Poster Presentation Australian and New Zealand Stroke Organisation Conference 2026

A single session of cathodal transcranial direct current stimulation decreases somatosensory evoked potentials in stroke survivors. (#141)

Camila D. Lima 1 2 3 4 5 , Cassio V. Ruas 1 2 5 6 , Karoliny Cruz 1 5 , Luara Inocêncio 1 5 , Matilde Balbi 3 , Gabriela Castellano 1 5
  1. Neurophysics Group, Institute of Physics Gleb Wataghin, University of Campinas, Campinas, Sao Paulo, Brazil
  2. School of Exercise and Nutrition Sciences, Queensland University of Technology , Brisbane, Queensland, Australia
  3. Queensland Brain Institute, The University of Queensland, Brisbane, QUEENSLAND, Australia
  4. Centre for Sensorimotor Performance, School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Queensland, Australia
  5. BRAINN, FAPESP, Campinas, Sao Paulo, Brazil
  6. School of Medical and Health Sciences, Edith Cowan University, Perth, Western Australia, Australia

Background/aims:
Approximately 94 million people worldwide are living with the consequences of stroke. Hemiparesis and spasticity are among the main causes of motor impairment in stroke survivors, with at least 30% developing persistent spasticity after the event. The aim of this study was to investigate a single session of cathodal transcranial direct current stimulation (c-tDCS) on spasticity by examining somatosensory evoked potentials (SSEPs) in stroke survivors.

Methods:
Fourteen chronic stroke survivors (55±14.1yrs; 81±29.2kg; 159.8±27.8cm) presenting ankle spasticity participated. Seven females and seven males, with 5 left- and 9 right-hemisphere lesions were included. They were randomly allocated into two groups: (1) active c-tDCS and (2) sham stimulation. Both groups received 15 minutes of stimulation over the somatosensory cortex (Cz) while performing lower-limb exercises. Spasticity levels were assessed using the Modified Ashworth Scale (2.2±0.8), indicating moderate rigidity. SSEPs were recorded by electrically stimulating the tibial nerve and the responses recorded at Cz-Fz. A bandpass 1–30 Hz filter and visually inspected at 37ms latency after the stimulus artefact. Two-way repeated measures ANOVA was performed to assess significance.

Results:

A significant time × group interaction was observed (p=0.01). Post-hoc Bonferroni comparisons revealed a significant reduction in SSEPs amplitude from pre (-25.4±30.2 µV) to post (-13.4±16.1µV) intervention (p=0.02) following active c-tDCS.  In contrast, no significant change was detected in the sham group with SSEPs amplitudes remaining stable from pre (-18.6±19.3µV) to post (-20±17.1µV) intervention (p=0.12).

Conclusions:
A single session of c-tDCS applied over the somatosensory cortex reduced SSEPs, suggesting a potential reduction in spasticity.

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