Cerebral blood flow in pure dysarthria: role of frontal cortical hypoperfusion.
OBJECTIVE
Isolated dysarthria, termed pure dysarthria, develops rarely after stroke, and its pathophysiology remains unclear. To clarify the underlying mechanism of pure dysarthria, we investigated lesion sites and cerebral blood flow in patients with pure dysarthria.


METHODS
We examined 12 patients with pure dysarthria who underwent MRI and cerebral blood flow study. To visualize cortical blood flow, a three-dimensional display was generated from single-photon emission computed tomography (SPECT). Regional cerebral blood flow of the patients was semiquantitatively measured with SPECT and N-isopropyl-p[123I]iodoamphetamine as a tracer and compared with that of 11 control subjects.


RESULTS
On MRI, multiple lacunar infarctions were noted bilaterally in 11 patients, all of whom had lesions involving the internal capsule or corona radiata. The other patient had a unilateral internal capsule-corona radiata infarction. Three-dimensional display showed frontal cortical hypoperfusion in 8 patients. Since interhemispheric differences of blood flow were not significant in any region of the 12 patients, the mean of left and right cortical blood flow was analyzed. Compared with the control subjects, cortical perfusion was significantly reduced in the patients' frontal regions, sparing the sensorimotor, temporal, and parietal cortices and the cerebellum. Reductions of perfusion were rather pronounced in the anterior opercular, medial prefrontal and premotor, and anterior cingulate regions.


CONCLUSIONS
Pure dysarthria results mainly from multiple lacunar infarctions, which induce frontal cortical hypoperfusion, probably due to interruption of corticosubcortical networks. We conclude that frontal cortical hypoperfusion, particularly in the anterior opercular and medial frontal regions, plays an important role in the development of pure dysarthria.
Okuda
B
B
Division of Neurology, Fifth Department of Internal Medicine, Hyogo College of Medicine, Nishinomiya, Japan.
Kawabata
K
K
Tachibana
H
H
Sugita
M
M
D000368:Aged; D000369:Aged, 80 and over; D002540:Cerebral Cortex / Q000098:blood supply / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000502:physiology*; D004401:Dysarthria / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005260:Female; D005625:Frontal Lobe / Q000098:blood supply / Q000503:physiopathology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D015899:Tomography, Emission-Computed, Single-Photon