Lesion locations associated with outcomes for post-stroke aphasia

Abstract

Several studies identified age, gender, handedness, lesion size, stroke subtype, aphasia/stroke initial severity as prognostic factors for recovery from aphasia. However, prediction of recovery still remains difficult to establish initially for patients with initial severe aphasia. The aim of this study was to identify the lesion location associated with poor recovery. One hunderd aphasic patients were included within fourteen days after a first ischemic or haemorrhagic stroke of the left hemisphere and had analysable MRI sequences. The severity of aphasia was determined using the Aphasia Severity Rating Scale in the acute phase and six months post-stroke. The ASRS is a 6-point Likert scale from the lowest score 0 to 5. A severe aphasia initially was defined as an ASRS score < 3. Good recovery at M6 was defined as an ASRS = 4–5. In a first step, axial diffusion-weighted images, or T2*-weighted images for intra-cerebral haemorrhage, were imported. Lesions were drawn manually as regions of interest blinded to clinical data. Images were normalized to a standard brain template. The resulting normalized lesion maps were analysed in a VLSM approach, which applies the graded information at the behavioural level to voxel-wise binary lesion information. The resulting maps were corrected for multiple comparisons. Regarding all patients, a better outcome was significantly associated ( P < 0.01) with lesion excluding the following areas of the left hemisphere: Putamen, transverse temporal gyrus (Heschl gyrus), Insula, Rolandic Operculum. Regarding patients with severe aphasia initially, a poor recovery (i.e. ASRS at M6 < 4) was significantly associated ( P < 0.05) with lesion in the Putamen and transverse temporal gyrus (Heschl gyrus). The present study identified critical areas associated with poor outcomes for aphasia, particularly lesions of the superior temporal gyrus for patients with severe aphasia initially. These findings are in line with previous results in the literature.