André Capon

Evidence of cortical reorganization in hemiparetic patients.

We studied the mechanisms underlying the recovery of motor function of the hand using a bidimensional xenon-133 inhalation technique to measure regional cerebral blood flow at rest and during the performance of a motor task (test condition). The regional cerebral blood flow patterns under rest and test conditions were compared in normal control and in stroke patients with either a cortico-subcortical or a deep-seated lesion. Functional recovery appears to depend upon cortical reorganization involving both hemispheres, particularly in both parietal regions in the subgroup of patients with cortico-subcortical lesions.

Quantitative study of the rate of recovery from aphasia due to ischemic stroke.

The extent of recovery from aphasia following ischemic stroke has been evaluated by a quantitative method. The greatest improvement was observed during the first 3 months following onset. The rate of recovery was similar for expression and for comprehension, but comprehension was usually less disturbed than expression. Final prognosis depends on the type of aphasia (the poorest prognosis was found for total or global aphasia) and on the severity of the initial insult.

Seasonal variation of cerebral hemorrhage in 236 consecutive cases in Brussels.

Background and Purpose Seasonal variation in the incidence of cerebral hemorrhage has been previously demonstrated. In this study, we sought to identify the climatological data best correlated with this seasonal variation. Methods In a retrospectively studied sequential series of 236 patients with nontraumatic cerebral hemorrhage observed in Brussels over a period of 8 years, we cumulatively grouped the dates of stroke occurrence into a single calendar year. Results We found marked seasonal variation in incidence, with the highest value (23%) observed in November–December and the lowest (10%) in July–August Seasonal variations in incidence of cerebral hemorrhage were shown to be correlated not only with the inverse of ambient temperature, but also with the inverse of hours of sunshine and with ambient humidity. We found no difference between hypertensive and normotensive patients. Conclusions Our study fails to bear out the hypothesis that the higher incidence of cerebral hemorrhage in late autumn and winter is due to the influence of low ambient temperature on blood pressure.

Lack of evolution of the cerebral blood flow during clinical recovery of a stroke.

Cerebral blood flow and clinical parameters were studied in 30 stroke patients at 15th, 30th, 60th, 90th days after the cerebral insult (Xenon 133 inhalation method). The clinical improvement was not accompanied by a progressive normalization of the CBF at rest. No relationship was found between the clinical data and the CBF values; either on the affected hemisphere or on the contralateral one. It is concluded that measurement of the CBF at rest has no predictive value as regards further clinical evolution.

Atrial fibrillation as a risk factor for deep venous thrombosis and pulmonary emboli in stroke patients.

In 539 consecutive stroke patients admitted to a rehabilitation department, we studied the possible role of atrial fibrillation as a risk factor for deep venous thrombosis and pulmonary embolism by analyzing a series of relevant clinical data in patients with and without atrial fibrillation and in patients with and without venous thromboembolic complications. Deep venous thrombosis as well as advanced age and cardiac disease were significantly (p less than 0.001) more frequent in patients with atrial fibrillation. However, in a model of simultaneous logistic regression carried out on the presence of absence of venous thromboembolic complications, atrial fibrillation was the only significant risk factor. In view of the morbidity and mortality linked to deep venous thrombosis, our findings argue for preventive anticoagulation therapy in stroke patients suffering from atrial fibrillation and merit further study.

Language recovery in aphasic stroke patients: Clinical, CT and CBF studies

Abstract This paper reviews a number of studies with aphasic stroke patients after the acute stage. It is suggested that the main pathophysiological mechanism of recovery is a cortical functional reorganization involving both hemispheres and that the participation of the various cortical areas in the recovery process is not uniformly efficient. In some categories of aphasia there is a partial shift of language towards the right hemisphere. It is noted that information concerning the prognosis can be obtained from the analysis of the initial clinical picture (type and severity of aphasia), from CTScan data (size of the lesion when the infarct is cortico-subcortical) and from rCBF studies during functional tests. In general, the presence of widespread and important activation patterns in the left hemisphere characterizes the patients with a good prognosis and, moreover, in each clinical category of aphasia, the activation of some particular regions proves necessary for a good recovery.

Pathogenesis of aphasia in deep-seated lesions: likely role of cortical diaschisis.

In order to study the pathophysiology of language disorders due to deep-seated left-hemisphere lesions not involving the cortex, a population of 43 right-handed stroke patients (29 aphasic) presenting with such lesions was studied clinically and by regional cerebral blood flow measurements (two-dimensional xenon-133 inhalation method). Most of the patients were studied sequentially between the 1st and 3rd months after stroke. Cortical diaschisis did not account for the whole clinical picture: the remote effect on the cortex could explain the occurrence of aphasia and its severity but not the type of aphasia. Furthermore, the clinical improvement observed in most cases was not accompanied by the disappearance of the diaschisis.

Prognostic value of computed tomography in aphasic stroke patients

In order to evaluate the prognostic value of CT scan in aphasic stroke patients, a prospective study was performed during the first 3 months of the disease. The severity of the language disorders was assessed by means of a quantitative method. In cortico-subcortical lesions, the verbal expression recovery rate and the final verbal expression and comprehension status depended on the infarct size. No relation was observed between the latter and the verbal comprehension recovery rate. In deep-seated lesions, computed tomography provided no information concerning the prognosis.

Remote cortical dysfunction in aphasic stroke patients.

We studied the effect of deep-seated left hemispheric lesions on cortical blood flow in 18 right-handed aphasic stroke patients. Regional cerebral blood flow was measured at rest and during the performance of a functional naming test using the two-dimensional xenon-133 inhalation method. Compared with 10 controls, at rest the patients showed regional cortical hypoperfusion in the left frontoparietal region. In the controls, activation patterns from the rest to the test condition involved mainly the left hemisphere areas. In the patients, a lack of blood flow change was observed in several areas that were usually hypoperfused at rest. However, in patients with slight verbal expression disorders there were obvious blood flow increases in other brain regions in both hemispheres. Such cortical functional reorganization and the presence of a remote cortical dysfunction could play a role in the pathophysiology of language disorders.

Resting CBF sequential study during recovery from aphasia due to ischemic stroke

Cerebral blood flow (133Xenon inhalation method) has been studied in 30 aphasic stroke patients at 15, 30, 60 and 90 days after onset. In total aphasia the CBF values are low and the regional hypoperfused areas are extensive. In Brocas, Wernickes and nominal aphasias, resting CBF measurements do not provide the clinician with useful additional information and clinical improvement can by no means be attributed to a resting CBF rise during the observation period.