The Effect of Nervus Vagus Stimulation on Spasticity, Autonomic Function, Motor Function and Quality of Life in Children With Spastic Cerebral Palsy

Introduction: Cerebral palsy (CP) is a heterogeneous neurodevelopmental syndrome affecting muscle tone, motor skills, and movement due to brain injury during developmental stages. The etiology of CP is associated with factors such as prematurity, low birth weight, and pregnancy or birth complications. The spastic type is the most common motor disorder, characterized by increased reflexes and muscle hypertonia in the extremities. Spasticity arises from upper motor neuron lesions, leading to dysregulation in spinal and brain pathways (corticospinal, reticulospinal, vestibulospinal) and involves complex modulation of muscle tone and stretch reflexes. The autonomic nervous system regulates visceral functions, while the vagus nerve, through its parasympathetic fibers, exerts widespread influence on the heart, respiratory system, and gastrointestinal system. It controls organ function via motor, sensory, and parasympathetic fibers originating from three medullary nuclei (nucleus ambiguus, dorsal motor nucleus, and nucleus solitarius). Vagus nerve stimulation (VNS) modulates the central nervous system by stimulating afferent fibers, increasing GABA and other inhibitory neurotransmitter levels, reducing excitatory signals, and potentially influencing spasticity. VNS can be applied invasively or non-invasively (transcutaneous VNS, tVNS); particularly, tVNS applied to the left ear is a safe and well-tolerated method with therapeutic potential in epilepsy and motor disorders. This study aims to investigate the effects of non-invasive auricular vagus nerve stimulation (taVNS) combined with the Bobath approach on motor function, autonomic function, spasticity, activities of daily living, and quality of life in children with spastic cerebral palsy (CP). Materials and Methods: Planned as a prospective, controlled study, children with CP will be randomly assigned to two groups. The intervention group will receive the standard Bobath program administered by physiotherapists with at least 3 years of experience, combined with transcutaneous auricular vagus nerve stimulation (taVNS). The control group will receive only the Bobath approach. Both groups will undergo therapy twice a week for 8 weeks. Outcome Measures: Motor function: Assessed using the Gross Motor Function Measure (GMFM-88) and the Gross Motor Function Classification System (GMFCS). Spasticity: Measured with the Modified Ashworth Scale (MAS). Quality of life: Evaluated using the Pediatric Quality of Life Inventory (PedsQL). Autonomic function: Heart rate variability (HRV) analyzed using the Elite HRV Corsense device. Measured parameters include RMSSD, LF power, HF power, LF/HF ratio, and mean heart rate. Inclusion Criteria: Diagnosis of spastic cerebral palsy Aged 8-18 years MAS score between 1 and 3 GMFCS Level I-III Adequate cognitive level No previous vagus nerve stimulation No cardiovascular or chronic respiratory disease Informed consent from parent/legal guardian Exclusion Criteria: Severe cardiovascular or pulmonary disease Respiratory failure requiring mechanical ventilation History of epilepsy or active seizures MAS 0 or 4, GMFCS IV-V Skin conditions in the neck/ear region preventing stimulation Inability to obtain sufficient consent or perform assessments

Inclusion Criteria: * Diagnosed with spastic cerebral palsy * Aged between 8 and 18 years * No chronic respiratory or cardiovascular disease * Having spasticity between 1 and 3 according to the Modified Ashworth Scale (MAS) * Classified as Level I-III according to the Gross Motor Function Classification System (GMFCS) * Sufficient cognitive ability to participate in the study and complete assessments * No previous vagus nerve stimulation and no contraindications for the procedure * No congenital or acquired cardiovascular disease * Written informed consent obtained from parents or legal guardians Exclusion Criteria: * History of congenital or acquired severe cardiovascular or pulmonary disease * Requirement of mechanical ventilation due to respiratory failure * History of epilepsy or active seizures * Previous vagus nerve stimulation * Inability to complete assessments due to severe cognitive impairment * Having spasticity of 0 or 4 according to the Modified Ashworth Scale (MAS) * Classified as Level IV-V according to the Gross Motor Function Classification System (GMFCS) * Presence of skin disease in the neck or ear region or any condition preventing vagus nerve stimulation * Inability to obtain parental/legal guardian consent for participation in the study Withdrawal Criteria for Participants: Participants will be withdrawn from the study if they are unable to complete the administered tests, assessments, or questionnaires. Study Termination Criteria: The study will be concluded once the planned sample size has been reached.