other Medical Conditions, e.g. Stroke?

Facial paralysis is often mistaken for stroke. Additional symptoms are often found in stroke patients, such as one-sided weakness or numbness. As only the lower part of the face is affected by dual innervation, stroke patients can still raise eyebrows with their forehead muscles. Other causes of unilateral facial paralysis are rare, such as head injury, brain tumour, parotid tumour, sarcoidosis, Lyme disease, etc.

In general, doctor will first exclude other possible causes by history taking and physical examination. Further investigations may be performed to confirm or exclude other causes when necessary, such as imaging studies, electromyography (EMG), blood tests, etc. EMG can help diagnosis by assessing the severity of the condition and predict recovery.

Treatment of Bell’s palsy

Most patients can fully or partially recover from the condition without treatment. A course of oral steroids is usually prescribed to enhance recovery and mitigate inflammation. The outcome is more satisfactory if the medications are taken within 72 hours after onset of symptoms. Severe side effects are rare when steroids are used as short-term treatment. Anti-viral medication maybe prescribed if serious.

Inability to close eyelids fully and impaired lacrimal gland secretion may result in corneal damage. Hence, eye drops (for day time use) and eye cream (for night time use) are recommended to keep the eye moisturised. Besides, wear eye patches or goggles whenever necessary. It is especially important to tape the upper and lower eyelids to keep the eyes shut during sleep.

Recovery and Follow-up Treatment

Most patients (about 70%) can recover within 3 to 6 months without treatment. The chance of full recovery increases (in about 80 to 85% of cases) with steroid medications. A minority of patients may suffer from persistent residual facial weakness.

In case of incomplete recovery, please consult a specialist for further treatment, such as physical therapy, injection of botulinum toxin or other plastic surgeries.