Bell's Palsy: Diagnosis
Bell’s palsy is diagnosed on the basis of a thorough history and physical examination, as well as further diagnostic testing such as an MRI of the brain, lumbar puncture, and electromyography (EMG) where appropriate.

Additionally, serologic testing may be used to determine the underlying cause for the onset of the disorder. For example, in recent years, Lyme disease has been identified as one of many possible causes of facial paralysis. Blood work may be used to atempt to confirm a diagnosis of Lyme disease.