Effects of the Timing of Vagus Nerve Stimulation Combined With Exercise in Chronic Neck Pain

Chronic neck pain is a common musculoskeletal condition associated with pain, functional limitations, sleep disturbances, and alterations in autonomic nervous system activity. Exercise therapy is one of the main conservative treatment approaches for chronic neck pain. Transcutaneous auricular vagus nerve stimulation (taVNS) is a non-invasive neuromodulation method that aims to stimulate the auricular branch of the vagus nerve and may influence parasympathetic activity and pain modulation.

The purpose of this randomized controlled trial is to investigate whether the timing of taVNS relative to exercise influences clinical and physiological outcomes in individuals with chronic neck pain.

A total of 81 participants with chronic neck pain will be randomly allocated to three parallel groups. Participants in the first group will receive taVNS before performing a standardized exercise program. Participants in the second group will perform the same exercise program followed by taVNS. Participants in the control group will receive the exercise program alone.

The exercise program will include postural correction exercises, deep cervical flexor activation exercises, cervical mobility exercises, scapular stabilization exercises, and stretching exercises. The intervention period will last approximately 6-8 weeks.

Participants will be evaluated before and after the intervention period. Pain intensity will be assessed using the Numeric Pain Rating Scale, neck-related disability using the Neck Disability Index, sleep quality using the Pittsburgh Sleep Quality Index, and autonomic nervous system activity using heart rate variability, particularly the root mean square of successive differences (RMSSD). Exercise adherence and session attendance will also be recorded.

The study will compare changes in these outcomes among the three groups to determine whether the timing of taVNS relative to exercise influences the effectiveness of rehabilitation in individuals with chronic neck pain.

Inclusion criteria

• Diagnosis of chronic neck pain confirmed by a physical medicine and rehabilitation physician.
• Age between 18 and 65 years.
• Neck pain persisting or recurring for at least 3 months.
• Ability to participate in the exercise program included in the study protocol.
• No contraindication to transcutaneous auricular vagus nerve stimulation.
• Willingness to provide written informed consent.
• Willingness to participate regularly in the planned exercise and assessment sessions.

Exclusion criteria

• Cervical radiculopathy or specific neurological findings.
• Previous cervical spine surgery.
• Serious cardiovascular disease.
• Serious neurological or systemic disease.
• Pregnancy.
• Orthopedic or musculoskeletal conditions preventing participation in exercise.
• Cognitive or communication problems that prevent completion of the assessment instruments.
• Inability or unwillingness to comply with the study protocol or attend scheduled sessions.