Bell’s Palsy

The term Bell’s palsy and facial paralysis should not be used interchangeably. Bell’s palsy is one of a number of disorders that can cause facial paralysis.

The most common cause of facial paralysis is Bell’s Palsy. This condition is poorly understood, but is thought to arise from a virus called the herpes simplex virus.

The diagnosis is made from the clinical history and physical examination and the exclusion of other diagnoses. The onset of paralysis is sudden and usually preceded by either a cold, a stressful event or exposure to extreme temperatures. Associated symptoms include numbness of the face, a sensation that sounds are too loud, pain around the ear and infrequently, hoarseness of the voice and swallowing difficulties.

One theory is that at some time in one’s life an initial infection from the herpes simplex virus occurred. More commonly this manifests itself as a cold sore. Viral particles from this kind of infection remain dormant within the nerve only to become reactivated with a stressful event. The virus then replicates causing inflammation within the nerve. It is also postulated that release of proteins from the damaged nerve fiber incites an autoimmune response against the nerve fibers. Eventually the immune response wanes and the nerve fibers heal. There is some evidence to support this theory however it is not overwhelming.

Another theory is that the inflamed nerve has little room to expand within the tight narrow bony canal. The area of greatest constriction of the nerve is the meatal segment found where the nerve courses through the inner ear. There is belief that surgical decompression of this segment of the nerve may help hasten recovery.

Left untreated, 84 % of patients with Bell’s palsy will have spontaneous recovery of their facial function to a normal or near-normal state. In this instance the first signs of recovery usually occur within the first three weeks. The remaining 16 % have moderate to poor recovery. These are the patients we hope to help with treatment.

Those patients who show their first signs of recovery within three weeks after onset of the paralysis fall within a favorable group for facial nerve recovery. Those patients who present with a weakness, where there is still some facial motion preserved, as opposed to a complete paralysis, where there is no motion also fall within a favorable group for facial nerve recovery.

Management & Treatment of Bell’s Palsy

When a facial paralysis occurs, there is an inability to completely close the eyelids completely. This may leave the cornea of the eye vulnerable to dryness. If the sclera or the non-pigmented part of the eye becomes reddened or there is a sensation of a foreign body in the eye, the cornea is drying. Left untreated ulcerations my develop and impair vision. To prevent this from occurring, artificial tear drops should be used every hour while awake and ointment should be used at nighttime. On occasion with severe paralysis a gold weight may be surgically implanted in the upper eyelid to allow closure of the eyelids. The gold weight is heavy enough to allow closure and protection of the cornea but light enough so that it may not impede vision when the eye is opened.

The treatment of Bell’s Palsy is filled with debate and controversy. It should be remembered that 84% of patients with Bell’s palsy have normal or near-normal recovery spontaneously without any treatment. It is the 16 % that will have moderate to poor recovery that we are trying to help with treatment. It is widely believed that the use of steroids to reduce inflammation within the nerve and an antiviral agent called acyclovoir or its derivatives may hasten and improve facial nerve recovery.

When there is complete paralysis within three weeks of onset, it is useful to perform an electrical test called an ENoG or electroneuronography. This is a test used to stimulate the nerve just below the ear and record a waveform generated by the facial muscle, called the CAP or compound action potential. The involved side is compared to the opposite side. The amplitude of the waveforms is compared. If the amplitude on the involved side is 90 % of the uninvolved side, surgical decompression of the facial nerve may be helpful in hastening and improving facial nerve recovery.

Surgery more than three weeks after onset of paralysis may not be helpful in improving facial nerve recovery.

Surgical Decompression

Middle fossa facial nerve decompression involves general anesthesia. A lumbar drain is inserted in the back to exacuate some spinal fluid and allow brain relaxation. An incision is made above the ear and the bone over the brain is removed. This bone is placed back at the end of the operation. The floor of the brain is referred to as the base of the skull. The bone over the facial nerve is removed allowing room for the inflamed nerve to expand.

Links to:
Bells Palsy
Ramsey-Hunt Syndrome