Bell's palsy
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《英国医生杂志》
1 Division of Medical Education, Warwick Medical School, University of Warwick, Coventry CV4 7AL Joanna.piercy@warwick.ac.uk
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.
Aetiology—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 100 000 people occur.
What you should do
Examination
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.
Information websites for patients
Bell's Palsy Information Site (www.bellspalsy.ws). This site has information on causes, symptoms, treatment, and rehabilitation. It also has a good "frequently asked questions" page.
Bell's Palsy Association (www.bellspalsy.org.uk). This is a UK based information site for patients.
Useful reading
Bandolier. Bell's palsy systematic reviews. www.jr2.ox.ac.uk/bandolier/booth/neurol/Bellsyre.html
Holland NJ, Weiner GM. Recent developments in Bell's palsy. BMJ 2004;329: 553-7
Salinas R. Bell's palsy. In: Clinical evidence concise. Issue 11. London: BMJ Publishing, 2004: 311
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 3-6 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 lecturer1)
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.
Aetiology—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 100 000 people occur.
What you should do
Examination
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.
Information websites for patients
Bell's Palsy Information Site (www.bellspalsy.ws). This site has information on causes, symptoms, treatment, and rehabilitation. It also has a good "frequently asked questions" page.
Bell's Palsy Association (www.bellspalsy.org.uk). This is a UK based information site for patients.
Useful reading
Bandolier. Bell's palsy systematic reviews. www.jr2.ox.ac.uk/bandolier/booth/neurol/Bellsyre.html
Holland NJ, Weiner GM. Recent developments in Bell's palsy. BMJ 2004;329: 553-7
Salinas R. Bell's palsy. In: Clinical evidence concise. Issue 11. London: BMJ Publishing, 2004: 311
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 3-6 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 lecturer1)