Investigations (general)

As Bells palsy is an idiopathic condition, there is no diagnostic test currently available that will confirm the diagnosis. Although the aetiology is felt to be related to herpes virus infection, serum tests for rising antibody titres to herpes simplex are not reliable [11].

Serological testing will be required if other causes of peripheral facial weakness, such as Lyme disease or HIV, are suspected.

The only other investigations required are those to exclude a secondary cause for facial weakness. All patients must have their capillary blood glucose measured and routine observations performed.

In the presence of either a central facial weakness or a peripheral weakness with other features (e.g. history of trauma, systemic upset or co-existing neurological deficit), radiological imaging will be required.