Spinal crack or brain hack? how a Back-Popping maneuver may rewire pain circuits

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: Patients with lumbar disc herniation (LDH): * Diagnosis of LDH based on clinical symptoms, physical examination findings, and lumbar imaging consistent with neurological localization; central, paracentral, far-lateral, foraminal, or subarticular lumbar disc protrusion. * Aged 18-65 years, of either sex, and right-handed. * In the non-acute phase of LDH, with symptom duration of more than 2 weeks. * Visual Analog Scale (VAS) score greater than 4 and Japanese Orthopaedic Association (JOA) score less than 15. * No use of analgesics, neurotrophic drugs, or sedatives within 1 month before enrollment. * No systematic treatment, spinal manipulation, or other physical therapies within 1 month before enrollment. * Able to understand the study procedures and complete clinical assessments and MRI scans. * Provides written informed consent. Healthy controls: * Aged 18-65 years, of either sex, and right-handed. * No history of LDH or chronic low back pain. * No current pain condition requiring treatment. * No neurological or psychiatric disorders. * No known structural brain abnormalities. * No MRI contraindications. * Able to complete clinical assessments and MRI scans. * Provides written informed consent. Exclusion Criteria: Patients with LDH: * Low back pain or sciatica caused by conditions other than LDH. * Lumbar spondylolisthesis, lumbar tumor, spinal tuberculosis, severe osteoporosis, or localized lumbar skin lesions that may interfere with treatment. * Severe cardiovascular, cerebrovascular, hepatic, renal, hematopoietic, neurological, or psychiatric disease. * History of severe head trauma, loss of consciousness, or known structural brain abnormality. * Impaired consciousness, severe visual or hearing impairment, speech disorder, or inability to complete clinical assessments. * Non-MRI-compatible metal implants, implanted electronic devices, cardiac pacemakers, severe claustrophobia, or inability to tolerate MRI scanning. * Asymptomatic LDH. * Pregnancy, lactation, or planned pregnancy during the study period. * Participation in another clinical trial within the previous 3 months. * Any condition judged by the investigators to make the patient unsuitable for participation. Healthy controls: * Any condition that may affect eligibility, MRI safety, or data quality.