Cognitive assessment in patients with myotonic dystrophy type 2.

Myotonic dystrophy type 2 (DM2) is an autosomal dominant multisystemic disorder. Previous studies conducted on small cohorts of DM2 patients indicated presence of a cognitive dysfunction. We aimed to assess cognitive functions in a larger cohort of Serbian DM2 patients using an extensive battery of neuropsychological tests. The study included 76 patients with a genetically confirmed DM2, 68 of whom had all tests for different cognitive domains performed. Patients underwent clinical and neuropsychological testing, including cognitive screening and assessment of general intellectual level, attention, executive and visuospatial abilities, memory, and language functions. Only 6% of patients achieved a below-average score on the general intellectual level test. Cognitive screening tests indicated presence of cognitive deficits in 5.5% of patients according to the Mini Mental State Examination test and 25.8% according to the Addenbrooke's Cognitive Examination Revised test. Twenty-four (35.3%) patients had a cognitive impairment (being two standard deviations out of norm in at least two cognitive domains). Around one quarter of DM2 patients had a significant cognitive impairment that interfered with their everyday functioning. Patients with significant cognitive impairment were older at testing and at disease onset, less educated, and had more severe muscle weakness.

Unraveling ALS due to SOD1 mutation through the combination of brain and cervical cord MRI.

OBJECTIVE: To explore structural and functional changes of the brain and cervical cord in patients with amyotrophic lateral sclerosis (ALS) due to mutation in the superoxide dismutase (SOD1) gene compared with sporadic ALS. METHODS: Twenty patients with SOD1 ALS, 11 with sporadic ALS, and 33 healthy controls underwent clinical evaluation and brain MRI. Cortical thickness analysis, diffusion tensor MRI of the corticospinal tracts (CST) and corpus callosum, and resting-state functional connectivity were performed. Patients with ALS also underwent cervical cord MRI to evaluate cord cross-sectional area and magnetization transfer ratio (MTR). RESULTS: Patients with SOD1 ALS showed longer disease duration and slower rate of functional decline relative to those with sporadic ALS. No cortical thickness abnormalities were found in patients with ALS compared with controls. Fractional anisotropy showed that sporadic ALS patients had significant CST damage relative to both healthy controls (p = 0.001-0.02) and SOD1-related ALS (p = 0.05), although the latter showed alterations that were intermediate between controls and sporadic ALS. Functional hyperconnectivity of the motor cortex in the sensorimotor network was observed in patients with sporadic ALS relative to controls. Conversely, patients with SOD1 ALS showed lower cord cross-sectional area along the whole cervical cord relative to those with sporadic ALS (p < 0.001). No cord MTR differences were found between patient groups. CONCLUSIONS: Patients with SOD1 ALS showed cervical cord atrophy relative to those with sporadic ALS and a relative preservation of brain motor structural and functional networks. Neurodegeneration in SOD1 ALS is likely to occur primarily in the spinal cord. An objective and accurate estimate of spinal cord damage has potential in the future assessment of preventive SOD1 ALS therapies.

Brain positron emission tomography in patients with myotonic dystrophy type 1 and type 2.

AIM: To determine regions of reduced brain metabolism in patients with myotonic dystrophy type 1 (DM1) and type 2 (DM2) using 18F-fluoro-2-deoxy-d-glucose positron emission tomography (FDG-PET), and to analyse their potential association with cognitive deficit. METHOD: Study included 29 patients (16 DM1 and 13 DM2). FDG-PET and detailed neuropsychological testing were performed in both groups. RESULTS: The most common cognitive findings were executive, visuospatial, and naming dysfunction in DM1, and executive and naming dysfunction in DM2. FDG-PET showed the most prominent glucose hypometabolism in prefrontal, temporal, and pericentral regions in both DM1 and DM2 patients, with additional affection of insula and subcortical grey matter in DM2. In DM1 patients, we found association between right frontotemporal hypometabolism and executive dysfunction (p<0.05). In DM2 patients attention deficit was in association with prefrontal, insular, and striatal hypometabolism, as well as right frontotemporal hypometabolism (p<0.05). Executive dysfunction in DM2 was more common in patients with prefrontal and insular hypometabolism, right parietotemporal and frontotemporal hypometabolism, as well as left striatal hypometabolism (p<0.05). Patients with parietotemporal defect on FDG-PET were more likely to have naming dysfunction (p<0.01). CONCLUSION: FDG-PET findings corresponded well with the results of neuropsychological testing. FDG-PET may be a good biomarker of central nervous system involvement in DM1 and DM2, but this hypothesis will have to be more strongly supported by larger studies.