This study used data retrospectively extracted from a prospective, observational, multicenter registry, which is part of the broad-area, network-based project to drive clinical research at Kyushu University Hospital. The methods of our registry have been previously described in detail [6]. In brief, the database enrolled all consecutive patients with acute ischemic stroke admitted to the neurological stroke units of three hospitals (Saiseikai Fukuoka General Hospital, Fukuoka City Hospital, Iizuka Hospital) within 7 days from onset. Each local ethics committee (Kyushu University Hospital, Saiseikai Fukuoka General Hospital, Fukuoka City Hospital, and Iizuka Hospital) approved the study, and patient clinical data were submitted from the study office in each facility to the data center in Kyushu University Hospital. Between September 2011 and April 2014, patients who fulfilled the following criteria were extracted from the database: (1) presenting PD or DFP upon admission; (2) no previous history of stroke; and (3) an acute single ischemic lesion in the internal capsule and/or corona radiata in the territory of the lenticulostriate artery confirmed on diffusion-weighted imaging (DWI) upon admission.
All patients received neurological assessment upon admission. Dysarthria was reported when clinically apparent upon neurologic examination, which corresponds to the National Institutes of Health Stroke Scale subscore (item 10) of 1 or higher. PD was defined as dysarthria of sudden onset without any other significant symptoms or signs of neuropsychological abnormalities, including aphasia, motor weakness, ataxia, sensory loss, or cranial nerve dysfunction, except for those related to articulation [4], and not accompanied by facial paresis. DFP was defined as PD combined with supranuclear facial paresis. The patient’s clinical background characteristics, including sex, age, cardiovascular risk factors including hypertension, diabetes mellitus, dyslipidemia, and atrial fibrillation, onset-to-door time, and onset-to-imaging time were collected from medical charts. Patients were routinely reassessed at 90 days from onset by an attending neurologist in the outpatient clinic. If the patient could not visit the clinic, follow-up was performed by telephone interview or by a mail-in survey.
All MRI studies, including DWI and time-of-flight MRA, were performed on one of the three 1.5-T echo-planar imaging equipped clinical whole body scanners (Gyroscan NT intera [n = 3], Philips Medical Systems, Best, the Netherlands; Magnetom Avanto [n = 12], Siemens Medical Solutions, Erlangen, Germany; GE Signa [n = 16], GE Medical Systems, Milwaukee, WI, USA). MRI protocols were not entirely uniform in each center, but all included axial DWI using single-shot echo-planar imaging (repetition time 2875–6000 ms; echo time, 70–100 ms; flip angle, 90°; matrix, 256 × 256; b values of 1000 s/mm2; slice thickness, 5 mm; inter-slice gap, 1–1.5 mm). MRA and carotid ultrasound were performed on all patients to assess atherosclerotic lesions of cervicocephalic arteries. DWI data were transferred to the coordinating center and analyzed using image analysis software (ImageJ version 1.48; National Institute of Health, Bethesda, MD, USA) by investigators blinded to clinical information. The infarct volume on DWI was calculated by the ABC/2 method [7, 8]. The slice with the largest lesion was visually selected and the longest lesion axis, x (A), on this slice was measured. A second line, y (B), was drawn perpendicular to the first line at the widest dimension. The z (C) axis was computed by multiplying the number of slices by slice thickness including inter-slice gap. Afterwards, images were normalized to the Montreal Neurological Institute (MNI) space using SPM8 software (Wellcome Department of Cognitive Neurology, London, UK) based on MATLAB version R2013b (The Mathworks, Sherborn, MA, USA) [9, 10]. Lesion plots were created on a voxel-by-voxel basis indicating the infarction frequency in each voxel. Color-coded lesion plots at the level of internal capsule and corona radiata were superimposed on the normalized T1-weighted image template.
Statistical analysis was performed using statistical software (JMP version 9.0; SAS Institute Inc., Cary, NC, USA). Results are expressed as mean ± standard deviation, or median (inter-quartile range). Differences in continuous variables were assessed using the Student t-test or Mann–Whitney U test, as applicable. Differences in categorical variables were assessed using Fisher’s exact tests. Clinical characteristics and radiographic parameters were compared between patients with PD and DFP. All probability values reported are two-sided, and probability values < 0.05 were considered significant.
