[Bell's palsy--a field of controversies. I. Etiology and pathogenesis--diagnostic delimitation--prognosis].

Facial paresis as a sign or symptom is caused by a number of different conditions. Although being the most common type of facial paresis, Bell's palsy represents a diagnosis of exclusion characterized by an acute, unilateral peripheral facial palsy of unknown etiology. Clinical features and laboratory findings are considered with regard to their diagnostic as well as prognostic significance.