Transient Hemiglossal Denervation during
Acute Internal Capsule Infarct in the Setting
of Dysarthria−Clumsy Hand Syndrome
D.S. Titelbaum, N.B. Sodha and M. Moonis
This information is current as
of April 12, 2024.

AJNR Am J Neuroradiol 2010, 31 (7) 1266-1267
doi: https://doi.org/10.3174/ajnr.A1874
http://www.ajnr.org/content/31/7/1266

CASE REPORT
D.S. Titelbaum
N.B. Sodha
M. Moonis

Transient Hemiglossal Denervation during Acute
Internal Capsule Infarct in the Setting of
DysarthriaⴚClumsy Hand Syndrome
SUMMARY: A case of MR imaging⫺documented transient unilateral tongue denervation presenting

during acute internal capsule infarction is described. Understanding the corticolingual pathway innervation of the hypoglossal nucleus is essential for explaining these findings. Awareness of the findings
in this case will facilitate appropriate diagnosis, provide neuroanatomic explanation, and prevent
misdiagnosis.
ABBREVIATIONS: DCHS ⫽ dysarthria⫺clumsy hand syndrome; TMS ⫽ transcranial magnetic

stimulation

W

hile permanent hypoglossal denervation is well known
to occur subsequent to lower motor neuron injury,1 hypoglossal palsy due to supranuclear infarction has rarely been
reported.2-7 We report a case of transient reversible hemiglossal denervation edema on MR imaging, contralateral to acute
internal capsule infarction in the clinical setting of DCHS. A
neuroanatomic basis is discussed.
Case Report
A 73-year-old man with chronic hypertension presented with acute
dysarthria and right arm weakness. Physical examination also revealed right facial droop and right arm incoordination. The tongue
and uvula were midline without fasciculations or atrophy. The clinical diagnosis was DCHS. MR imaging performed at 1.5T revealed a
focal area of restricted diffusion at the posterior limb of the left internal capsule, indicating acute infarction (Fig 1A). Additionally, the
right hemitongue was markedly diffusely swollen and hyperintense
on T2-weighted imaging with right-sided posterior prolapse into
the oropharynx (Fig 1B). Fatty atrophy was not identified on T1weighted images. The brain stem was normal.
Repeat MR imaging with gadolinium performed 2 days later to
assess possible tongue mass revealed persistence of restricted diffusion in the posterior limb of the left internal capsule but with resolved
right hemiglossal swelling and T2 hyperintensity and resolved posterior prolapse (Fig 2). There was no abnormal tongue enhancement or
brain stem abnormality.
After 1 year, the patient had persistent ataxic right hemiparesis
with spasticity. The tongue was midline with spasticity.

Discussion
Hypoglossal nerve dysfunction, often with tongue atrophy, is
well known to occur secondary to lower motor neuron injury
to the nerve or ganglion, with causes including brain stem
Received August 9, 2009; accepted after revision August 14.
From the Department of Radiology (D.S.T.), Shields Health Care, Brockton, Massachusetts;
and Department of Neurology (N.B.S., M.M.), University of Massachusetts Medical Center,
Worcester, Massachusetts.
Please address correspondence to David S. Titelbaum, MD, c/o Lorraine Abbene, Department of Radiology, Shields Health Care, 265 Westgate Dr, Brockton, MA 02301; e-mail:
dtitelbaum@shields.com
Indicates open access to non-subscribers at www.ajnr.org
DOI 10.3174/ajnr.A1874

1266

Titelbaum 兩 AJNR 31 兩 Aug 2010 兩 www.ajnr.org

infarction, nerve invasion or compression by tumor or internal carotid artery dissection, and following injury during carotid endarterectomy or radical neck dissection surgery. MR
imaging of acute hypoglossal denervation has been shown to
produce edemalike hyperintensity on T2-weighted images,
which may rapidly progress to fatty atrophy.1 Intramuscular
T2 hyperintensity is commonly seen in the setting of lower
motor neuron injury, may be detected as early as 24 hours
following injury,8 and is thought to represent muscular edema
from acute denervation due to fluid expansion of the extracellular space.9 Denervation has been shown to depolarize the
resting potential of muscle cell membranes within 2 hours
following injury due to inhibition of sodium-potassium pump
function, thereby allowing increased membrane permeability
of sodium and water.10-12 Muscle fiber is dependent on motor
neuron integrity for maintenance of normal function and
structure, mediated by sustaining action of electric impulse
stimulation.11 As long as atrophy has not occurred, denervation or partial denervation is reversible if neuromuscular connections are re-established, resulting in recovery of membrane
potential.11
Corticolingual tract fibers (also referred to as corticohypoglossal tract or corticonuclear tract) extend from the precentral gyri through the corona radiata, internal capsules, and
cerebral peduncles to the pontomedullary junction where
some fibers decussate.6 Isolated dysarthria due to lacunar or
cortical infarction is rare and is thought to be due to corticolingual tract dysfunction.2,7 DCHS has been reported to occur
in 1.6% of patients with stroke and in 6% of those with lacunar
infarcts.2 Commonly, supranuclear hypoglossal palsy is associated with ipsilesional arm weakness and supranuclear facial
palsy, dysarthria, and dysphagia, presumably due to the close
anatomic relationship of the respective motor pathways.6,7
While the hypoglossal nerve is a lower motor neuron, crossed
and uncrossed upper motor neuron corticolingual fibers extend from both hemispheres to the hypoglossal nuclei.5 Following unilateral infarction, TMS of the affected hemisphere
fails to produce an ipsilateral or contralateral lingual response,
whereas TMS of the unaffected hemisphere produces a bilateral lingual response, even in the setting of unilateral lingual
paralysis.5 Also, unilateral infarction inconsistently results in
lingual paralysis and is presumably dependent on the ability of
the unaffected hemisphere to activate uncrossed corticolin-

Fig 1. A 73-year-old man with acute onset of right arm
weakness and dysarthria. A, Diffusion-weighted image
(b⫽1000) reveals focal hyperintensity at the posterior limb of
the left internal capsule, indicating acute infarction. Hypointensity was present on an apparent diffusion coefficient map
(not shown). B, Axial T2-weighted image obtained at the time
of acute infarction shows diffuse right hemiglossal edema
with swelling and posterior prolapse.

us.4,5 The transient nature of the tongue edema in this case
presumably represented a reversible or compensated event
that could be explained by reperfusion, by partial denervation
with recruitment or re-establishment of latent neural pathways, or by transient voluntary inaccessibility of ipsilateral uncrossed corticolingual projections during the acute phase of
the infarct.5,6

References
1. Russo CP, Smoker RK, Weisman JL. MR appearance of trigeminal and hypoglossal motor denervation. AJNR Am J Neuroradiol 1997;18:1375– 83
2. Arboix A, Bell Y, Garcia-Eroles L, et al. Clinical study of 35 patients with dysarthria-clumsy hand syndrome. J Neurol Neurosurg Psychiatry 2004;75:231–34
3. Durieu I, Leys D. Lingual motility in unilateral hemispheric vascular
complications: study of the cortico-hypoglossal afferences [in French]. Rev
Neurol (Paris) 1994;50:844 – 49
4. Kuypers HG. Corticobular connexions to the pons and lower brain-stem in
man: an anatomical study. Brain 1958;81:364 – 88
5. Muellbacher W, Artner C, Mamoli B. Motor evoked potentials in unilateral
lingual paralysis after monohemispheric ischaemia. J Neurol Neurosurg Psychiatry 1998;65:755– 61
6. Umapathi T, Venketasubramanian N, Leck KJ, et al. Tongue deviation in acute
ischaemic stroke: a study of supranuclear twelfth cranial nerve palsy in 300
patients. Cerebrovasc Dis 2000;10:462– 65
7. Urban PP, Wicht S, Hopf HC, et al. Isolated dysarthria due to extracerebellar
lacunar stroke: a central monoparesis of the tongue. J Neurol Neurosurg Psychiatry 1999;66:495–501
8. Bendszus M, Koltzenburg M, Wessig C, et al. Sequential MRI of denervated
muscle: experimental study. AJNR Am J Neuroradiol 2002;23:1427–31
9. Polak JF, Jolesz FA, Adams DF. Magnetic resonance imaging of skeletal muscle:
prolongation of T1 and T2 subsequent to denervation. Invest Radiol
1988;23:365– 69
10. Albuquerque EX, Schuh FT, Kauffman FC. Early membrane depolarization of
the fast mammalian muscle after denervation. Pflugers Arch 1971;328:36 –50
11. MacIntosh BR, Gardiner PF, McComas AJ. Skeletal Muscle Form and Function.
2nd ed. Champaign, Illinois: Human Kinetics Publishers; 2006
12. Wareham AC. Effect of denervation and ouabain on the response of the resting membrane potential of rat skeletal muscle to potassium. Pflugers Arch
1978;373:225–28

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CASE REPORT

gual projections.5 Corticolingual pathways are also variable
between individuals, most commonly revealing bilateral cortical dependence, less commonly exclusive contralateral dependence, or rarely ipsilateral dependence.3
Tongue movement dysfunction is inconsistently seen in
patients with dysarthria, even with abnormal corticolingual
conduction measured by TMS, and is attributable to bilateral
innervation.7 Even with motor impairment, physical findings
may be masked by apraxia, because tongue deviation may only
be detected at full protraction.3 Of additional note, despite the
close anatomic proximity of the corticolingual and corticofacial motor tracts, corticofacial tracts are primarily contralateral, without bilateral uncrossed fibers, so that corticofacial
infarction most often results in facial paresis.7
Unilateral findings in this case support the existence of predominant contralateral innervation from the motor cortex to
the hypoglossal nucleus. Lack of tongue deviation on physical
examination in this case could be explained by transient or
incomplete denervation of the tongue that was in the process
of recovering, preserved contralesional corticolingual innervation of the hypoglossal nucleus maintaining normal bilateral tongue function, or tongue apraxia preventing full tongue
protraction, thus masking deviation.
Transient supranuclear tongue paralysis subsequent to
unilateral internal capsule lacunar infarct is explainable by bilateral corticolingual innervation of the hypoglossal nucle-

HEAD & NECK

Fig 2. Axial T2-weighted image obtained 2 days later shows resolved right hemiglossal
swelling and edema and resolved posterior prolapse.

Conclusions
Hemiglossal denervation is not always due to lower motor
neuron injury, can occur with supranuclear infarction, and
can be transient and reversible. Awareness of the existence of
individually variable bilateral crossed and uncrossed corticolingual projections facilitates a neuroanatomic explanation for
these findings. In the future, one could postulate a potential
role for diffusion tensor fiber tractography and functional MR
imaging in the assessment of normal and impaired corticolingual pathways and lingual motor response.