Letters to the Editor

I refer to the above matter. I read with interest the article entitled ‘Facial palsy: aetiology, diagnosis and management’ by Dr McKernon and colleagues (Dent Update 2019; 46: 565–572). I believe it will benefit your readers if information regarding bilateral occurrence of facial nerve paralysis is also included. Bilateral facial nerve palsy is defined as a paralysis that affects the opposite side within 30 days of the onset of the first side.¹

There is no doubt that bilateral facial nerve palsy is a rare phenomenon, if compared to unilateral nerve involvement. It is reported to have an incidence of 1 per 5 million population, occurring in 0.3% to 2.0% of facial palsy cases. Like unilateral peripheral facial palsy, it occurs in both paediatric and adult patients and the aetiology can be either congenital or acquired. However, bilateral facial nerve palsy is idiopathic in only 23% of cases, and an underlying systemic pathology or medical condition, which can be congenital, neurological, infectious, neoplastic, traumatic, or metabolic is often demonstrable.^2,3