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Merck Manual

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Hypoglossal Nerve Disorders


Michael Rubin

, MDCM, New York Presbyterian Hospital-Cornell Medical Center

Last full review/revision Sep 2020| Content last modified Sep 2020
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Disorders of the 12th cranial nerve (hypoglossal nerve) cause weakness or wasting (atrophy) of the tongue on the affected side. This nerve moves the tongue.

  • Hypoglossal nerve disorders may be caused by tumors, strokes, infections, injuries, or amyotrophic lateral sclerosis.

  • People with hypoglossal nerve disorder have difficulty speaking, chewing, and swallowing.

  • Doctors usually do magnetic resonance imaging and/or a spinal tap to identify the cause.

  • The cause is treated.


Causes of hypoglossal nerve disorders include

  • A tumor or bone abnormality at the base of the skull

  • A bulge (aneurysm) in an artery at the base of the brain

  • A stroke

  • Infection of the brain stem

  • An injury to the neck, as may occur after surgical removal of a blockage from an artery in the neck (endarterectomy)

  • Amyotrophic lateral sclerosis (Lou Gehrig disease)


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 causes tiny, subtle twitching movements (fasciculations) on the surface of the tongue.


  • Magnetic resonance imaging

  • Sometimes a spinal tap

Magnetic resonance imaging (MRI) is usually done to look for a tumor or evidence of a stroke.

A spinal tap (lumbar puncture) may be necessary if cancer or infection is possible.


  • Treatment of the cause

Treatment of hypoglossal nerve disorders depends on the cause.

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