Biomedical subjects

Leonello Guidi

Publications and source records attributed to Leonello Guidi.

6 recordsLinked to original sources

PubMed2006

Brain damage as detected by magnetization transfer imaging is less pronounced in benign than in early relapsing multiple sclerosis.

The trend to start disease-modifying therapy early in the course of multiple sclerosis makes it important to establish whether the benign form is a real entity. In previous studies, measures of magnetization transfer (MT) ratio (MTr) have been shown to provide good estimates of the amount of tissue damage occurring in multiple sclerosis brains. Thus, with the hypothesis that if benign multiple sclerosis patients were really benign, sensitive measures of subtle tissue damage would be less pronounced in these patients than in very early relapsing-remitting (RR) multiple sclerosis patients. We carried out conventional MRI and MT imaging in 50 patients with benign multiple sclerosis [defined as having Kurtzke Expanded Disability Status Score (EDSS) <3 and disease duration >15 years] and in 50 early RR patients selected to have similar disability (EDSS <3) and short disease duration (<3 years). Data were compared with those of 32 demographically-matched normal controls. We used a fully automated procedure to measure lesional-MTr, perilesional-MTr, normal-appearing white matter (NAWM) MTr and cortical-MTr. We found that, after correction for common effects of age, lesional-MTr and perilesional-MTr of benign patients were significantly (P < 0.0001) lower than WM of normal controls, but significantly (P < 0.0001) higher than corresponding tissues of RR patients. In NAWM and cortex, MTr values of benign patients were similar to those of normal controls (P > 0.5) and significantly higher than those of the RR patients (P < 0.0001 and P < 0.01, respectively). Similar differences in MTr measures between benign and RR patients were found when patient groups were selected to have no disability (EDSS < or = 2) and, for benign multiple sclerosis, very long disease duration (>20 years) or when both groups were matched for high lesion load (T2-weighted lesion volume >10 cm3). We conclude that lesional and non-lesional MTr values can be significantly less pronounced in benign multiple sclerosis than in a cohort of RR patients at their earliest disease stages, suggesting that brain tissue damage is milder in benign multiple sclerosis than in early RR disease. This can be due to an extraordinary beneficial response to demyelination of benign patients and may represent the evidence that benign multiple sclerosis truly exists and might be differentiated from other forms of this illness.

Adult↗

PubMed2006

Neocortical volume decrease in relapsing-remitting multiple sclerosis with mild cognitive impairment.

The aim of the study was to assess neocortical changes and their relevance to cognitive impairment in early relapsing-remitting multiple sclerosis (RRMS). Conventional magnetic resonance was acquired in 41 RRMS patients and 16 demographically matched normal controls (NC). An automated analysis tool was used to obtain measures of cortical brain volumes normalized for head size. Neuropsychological performance of MS patients was assessed through the Rao's Brief Repeatable Battery. We identified 18 cognitively preserved (MS-cp) and 23 cognitively impaired (MS-ci) MS patients. Values of normalized cortical volumes (NCV) in the whole MS sample were lower than those in the NC group (p=0.01). MS-ci patients showed NCV values lower (p=0.02) than did both MS-cp patients and NC. Moreover, we found a positive correlation between NCV values and measures of verbal memory (r=0.51, p=0.02), verbal fluency (r=0.51, p=0.01) and attention/concentration (r=0.65, p<0.001) in MS-ci patients. Furthermore, NCV values were significantly decreased in patients who scored lower on a greater number of tests (r=-0.58, p<0.01) in the MS-ci group. Only MS-ci patients had cortical atrophy significantly correlated with a poorer neuropsychological performance. Grey matter pathology may contribute to the development of cognitive impairment in MS from the earliest stages of the disease.

Adult↗

PubMed2005

Magnetic resonance spectroscopy as a measure of brain damage in multiple sclerosis.

Recent MR studies have emphasised the importance of neuronal and axonal damage in multiple sclerosis. In this respect, proton MR spectroscopy (by monitoring levels of N-acetylaspartate, a putative marker of axonal integrity) has been particularly illuminating by showing indirect evidence of neurodegeneration in both lesional and non-lesional brain tissues from the earliest stages of the disease. The importance of these changes to patients' clinical disability argues for the primary role of neuronal pathology in the pathogenesis of the disease.

Aspartic Acid↗

PubMed2004

Influence of apolipoprotein E epsilon4 genotype on brain tissue integrity in relapsing-remitting multiple sclerosis.

BACKGROUND: Recent clinical and imaging studies have raised the hypothesis that patients with multiple sclerosis (MS) and the apolipoprotein E (ApoE) epsilon4 allele may have a more severe disease course than those without the ApoE epsilon4 allele. This seems to be related to more extensive tissue destruction and less efficient neuronal maintenance and repair in ApoE epsilon4 carriers. OBJECTIVE: To evaluate the influence of different ApoE genotypes on brain tissue integrity in patients with relapsing-remitting MS (RRMS). DESIGN: We determined the ApoE genotype in 76 RRMS patients. Conventional T1-, T2-, and proton density-weighted magnetic resonance (MR) images were obtained for each patient and in a group of demographically matched healthy control subjects. On conventional T1-weighted MR images, an automated analysis tool was used to obtain total brain volumes normalized for head size (NBVs). Total brain lesion load was estimated on proton density- and T2-weighted MR images. RESULTS: From the whole group of RRMS patients, we identified 18 with and 58 without the epsilon4 allele. Both patient groups were not significantly different in age, age of disease onset, clinical disability, and disease duration. Carriers of the epsilon4 allele showed significantly (P =.01) lower NBVs than controls and non-epsilon4 allele carriers. When a similar analysis was performed on only those patients with both very short disease duration and absence of clinical disability, NBV values were still significantly lower in RRMS patients with the epsilon4 allele than in those without it (P =.02) and in controls (P =.007). In contrast, RRMS patients with different ApoE genotypes did not show significant differences in values of total brain T2-weighted lesion volumes. CONCLUSIONS: The presence of significant NBV decreases only in the group of RRMS patients with the ApoE epsilon4 genotype provides new evidence that links ApoE epsilon4-related impaired mechanisms of cell repair and severe tissue destruction in MS. Results of the present study suggest that this negative influence of the ApoE epsilon4 genotype might be active from the earliest disease stages.

Adult↗

PubMed2002

Diffuse axonal and tissue injury in patients with multiple sclerosis with low cerebral lesion load and no disability.

BACKGROUND: Although in situ pathological studies and in vivo magnetic resonance (MR) investigations have shown that axonal injury can be significant in the early stages of multiple sclerosis (MS), diffuse axonal injury is generally considered a secondary event. Cerebral axonal damage can be specifically assessed in vivo by measuring levels of brain N-acetylaspartate (NAA, a specific index of axonal integrity detected by MR spectroscopy). Other new MR measurements such as magnetization transfer ratio (MTr) or computed estimation of brain volume can provide less specific indexes of tissue damage. OBJECTIVE: To determine whether diffuse axonal and tissue injury is present in patients with definite MS who do not show clinically significant disability. METHODS: We measured brain NAA levels (normalized to creatine [Cr]), MTr values, and cerebral volumes in patients with definite MS who had low T2-weighted MR imaging lesion volumes and no clinical disability, and also in age-matched healthy control subjects. RESULTS: Values of central brain NAA/Cr and MTr in normal-appearing white matter were significantly lower in the MS patients than in controls (P<.001). In contrast, total brain volumes were not significantly different between these groups. Similar results were found for MS patients with early disease (duration, <3 years) and with a particularly low cerebral T2-weighted MR imaging lesion load (< or = 2 cm(3)). CONCLUSIONS: Cerebral NAA/Cr and MTr values are diffusely decreased in MS patients with early disease, low demyelinating lesion load, and no significant disability. This suggests that axonal and/or tissue injury begins very early in the course of MS and might be at least partially independent of cerebral demyelination.

Adolescent↗

PubMed2002

MR correlates of cerebral atrophy in patients with multiple sclerosis.

OBJECTIVE: To investigate the in-vivo correlates of brain atrophy in patients with multiple sclerosis (MS) by assessing the relationship between normalized measures of brain volume (NBV) and other magnetic resonance (MR) measures of tissue damage. BACKGROUND: Brain atrophy diffusely occurs and progressively increases in patients with MS. Nevertheless, the mechanisms leading to brain atrophy in this disease are not fully understood. METHODS: MR examinations were performed in 20 patients with relapsing-remitting MS. Conventional MRI was used to assess NBV and total brain T2-hyperintense and T1-hypointense lesion volumes. Proton MR spectroscopic imaging and diffusion tensor MR imaging were also performed for large portions of brain containing mainly normal-appearing tissue to provide indices of tissue damage, including N-acetylaspartate to creatine ratio (NAA/Cr) and mean diffusivity (D). RESULTS: Values of NBV correlated significantly with those of average brain (r = -0.58, p = 0.007) and NAA/Cr (r = 0.67, p < 0.001). The relationship of these markers of tissue damage to NBV was also found when NAA/Cr and were computed together in a composite MR score (r = 0.70, p < 0.001). In contrast, NBV values did not correlate with measurements of average lesion, T(2) and T(1) weighted total brain MRI lesion volumes. CONCLUSIONS: This study suggests that brain atrophy in MS is not simply due to axonal loss, but rather reflects a more generalized process that involves various brain tissue components. Damage to the normal-appearing tissue rather than the extent and intrinsic pathology of macroscopic lesions seems to be important in the destructive process leading to MS-related irreversible cerebral atrophy.

Adult↗