Journal of Clinical Neuroscience 17 (2010) 812–813

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Journal of Clinical Neuroscience
journal homepage: www.elsevier.com/locate/jocn

Short Communication

Pure dysarthria due to an insular infarction
Akiyuki Hiraga *, Saiko Tanaka, Ikuo Kamitsukasa
Department of Neurology, Chiba Rosai Hospital, 2-16 Tatsumidai-Higashi, Ichihara-shi, Chiba 290-0003, Japan

a r t i c l e

i n f o

Article history:
Received 16 May 2009
Accepted 11 October 2009

Keywords:
Insula
Pure dysarthria

a b s t r a c t
Cortical infarction presenting with pure dysarthria is rarely reported. Previous studies have reported pure
dysarthria due to cortical stroke at the precentral gyrus or middle frontal gyrus. We report a 72-year-old
man who developed pure dysarthria caused by an acute cortical infarction in the insular cortex. The role
of the insula in language has been difficult to assess clinically because of the rarity of pure insular strokes.
Our patient showed pure dysarthria without aphasia, indicating that pure dysarthria can be the sole manifestation of insular infarctions.
Ó 2010 Elsevier Ltd. All rights reserved.

1. Introduction
Most instances of pure dysarthria caused by cerebral infarction
are reported to occur due to corona radiata or internal capsule lesions.1 Cortical infarction presenting with pure dysarthria or dysarthria with few other neurologic signs is rarely reported.2
2. Case report
A 72-year-old right-handed man with a history of atrial fibrillation suffered dysarthria upon awakening in the morning and was
admitted to our hospital. On admission, his blood pressure was
166/114 mmHg. He was alert and cooperative. He had paretic dysarthria but no aphasia. His comprehension and repetition were
normal with an effortless speech and no trial-and-error patterns
were observed. He did not have articulatory inconsistency, groping
articulatory movements with attempts at self-correction, anomia
and paraphasia or facial paresis. There was no deviation of the tongue on protrusion; however, his tongue movements were slow. The
muscle strength of the four extremities and tendon reflexes were
all normal. In addition, the sensory examination was normal.
Although no abnormalities were detected on brain CT scan, the
brain MRI showed a hyperintense lesion in the left insular cortex
on diffusion-weighted imaging (DWI) (Fig. 1). The patient was
diagnosed with cerebral infarction and underwent therapy with
intravenous edaravone and anticoagulants. He was discharged
with mild dysarthria 14 days after onset.
3. Discussion
Our patient presented with pure dysarthria, and DWI showed
an insular infarction. Kim et al. have previously reported five
* Corresponding author. Tel.: +81 436 74 1111; fax: +81 436 74 1151.
E-mail address: hiragaa@yahoo.co.jp (A. Hiraga).
0967-5868/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.jocn.2009.10.026

patients with pure dysarthria or dysarthria with minimal other
symptoms caused by a small cortical stroke.2 Two strokes were located lateral to the precentral knob at the most lateral part of the
image, and three were located in the most lateral cortical area at
the level of the lateral ventricle.2 In a recent DWI study of 101 patients with dysarthria due to cerebral infarctions, Kumral et al.
indicated that the lesions responsible for dysarthria were located
in the supratentorial area in 62%, and in the middle cerebral artery
territory, including the motor cortex and/or insular cortex, in 13%
of the patients.3 In that study, there were five instances of motor
cortex infarctions which caused pure dysarthria; however, pure
dysarthria was not seen in insular lesions. Gatto et al. reported that
the responsible site of pure dysarthria due to cortical stroke is the
middle frontal gyrus.4
The role of the insula in language has been difficult to assess
clinically because of the rarity of pure insular strokes.5 Insular
infarction is rarely seen without the involvement of other adjacent structures supplied by the middle cerebral artery.5 A previous study of four patients with stroke restricted to the insular
cortex found that two of the four patients with left posterior insular lesions showed aphasia and dysarthria, and the remaining two
with right posterior insular lesions showed no speech disturbance.6 The insula may have a major role in speech articulation,
as suggested by a study in which the insula was the injured area
of 25 patients presenting apraxia of speech (40% of whom had
dysarthria).7 In our patient, the injured area, almost restricted
to the insular cortex, resulted in pure dysarthria without aphasia,
indicating that pure dysarthria can be the sole manifestation of
insular infarctions.
In studies not using DWI, small cortical infarctions are easily
overlooked or misidentified, so pure dysarthria due to cortical
stroke has been reported only in recent years. The identification
of small cortical infarcts, as well as acute infarction by DWI improves the accuracy of these studies. As shown by this patient, it
is necessary to consider the possibility of small cortical infarcts

A. Hiraga et al. / Journal of Clinical Neuroscience 17 (2010) 812–813

813

Fig. 1. Diffusion-weighted axial MRI performed 4 days after onset of dysarthria showing a high signal intensity lesion in the left insular cortex.

other than the precentral gyrus (motor vocal cortex), in patients
with pure dysarthria.

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