This is an idiopathic acute non-suppurative inflammation of the facial nerve within the stylomastoid foramen. It sometimes occurs after exposure to cold. The nerve sheath of the bony canal is inflamed and swollen and compresses the nerve in the stylomastoid foramen.
Direct compression and secondary ischemia are possible causes of paralysis. Physicians now consider Bell’s palsy to be due to viral polyneuropathy with inflammatory demyelination extending from the brain stem to the periphery. Other nerves involved are V, IX, X, and C2.
SYMPTOMS
Pain in the root of the ear, sometimes pain around the ear precedes paralysis. In some cases, inability to wrinkle forehead, close the eye, move lips on the affected side are seen.
Inability to blow or whistle, numbness and stiffness of the cheek on the affected side, dribbling of saliva and fluid through the angle of the mouth on the affected side, and watering from the eye are some other common symptoms of Bell’s palsy.
SIGNS:
Facial asymmetry is present. Voluntary and emotional movements are all lost on the paralyzed side. On asking the patient successively to wrinkle the forehead, close the eyes and to show the teeth, it will be observed that there is no closure of the eye and no opening of the oral aperture.
Frowning is not possible on the affected side. On the affected side, the angle of the mouth is drooped, nasolabial furrow is flat and blowing of the cheek is not possible. Cheek may be puffed out during respiration on the paralyzed side. The eyeball rolls upwards and outwards which is called Bell’s phenomenon. In some cases, there may be even loss of taste sensation on the anterior 2/3 of the tongue on the affected side.