Biomedical subjects

T Saint Michel

Publications and source records attributed to T Saint Michel.

5 recordsLinked to original sources

PubMed2001

Pupillary disturbances in multiple sclerosis: correlation with MRI findings.

UNLABELLED: Autonomic nervous system disturbances such as pupillary abnormalities have rarely been evaluated in multiple sclerosis (MS). However, pupillary impairment is not uncommon in MS and its origin is still unclear. The aim of this study was to investigate pupillary disturbances in MS and to try to correlate pupillary defects with spinal cord and brainstem magnetic resonance imaging (MRI) findings. We prospectively studied 45 MS patients and 30 normal subjects. METHODS: The pupillary contraction latency and the amplitude of contraction were recorded by pupillometry. We also determined afferent and efferent pathway defects by comparing the direct and consensual pupillary reflexes. We evaluated brainstem and spinal cord demyelinating lesions and spinal cord cross-sectional area on MRI. At least one pupillometric parameters were significantly impaired in 60% of patients and in none of the controls. We did not find any correlation between pupillary defect and demyelinating lesions on MRI. The most frequent abnormality was efferent pathway shift and this was correlated with spinal cord atrophy (P<0.02). These results confirm that the autonomic nervous system, and especially pupillary function, is frequently impaired in MS. The parasympathetic system is most commonly affected and this is most likely linked to axonal loss (demonstrated by spinal cord atrophy) rather than to demyelinating lesions.

Adult↗

PubMed2001

Autonomic dysfunction in multiple sclerosis: cervical spinal cord atrophy correlates.

Autonomic dysfunction has rarely been studied in patients suffering from multiple sclerosis (MS). Some hypotheses have concerned the pathophysiology, especially with regard to a possible spinal cord origin. However, there have been no previous studies on autonomic dysfunction in MS and spinal cord lesions. This study assessed the frequency of autonomic dysfunction (AD) in MS and the correlation to spinal cord magnetic resonance imaging (MRI) findings. We prospectively studied 75 MS patients (25 with relapsing-remitting forms, 25 with secondary progressive forms and 25 with primary progressive forms). We performed sympathetic skin response, R-R interval variability and orthostatic hypotension testing. Spinal cord MRI was performed to detect demyelinating lesions (sagittal and axial plane) or spinal cord atrophy. Clinical and laboratory evidence of AD was found in 84% and 56% of MS patients, respectively. The correlation of the latter with disability was evaluated using the Extended Disability Status Scale. AD was more frequent in primary progressive MS than in the other two forms. AD was correlated with spinal cord cross-sectional area reduction but not with spinal cord hyperintensities. This study confirms that the frequency of AD in MS, especially in primary progressive forms, has until now been underestimated. Furthermore, AD appears to be more closely related to axonal loss, as demonstrated by spinal cord atrophy, than to demyelinating lesions.

Adult↗

PubMed2000

Cardiac repolarization abnormalities in multiple sclerosis: spinal cord MRI correlates.

Ventricular repolarization dysfunction has recently been reported in multiple sclerosis (MS). We evaluated ventricular repolarization dysfunction in 52 MS patients and looked for a relationship between corrected QT (QTc) abnormalities (i.e., abnormalities of QT intervals corrected for rate) and spinal cord magnetic resonance imaging (MRI) findings. QTc intervals were increased in MS patients compared with controls (P < 0.01) and were correlated with a reduction of spinal cord area (P < 0.01). QTc abnormalities in MS were thus associated with axonal loss, reflected by spinal cord atrophy, rather than demyelination.

Adult↗

PubMed2000

[Spinal cord magnetic resonance imaging in multiple sclerosis: importance of determining degree of atrophy as a marker of disease course].

Spinal cord magnetic resonance imaging (MRI) is of particular interest in the management of multiple sclerosis (MS) especially in primary progressive forms. Most of the demyelinating lesions are located in the cervical or dorsal cord. Spinal cord area reduction has been recently correlated with the progression of disability (Losseff et al., 1996, Lycklama a Nijeholt et al., 1998). The aim of this study was to confirm this first result, to assess the reproducibility of this method and to correlate demyelinating lesions with spinal cord area reduction. Fifty two patients were included and compared with 15 controls (normal subjects). T2 Sagittal and axial plane images were performed to localized hypersignal lesions. Spinal cord area was obtained by a volume acquired inversion prepared fast spoiled gradient echo acquisition (MP-Rage) sequence. We compared the mean area value with clinical parameters (age, course of the disease, expanded disability status scale ¿EDSS) and with the number and location of demyelinating lesions. Demyelinating lesions were found in 82p.100 of MS patients and in none of controls. Mean spinal cord area was closely similar to Losseff et al. (1996) results and was reduced compared with controls (p<0.001). Spinal cord reduction was correlated with disability, studied by the EDSS. Furthermore, no correlation was found between demyelinating lesions and spinal cord area reduction. This study confirms the interest of spinal cord area mesurement in MS. Spinal cord atrophy is a reliable marker for axonal loss. This method should be of particular interest for the follow-up of axonal loss in thepeutic trials especially in primary progressive MS.

Adult↗

PubMed1998

Brain-behaviour relationships. Some models and related statistical procedures for the study of brain-damaged patients.

The study of brain-damaged patients provides the opportunity to examine the anatomy of brain functions, and has been renewed by the development of structural neuroimaging. Despite the development of neuroimaging and neuropsychological assessment, major uncertainties persist on the exact delimitation of the brain areas involved in specific processes, and these contribute to the enduring controversies over the effective lesions associated with neuropsychological disorders. These uncertainties are mainly due to the methods used in the study of brain-behaviour relationships, which frequently rely on a group comparison design. The aim of this study was to provide models for the study of brain-behaviour relationships and to assess the reliability of related statistical procedures. In the present work, four theoretical modes of brain-behaviour relationship consistent with neuropsychological data are put forward: unicity, equivalence, association and summation. The first experimental study was based on a simulated population of patients. Lesions associated with the occurrence of a deficit were predetermined according to modes of brain-behaviour relationship and were compared with lesions selected by statistical analysis. The study showed that (i) the group comparison design did not allow determination of the effective lesion, (ii) stepwise regression analysis was sensitive to the relative frequency of lesions, especially when the occurrence of a deficit depended on two lesions, but did not allow determination of the mode of brain-behaviour relationship, and (iii) the classification tree test described the data very satisfactorily and permitted the determination of the mode of brain-behaviour relationships. In order to assess the validity of statistical analyses, a second study was performed in which lesion locations associated with motor weakness in stroke patients were examined. Selected lesions were compared with the anatomy of the human motor system. The study mainly showed that (i) the stepwise regression analysis of selected lesions was not related to the presence of a motor deficit, and (ii) the classification tree test provided perfect agreement with motor weakness predicted by lesion locations and suggested an equivalence mode of brain-behaviour relationship consistent with current neurological knowledge. These studies provide models of brain-behaviour relationships and related statistical procedures that may allow more precise documentation of the anatomy of brain functions and its pathology, and further investigation of the modalities of brain-behaviour relationships.

Behavior↗