Mechanisms and effectiveness of motor cortex stimulation for the treatment of refractory pain

Ana Paula Rodrigues dos Santos 1; Emily Calmon Londero 1, João Guilherme Santos Garrido 1; Luana Brandão de Sales Reis 1; Rafael Abib Fernandes de Barros 1; Renato Teixeira Conceição Júnior 1; Roberta Veiga Pestana Visco Costa 1

  1. Medicine students at Bahiana School of Medicine and Public Health, and Salvador University, Salvador, Bahia, Brazil.

OBJECTIVE: Aim to analyze the main mechanisms of motor cortex stimulation and its effectiveness for relief and treatment of refractory pain.

METHODS: This study is a literature review, which includes systematic reviews, clinical trials and observational studies, published on the PUBMED platform in the last 5 years, originally in English and Portuguese. The search strategy used was: ((motor cortex stimulation) AND (refractory pain), considering only studies conducted in humans.

RESULTS: This search resulted in 29 unique articles, and after selection criteria, 15 articles were included for final analysis. The mechanisms of motor cortex stimulation include epidural or cortical, and transcranial magnetic stimulation, demonstrating similarity in the results obtained. There was effectiveness in the treatment of refractory pain in 14 articles, among which one systematic review showed benefit in pathologies that affect the central or peripheral nervous system, such as post-CAV pain, trigeminal neuralgia, phantom limb pain and plexus lesions. Furthermore, a relevant decrease in the Visual Analog Scale (VAS) pain rates was noted after the cortical stimulation procedures. However, only one study presented a controversial efficacy, suggesting a possible placebo effect.

CONCLUSIONS: No conclusive difference was observed between the mechanisms of invasive and non-invasive stimulation of the motor cortex. But, these techniques present significant reduction of refractory pain in patients affected by lesions in the central and peripheral nervous system, improving their quality of life and decreasing the use of medicines.

KEYWORDS: refractory pain, treatment, cortex stimulation.