Authors: Lewis, Steven L.
Title: Field Guide to the Neurologic Examination, 1st Edition
Copyright ©2004 Lippincott Williams & Wilkins
> Table of Contents > Section 2
– Neurologic Examination > Cranial Nerve Examination > Chapter 20
– Examination of Tongue Movement
– Neurologic Examination > Cranial Nerve Examination > Chapter 20
– Examination of Tongue Movement
Chapter 20
Examination of Tongue Movement
PURPOSE
The main purpose of the examination of motor function of
the tongue is to look for evidence of dysfunction of the hypoglossal
(twelfth) cranial nerve. Another purpose for examination of the tongue
is to look for fasciculations, particularly in the clinical context in
which motor neuron disease (amyotrophic lateral sclerosis) is a
consideration.
the tongue is to look for evidence of dysfunction of the hypoglossal
(twelfth) cranial nerve. Another purpose for examination of the tongue
is to look for fasciculations, particularly in the clinical context in
which motor neuron disease (amyotrophic lateral sclerosis) is a
consideration.
WHEN TO EXAMINE TONGUE MOVEMENT
It is appropriate to assess that the tongue protrudes
grossly in the midline and that it can wiggle from side-to-side in all
patients during a routine neurologic examination. When a patient is
being evaluated for the possibility of motor neuron disease, it is also
appropriate to specifically inspect the tongue for fasciculations.
grossly in the midline and that it can wiggle from side-to-side in all
patients during a routine neurologic examination. When a patient is
being evaluated for the possibility of motor neuron disease, it is also
appropriate to specifically inspect the tongue for fasciculations.
NEUROANATOMY OF TONGUE MOVEMENT
The muscles that move the tongue are supplied by the
twelfth cranial nerves, which arise from the medial part of the
medulla. The left twelfth nerve, which arises from the left medulla,
supplies the muscles on the left side of the tongue and moves the
tongue to the right. The right twelfth nerve, which arises from the
right medulla, supplies the muscles on the right side of the tongue and
moves the tongue to the left.
twelfth cranial nerves, which arise from the medial part of the
medulla. The left twelfth nerve, which arises from the left medulla,
supplies the muscles on the left side of the tongue and moves the
tongue to the right. The right twelfth nerve, which arises from the
right medulla, supplies the muscles on the right side of the tongue and
moves the tongue to the left.
EQUIPMENT NEEDED TO TEST TONGUE MOVEMENT
None (except for a flashlight when needed to look for tongue fasciculations).
HOW TO EXAMINE TONGUE MOVEMENT
-
Ask the patient to stick out his or her tongue.
-
Assess whether the tongue protrudes in
the midline or obviously deviates to one side. Look at the tongue for
obvious asymmetric atrophy of either side. -
Ask the patient to wiggle the tongue to one side and then the other.
-
If it appears that there is weakness or
unilateral atrophy of the tongue, further assessment of tongue strength
can be performed by asking the patient to push the tongue against the
inside of one cheek, and then the other, while you assess the
resistance of the tongue by pushing against the outside of the cheek
with your fingers. -
To inspect the tongue for fasciculations,
ask the patient to relax the tongue on the floor of the mouth, with the
tongue resting anteriorly against the lower teeth. Look at the tongue
with a flashlight and observe for fasciculations.
NORMAL FINDINGS
Normally, the tongue is approximately midline and does
not deviate significantly to either side, moves well to each side, and
there is no atrophy or fasciculations.
not deviate significantly to either side, moves well to each side, and
there is no atrophy or fasciculations.
P.63
ABNORMAL FINDINGS
-
Obvious deviation of the protruded tongue
to one side is consistent with a lesion of a twelfth nerve or its
origin in the medulla. Deviation of the tongue to the left would be
consistent with a left twelfth nerve lesion, because the “good” right
twelfth nerve is unopposed as it pushes the tongue toward the left.
Deviation of the tongue to the right would be consistent with a right
twelfth nerve lesion. -
Significant asymmetry of ability of the
tongue to wiggle to one side or to withstand resistance to the pressure
of your finger against the cheek is further evidence for a unilateral
twelfth nerve lesion. Weakness of tongue movement toward the left cheek
is suggestive of a right twelfth nerve lesion, and weakness of tongue
movement toward the right cheek is suggestive of a left twelfth nerve
lesion. -
Unilateral twelfth nerve lesions may also
be accompanied by atrophy and fasciculations (visible undulating
movements of the muscle fibers) of one side of the tongue due to
denervation of the intrinsic tongue muscles on that side. -
Bilateral fasciculations of the tongue,
usually accompanied by atrophy, may rarely be observed and are
typically seen in the setting of motor neuron disease. Tongue
fasciculations in this setting are likely to be accompanied by symptoms
of slurred speech (dysarthria) and difficulty with swallowing
(dysphagia).
ADDITIONAL POINTS
-
Lesions of a hypoglossal nerve or the
medial medulla are unusual, so it is rare to find significant tongue
deviation. Subtle deviation of the tip of the tongue is usually not of
clinical significance. -
Lesions within the cerebral hemispheres
or upper brainstem don’t usually cause significant tongue deviation;
this test is, therefore, rarely useful for localization of strokes
except in the rare instance when a medullary lesion is suspected. -
Many patients have a subtle tongue tremor that can be mistaken for fasciculations.