Pure dysarthria and dysarthria-facial paresis syndrome due to internal capsule and/or corona radiata infarction

Pure dysarthria (PD) and dysarthria-facial paresis syndrome (DFP) mainly result from lenticulostriate artery territory infarction. PD and DFP are rare clinical entities, often grouped without distinction. The purpose of this study was to examine clinical and radiographic differences between PD and DFP due to unilateral internal capsule and/or corona radiata infarction.

Using a database that included consecutive patients with ischemic stroke admitted to the neurological stroke units of three hospitals within 7 days from onset between September 2011 and April 2014, we retrospectively extracted first-ever stroke patient data, who presented with PD or DFP with a single ischemic lesion localized in the internal capsule and/or corona radiata. Patients with weakness, ataxia, sensory deficit, or cortical symptoms were excluded. Ischemic lesion volume was calculated by the ABC/2 method on diffusion-weighted imaging (DWI). DWI images were normalized and superimposed to the template for PD and DFP. We compared patients' characteristics between PD and DFP.

A total of 2126 patients, including 65 patients (3.1 %) with PD or DFP, were registered. Of these, 13 PD patients and 18 patients with DFP due to unilateral internal capsule and/or corona radiata infarction were included for analysis. Compared with DFP patients, PD patients had longer onset-to-door time (median 37.5 vs. 10.8 h, p = 0.031), shorter vertical length (C component) of ischemic lesions (median 12.0 vs. 18.8 mm, p = 0.007), and smaller ischemic lesion volume (median 285 vs. 828 mm³, p = 0.023). Ischemic lesions causing PD were located more frequently in the left hemisphere than DFP (92 % vs. 56 %, p = 0.045). The superimposed lesion pattern indicated that DFP had lesions more medial and involving posterior portions of the putamen and the caudate body, as well as more of the genu and posterior limb of the internal capsule, than PD. Ninety days after onset, symptoms disappeared in 21 (72 %) out of 29 patients.

In cerebral infarction limited to the internal capsule and/or corona radiata, PD is derived from smaller and left-sided lesions with delay in diagnosis compared with DFP. The clinical course of those with PD and DFP might be benign.