Section 6. Brain, Spinal Cord, and Nerve Disorders

Chapter 96. Cranial Nerve Disorders

Topics: Introduction | Internuclear Ophthalmoplegia | Palsies of Cranial Nerves That Control Eye Movement | Trigeminal Neuralgia | Bell's Palsy | Hemifacial Spasm | Glossopharyngeal Neuralgia | Hypoglossal Nerve Disorders

Hypoglossal Nerve Disorders

Disorders of cranial nerve XII (hypoglossal nerve) cause weakness or wasting (atrophy) of the tongue on the affected side.

Disorders of the hypoglossal nerve may result from a tumor at the base of the skull, a stroke, infections of the brain stem, or an injury to the neck, including that due to surgical removal of a blockage from an artery in the neck (endarterectomy (see Section 6, Chapter 86)). Amyotrophic lateral sclerosis (Lou Gehrig's disease) can also damage the hypoglossal nerve.

The tongue becomes weak on the affected side and eventually wastes away (atrophies). As a result, people have difficulty speaking, chewing, and swallowing. Damage due to amyotrophic lateral sclerosis produces a distinctive wormlike movement of the tongue.

Magnetic resonance imaging (MRI) is usually performed to look for a tumor or evidence of a stroke. A spinal tap (lumbar puncture (see Section 6, Chapter 77)) may be necessary if cancer or infection is possible. Treatment depends on the cause.