| INTRODUC TI ONSpinocerebellar ataxia (SCA) type 1 and 2 are dominantly inherited neurodegenerative disorders. These SCA subtypes are two of the most widely prevalent SCAs worldwide with a similar pattern found in India as well. SCA1 and SCA2 are caused by the abnormal expansion of CAG trinucleotide repeats in ATXN1 and ATXN2 genes, respectively. This results in progressive neuronal loss in the cerebellum along with certain cortical and subcortical brain regions in SCA subtypes 1,2 which subsequently leads to widespread clinical manifestations. Motor symptoms of SCA comprise cerebellar ataxia, peripheral neuropathy, ophthalmoplegia, pyramidal and extrapyramidal signs. 3 Furthermore, symptoms of autonomic dysfunction have also been observed in SCA patients. Thus, the evaluation of autonomic profile in SCA subtypes has an extensive clinical value. Objectives: To assess the time and frequency domain measures of cardiac autonomic activity/tone in patients of genetically defined spinocerebellar ataxia (SCA) types 1 and 2, as well as to decipher the probable associations among the cardiovascular autonomic parameters and genetic and clinical characteristics. Materials and methods:Simultaneous 5-min recording of RR interval (RRI) and blood pressure (BP) for the calculation of heart rate variability (HRV), blood pressure variability (BPV) and baroreflex sensitivity (BRS) were performed in genotypically confirmed SCA1 (n = 31) and SCA2 (n = 40) patients and healthy controls (n = 40).Additionally, the International Cooperative Ataxia Rating Scale (ICARS) was used for scoring of clinical severity in SCA patients.Results: Time and frequency domain parameters of HRV, BPV and BRS were depressed in SCA1 and SCA2 subtypes as compared to controls, although there was no statistically significant difference in autonomic tone between the two SCA subtypes.On correlation analysis, autonomic tone parameters were found to be associated with the clinical and genetic features of the SCA subtypes. Also, ICARS was associated with the genotype (CAG repeat length) in SCA2 patents. Conclusions:Cardiac autonomic tone is depressed in both SCA1 and 2 as compared to healthy controls while the two SCA subtypes do not differ in terms of autonomic tone. Also, a typical association exists between disease characteristics and autonomic indices. K E Y W O R D Sbaroreflex sensitivity, blood pressure variability, cardiac autonomic activity/tone, heart rate variability, spinocerebellar ataxia

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Yoga has been shown to improve autonomic conditioning in humans, as evidenced by the enhancement of parasym-pathetic activity and baroreflex sensitivity. Therefore, we hypothesized that the experience of yoga may result in adaptation to acute hemodynamic changes. To decipher the long-term effects of yoga on cardiovascular variability, yoga practitioners were compared to yoga-naïve subjects during exposure to –40 mm Hg lower-body negative pressure (LBNP). A comparative study was conducted on 40 yoganaïve subjects and 40 yoga practitioners with an average age of 31.08 ± 7.31 years and 29.93 ± 7.57 years, respectively. Heart rate variability, blood pressure variability, baroreflex sensitivity, and correlation between systolic blood pressure and RR interval were evaluated at rest and during LBNP. In yoga practitioners, the heart rate was lower in supine rest (p = 0.011) and during LBNP (p = 0.043); the pNN50 measure of heart rate variability was higher in supine rest (p = 0.011) and during LBNP (p = 0.034). The yoga practitioners’ standard deviation of successive beat-to-beat blood pressure intervals of systolic blood pressure variability was lower in supine rest (p = 0.034) and during LBNP (p = 0.007), with higher sequence baroreflex sensitivity (p = 0.019) and ~ high-frequency baroreflex sensitivity. Mean systolic blood pressure and RR interval were inversely correlated in the yoga group (r = –0.317, p = 0.049). The yoga practitioners exhibited higher parasympathetic activity and baroreflex sensitivity with lower systolic blood pressure variability, indicating better adaptability to LBNP compared to the yoga-naïve group. Our findings indicate that the yoga module was helpful in conditions of hypovolemia in healthy subjects; it is proposed to be beneficial in clinical conditions associated with sympathetic dominance, impaired barore-flex sensitivity, and orthostatic intolerance.

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