Bell’s Palsy

Bells palsy-A rapid onset , isolated , unilateral , lower motor neurone facial weakness of unknown cause ( idiopathic )

Named after Scottish anatomist Sir Charles Bell - described 1st in 1829 Most common acute mononeuropathy ( accounts for 60 % of all cases of sudden onset facial paralysis ) Relatively uncommon- affects 20-40 per 100,000 people per year ( ie in UK about 12,400- 24,800 people / year ) Equal sex distribution No side preference ( ie can happen equally either side ) Treatment is controversial ( about 70 % recover spontaneously untreated ) No seasonal or geographical predisposition Affects more -○ peak incidence 2nd and 4th decade of life○ diabetics○ immunocompromised○ obese○ hypertensives○ URTIs○ pregnant (↑ ed risk 3rd trimester )

cause -Cause is unknown Pathophysiology - vascular distension , inflammation and oedema with ischaemia of the facial nerve Viral aetiology is widely suspected○ reactivation of herpes simplex virus or herpes zoster virus○ destruction of ganglion cells and infection of Schwann cells → demyelination and neuronal inflammation Suspected theories○ infective○ inflammatory○ autoimmune○ ischaemia. Exact pathogenesis is controversial and significance of these factors remains unclear.

Grading scales can be used to judge severity and ascertain prognostic information e.g (House-Brackmann...