Gaze-stabilization exercise (GSE) is often conducted in vestibular rehabilitation, but its effect on vestibular function in postural control is not clear. We investigated whether GSE affects vestibular function during static upright standing and vestibulospinal reflex (VSR) in healthy young adults. First, the center of pressure of the total trajectory length (CoP-L) was measured before each GSE task or control (only standing) task (pre), immediately after (post), and 10 min after (post10) in the static standing position on foam rubber with the eyes open or closed (EC). Second, the H-reflex on the soleus muscle was measured after the onset of ipsilateral anodal galvanic vestibular stimulation before and after a GSE or a control task to estimate the amount of VSR induced by electrical vestibular input. CoP-L for the pre, post, and post10 control tasks and the GSE in EC did not differ significantly; the CoP-L for the post and post10 tasks in EC were significantly lower than that for the pretask. The H-reflex was inhibited by galvanic vestibular stimulation in the pre-GSE tasks. The inhibition increased after GSE, but not during control tasks. These findings suggest that GSE immediately improves the postural stability required for vestibular function and can be mediated by VSR improvements.

Background: Evidence of the effectiveness of physiotherapy, including muscle strength training, coordination training, aerobic exercise, cycling regimen, balance training, gait training, and activity of daily living training, in patients with degenerative cerebellar ataxia (DCA) was insufficient for clinical decision making. We aimed to explore clinical outcomes and examine the parameters associated with physical impairment and activity in people with DCA based on preregistration (PROSPERO: CRD42024493883).Methods: The PubMed, Cochrane Library, CHINAL, and PEDro databases were searched for relevant randomized controlled trials (RCTs). Data extraction, quality assessment, and heterogeneity analyses were conducted. The Grading of Recommendations Assessment, Development, and Evaluation framework (GRADE) was used to assess the quality of evidence, and a meta-analysis was performed.Results: Eighteen RCTs, which included 398 participants, showed a serious risk of bias (RoB) and low certainty of evidence for this primary outcome. For meta-analysis, 315 patients assessed based on the Scale for Assessment and Rating of Ataxia (SARA) were included. Overall, physiotherapy significantly reduced SARA scores (MD = −1.41, [95% CI: −2.16, −0.66]); the subgroup analysis showed that the following interventions exerted significant effects: multi-aspect training program (5 studies, MD = −1.59, [95% CI: −5.15, −0.03]), balance training (3 studies, MD = −1.58, [95% CI: −2.55, −0.62]), and aerobic training (3 studies, MD = −1.65, [95% CI: −2.53, −0.77]). By contrast, vibration (2 studies, MD = −0.56, [95% CI: −2.05, 0.93]) and dual-task training (1 study, MD = 0.24, [95% CI: −6.4, 6.88]) exhibited no significant effects.Conclusion: Physical therapy, especially multi-aspect physical therapy such as muscle strengthening, coordination training, gait training, and ADL training, may reduce DCA symptoms. Further, balance and aerobic training can be added to the program. However, the estimated effect size may change in future studies because of the serious RoB, very low certainty of evidence, and high heterogeneity with SARA as the primary outcome. High-quality RCTs are required to establish evidence for the effectiveness of physical therapy in patients with DCA.Systematic review registration: https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=493883, identifier: CRD42024493883.

Transcranial magnetic stimulation (TMS) over the cerebellum facilitates the spinal reflex in healthy humans. The aim of this study was to investigate whether such cerebellar spinal facilitation (CSpF) appears in patients with spinocerebellar ataxia (SCA) presenting with atrophy in the cerebellar gray matter and dentate nucleus. One patient with SCA type 6 and another with SCA type 31 participated in this study. TMS over the right primary motor cortex was used to induce motor-evoked potentials in the right first dorsal interosseous muscle, which were detected using electromyography. Conditioning TMS using interstimulus intervals of 1–8 ms was performed over the right cerebellum as a test to measure cerebellar brain inhibition (CBI). To assess the H-reflex and the M-wave recruitment curve of the right soleus muscle, we performed electrical stimulation of the right tibial nerve. The stimulation intensity was set to that at the center of the H-reflex curve of the ascending limb. To measure CSpF, we delivered TMS over the right cerebellum 100, 110, 120, and 130 ms before the right tibial nerve stimulation. Voxel-based morphometry was used to verify the presence of atrophy in the cerebellar gray matter and dentate nucleus. CBI was absent in both cases. However, a significant facilitation of the H-reflex occurred with an interstimulus interval of 120 ms in both cases. These findings indicate that the pathways associated with the induction of CSpF and CBI are different, and that the cerebellar gray matter and dentate nucleus are not needed for the induction of CSpF. The possible origin of CSpF may be examined by stimulation of other cerebellar deep nuclei or the brainstem.

To investigate whether gaze stabilization exercises (GSEs) improve eye and head movements and whether low-frequency cerebellar repetitive transcranial magnetic stimulation (rTMS) inhibits GSE trainability. 25 healthy adults (real rTMS, n = 12; sham rTMS, n = 13) were recruited. Real or sham rTMS was performed for 15 min (1 Hz, 900 stimulations). The center of the butterfly coil was set 1 cm below the inion in the real rTMS. Following stimulation, 10 trials of 1 min of a GSE were conducted at 1 min intervals. In the GSE, the subjects were instructed to stand upright and horizontally rotate their heads according to a beeping sound corresponding to 2 Hz and with a gaze point ahead of them. Electrooculograms were used to estimate the horizontal gaze direction of the right eye, and gyroscopic measurements were performed to estimate the horizontal head angular velocity during the GSE trials. The percentage change from the first trial of motion range of the eye and head was calculated for each measurement. The percent change of the eye/head range ratio was calculated to assess the synchronous changes of the eye and head movements as the exercise increased. Bayesian two-way analysis of variance showed that cerebellar rTMS affected the eye motion range and eye/head range ratio. A post hoc comparison (Bayesian t-test) showed evidence that the eye motion range and eye/head range ratio were reduced in the fifth, sixth, and seventh trials compared with the first trial sham stimulation condition. GSEs can modulate eye movements with respect to head movements, and the cerebellum may be associated with eye–head coordination trainability for dynamic gazing during head movements.