prognosis

Last reviewed 01/2018

• almost 75% of patients recovering normal mimetical function and just over a tenth having minor sequelae
• about one sixth of patients are left with either moderate to severe weakness, hemifacial spasm, contracture or synkinesis
• patients with a partial palsy fair better
  • 94% making a full recovery
  • in partial palsy, outcome is worse when herpes zoster virus infection is involved
• in patients who recover without treatment
  • in the majority, major improvement occurs within three weeks
  • if recovery does not occur within this time
    • recovery is then unlikely to be seen until four to six months - this is when nerve regrowth and reinnervation have occurred
• it is clear by six months who will have moderate to severe sequelae
  • indicators of poor prognosis in Bell's palsy include:
    • a complete facial palsy
    • no recovery by three weeks
    • if there are associated conditions
      • hypertension, diabetes, pregnancy
    • if the patient is aged over 60 years
    • if there is severe pain associated with the facial palsy
    • Ramsay Hunt syndrome (herpes zoster virus)
    • if electrophysiological testing shows severe degeneration of the facial nerve
• in facial palsies caused by herpes simplex virus or herpes zoster virus there remains a strong correlation between the peak severity of the palsy and the outcome
• there is currently no reliable investigation or test at presentation that can indicate who will make a full recovery
• 80% of patients with Bell's palsy have a conduction block in the facial canal which is probably caused by segmental demyelination
  • in this group, recovery occurs within about 4 weeks

Reference:

• (1)Holland NJ, Weiner GM.Recent developments in Bell's palsy. BMJ 2004;329:553-557