Trauma	Basal skull fractures Birth trauma Facial injuries Otitic barotrauma
Neurologic	Brainstem infarction Multiple sclerosis Myasthenia gravis
Infection	Otitis media Mastoiditis Herpes zoster oticus Mumps Guillain-Barré syndrome Syphillis Leprosy Lyme disease Cat scratch
Metabolic	Diabetes mellitus Pre-eclampsia Acute porphyria
Neoplastic	Lymphoma Tumours of the parotid gland Tumours of the middle ear including cholesteatoma Tumours of the petrosal bone Tumours of the cerebellopontine angle including acoustic neuroma Idiopathic Bell's palsy Melkersson-Rosenthal syndrome
Iatrogenic	Parotid surgery Mastoid surgery
Autoimmune	Temporal arteritis Systemic lupus erythematosus Sarcoidosis Thrombotic thrombocytopenic purpura