Magnetic resonance study of the influence of tissue damage and cortical reorganization on PASAT performance at the earliest stage of multiple sclerosis

We sought to determine the influence of tissue damage and the potential impact of cortical reorganization on the performance to the Paced Auditory Serial Addition Test (PASAT) in patients at the earliest stage of multiple sclerosis (MS). Magnetization transfer ratio (MTR) imaging and functional magnetic resonance imaging (fMRI) experiments using PASAT as paradigm were carried out in 18 patients with clinically isolated syndrome suggestive of MS (CISSMS) compared to 18 controls. MTR histogram analyses showed structural abnormalities in patients involving the normal-appearing white matter (NAWM) but also the gray matter (GM). Mean PASAT scores were significantly lower in the group of patients taken as a whole, and were correlated with the mean NAWM MTR value. No correlation was observed between PASAT scores and GM MTR. However, in the subgroup of patients with normal PASAT performance (n = 9), fMRI showed larger activations in bilateral Brodmann area 45 (BA45) and right BA44 compared to that in controls (n = 18). In these areas with potentially compensatory reorganization, the whole group of patients (n = 18) showed significantly greater activation than controls (n = 18). Activation in the right BA45 was inversely correlated with the mean NAWM MTR and the peak position of GM MTR histograms of patients. This study indicates that even at the earliest stage of MS, cortical reorganization is present inside the executive system of working memory and could tend to limit the determinant functional impact of NAWM injury on the execution of the PASAT.     

Voxel-based analysis of MTR images: a method to locate gray matter abnormalities in patients at the earliest stage of multiple sclerosis

PURPOSE: To determine whether voxel-based analysis of magnetization transfer ratio (MTR) maps can provide evidence of a coherent pattern of gray matter (GM) macroscopic and microscopic tissue damage in patients at the earliest stage of multiple sclerosis (MS). MATERIALS AND METHODS: We acquired GM MTR maps in 18 patients with clinically isolated syndrome suggestive of MS (CISSMS), and 18 sex- and age-matched healthy controls. We evaluated the clinical status of the patients using the MS functional composite score and the expanded disability status scale. A two-sample t-test (P <0.0001, k=20, uncorrected for height threshold) was used to compare GM MTR maps from patients and controls on a voxel-by-voxel basis. We then extracted data from regions with t-values above the statistical threshold to verify the significance of differences using a nonparametric Mann-Whitney U-test. RESULTS: A between-groups comparison of GM maps revealed large abnormalities in the basal ganglia, including the bilateral thalamus, bilateral lenticular nucleus, bilateral head of caudate, and protuberance, and smaller abnormalities in the right insula, right BA 4, and left BA 40. The MTR measured in the left caudate and right insula was inversely correlated with duration following the first clinical event. CONCLUSION: These results suggest that although MS is a multifocal demyelinating disease that affects white matter (WM), a pattern of tissue damage is present inside the GM involving predominantly basal ganglia at the earliest stage of the disease.     

Compensatory cortical activation observed by fMRI during a cognitive task at the earliest stage of MS

Recent functional magnetic resonance imaging (fMRI) studies have suggested that functional cortical changes seen in patients with early relapsing-remitting multiple sclerosis (MS) can have an adaptive role to limit the clinical impact of tissue injury. To determine whether cortical reorganization occurs during high cognitive processes at the earliest stage of multiple sclerosis (MS), we performed an fMRI experiment using the conventional Paced Auditory Serial Addition Test (PASAT) as paradigm in a population of ten patients with clinically isolated syndrome suggestive of multiple sclerosis (CISSMS). At the time of the fMRI exploration, mean disease duration was 6.8 +/- 3.3 months. We compared these results to those obtained in a group of ten education-, age-, and sex-matched healthy controls. Subjects were explored on a 1.5 T MRI system using single-shot gradient-echo EPI sequence. Performances of the two groups during PASAT recorded inside the MR scanner were not different. Statistical assessment of brain activation was based on the random effect analysis (between-group analysis two-sample t-test P < 0.005 confirmed by individual analyses performed in the surviving regions P < 0.05 Mann Whitney U-test). Compared to controls, patients showed significantly greater activation in the right frontopolar cortex, the bilateral lateral prefrontal cortices, and the right cerebellum. Healthy controls did not show greater activation compared to CISSMS patients. The present study argues in favor of the existence of compensatory cortical activations at the earliest stage of MS mainly located in regions involved in executive processing in patients performing PASAT. It also suggests that fMRI can evidence the active processes of neuroplasticity contributing to mask the clinical cognitive expression of brain pathology at the earliest stage of MS.     

Étude du Transport INTrA-Hospitalier du MAlade de Réanimation (TINTAHMAR)

Introduction

Intra-hospital transport (IHT) of critically ill patients is a frequent care associated with an important risk of adverse events (AEs). To decrease the occurrence of AEs, recent guidelines have been edited. Their consequences on adverse event incidence and nurse workload have not been assessed.

Aim of study

The primary objective was to assess the time necessary for the achievement of IHT. Secondary objectives were to describe practices related to IHT, to compare workload according to the presence of nurses during the IHT, and to assess the occurrence of AEs.

Patients and methods

This French multicentric observational study conducted by the SRLF was conducted in 18 French-speaking intensive care units. All critically ill adults requiring IHT were included.

Results

Three hundred and ninety-six IHTs (mean age 61 ±19, mean IGS II 46±24) were assessed. The mean duration of IHT was 67±35 minutes. There was a training program of IHT in only 11% of centers, a check-list in 22%, and traceability procedures in 17%. There was a nurse during the IHT in 51% of cases. The presence of a nurse had no consequence on IHT durations. Adverse events occurred in 15% of IHT. In multivariable analysis, nurse presence was not associated with IHT associated AEs.

Conclusion

An IHT requires time. Despite the poor adherence to the guidelines, this care was associated with low incidence of AES. The presence of nurses during the IHT had no consequence on IHT duration and AEs occurrence.

     

Future of non conventional MR techniques in MS

Although conventional magnetic resonance imaging (MRI) is used for diagnosing multiple sclerosis (MS) and monitoring disease activity and course, the correlation between conventional MRI data and clinical findings remains weak. This "clinical-MRI paradox" could be partly due to the lack of MRI specificity related to the heterogeneous pathological substrates of MS and to its inability to quantify the extent of damage in the normal-appearing tissue. Recently, non-conventional MRI techniques, including magnetization transfer MRI, diffusion tensor MRI, and proton MR spectroscopy have been applied to improve our understanding of the pathophysiology of MS. These techniques may provide information about structural and biochemical changes occurring within and outside macroscopic MS lesions (inflammation, demyelination, axonal loss), in particular in the normal-appearing white and grey matter. These techniques could also significantly improve our ability to monitor inflammatory demyelination and axonal injury. In the same way, functional MRI gives us the potential substrate to assess the mechanisms of adaptive cortical reorganization, which may limit the irreversible consequences of MS tissue injury.     

Early cognitive impairment in patients with clinically isolated syndrome suggestive of multiple sclerosis

Cognitive impairment in patients with multiple sclerosis (MS) is a common occurrence and is generally fairly circumscribed. The prevalence of the cognitive deficits usually encountered could vary with the clinical course of the disease. To investigate whether the presence of cognitive impairment may occur in the very early stage of MS, we assessed the cognitive status of a group of 40 patients presenting with a recently diagnosed clinically isolated syndrome suggestive of MS (CISSMS), in comparison with 30 age-, sex-, and educational level-matched healthy control subjects. An extensive battery of neuropsychological tests was used to explore verbal and non-verbal memory, attention, concentration, speed of information processing, language and abstract reasoning. Patients with CISSMS had a significant, frequent (57%), and circumscribed cognitive impairment, focused on memory, speed of information processing, attention and executive functions.