Cranial nerve XII - the Hypoglossal nerve
Signs and Symptoms of Lesions
Supranuclear lesion: with the
individuals tongue at rest - normal size with no fibrillation (twitching); contralateral hemiplegia
(paralysis); on protrusion - deviates contralateral to lesion. Conditions to
consider: Medullary hemorrhage; brain tumors/abscess; arteriosclerosis; multiple
sclerosis; poliomyelitis; amyotrophic lateral sclerosis; bulbar paralysis;
pseudobulbar paralysis; syringobulbia; syphilis. Somatoform disorders must be
differentiated.
Peripheral lesion (dependent upon degree of
degeneration) with the individuals tongue at rest - ipsilateral atrophy and/or lingual paralysis;
with protrusion of the tongue - ipsilateral deviation to the side of the lesion
with possible fibrillation (twitching). Conditions to consider: concussion or
skull fracture; upper cervical misalignments, dislocation (SD); vertebral
basilar accidents; aneurysms or thrombosis at the Circle of Willis;
tuberculosis; syphilitics with CNS involvement; neurotoxins.
Nuclear (Medullary) lesion: in addition to
the symptoms mentioned with peripheral lesion fasciculation precedes lingual
atrophy as well as ipsilateral loss of sensation of touch, temperature and pain;
when bilateral there is total paralysis of the tongue conditions to consider are
the same as with supranuclear lesion.
Cortical Lesion: uncoordinated speech and
language.
Striatum Lesion: periodic non-rhythmic
movements of the tongue.
Psychogenic:
demonstrates speech impediment such as lisping, slurring, stuttering and lingual
tics; with hysterical paralysis there is no degeneration of shape or size of the
tongue but there will be a noticeable resistance to passive movement which is
not exhibited with a true neurogenic involvement.
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Hypoglossal
Nerve Test
Initially the individual
is requested to press their tongue to the inside of each cheek, the practitioner
utilizing one or two fingers can monitor the outside of the cheek for tongue
strength.
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Hypoglossal nerve test 1
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The
individual is then requested to open their mouth and with tongue at rest the
practitioner observes for twitching as well as the size and shape of the tongue.
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Hypoglossal nerve test 2
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Finally
the individual is requested to protrude the tongue, the practitioner observes
for paralysis and/or deviation to one side or the other in addition to tremors.
Utilizing gloves or a gauze strip between the practitioners thumb and index
finger, the practitioner grasp the tip of the tongue and attempts to laterally
deviate from side to side, noticing resistance and again observing for
coordinated effort. With tremors/twitching consider Amyotrophic Lateral
Sclerosis (ALS / Lou Gehrig’s Disease).
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Hypoglossal nerve test 3
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