Neuropathic pain (NP) is one type of refractory chronic pain condition,medical treatments for NP is limited because of its poorly response.Repetitive transcranial magnetic stimulation (rTMS) can induce neuroplastic changes which has been used to manage chronic pain conditions. Indeed, high-frequency (≥ 5 Hz) rTMS over the primary motor cortex (M1) is suggested to be able to reduce neuropathic pain in randomized controlled studies. Overall, the clinical application of rTMS in chronic pain is still limited by the response rate, whereby it is close to moderate and far from being excellent at its best. Therefore this project designed a series of clinical trials to optimize the analgesic efficacy of rTMS. According to the research results of investigators previous project, patients with neuropathic pain were divided into responders and non-responders after 5 consecutive days of 10HZ rTMS or pcTBS intervention (see project ID:2021-0751)according to the change of pain intensity, and then different trials will be applied to responders and non-responders to optimize the analgesic effect of rTMS.
For non-responders (whose visuo-analogic scale (VAS) decreased less than 20 mm or T1-T0/T0×100%\<30%), a feasible method is to switch stimulation targets. So the investigator will change the stimulation target from M1 to dorsolateral prefrontal cortex (DLPFC), and then delivered another 5 days consecutive interventions to assess the efficacy. For responders (whose VAS decreased an average of 20 mm or more or T1-T0/T0×100%≥30%), the investigator further investigate the long-lasting effect of rTMS. the patients will participate a continuous trials (2 sessions weekly for 2 weeks) and 4 weeks follow up.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
PREVENTION
Masking
DOUBLE
Enrollment
40
Magnetic stimulation was performed using a figure-eight coil connected to a Magstim Rapid2 system, All patients seat in a comfortable reclining chair and delivered pcTBS protocol using repetitive transcranial magnetic stimulation . The stimulation intensity was set to 80% of the resting motor threshold, which is measured as the minimal intensity of stimulation evoking an electromyographic response ≥50µV on the first dorsal interosseus muscle of the hand contralateral to the stimulated hemisphere in at least 5 out of 10 trials. For this measurement, a figure-of-eight coil is positioned over the hand motor hotspot and oriented perpendicular to the central sulcus (parallel to the hemispheric midline).
Magnetic stimulation was performed using a figure-eight coil connected to a Magstim Rapid2 system, All patients seat in a comfortable reclining chair and delivered 10HZ protocol using repetitive transcranial magnetic stimulation . The stimulation intensity was set to 80% of the resting motor threshold, which is measured as the minimal intensity of stimulation evoking an electromyographic response ≥50µV on the first dorsal interosseus muscle of the hand contralateral to the stimulated hemisphere in at least 5 out of 10 trials. For this measurement, a figure-of-eight coil is positioned over the hand motor hotspot and oriented perpendicular to the central sulcus (45° away from the hemispheric midline).
The second affliated hospital of zhejiang university
Hangzhou, Zhejiang, China
pain intensity measured with the visuo-analogic scale (VAS)
For non-responders:the primary outcome measure is the mean change from baseline over the course of 5 (group by time interaction) in average pain intensity measured with the visuo-analogic scale (VAS) ( 0= no pain and 10= maximal pain). Pain intensity is further assessed immediately before each rTMS session at days 2, 3, 4, 5, and then at weeks 2, 3, 4 after the intervention. For responders: pain intensity is assessed after two sessions of rTMS session and then at weeks 2, 3, 4 after the intervention.
Time frame: through study completion, an average of 8 months
Motor-evoked potential (MEP)
Corticospinal excitability was measured with MEP at rest of the first dorsal interosseous (FDI) muscle, A total of 20 single pulses were consecutively delivered to the hand region of the left M1 at 120% RMT (45° to the midline, handle pointing backward).
Time frame: through study completion, an average of 8 months
Cortical silent period (CSP)
Corticospinal excitability was measured with CSP during a sustained voluntary FDI muscle contraction, A total of 20 single pulses were consecutively delivered to the hand region of the left M1 at 120% RMT (45° to the midline, handle pointing backward).
Time frame: through study completion, an average of 8 months
The sensory dimension of pain
The sensory dimension of pain (rated on 33) measured with Short form of the McGill Pain questionnaire (SF-MPQ) .
Time frame: through study completion, an average of 8 months
The affective dimension of pain
The affective dimension of pain measured with Short form of the McGill Pain questionnaire (SF-MPQ) .
Time frame: through study completion, an average of 8 months
Pain interference scale
7 items rated from 0= does not interfere to 10= complete interference, total score 70 from the Brief Pain Inventory.
Time frame: through study completion, an average of 8 months
Patients global impression of change
the 7 items Patients global impression of change (PGIC) (from very much worse to very much improved)
Time frame: through study completion, an average of 8 months
The depression score
ranging from 0 to 13 with higher scores indicating more severe depression from the 13 items Beck Depression Inventory (BDI)
Time frame: through study completion, an average of 8 months
This platform is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional.