Inverse associations between cerebellar inhibition and motor impairment in spinocerebellar ataxia type 3

BackgroundCerebellar ataxia generally results from a lesion disrupting the corticopontocerebellar or cerebellothalamocortical tract. The cerebellar inhibition (CBI) paradigm represents dual-coil transcranial magnetic stimulation protocol that interrogates integrity of latter pathway. Whether CBI has clinical relevance in patients remains largely unknown because associations with pertinent disease severity measures etiologically homogeneous cohorts have not been previously examined.ObjectiveTo investigate if correlates and functional indices individuals spinocerebellar type 3 (SCA3).MethodsCBI was assessed fourteen SCA3 by paired-pulse cerebellar-motor cortex (M1) using interstimulus intervals 3, 5, 10 ms. Correlation coefficients were determined between severity, manual dexterity, walking speed.ResultsSuppression M1 excitability occurred 5 ms following contralateral conditioning stimulus patients, but, on average, significantly reduced as compared to healthy control group literature (p < 0.001). A significant association found decreased levels higher Scale for Assessment Rating Ataxia (SARA) scores (r = −0.62, p 0.019). negatively correlated axial, appendicular, speech subscores, well nine-hole peg test performance −0.69, 0.006). No observed speed. As expected, there no clinical-neurophysiological correlations at intervals.ConclusionOur provide first neurophysiological evidence an inverse tract integrity, reflected CBI, patients. Longitudinal studies are required evaluate could serve marker progression.