The Hypoglossal Nerve.
The hypoglossal nerve is the motor nerve of the tongue, and, like the preceding nerves, is affected by degenerative changes, injury, meningitis, tumors, syphilis, and toxemia.
Nuclear lesions, usually bilateral, are frequently associated with locomotor ataxia; cortical lesions with hemiplegia. Spasm or paralysis may attend disease of this nerve.
Spasm.—Spasm of the tongue may result from reflex irritation of the fifth nerve, or it may be a part of a general spasm, such as epilepsy or chorea. It sometimes occurs in hysteria and in some forms of stuttering. A rare and peculiar form of clonic spasm is where the tongue is thrust in and out with great rapidity.
Paralysis.—When a complete bilateral paralysis occurs, the tongue lies motionless on the floor of the mouth, and speech, mastication, and deglutition are difficult, but taste and touch are not impaired.
When the paralysis is unilateral, the tongue deviates to the affected side when protruded, unless the lesion is within the medulla, when it turns toward the sound side.
Prognosis.—It is generally unfavorable.
Treatment.—This is symptomatic, and consists of removing the causes, where possible, and building up the general health. The judicious use of tonics and alteratives and the indicated remedy will form the wisest form of medication. Electricity will deserve a trial.