The objective of this study was to determine the degree of brain involvement in a cohort of myotonic dystrophy type 1 and type 2 (DM1, DM2) patients by brain studies and functional tests and to compare the results of the two groups. DM1, DM2 are multisystemic disorders due to polynucleotide expansions. Previous studies on brain involvement by neuroimaging and functional methods have led to contradictory results. Fifty molecularly defined DM1 patients and 14 DM2 patients, were recruited for the study. Age at recruitment, age at disease onset, disease duration and educational level were recorded. Neuromuscular assessment was done by MIRS. An extensive neuropsychological battery was performed in 48/50 DM1 and in a control group of 44 healthy matched subjects. Forty six of 50 DM1 and 12/14 DM2 underwent brain MRI; 21/50 DM1 and 9/14 DM2 underwent brain perfusion SPECT, with semiquantitative analysis of the results. MRI images were classified by ARWMC (age-related white matter changes) score, in order to quantify recurrence, localization and patterns of distribution of white matter hyperintense lesions (WMHLs) in our two cohorts. MRI results were matched to SPECT and to neuropsychological results. Thirty-seven of 46 DM1 and 10/12 DM2 had abnormal MRI imaging, showing scattered supratentorial, bilateral, symmetrical focal or diffuse WMHLs. A typical temporo-insular diffuse subcortical pattern was seen in DM1 subjects only, with no correlation with cognitive involvement. Major cognitive involvement was seen in the case of diffuse frontal lesions. A relationship with CTG expansion size was documented for DM1 subjects. SPECT showed minimal hypoperfusion in the posterior cortex planes in DM1 and, to a lesser extent, in DM2. Very mild degrees of involvement in the DM2 cohort were seen. Neuroimaging and functional investigations confirmed a more severe involvement of the brain in DM1 compared to DM2. A temporo-insular diffuse lesional pattern, specific for DM1, was found on MRI. This confirms greater expansion size as a risk factor for more extensive brain involvement in DM1.

Despite much evidence of cognitive and affective disorders in Friedreich's ataxia (FRDA), the nature of mental status in FRDA has received little systematic attention. It has been proposed that the cerebellum may interfere indirectly with cognition through the cerebello-cortical loops, whereas the role of pathological changes in different areas of the central nervous system is still undetermined. In the present study, 13 patients with molecularly determined FRDA and a group of matched controls were evaluated by a comprehensive battery of neuropsychological tests and the Minnesota Multiphasic Personality Inventory. A repetitive task of simple visual-reaction times was used to investigate implicit learning in all subjects. Pathological changes in cortical areas were explored comparing cerebral activations of patients and controls during finger movements (functional MRI). The intelligence profile of FRDA patients is characterized by concrete thinking, poor capacity in concept formation and visuospatial reasoning. FRDA patients show reduced speed of information processing. The learning effect seen in controls was notably absent in patients with FRDA. The patients' personality is characterized by some pathological aspects and reduced defensiveness. Patterns of cortical activation during finger movements are heterogeneous in patients compared to controls. Cognitive impairment, mood disorders and motor deficits in FRDA patients may be the result of the cumulative damage caused by frataxin deficiency not only in the cerebellum and spinal cord but also in other brain areas.

This study suggests that hypertension may contribute to functional impairment in CADASIL and that memory impairment has a large influence on functional decline in contrast with that observed in a sample of subjects with ARL.

The aim was to study brain involvement in myotonic dystrophy type 1 by single photon emission tomography (SPECT) and positron emission tomography (PET). 58 DM1 patients were subjected to SPECT; 17 to both SPECT and PET. SPECT patients were grouped as 'normally perfused' and 'abnormally perfused'; PET patients as 'normal performers' and 'abnormal performers'. To quantify hypoperfusion and/or hypometabolism, we used a semi-quantitative scale. To localize focal hypoperfusion/hypometabolism, nine cerebral areas of involvement were identified. The Chi-square, Wilcoxon, McNemar tests were used for statistics. SPECT showed abnormalities in 52/58 patients. PET showed an abnormal glucidic uptake in 15/17. Hypoperfusion was mild/moderate in 50/58 patients, mostly involving the left supratentorial areas. Abnormal glucidic uptake was mainly observed in the left frontal lobe. Abnormalities in blood perfusion and/or glucose metabolism are frequent in DM1. These abnormalities involve the left more often than the right hemisphere, the frontal lobe more than other lobes. Such abnormalities are more often cortical than subcortical.

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