Bell's palsy may be defined as an acute, unilateral, idiopathic, facial nerve paralysis. The aetiology is unknown although the role of the herpes simplex virus has been investigated previously.

The peak incidence is 20-40 years and the condition is more common in pregnant women.

PC

• lower motor neuron facial nerve palsy - forehead affected
  • in contrast, an upper motor neuron lesion 'spares' the upper face
• patients may also notice post-auricular pain (may precede paralysis), altered taste, dry eyes, hyperacusis

Management

• there is consensus that all patients should receive oral prednisolone within 72 hours of onset of Bell's palsy
• there is an ongoing debate as to the value of adding in antiviral medications
  • NICE Clinical Knowledge Summaries state: 'Antiviral treatments alone are not recommended. Antiviral treatment in combination with a corticosteroid may be of small benefit, but seek specialist advice if this is being considered.'
  • UpToDate recommends the addition of antivirals for severe facial palsy
• eye care is important - prescription of artificial tears and eye lubricants should be considered

Follow-up

• if the paralysis shows no sign of improvement after 3 weeks, refer urgently to ENT
• a referral to plastic surgery may be appropriate for patients with more long-standing weakness e.g. several months

Prognosis

• most people with Bell's palsy make a full recovery within 3-4 months
• if untreated around 15% of patients have permanent moderate to severe weakness