Acute Effects of Transcutaneous Auricular Vagus Nerve Stimulation on Autonomic Nervous System Regulation and Spasticity in Children with Spastic Cerebral Palsy: A Preliminary Study

Objective: This study aims to investigate the acute effects of transcutaneous auricular vagus nerve stimulation (taVNS) on autonomic nervous system (ANS) regulation and spasticity in children with spastic cerebral palsy (SCP). Methods: This preliminary study includes 20 children aged 2–15 years diagnosed with SCP. Participants undergo a single session of taVNS. Spasticity is assessed using the Modified Ashworth Scale, and autonomic regulation is evaluated through heart rate variability (HRV) parameters measured before and immediately after stimulation. Results: Following taVNS, spasticity scores decrease significantly (Modified Ashworth Scale: pre 2.00 ± 0.64 vs. post 1.60 ± 0.52; p = 0.004). Significant reductions are also observed in mean heart rate (pre 98.60 ± 16.32 bpm vs. post 91.25 ± 20.22 bpm; p = 0.022), LF/HF ratio (pre 2.22 ± 2.22 vs. post 1.12 ± 0.84; p = 0.006), and LF power (p = 0.009). No significant changes are detected in RMSSD, pNN50, or HF power (all p > 0.05). No adverse events are reported. Conclusions: This preliminary study suggests that a single session of taVNS may be associated with acute changes in autonomic regulation and reductions in spasticity in children with SCP. The observed shifts in HRV parameters indicate a modulation of sympathovagal balance. These findings support the feasibility of taVNS as a non-invasive neuromodulatory approach and warrant further large-scale, controlled studies with longer follow-up. Because of the small sample size, the absence of a control or sham group, and the short (1-min) HRV recording window, these results should be regarded as preliminary and hypothesis-generating, and they require confirmation in larger, randomised, sham-controlled studies. Clinical Trial Registration: This study was registered at ClinicalTrials.gov (Identifier: NCT06880887) on 10 March 2025. The study was conducted between January 2025 and March 2025; registration on 10 March 2025 therefore occurred during the enrolment and data-collection period rather than prior to it. This retrospective registration is acknowledged as a limitation.