Usefulness of transcranial magnetic stimulation to predict the development of reflex sympathetic dystrophy poststroke: a pilot study

A Meta-Analysis and Meta-Regression of Frequency and Risk Factors for Poststroke Complex Regional Pain Syndrome

Background and Objectives: This article aimed to investigate the risk factors for poststroke complex regional pain syndrome (CRPS). Materials and Methods: We searched electronic databases including PubMed, Medline, Web of Science, Cochrane Library, and Embase up to 27 October 2021. We enrolled analytical epidemiological studies comprising cohort, case-control, and cross-sectional studies. A quality assessment was performed using the Newcastle–Ottawa Quality Assessment Scale for cohort and case-control studies and the Joanna Briggs Institute critical appraisal checklist for analytical cross-sectional studies. Binary outcomes were reported as odds ratios (ORs), and continuous outcomes were described as standardized mean differences (SMDs) with 95% confidence intervals. For the meta-regression, beta coefficient and p value were adopted. Results: We included 21 articles comprising 2225 participants. Individuals with shoulder subluxation and spasticity were found to have higher risks for poststroke CRPS. Spasticity with higher modified Ashworth scale score, lower Brunnstrom hand stage, and inferior Barthel index scores were observed in patients with poststroke CRPS. The pooled incidence proportion in nine articles was 31.7%, and a correlation was found between effect sizes and the ratio of women and the proportion of left hemiparesis. The summarized prevalence in nine cross-sectional studies was 33.1%, and a correlation was observed between prevalence and the subluxation ratio and Brunnstrom stage. Conclusions: Based on our meta-analysis, being female, left hemiparesis, shoulder subluxation, spasticity, a lower Brunnstrom stage of distal upper limb, and an inferior Barthel index are all features for poststroke CRPS. Larger studies with greater statistical power may confirm our findings and clarify some other unknown risk factors for poststroke CRPS.

Effects of conditioning peripheral repetitive magnetic stimulation in patients with complex regional pain syndrome

OBJECTIVES

We tested whether repetitive magnetic stimulation (rMS) induces an afferent input to the spinocerebral tract in patients with complex regional pain syndrome (CRPS).

METHODS

Cortical and spinal motor evoked potentials (cMEP and sMEP), as well as the contra- and ipsilateral silent period (cCSP and iCSP), were recorded in patients with CRPS type I before and after conditioning rMS, applied at cervical nerve roots innervating affected muscles. Patients were compared with a group of healthy subjects.

RESULTS

In the group of patients we found that cMEP amplitudes were always significantly smaller for both hemispheres. In the group of healthy subjects we found a significant prolongation of the cCSP and iCSP after rMS. This was absent in patients. SMEP were always unchanged in both groups.

DISCUSSION

This led us to the explanation that the afferent input to the motor cortical system in CRPS patients is less effective than in healthy subjects.

Transcranial magnetic stimulation for diagnosis of residual limb neuromas

OBJECTIVE

To analyze the mechanism and examine the potential diagnostic contribution of transcranial magnetic stimulation (TMS) in diagnosing painful, clonic, and/or autonomic manifestations in amputees' residual limbs.

DESIGN

Prospective study.

SETTING

Regional rehabilitation institute at a medical school in France.

PARTICIPANTS

Thirty-four amputees (24 with myoclonus, stump pain, or trophic skin disorders; 10 controls with no stump symptoms).

INTERVENTIONS

Not applicable.

MAIN OUTCOMES MEASURES

TMS performed before and after correcting prosthesis adaptation.

RESULTS

TMS induced pain in 12 amputees, clonic manifestations in 4, and autonomic manifestations in 2. Twelve patients underwent magnetic resonance imaging that showed neuromas in all 12. After neuroma resection in 9 amputees, TMS no longer provoked abnormal manifestations. TMS did provoke abnormal manifestations after resection in 3 patients who had postoperative recurrent neuromas. The response to TMS was negative in subjects with a clinically silent neuroma (n=7). The response was also negative in all patients with other stump anomalies whose clinical manifestations fully regressed after conservative treatment. There was a highly significant correlation between the presence of a pathologic neuroma and TMS-induced abnormal manifestations (P<.0001).

CONCLUSIONS

TMS can provoke symptoms in patients who experience spontaneous or evoked symptoms related to a neuroma. Induced symptoms are proportional to spontaneous symptoms. Removing the neuroma can stop stump symptoms and reverse the TMS effect. The response to TMS was negative in the control subjects with clinically silent neuromas; conservative treatment was successful in these cases. TMS-induced abnormal manifestations underlying mechanisms are discussed (ephaptic transmission in neuromas).