BELL’S PALSY is an idiopathic acute non-suppurative inflammation of the facial nerve within the stylomastoid foramen. It sometimes occurs after exposure to cold or chill. The nerve sheath or periosteum of the bony canal is inflamed and swollen and compresses the nerve in the stylomastoid foramen. Direct compression and secondary ischaemia are possible causes of paralysis. Many physicians now regard 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
Onset is acute or subacute.
1. Pain in the root of the ear. Sometimes pain around the ear precede the paralysis.
2. Inability to wrinkle the forehead, close the eye and move the lips on the affected side.
3. Inability to blow or whistle
4. Numbness and stiffness of the check on the affected side.
5. During chewing, food may accumulate between the cheek and the teeth on the affected side.
6. Dribbling of saliva and fluid through the angle of the mouth on the affected side.
7. Watering from the eye due to eversion of the punctum, or due to exposure keratitis.
Facial asymmetry is present. Voluntary and emotional movements are atl tost on the paralysed side. On asking the patient successively to wrinkle the forehead, close the eyes and to show the teeth it will be observed that on the affected side there is no wrinkling of the forehead, there is no closure of the eye and no opening of the oral aperture. Frowning is not possible on the affected side. In addition, on the affected side the angle of the mouth is dropped, nasolabial furrow is flat and blowing of the cheek is not possible.) Cheek may be Puffed out during respiration on the paralysed side. On the healthy side however, the nasolabial furrow is prominent, angle of the mouth is deviated upwards.)On asking the patient to close the eyes, the eyeball rolls upwards and outwards which is called Bell’s phenomenon. Due to weakness of orbicularis oculi the ocular fissure is wider on the affected side (Negro’s sign). In some cases there may be loss of taste sensation on the anterior two-thirds of the tongue on the affected side due to involvement of chorda tympani nerve, if the inflammatory lesion extends upwards. There may be pseudodeviation of the tongue on the paralysed side. A very rare syndrome consisting of a triad of recurrent facial palsy, facial oedema with plication of the tongue may be seen, called Melkersson’s syndrome.
During recovery from facial palsy when motor weakness is still existent and attempts to move one group of facial muscles may result in movement of various other groups. Anomalous reinnervation of the fibres may result in curious phenomena such as closure of eyes may result in retraction of mouth or even appearance of tears called crocodile tears. Even during eating, tears may come out called Bogorad’s syndrome. It is believed that degeneration of greater superficial Petrosal nerve which serves the lacrimal gland excites sprouting from the lesser superficial petrosal nerve which connects parotid gland at the meeting point. From here they connect the lacrimal gland where they cause flow of tears and not saliva. The effect of this abnormal connection may be obviated by cutting the tympanic branch of IXth nerve. When a diagnosis of Bell’s Palsy is made one should see that there is no diabetes, severe pain in the ear or discharge in the ear or bilateral facial palsy either at onset or with progression of disease. There should not be any added neurological signs other than those seen in Bell’s Palsy.
Usually prognosis is good. Recovery starts within 3-4 weeks and is complete in three to six months time in vast majority of cases (70%-80%). Diminished amplitude of action potential of the facial muscles in EMG is usually indicative of slow recovery.
or other analgesic drugs (NSAID) may be given for pain.
2. Vitamin Bi and B12 preparations may be given parenterally.
3. Steroids may reduce the inflammation and oedema.
4. Application of facial splint or adhesive straps to prevent overstretching of the angle of the mouth may be done.
5. Facial exercises in front of a mirror may be beneficial.
6. Electrical stimulation may be of help.
7. Decompression or nerve grafting operation may rarely be undertaken.
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