Dr Shameen Jaunoo (left) and Mr Robert Sudderick explain what the GP should consider when identifying a case of Bell’s palsy and highlight suitable management and treatment options


An anxious 27-year-old male patient comes to see you complaining of weakness of the right side of the face which, came on suddenly. He is unable to close his right eye, but is otherwise well

Incidence of Bell's palsy

The incidence of Bell's palsy is 20–30 cases per 100,000 population per year. It affects both sexes equally and accounts for 60–75% of all cases of unilateral facial paralysis. The median age of onset is 40 years but any age may be affected. The incidence is lowest in those under 10 years of age, increases between the ages of 10 to 29 years, remains stable between the ages of 30 to 69 years, and is highest in those over 70 years of age.1

History taking

The following things should be looked for while taking the patient's history:2–4

  • pain—patients with Bell's palsy frequently complain of pain behind the ear
  • paraesthesia/numbness—this can occur on the affected side
  • taste disturbance—loss of taste sensation on the anterior two-thirds of the tongue on the ipsilateral side is a common finding
  • rash—typically, but not invariably, multiple small vesicles over the ear, external auditory canal, and in the pharynx may indicate herpes zoster infection. Involvement of the facial nerve by herpes zoster is a recognised cause of facial palsy (Ramsay Hunt syndrome)
  • hyperacusis—perceiving sound as unduly loud in the ipsilateral ear, occurs in approximately one-third of patients and is secondary to weakness of the stapedius muscle
  • recent viral infection and recent vaccination—although the aetiology of Bell's palsy remains unknown, the most likely possible cause is viral infection (other possibilities include: autoimmune disorders, vascular disease, or a hereditary factor).

Diagnosis by exclusion

Is it an upper or lower motor neurone lesion?

A lower motor neurone lesion may occur in Bell's palsy, and results in ipsilateral weakness of all the muscles of facial expression, with drooping at the corner of the mouth, weakness of the frontalis muscle, and reduced or absent eye closure.

An upper motor neurone lesion, which is suggestive of a stroke, spares the frontalis muscle, preserving normal furrowing of the brow. Eye closure and blinking are usually unaffected, however, the orbicularis oculus muscle has variable bilateral upper motor neurone innervation and as a result of this eye closure can be affected in this type of lesion.

Are any other cranial nerves involved?

The classic definition of Bell's palsy describes an 'isolated' palsy of the facial nerve, yet other cranial nerves are probably affected. However, the facial nerve is arguably the only cranial nerve to elicit such obvious signs on clinical examination because of its unique anatomical course from the brain to the face.

Is there an associated rash?

A painful rash over the ear with or without vesicles is strongly suggestive of Ramsay Hunt syndrome. This is caused by herpes zoster infection.

Has the ear been examined?

It is essential to examine the ipsilateral ear with an auroscope to assess the ear canal, tympanic membrane, and middle ear. Otitis media, cholesteatoma, and malignant otitis externa can all cause facial palsy.

Has the parotid gland been examined?

The parotid gland must be palpated for masses, as malignant tumours can also cause facial palsy.

Has something more serious been overlooked?

Red flag signs, which necessitate urgent referral to a specialist, include:

  • recurrent Bell's palsy
  • bilaterality
  • associated rash elsewhere on the body
  • associated general malaise (possible sarcoidosis or Lyme disease).

A previous episode could have been the effect of demyelination, which introduces the possible diagnosis of multiple sclerosis.

Clinical features of exposure keratopathy, such as irritation of the eye, blurred vision, photophobia, reduced visual acuity, conjunctival redness, and a corneal haze are indications for urgent referral to an ophthalmologist. The possibility of a 7th nerve palsy secondary to a space-occupying lesion should be considered.

The grading system for facial palsy

Various grading systems are available to facilitate objective documentation of facial palsy, but the most widely used is the House-Brackmann scale (see Box 1), which allocates patients to one of six categories according to the degree of facial function.5–7

Box 1: House—Brackmann scale for grading severity of facial palsy5

Grade I Complete eye closure
Normal symmetrical function in all areas
Grade II Complete eye closure with minimal effort Slight weakness only on close inspection Slight asymmetry of smile with maximal effort
Grade III Complete eye closure and strong but asymmetrical mouth movement with maximal effort
Obvious weakness but not disfiguring
May not be able to lift eyebrow
Grade IV Incomplete eye closure and asymmetry of mouth with maximal effort
Obvious disfiguring weakness
Inability to lift brow
Grade V Incomplete eye closure, slight movement at corner of mouth Motion barely perceptible
Grade VI Incomplete eye closure
No movement

Management of the patient with Bell's palsy

There is no cure or standard course of treatment for Bell's palsy. In general, patients with true Bell's palsy have an excellent prognosis. Some cases are mild and do not require treatment as the symptoms usually subside on their own within 2 weeks;8 for others, treatment includes reassurance, medications, eye care, and appropriate follow-up care, at an interval according to the requirements of each case.

The use of steroids and aciclovir in the treatment of Bell's palsy has been addressed in two Cochrane reviews.9,10 These reviews found that there was no proven benefit from aciclovir, and that early treatment with corticosteroids may be more effective than aciclovir or valaciclovir. They nevertheless concluded that available studies had insufficient clinical follow-up to detect treatment effects. Hence, current evidence does not support the use of antivirals alone or in combination for Bell's palsy. Steroids appear to confer minimal benefit in the final functional recovery.

Eye care is very important in the management of Bell's palsy patients who are unable to close an eye completely. It is essential to keep the eye moist with lubricating eye drops, such as artificial tears or eye ointments/gels, to prevent corneal drying and ulceration. Many advocate the use of an eye patch to protect the eye from debris and injury, particularly at night. However, the use of an eye patch over an insensate cornea may actually increase the risk of abrasion. This can occur if the eye opens under the patch while the patient is sleeping. It may, therefore, be preferable to tape the eyelid closed, after applying a protective ointment.

The Scottish Bell's Palsy Study

Patient recruitment into a NHS-funded randomised clinical trial—the Scottish Bell's Palsy Study—was completed recently. The study aimed to evaluate the recovery of four groups of patients with Bell's palsy: those treated with prednisolone, with aciclovir, both agents, or neither. The findings of the Scottish Bell's Palsy Study11 are eagerly awaited and it is to be hoped that they will be conclusive.

Referral

Referral to an otorhinolaryngologist is advisable in all cases once treatment has been instituted. However, there are no hard and fast rules for this and local policies differ.

Further information

Further information can be obtained from the Bell's Palsy Information Site (www.bellspalsy.ws), and from the Bell's Palsy Association (www.bellspalsy.org.uk).

 

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  8. National Institute of Neurological Disorders and Stroke. Bell's Palsy Fact Sheet. April 2003. www.ninds.nih.gov/disorders/bells
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  11. Scottish Bell's Palsy Study. www.dundee.ac.uk/bells/G