The likelihood that the facial palsy is caused by Lyme disease should be estimated, based on recent history of outdoor activities in likely tick habitats during warmer months, recent history of rash or symptoms such as headache and fever, and whether the palsy affects both sides of the face (much more common in Lyme than in Bells palsy). If that likelihood is more than negligible, a serological test for Lyme disease should be performed. If the test is positive, the diagnosis is Lyme disease. If no cause is found, the diagnosis is Bells Palsy. Classification
Facial nerve paralysis may be divided into supranuclear and infranuclear lesions. In a clinical setting, other commonly used classifications include: intra-cranial and extra-cranial; acute, subacute and chronic duration. Supranuclear and nuclear lesions
Central facial palsy can be caused by a lacunar infarct affecting fibers in the internal capsule going to the nucleus. The facial nucleus itself can be affected by infarcts of the pontine arteries. These are corticobulbar fibers travelling in internal capsule. Infranuclear lesions
Infranuclear lesions refer to the majority of causes of facial palsy. Treatment
If an underlying cause has been found for the facial palsy, it should be treated. If it is estimated that the likelihood that the facial palsy is caused by Lyme disease exceeds 10%, empiric therapy with antibiotics should be initiated, without corticosteroids, and reevaluated upon completion of laboratory tests for Lyme disease. All other patients should be treated with corticosteroids and, if the palsy is severe, antivirals.
In the best case scenario, paralysis can be corrected with techniques including hypoglossal-facial nerve anastomosis, end-to-end nerve repair, cross facial nerve grafting, or muscle transfer/transposition techniques, such as the gracilis free muscle transfer. Patients with facial nerve paralysis resulting from tumours usually present with a progressive, twitching paralysis, other neurological signs, or a recurrent Bells palsy-type presentation. The latter should always be suspicious, as Bells palsy should not recur. A chronically discharging ear must be treated as a cholesteatoma until proven otherwise; hence, there must be immediate surgical exploration. Computed tomography (CT) or magnetic resonance (MR) imaging should be used to identify the location of the tumour, and it should be managed accordingly. Other neoplastic causes include leptomeningeal carcinomatosis. Stroke
Central facial palsy can be caused by a lacunar infarct affecting fibers in the internal capsule going to the nucleus. The facial nucleus itself can be affected by infarcts of the pontine arteries. Unlike peripheral facial palsy, central facial palsy does not affect the forehead, because the forehead is served by nerves coming from both motor cortexes. Other
Other causes may include:

Diabetes mellitus
Facial nerve paralysis, sometimes bilateral, is a common manifestation of sarcoidosis of the nervous system, neurosarcoidosis. Bilateral facial nerve paralysis may occur in Guillain–Barré syndrome, an autoimmune condition of the peripheral nervous system. Moebius syndrome is a bilateral facial paralysis resulting from the underdevelopment of the VII cranial nerve (facial nerve), which is present at birth.