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

• Published in: Brain stimulation 2021-03, Vol.14 (2), p.351-357
• Main Authors: Maas, Roderick P.P.W.M., van de Warrenburg, Bart P.C., Schutter, Dennis J.L.G.
• Format: Article
• Language: English
• Subjects: Cerebellar inhibition; Cerebellothalamocortical tract; Scale for the Assessment and Rating of Ataxia; Spinocerebellar ataxia type 3; TMS
• ISSN: 1935-861X; 1876-4754
• DOI: 10.1016/j.brs.2021.01.020

Cerebellar ataxia generally results from a lesion disrupting the corticopontocerebellar or cerebellothalamocortical tract. The cerebellar inhibition (CBI) paradigm represents a dual-coil transcranial magnetic stimulation protocol that interrogates the integrity of the latter pathway. Whether CBI has clinical relevance in ataxia patients remains largely unknown because associations with pertinent disease severity measures in etiologically homogeneous cohorts have not been previously examined. To investigate if CBI correlates with clinical and functional indices of disease severity in individuals with spinocerebellar ataxia type 3 (SCA3). CBI was assessed in fourteen SCA3 patients by paired-pulse cerebellar-motor cortex (M1) stimulation using interstimulus intervals of 3, 5, and 10 ms. Correlation coefficients were determined between CBI and ataxia severity, manual dexterity, and walking speed. Suppression of M1 excitability occurred 5 ms following a contralateral cerebellar conditioning stimulus in SCA3 patients, but, on average, CBI was significantly reduced as compared to a healthy control group from the literature (p