Overview

This is a single-center, randomized, double-blind, sham-controlled trial evaluating dual-carrier-frequency transcranial alternating current stimulation targeting the hippocampus in 60 patients with chronic non-specific low back pain. Participants will be randomized into four groups: active stimulation, active stimulation with iTBS, superficial stimulation control, and sham control. All groups will receive standard rehabilitation. The intervention is 20 minutes per session, 5 sessions weekly for 2 weeks (10 sessions total).

The primary objective is to assess improvements in pain intensity (VAS) and emotional symptoms (anxiety, depression) at week 2. Exploratory objectives include examining functional connectivity changes between the hippocampus and prefrontal/sensory cortices using fMRI, MEG, and fNIRS, and correlating these with clinical improvements.

Outcomes include VAS (primary), McGill Pain Questionnaire, HAMA, HAMD, ODI, CSI, PSQI, and objective measures (brain imaging, EEG, EMG). Assessments occur at baseline (T0), post-first stimulation (T1), mid-treatment (T2), treatment end (T3), and 2-week follow-up (T4).

Linear mixed-effects models will be used for analysis with multiple comparison correction. This study aims to provide evidence for hippocampal-targeted neuromodulation in chronic non-specific low back pain.

Eligibility

Inclusion Criteria:

1. Age between 18 and 80 years;
2. Meets the diagnostic criteria for non-specific low back pain as specified in the Chinese Clinical Guidelines for the Diagnosis and Treatment of Non-specific Low Back Pain (2022) ;
3. Diagnosed with chronic non-specific low back pain within the past 3 months, or pain located between T12 and the gluteal fold for at least half of the days within the past 6 months;
4. VAS score ≥ 3 (Visual Analogue Scale, 0-10);
5. Mechanical pain induced by posture, activity, and movement (e.g., flexion and functional movement tasks);
6. Voluntarily agrees to participate in this study and has signed the informed consent form.

Exclusion Criteria:

1. Clear etiology of specific low back pain, such as vertebral fracture, severe spinal cord/nerve root compression symptoms (progressive neurological deficit), spinal infection, tumor, ankylosing spondylitis, etc.;
2. Prior major lumbar surgery or implants (e.g., internal fixation, spinal cord stimulation devices, etc.), or recent (within 3 months) invasive analgesic treatments such as nerve blocks or radiofrequency ablation;
3. Contraindications to MEG or MRI, including the presence of ferromagnetic metal implants in the body (e.g., cardiac pacemakers, hearing aids, carotid artery stents, etc.), claustrophobia that precludes MEG examination, or failed MEG acquisition;
4. History of severe cardiovascular disease, epilepsy, or other conditions that contraindicate electrical stimulation;
5. Pregnancy or lactation;
6. Cognitive impairment, psychiatric disorders, or other conditions that prevent understanding or compliance with the study procedures;
7. Rheumatic diseases, connective tissue diseases, or diabetes.