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Bell's paralysis
Last reviewed: 23.04.2024
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Bell's paralysis is an idiopathic sudden one-sided peripheral paralysis of the facial nerve (VII pair).
The diagnosis of the paralysis of Bell is a hemifacial paresis of the upper and lower parts of the face. Specific methods of research there. Treatment of Bell's paralysis includes glucocorticoids, lubricants and eye patches.
[What causes Bell's paralysis?
The cause of Bell's paralysis is unknown, the mechanism is associated with edema of the facial nerve due to immune or viral damage (possibly the herpes simplex virus). The nerve passes through a narrow canal in the temporal bone and is very easily squeezed with the development of ischemia and paresis. With peripheral (but not central!) Lesions, paralysis of the circular eye muscle and frontal abdomen of the occipitus-frontal muscle develops, receiving innervation from the left and right nuclei of the VII pair.
Symptoms of Bell's Palsy
Paresis is often preceded by pain behind the ear. Symptoms of Bell's paralysis are paresis or complete paralysis, which develops in a few hours and usually reaches a maximum after 48-72 hours. Patients complain of numbness and / or a feeling of heaviness in their face. The affected side is smoothed out, loses its expressiveness, decreases or disappears ability to wrinkle the forehead, blink and produce other movements of mimic muscles. In severe cases, the eye gap is widened, the eye does not close, the conjunctiva is irritated, the cornea is dry. The sensitivity test shows no abnormalities, except for the external auditory canal and a small area behind the auricle. When the proximal segment is injured, salivation, lacrimation and taste sensitivity of the anterior 2/3 of the tongue are violated, hyperalgesia appears in the area of the external auditory canal.
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Diagnosis of Bell's paralysis
Specific diagnostic tests of Bell's paralysis do not. Bell's paralysis is distinguished from the central lesion of the VII pair of cranial nerves (for example, in stroke or tumor), when the weakness of facial muscles develops only in the lower parts of the face. Among the causes of peripheral lesion of the facial nerve, the herpetic ganglionitis of the geniculus (Ramsey Hunt syndrome with herpes zoster), the infection of the middle ear or mastoid process, sarcoidosis (especially in African Americans), Lyme disease (especially in endemic areas), fractures of the temporal bone pyramid, carcinomatosis or leukemia nerve invasion, chronic meningitis or a tumor of the bridge-cerebellar angle or jugular glomus. These diseases develop more slowly than Bell's paralysis, there are other differences. If the diagnosis is uncertain, MRI is done with contrast; CT scan in Bell's palsy usually does not reveal any changes and is performed if there is a suspicion of a fracture or stroke. In the areas endemic for the Lyme disease, in the acute period or in the recovery period, a serological study is carried out. To exclude sarcoidosis, chest radiography is performed.
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The prognosis and treatment of Bell's paralysis
The outcome determines the degree of nerve damage. If any function is stored, it usually takes a few months to recover completely. With complete paralysis, electromyography and the study of nerve conduction are useful for prognosis. If the normal excitability to the electro-stimulation is detected, then the probability of complete recovery is 90%, and if there is no electrical excitability - 20%.
When recovered, the growth of nerve fibers can go in the wrong direction, so that the facial muscles of the lower part of the face can innervate the periocular fibers and vice versa. As a result, the attempt of arbitrary facial movements leads to unexpected results (synkinesia), and during the salivation there are "crocodile tears". Chronic inactivity of facial muscles can lead to contractures.
For Bell's idiopathic paralysis, there are no treatments whose effectiveness would be proven. Treatment of Bell's paralysis consists in the early administration of glucocorticoids (in the first 48 hours from the debut) somewhat reduces the duration and degree of residual paralysis. Prescribe prednisolone 60-80 mg orally 1 time / day for 1 week, followed by a decrease in dose for 2 weeks. Usually, antiviral drugs effective against herpes simplex virus (eg valaciclovir 1 g 3 times / day for 7-10 days, famciclovir 500 mg orally 3 times / day for 5-10 days, acyclovir 400 mg orally 5 times / day for 10 days).
To prevent dryness of the cornea, frequent instillation of natural tear, isotonic solution or drops with methylcellulose is prescribed, periodic application of a bandage covering the affected eye, especially during sleep. Sometimes it is required tarzorafiya (full or partial suturing the edges of the eyelids).
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