10 Minute consultation: Bell's palsy

A 32 year old man presents to you with sudden onset of weakness on the left side of his face. He also says that he is unable to close his left eye. He is otherwise well and last saw a doctor five years ago. He is anxious and thinks he has had a stroke.

What issues you should cover

Associated symptoms—Patients with Bell's palsy commonly feel pain in or behind the ear. Numbness can occur on the affected side of the face. Loss of taste on the ipsilateral anterior two thirds of the tongue is common. Ask about associated hyperacusis and any presence of rash that may indicate herpes zoster.

Cause—Ask about recent viral infection and recent immunisation. The causes of Bell's palsy are unknown, but the possibilities include viral infection, heredity, autoimmune or vascular ischaemia, of which the most likely cause is viral.

Incidence—Bell's palsy is commonest in the age group 10 to 40 years. Each year about 20 cases per 100000 people occur.

What you should do

You will need to differentiate between an upper and lower motor neurone lesion of the facial nerve. A lower motor neurone lesion occurs with Bell's palsy, whereas an upper motor neurone lesion is associated with a cerebrovascular accident. A lower motor neurone lesion causes weakness of all the muscles of facial expression. The angle of the mouth falls. Weakness of frontalis occurs, and eye closure is weak. With an upper motor neurone lesion frontalis is spared, normal furrowing of the brow is preserved, and eye closure and blinking are not affected.

Check that no other cranial nerves are involved. Bell's palsy is seventh nerve palsy in isolation. Look also for a painful rash over the ear, which indicates Ramsay Hunt syndrome caused by herpes zoster virus.

Look for pointers to a more serious underlying cause that might require urgent referral of the patient: bilateral Bell's palsy; recurrent Bell's palsy; association with a rash elsewhere or with feeling generally unwell (which may indicate sarcoid or Lyme disease); or a previous episode that could have been the effect of demyelination. Although it is rare, always bear in mind the possibility of a seventh nerve palsy caused by a space occupying lesion.

Treatment

Two recent systematic reviews concluded that Bell's palsy can be effectively treated with corticosteroids in the first seven days after onset, with a further 17% of patients having a good outcome in addition to the 80% that spontaneously improve. Recovery rates in patients treated within 72 hours were enhanced with the addition of aciclovir. It is thought that prednisolone acts by reducing oedema of the facial nerve. Antivirals inhibit viral replication. So, recent evidence supports the use of oral prednisolone and aciclovir in patients with moderate to severe palsy, ideally within 72 hours but up to seven days from onset of symptoms. Prednisolone should be prescribed at a dosage of 1 mg/kg/day (maximum 80 mg daily) for the first week, with the dosage tapering off over the second week. Aciclovir is given at a dosage of 800 mg five times a day for five days.

As blinking is affected, and his eye may not close, consider an eye pad or taping of the lid so that he can sleep. His cornea will be dry, so prescribe artificial tears.

Reassure him. Patients are often highly anxious and will need to be firmly reassured that this is not a cerebrovascular accident. Tell him that most patients get better but that a minority won't.

Follow-up

Two thirds of patients recover spontaneously, and 85% report some improvement in the first three weeks. In the other 15% of patients some improvement occurs by three to six months. Patients need follow up for assessment of recovery and support.

Referral to an ear, nose, and throat specialist is advisable for all cases after treatment is begun. Patients with incomplete recovery of facial nerve function may ultimately need to be referred to an ophthalmologist for tarsorrhaphy.

Jo Piercy, clinical lecturer, Division of Medical Education, Warwick Medical School, University of Warwick, Coventry CV4 7AL
Email: Joanna.piercy@warwick.ac.uk

This article was first published in the BMJ (2005;330:1374).

studentBMJ 2005;13:265-308 July ISSN 0966-6494

       

           

	Responses published this month

Articles	Responses
EDUCATION 10 Minute consultation: Bell's palsy       Jo Piercy (July 2005)	Umar Sadat (August 20, 2005) Read this response

	EDUCATION 10 Minute consultation: Bell's palsy       Jo Piercy (July 2005)
	Umar Sadat (August 20, 2005)       Clinical Attachment, Department of Surgery,Addenbrooke's Hospital, Cambridge. sadat.umar@gmail.com
	ACUTE STAGE Decompression of the facial nerve can be accomplished by a delicate microsurgical procedure. This surgery can make a critical difference with some types of severe nerve damage, but not generally for Bell's Palsy. For Bells Palsy it remains highly controversial, even when nerve degeneration is severe. There is not likely to be any benefit over prompt treatment by standard meds, and there are serious risks involved. The most common complications are hearing loss and damage to the facial nerve, which can be permanent. If this procedure is done for any reason, it should be done within 3 weeks of nerve damage. After this time statistics show no benefit for enduring the surgery and the potential risks. FOR LONGTERM WEAKNESS AND RESIDUALS There are reconstructive options for long-term weakness or paralysis. Some are "static" - purely cosmetic; some may help regain function. These procedures are more often performed when the nerve has been cut or severely compressed than after the "typical" short-term compression of viral and bacterial induced paralysis. While these techniques can offer improvement (better symmetry at rest or some improvement to the smile), they cannot fully restore natural movement or expressions. Cosmetic surgeries such as brow-lifts, face-lifts, muscle shortening, removal of excess upper eyelid skin, muscle relaxing procedures and static slings are available to improve appearance, but they will not improve muscle function. Nerve and muscle grafts or transpositions can offer functional improvement as well as improve appearance. These are complex procedures that should be considered carefully. Take care to insist that the surgeon fully explains the procedure, recovery, and risks. Risks include nerve damage that can leave the patient with worse paralysis than prior to surgery. One type of nerve transposition involves connecting the hypoglossal nerve (controls the tongue) to the facial nerve. After surgery, the patient learns how to move the face by moving the tongue. Ideally, the motion becomes automatic in time. There is likely to be a loss of sensation at the tongue. A muscle transposition can be performed using a muscle that isn't controlled by the facial nerve. The temporalis or masseter muscle can be connected to the corner of the mouth. The intention is that the enervated muscle will increase motion in the muscles around the mouth. In a combination muscle and nerve graft, two procedures are performed several months apart. Free muscle tissue is grafted from the leg to the face following a cross-facial nerve graft. The nerve graft becomes the nerve supply for the healthy, transplanted muscle.