Cerebral hemisphere asymmetry in CT and functional recovery from hemiplegia

CT scan cerebral hemispheric asymmetries: predictors of recovery from aphasia

Individual variations in anatomic cerebral asymmetries have been linked with specific neurodevelopmental processes, with patterns of cognitive ability, and with recovery from focal brain damage. The present study investigated relationships between cerebral asymmetries and recovery from aphasia. Aphasic patients (N = 25) were assessed for language recovery for 1 year poststroke, and linear measurements of cerebral asymmetries were performed on CT scans. Increasing left occipital width asymmetry was associated with faster rate of language recovery and with higher final language scores during the first year poststroke. There was, moreover, a tendency for increasing left occipital width asymmetry to be associated with less initial impairment. It is hypothesized that those aspects of neural organization conferring better premorbid language skills are the same factors conferring greater recovery of language skills and that occipital width asymmetry serves as a marker for such individual differences in neural organization.

Motor recovery after acute ischaemic stroke: a metabolic study

The metabolic changes occurring after ischaemic stroke were measured to investigate the functional anatomy of clinical motor recovery. Positron emission tomography (PET) and the steady-state 15O technique was used to compare resting relative metabolic distributions at the onset of functional deficit with those following recovery. Ten patients were studied with repeat scans. Motor recovery was associated in some patients with an increase of relative oxygen metabolism in anatomical structures normally involved in motor function in the affected hemisphere, particularly in the cortical motor areas. In those patients without such metabolic changes in the cortex of the diseased hemisphere, relative increases in cortical metabolism in the contralateral hemisphere were associated with better motor recovery than in patients with no relative cortical metabolic increase in either hemisphere. There was no correlation between the degree of improvement in motor function and the severity of motor deficit at onset, the size and site of the lesion and the metabolic changes in the infarcted zone. No particular pattern of global metabolic changes was observed after recovery. Thus different relative patterns of metabolic recovery were seen in patients with different lesions and evidence was found for the participation of contralateral structures in the recovery process in some patients.

Correlation of motor cortex brain mapping data with magnetic resonance imaging

Brain maps derived intraoperatively from patients undergoing tumor resection were correlated retrospectively with magnetic resonance (MR) images with respect to the precise localization of the motor cortex in an attempt to identify useful preoperative MR imaging landmarks that correspond to functional brain regions. Superior axial T2-weighted MR images consistently localized the central sulcus, whereas parasagittal and farlateral sagittal images readily identified the rolandic (sensorimotor) cortex, as a functional unit, based on the cingulate-marginal sulcus and insula, respectively. It is therefore concluded that multiplanar MR images may serve as a useful preoperative planning aid prior to removing intrinsic brain tumors within or adjacent to the motor cortex.

Skull asymmetries bear no relation to the occurrence of apraxia. A clinical and CT-scan study in patients with unilateral brain damage

This study aimed at assessing whether there was a relation between presence or absence of apraxia following a parietal and/or frontal left hemisphere lesion and "typical" skull asymmetries, evidenced by CT scan (prevalence of the left over the right occipital length and width and of the right over the left frontal length and width). Skull asymmetries were measured in a sample of 160 brain-damaged patients and their prevalence was found to agree with those reported by the literature in normal subjects. A subgroup of 72 patients with lesions restricted to the parietal and/or frontal lobe were given a movement imitation test and diagnosed as apraxic, borderline or normal making reference to the performance of 150 control subjects. The incidence in these three groups of typical or atypical occipital and frontal asymmetries was assessed and found not to differ significantly. It is concluded that no consistent relation between hemisphere dominance for praxis and skull asymmetry can be asserted. The study also investigated the relation of idemotor apraxia to the locus of left hemisphere damage and confirmed that both the incidence and the severity of the disorder are much greater following parietal than frontal lesions.

Volumetric asymmetries of the human brain: intellectual correlates

Volumetric measures of the brain and ventricles were derived from CT films and related to intellectual variables from the Wechsler Adult Intelligence Scale (WAIS). Subjects were patients referred for neurological examination for headache or somatic complaints, sometimes accompanied by anxiety or dysphoric affect (N = 41), for whom a comprehensive neurological work-up revealed no evidence of abnormality. The asymmetry of hemispheric volume (left minus right over total, times 100) was correlated (r = .57, p less than .001) with Verbal IQ minus Performance IQ within subjects. No relationship was observed between total brain or hemispheric volumes and IQ scores. Brain and ventricular volumes were larger for the left hemisphere than the right.

A blind, controlled study of occipital cerebral asymmetry in schizophrenia

In a computed tomography (CT) study, scans from 45 schizophrenic patients on an acute treatment research ward and 62 headache control subjects were blindly compared. A reliable two-dimensional measure of occipital asymmetry did not detect any differences between the two groups. Within the patient sample, however, both a correlational and group analysis indicated that absence of normal left occipital asymmetry was associated with greater psychopathology on measures of quality of interview, incomprehensibility, and auditory hallucinations. Other clinical variables including age, years of illness, previous hospitalizations, childhood adjustment, and therapeutic response to neuroleptics were not found to be related to occipital asymmetry. A relationship between absence of normal asymmetry and abnormalities of language and communication is hypothesized. Furthermore, since the original studies that noted an increased frequency of reversed asymmetry in schizophrenic patients studied populations with a very high frequency of other CT abnormalities (e.g., enlarged lateral ventricles) and this study did not, the importance of defining the relevant characteristics of schizophrenic patients with reversed occipital asymmetry is emphasized.

CT scan cerebral hemispheric asymmetry measurements in stroke cases with global aphasia: atypical asymmetries associated with improved recovery

This study was undertaken in order to examine the relationship between CT scan hemispheric asymmetries and recovery in aphasia. The study had two parts. In Part I, hemispheric asymmetries were measured on the CT scans of 60 right-handed male non-aphasic (non-neurological) controls and 89 right-handed male aphasics, using a modification of LeMay's (1977) techniques. Both the non-aphasic control and aphasic data were in agreement with that of LeMay for frontal width, occipital width and occipital length. In Part II, the degree of CT scan hemispheric asymmetry was quantified for 14 right-handed male global aphasics, in whom differences in degree of language recovery were observed in the months following stroke. Atypical occipital asymmetries were significantly associated with certain aspects of language recovery (naming, single-word comprehension and single-word repetition). The authors postulate that increased capacity for right hemisphere contribution to language function might in part explain recovery in the cases exhibiting atypical occipital CT asymmetries.