Facial nerve paralysis overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [2]
Overview
Facial nerve paralysis and Bell's palsy is due to a loss of voluntary movement of the muscles on one side of the face due to abnormal function of the facial nerve(s). A Peripheral palsy affects all ipsilateral muscles of facial expression (paralysis results on the entire ipsilateral side). A supranuclear palsy involves the lower part of the face.
Facial nerve paralysis is a common problem that involves the paralysis of any structures innervated by the facial nerve. The pathway of the facial nerve is long and relatively convoluted, and so there are a number of causes that may result in facial nerve paralysis. The most common is Bell's palsy, an idiopathicdisease that may only be diagnosed by exclusion.
A thorough medical history and physical examination are the first steps in making a diagnosis.
During the physical examination, a distinction must first be made between paralysis and paresis (incomplete paralysis). Not surprisingly, paralysis is far more serious and requires immediate treatment. It must also be determined whether the forehead is involved in the motor defect or not. This is usually accomplished by assessing how well a patient can raise her eyebrows. The question is an important one because it helps determine if the lesion is in the upper motor neuroncomponent of the facial nerve, or in its lower motor neuron component.
Laboratory investigations include an audiogram, nerve conduction studies (ENoG), computed tomography (CT) ormagnetic resonance (MR) imaging.