Transient aphasias after left hemisphere resective surgery

Abstract

Object Transient aphasias are often observed in the first few days in patients who undergo surgical resection in the language-dominant hemisphere. The aims of this prospective study were to characterize the incidence and nature of these aphasias, and to determine whether there are relationships between location of the surgical site and deficits in specific language domains. Methods 110 patients undergoing resection to the language-dominant hemisphere participated in the study. Patients’ language was evaluated prior to surgery, 2-3 days post-surgery, and 1 month post-surgery using the Western Aphasia Battery and the Boston Naming Test. Voxel-based lesion-symptom mapping was used to identify relationships between the location of the surgical site assessed by MRI, and deficits in fluency, information content, comprehension, repetition, and naming. Results 71% of patients were classified as aphasic based on the Western Aphasia Battery 2-3 days post-surgery, with deficits observed in each of the language domains examined. Fluency deficits were associated with resection of the precentral gyrus and adjacent inferior frontal cortex. Reduced information content of spoken output was associated with resection of the ventral precentral gyrus and posterior inferior frontal gyrus (pars opercularis). Repetition deficits were associated with resection of the posterior superior temporal gyrus. Naming deficits were associated with resection of ventral temporal cortex, with mid temporal and posterior temporal damage more predictive of naming deficits than anterior temporal damage. By 1 month post-surgery, nearly all language deficits were resolved, and no language measure except for naming differed significantly from pre-surgical levels. Conclusions These findings show that transient aphasias are very common after left hemisphere resective surgery, and that the precise nature of the aphasia depends on the specific location of the surgical site. This patient cohort provides a unique window on the neural basis of language, since surgical resections are discrete, their locations are not limited by vascular distribution or patterns of neurodegeneration, and language can be studied prior to substantial reorganization.

Voxel-based lesion symptom mapping analysis of depressive mood in patients with isolated cerebellar stroke: A pilot study

“…A t-statistic for each voxel was calculated to compare the severity of depression in patients with and without a lesion in that voxel. Cluster size and the permutation method were used to correct multiple comparisons (Wilson et al, 2015). Only voxels that were lesioned in at least 10% of all patients were included in the analysis.…”

Lesion-symptom mapping in the study of spoken language understanding

“…A alternative is to draw each patient's lesion on their own MRI or CT image, and then warp each brain (and associated lesion mask) to standard space (e.g. Wilson et al, 2015). This method is somewhat easier to implement, because the correspondence between the patient's brain and standard space is handled by the warping algorithm (e.g.…”

“…For instance, Leff et al (2009) used VBM in a study of stroke patients, assuming that lesions would be segmented as containing negligible GM, and that furthermore, there might be volume loss remote from the site of infarction that this approach would be sensitive to (see Geva et al (2012) for an empirical comparison of VLSM and VBM in stroke patients, and a discussion of the advantages and disadvantages of each approach). In another study, Wilson et al (2015) performed manual delineation of lesions, yet smoothed the resulting lesion masks in order to account for inter-individual variability. Because the lesion masks were smoothed, estimates of structural integrity were continuous rather than binary.…”

“…Bates et al, 2003). Another possibility is to perform post-hoc multiple regression analyses that model the function in terms of the potentially interacting contributions from multiple distinct brain regions (Rankin et al, 2009; Wilson et al, 2015). As mentioned above, some authors do not use voxel-based analyses at all, but rather skip straight to multivariate analyses involving multiple regions of interest (Caplan et al, 1996, 2007).…”

Individualized Map of White Matter Pathways

“…41 Future directions potentially include the use of automated tract identification to evaluate the disease trajectory, 40,42–44 modulate radiation therapy 42 or evaluate the response to therapy in patients with gliomas. 45,46 Finally, the integrity of white matter tracts is increasingly being applied in the clinical neurosciences as a biomarker of injury in a range of diseases from traumatic brain injury 47 to early Alzheimer's disease.…”