Impairment of Speech Production Predicted by Lesion Load of the Left Arcuate Fasciculus

Abstract

Background and Purpose Previous studies have suggested that patients’ potential for post-stroke language recovery is related to lesion size; however, lesion location may also be of importance, particularly when fiber tracts that are critical to the sensorimotor mapping of sounds for articulation (e.g. the arcuate fasciculus [AF]) have been damaged. In this study, we tested the hypothesis that lesion loads of the AF (i.e. volume of AF that is affected by a patient’s lesion) and of two other tracts involved in language processing (the extreme capsule [EmC] and the uncinate fasciculus [UF]) are inversely related to the severity of speech production impairments in stroke patients with aphasia. Methods Thirty chronic stroke patients with residual impairments in speech production underwent high-resolution anatomical MR imaging and a battery of cognitive and language tests. Impairment was assessed using three functional measures of spontaneous speech (e.g. rate, informativeness, and overall efficiency) as well as naming ability. To quantitatively analyze the relationship between impairment scores and lesion-load along the three fiber tracts, we calculated tract–lesion overlap volumes for each patient using probabilistic maps of the tracts derived from diffusion tensor images of ten age-matched healthy subjects. Results Regression analyses showed that AF-lesion load, but not EmC- or UF-lesion load or lesion size, significantly predicted rate, informativeness, and overall efficiency of speech, as well as naming ability. Conclusions A new variable, AF-lesion load, complements established voxel-based lesion-mapping techniques and, in the future, may potentially be used to estimate impairment and recovery potential after stroke and refine inclusion criteria for experimental rehabilitation programs.

Prediction of Aphasia Outcome Using Diffusion Tensor Tractography for Arcuate Fasciculus in Stroke

“…In contrast, in the current study, we performed DTI in the early stage of stroke because DTI parameters could be unstable at acute and subacute stages (onset, 5 days) of stroke, 42,43 and we tried to get outcome data approximately 6 months after stroke onset because the recovery of aphasia occurs mainly during the first 3-6 months after stroke. 22,24,35 Recently, Marchina et al in 2011 8 estimated the volume of 3 language-related neural tracts (the AF, extreme capsule, and uncinate fasciculus, which were affected by a stroke lesion). They found that lesion loads of the AF were predictive of language function in terms of rate, level of information provided, efficacy of speech, and naming ability in 23 patients with chronic aphasia.…”

“…[6][7][8] However, these neuroimaging modalities are limited in that they cannot reconstruct and estimate neural tracts. In contrast, DTT, a 3D visualized version of DTI, allows 3D visualization of the architecture and integrity of neural tracts at the subcortical level.…”

Right hemisphere structures predict poststroke speech fluency

“…Although many patients recover to some degree, this recovery is often incomplete even with intensive speech therapy. [1][2][3][4] While recent studies have succeeded in predicting recovery potential by quantifying the injury to relevant gray and white matter structures in the lesional left hemisphere, 5,6 the right hemisphere's role in recovery of speech-language functions remains both unclear and controversial. [7][8][9][10] Patients with small left hemisphere lesions may recruit perilesional areas with some involvement of right hemisphere homotops, 7,8,[11][12][13] while recovery for those with larger left lesions may occur entirely via the right hemisphere.…”

“…Previous studies have shown that LL is a better predictor of behavioral outcomes after stroke than is lesion volume. 6,34 To determine the extent to which each left hemisphere ROI was affected by a patient's lesion, we calculated a second LL variable between the lesion and left hemisphere ROIs, which we termed lesion/ROI overlap ratio for each patient, according to the following equation:…”

The Arcuate Fasciculus and Language Development in a Cohort of Pediatric Patients with Malformations of Cortical Development

“…4,21 Although the exact roles of this pathway remain the subject of debate, strong evidence suggests an important contribution to language function. 22,23 Furthermore, the absence of the arcuate fasciculus has been reported in several neurodevelopmental disorders that manifest language impairment. 24 Together with recent work demonstrating that absence of the arcuate fasciculus at diffusion tractography is a highly reproducible binary finding, these results make the arcuate a very attractive target as a potential imaging marker of language function.…”