Disturbances of speech and language in subcortical lesions

Abstract

Interest in the function of subcortical structures in cognitive function has grown in the last decades. Such interest has increased after the advent of modern innovations in radiology techniques, which provide a better visualization of subcortical lesions, like computerized tomography (CT) and magnetic resonance imaging (MRI). Cortical blood flow and metabolism studies also brought a better understanding of diaschisis mechanisms in vivo and improved our knowledge about the pathophysiology of subcortical lesions. The purpose of this study was to identify language and/or speech alterations in patients with exclusively subcortical lesions and to establish a profile of such alterations. The author compared the profiles obtained from thalamic and non-thalamic lesions, trying to define some pathophysiologic mechanisms subjacent to the lesions.To achieve this purpose, the author studied a group of 16 patients (9 patients with basal ganglia and adjacent white matter pathways lesions and 7 patients with thalamic lesions), chosen on the basis of their CT scan findings, selected from the Emergency Room of Hospital das Clínicas of the University of São Paulo School of Medicine (USP) and Hospital Universitário (USP). All patients were submitted to CT scan in the acute stage of illness, 13 patients were submitted to MRI and 12 patients were submitted to single photon emission computerized tomography (SPECT), in order to evaluate cortical blood flow. Patients were also submitted to language evaluation, using the Boston Diagnostic Aphasia Examination, Boston Naming and Token Test. Seventeen normal subjects were evaluated by the same language batteries as a control group.Articulatory and motor disturbances predominated in the non-thalamic group, and language alterations were poor (only one third of the patients showed some language disturbance). There was no characteristic profile in this group.In the thalamic group, however, there was a higher incidence of language disabilities, specially naming disturbances (5 cases) and comprehension disturbances (4 cases). Articulatory disabilities were found in only one patient. There was a high prevalence of cortical flow disturbances in these patients, compromising classical cortical language areas (in the frontal and temporal lobes), making it difficult to exclude cortical dysfunction as a contributing factor to explain the alterations.In the thalamic aphasias, the author also concludes about the possibility of verbal memory and attentional mechanisms disturbances impairing primary language processing; such aspects deserve future studies.

Thalamus and language: interface with attention, memory and executive functions

“…They take into account the effects related to the modalities of stimuli input and answer output and also those task-specific, in order to control linguistic and non-linguistic variables. The Brazilian reference values to BDAE and Token Test were based on previous studies conducted by the authors 24,25 . An additional test of frontal scripts, translated into Portuguese from Allain's et al original publication 26 , was applied in four patients (two with left lesion and two with right lesion) and nine normal individuals, for comparison (normal subjects had an average of 2.6 ordination mistakes and no intrusions).…”