Bell's palsy is defined as idiopathic lower motor neuron type of facial nerve paralysis. This is in fact the most common type of facial palsy. This condition was first described by Sir Charles Bell one century ago.
This condition is mostly unilateral, and rarely bilateral. Bell's palsy is a diagnosis of exclusion, which must be made only after excluding all the known causes of facial nerve paralysis.
Etiology and pathophysiology is highly controversial. The patient gives history of going to bed normally, and waking up with facial palsy, or there is a history or bus / train travel with the patient seated close to the window.
1. Exposure to cold air has been postulated as one of the causes
2. Viral infections involving the nerve sheath
There is inflammation of the facial nerve causing it to swell up. Since it is enclosed inside a rigid bony canal it has virtually no space to expand causing the damage to the nerve. The labyrinthine segment of the facial canal is the narrowest portion of the whole facial canal (about 0.6mm).
The patient wakes up with lower motor neuron type of facial paralysis.
1. Inability to close the ipsilateral eye
2. Reduction of tearing in the ipsilateral eye
3. Deviation of the angle of the mouth to the opposite side
4. Drooling of saliva
5. Metallic taste in the tongue
6. Inability to wrinkle the forehead
7. Bell's phenomenon (rolling of eyeball upwards)
This condition is very rare in pregnant women, and if present it tends to be very severe with poor recovery.
Prognosis is excellent. 99% of patients recovering completely.
1. Eye care: The patient should wear glasses to protect cornea. (Black glasses are preferable), use of artificial tears.
2. Regular physiotherapy (Balloon blowing)
3. Cheek / eye massage
4. Steroids: Very useful in early stages of the disease
5. Antiviral drugs like acyclovir has been tried with varying degrees of success
6. Facial nerve decompression can be considered in patients who don't show signs of recovery within 6 months