Voxel-Based Lesion Analysis of Ideomotor Apraxia

Abstract

Ideomotor apraxia is a cognitive disorder most often resulting from acquired brain lesions (i.e., strokes or tumors). Neuroimaging and lesion studies have implicated several brain regions in praxis and apraxia, but most studies have described (sub)acute patients. This study aimed to extend previous research by analyzing data from 115 left hemisphere chronic stroke patients using the praxis subtest of the Western Aphasia Battery, which is divided into four action types: facial, upper limb, complex, and instrumental. Lesion-symptom mapping was used to identify brain regions most critically associated with difficulties in each of the four subtests. Complex and instrumental action deficits were associated with left precentral, postcentral, and superior parietal gyri (Brodmann areas 2, 3, 4, 5, and 6), while the facial and upper limb action deficits maps were restricted to left inferior, middle, and medial temporal gyri (Brodmann areas 20, 21, 22, and 48). We discuss ideas about neuroplasticity and cortical reorganization in chronic stroke and how different methodologies can reveal different aspects of lesion and recovery networks in apraxia.

Keywords: chronic stroke; left hemisphere lesions; lesion–symptom mapping; praxis; western aphasia battery.

Figure 1

Overlay map of lesions of the 115 patients included in this study. The color bar shows the minimal overlap of five patients per voxel (in violet) up to the maximal overlap of 61 patients (in green).

Figure 2

Complex subtest. Map showing the regions significantly associated with impaired performance on the complex task (e.g., “pretend to drive a car”, “pretend to knock at the door”). Areas included BA 2, 3, 4, and 6 (precentral gyrus, postcentral gyrus, superior parietal gyrus) and white matter.

Figure 3

Instrumental subtest. Map showing the regions significantly associated with impaired performance on the instrumental task (e.g., “use a comb”, “use a toothbrush”). Areas included left BA 3, 4, 5, 6, and 11 (precentral and postcentral gyri, inferior frontal orbital cortex) and the precuneus.

Figure 4

Facial subtest. Map showing the regions significantly associated with impaired performance on the facial task (e.g., “put out your tongue”, “close your eyes”). Areas included BA 20 and 48 (inferior temporal gyrus).

Figure 5

Upper limb subtest. Map showing the regions significantly associated with impaired performance on the upper limb task (e.g., “make a fist”, “salute”). Areas included BA 20, 21, and 22 (inferior and medial temporal gyri).