To elucidate how the size of the expanded CAG repeat of the gene for dentatorubral pallidoluysian atrophy (DRPLA) and other factors affect the atrophy of the brainstem and cerebellum, and the appearance of high-intensity signals on T2-weighted MRI of the cerebral white matter of patients with DRPLA, we quantitatively analyzed the MRI findings of 26 patients with DRPLA, the diagnosis of which was confirmed by molecular analysis of the DRPLA gene. When we classified the patients into two groups based on the size of the expanded CAG repeat of the DRPLA gene (group 1, number of CAG repeat units > or = 66; group 2, number of CAG repeat units < or = 65), we found strong inverse correlations between the age at MRI and the areas of midsagittal structures of the cerebellum and brainstem in group 1 but not in group 2. Multiple regression analysis, however, revealed that both the patient's age at MRI and the size of the expanded CAG repeat correlated with the areas of midsagittal structures. Involvement of the cerebral white matter as detected on T2-weighted images was observed more frequently in patients belonging to group 2 than in group 1 patients. Furthermore it was demonstrated that high-intensity signals can be detected on T2-weighted images of the cerebral white matter of patients with a largely expanded CAG repeat (group 1) in their thirties. These results suggest that patient age as well as the size of the expanded CAG repeat are related to the degree of atrophy of the brainstem and cerebellum, and the white matter changes in patients with DRPLA.
The pathology of the peripheral nervous system (PNS) in 2 autopsied cases of group A xeroderma pigmentosum (De Sanctis Cacchione syndrome) are presented. Motor nerves including those of the oculomotor systems were severely affected, but involvement of the sensory system was even more marked. Minor hypertrophic changes were present in the distal portions of the peripheral nerve trunks, but there was no appreciable difference in the density of myelinated nerve fibres between proximal and distal levels. Morphometric data including teased fibre analyses and g ratio scattergrams suggest that the underlying pathogenetic mechanism is that of a neuronopathy. Unmyelinated axons were also severely depleted. Review of the previous literature revealed that the pathological changes of the PNS in group A xeroderma pigmentosum are thought to be slowly progressive, which is also suggested by the severe and widespread sclerotic changes of the CNS in the present 2 cases.
The mechanism of mirror movements in two patients was investigated; one with congenital mirror movement, the other with schizencephaly. Transcranial magnetic stimulation on one side elicited motor evoked potentials (MEPs) in their thenar muscles on both sides with almost the same latencies, minimal thresholds, and cortical topographies. During voluntary contraction of the thenar muscle on one side, contralateral transcranial magnetic stimulation induced a silent period not only on the voluntary contraction side but on the mirror movement side and of the same duration. By contrast, ipsilateral transcranial magnetic stimulation elicited MEPs without silent periods in both muscles. With intended unilateral finger movements, an H,'50-PET activation study showed that the regional cerebral blood flow increased predominantly in the contralateral sensorimotor cortex, as seen in normal subjects, although mirror movements occurred.It is considered that the ipsilateral motor cortex plays a major part in the generation of mirror movements, which may be induced through the ipsilateral uncrossed corticospinal tract. (JNeurolNeurosurg Psychiatry 1997;62:629-632)
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.