Session Time: 1:45pm-3:15pm
Location: Hall 3FG
Objective: This study evaluates and compares the RMT and CMCT in patients with genetically proven SCA1, SCA2, SCA3 and SCA12 using transcranial magnetic stimulation (TMS).
Background: Spinocerebellar ataxias 1, 2, 3 and 12 (SCA1, SCA2, SCA3 and SCA12) are autosomal dominant CAG repeat disorders. There are only a few comparative studies of neurophysiological measures such as cortical excitability (resting motor threshold, RMT) and central motor conduction (CMCT) in genetically proven SCA subtypes.
Methods: Fifty subjects with genetically proven SCA (SCA1= 20, SCA2= 14, SCA3= 8, SCA12= 8) were recruited for the study. TMS was performed using a Magstim 200 stimulator using a figure-of-eight coil. The motor evoked potentials (MEP) recordings were obtained from the first dorsal interosseous (FDI). Standard techniques were used to determine the RMT and the CMCT. ANOVA with post hoc correction was used to ascertain significance at a statistical threshold of p-value <0.05. This study was approved by the institutional ethics committee and all patients provided informed consent.
Results: Significant differences were obtained on the comparison of RMT in different subgroups of SCA (F=15.35, p<0.0001). On post-hoc analysis, the mean RMT was significantly different in SCA1 vs. SCA3 (59.35 ± 14.2 vs. 32.2 ± 8.5, p<0.01), SCA2 vs. SCA12 (44.1 ± 10.4 vs. 74.6 ± 21.6, p<0.01), and SCA3 vs. SCA12 (32.2 ± 8.5 vs. 74.6 ± 21.6, p<0.01). There was no significant difference in the CMCT values among the different SCA subtypes.
Conclusions: The neurophysiological abnormalities in RMT were most evident in SCA12 followed by SCA1, SCA2 and SCA3. However, CMCT was not significantly different in different SCA subtypes. The changes in the mean RMT values of different types of SCA denotes the varying extent of local axonal excitability of cortico-cortical projections and pyramidal dysfunction.
To cite this abstract in AMA style:A. Stezin, K. Jhujhunwala, N. Kamble, P. Pal. A comparative study on the alterations in the cortical excitability and central motor conduction time in spinocerebellar ataxias 1, 2, 3 and 12 [abstract]. Mov Disord. 2018; 33 (suppl 2). https://www.mdsabstracts.org/abstract/a-comparative-study-on-the-alterations-in-the-cortical-excitability-and-central-motor-conduction-time-in-spinocerebellar-ataxias-1-2-3-and-12/. Accessed December 10, 2023.
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