Intervention Review

Non-invasive brain stimulation techniques for chronic pain

  1. Neil E O'Connell1,*,
  2. Benedict M Wand2,
  3. Louise Marston3,
  4. Sally Spencer4,
  5. Lorraine H DeSouza1

Editorial Group: Cochrane Pain, Palliative and Supportive Care Group

Published Online: 8 SEP 2010

Assessed as up-to-date: 22 APR 2010

DOI: 10.1002/14651858.CD008208.pub2

Database Title

Additional Information

How to Cite

O'Connell NE, Wand BM, Marston L, Spencer S, DeSouza LH. Non-invasive brain stimulation techniques for chronic pain. Cochrane Database of Systematic Reviews 2010, Issue 9. Art. No.: CD008208. DOI: 10.1002/14651858.CD008208.pub2.

Author Information

  1. 1

    Brunel University, Centre for Research in Rehabilitation, School of Health Sciences and Social Care, Uxbridge, Middlesex, UK

  2. 2

    University of Notre Dame, School of Physiotherapy, Fremantle, Australia

  3. 3

    University College London, Research Department of Primary Care & Population Health, Division of Population Health, Faculty of Biomedical Sciences, London, UK

  4. 4

    Lancaster University, School of Health and Medicine, Lancaster, Lancashire, UK

*Neil E O'Connell, Centre for Research in Rehabilitation, School of Health Sciences and Social Care, Brunel University, Kingston Lane, Uxbridge, Middlesex, UB8 3PH, UK. neil.oconnell@brunel.ac.uk.

Publication History

  1. Publication Status: Edited (no change to conclusions)
  2. Published Online: 8 SEP 2010

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Abstract

  1. Top of page
  2. Abstract
  3. Plain language summary
  4. Resumen

Background

Non-invasive brain stimulation techniques aim to induce an electrical stimulation of the brain in an attempt to reduce chronic pain by directly altering brain activity. They include repetitive transcranial magnetic stimulation (rTMS), cranial electrotherapy stimulation (CES) and transcranial direct current stimulation (tDCS).

Objectives

To evaluate the efficacy of non-invasive brain stimulation techniques in chronic pain.

Search methods

We searched CENTRAL, MEDLINE, EMBASE, CINAHL, PsycINFO, LILACS, the Cochrane PaPaS Group Trials Register and clinical trials registers.

Selection criteria

Randomised and quasi-randomised studies of rTMS, CES or tDCS if they employed a sham stimulation control group, recruited patients over the age of 18 with pain of three months duration or more and measured pain as a primary outcome.

Data collection and analysis

Two authors independently extracted and verified data. Where possible we entered data into meta-analyses. We excluded studies judged as being at high risk of bias from the analysis.

Main results

We included 33 trials in the review (involving 937 people)(19 rTMS, eight CES and six tDCS). Only one study was judged as being at low risk of bias.

Studies of rTMS (involving 368 participants ) demonstrated significant heterogeneity. Pre-specified subgroup analyses suggest that low-frequency stimulation is ineffective. A short-term effect on pain of active high-frequency stimulation of the motor cortex in single-dose studies was suggested (standardised mean difference (SMD) -0.40, 95% confidence interval (CI) -0.26 to -0.54, P < 0.00001). This equates to a 15% (95% CI 10% to 20%) reduction in pain which does not clearly exceed the pre-established criteria for a minimally clinically important difference (> 15%).

For CES (four studies, 133 participants) no statistically significant difference was found between active stimulation and sham. Analysis of tDCS studies (five studies, 83 people) demonstrated significant heterogeneity and did not find a significant difference between active and sham stimulation. Pre-specified subgroup analysis of tDCS applied to the motor cortex suggested superiority of active stimulation over sham (SMD -0.59, 95% CI -1.10 to -0.08).

Non-invasive brain stimulation appears to be associated with minor and transient side effects.

Authors' conclusions

Single doses of high-frequency rTMS of the motor cortex may have small short-term effects on chronic pain. The effects do not clearly exceed the predetermined threshold of minimal clinical significance. Low-frequency rTMS is not effective in the treatment of chronic pain. There is insufficient evidence from which to draw firm conclusions regarding the efficacy of CES or tDCS. The available evidence suggests that tDCS applied to the motor cortex may have short-term effects on chronic pain and that CES may be ineffective. There is a need for further, rigorously designed studies of all types of stimulation.

 

Plain language summary

  1. Top of page
  2. Abstract
  3. Plain language summary
  4. Resumen

Stimulating the brain without surgery in the management of chronic pain

Various devices are available that can electrically stimulate the brain without the need for surgery or any invasive treatment. There are three main treatment types: repetitive transcranial magnetic stimulation (rTMS) in which the brain is stimulated by a coil applied to the scalp, cranial electrotherapy stimulation (CES) in which electrodes are clipped to the ears or applied to the scalp and transcranial direct current stimulation (tDCS), in which electrodes are applied to the scalp. These have been used to try to reduce pain by aiming to alter the activity of the brain but the efficacy of these treatments is uncertain.

This review included 33 studies, 19 of rTMS, eight of CES and six of tDCS. Only one study was judged as having a low risk of bias. Analysis suggests that low-frequency rTMS is not effective but that a single-dose of high-frequency stimulation of the motor cortex area of the brain provides short-term pain relief. This effect appears to be small. There is limited and conflicting evidence from studies involving multiple doses of rTMS. Most studies of rTMS are small and there is substantial variation between studies in terms of the treatment methods used.

There was insufficient evidence from which to draw strong conclusions regarding CES or tDCS but the available evidence does not suggest that CES is an effective treatment. There is limited evidence that tDCS to the motor cortex may have short-term effects on chronic pain but it is not possible to estimate the size of this effect accurately.

The reporting of side effects varied across the studies. Of the studies that clearly reported side effects only short-lived and minor side effects such as headache, nausea and skin irritation were reported.

More studies of rigorous design and adequate size are required to evaluate all forms of non-invasive brain stimulation for the treatment of chronic pain accurately.

 

Resumen

  1. Top of page
  2. Abstract
  3. Plain language summary
  4. Resumen

Antecedentes

Técnicas no invasivas de estimulación cerebral para el dolor crónico

Las técnicas no invasivas de estimulación cerebral se dirigen a inducir una estimulación eléctrica del cerebro con el fin de reducir el dolor crónico al alterar directamente la actividad cerebral. Incluyen estimulación magnética transcraneal repetitiva, estimulación craneal con electroterapia y estimulación transcraneal por corriente directa.

Objetivos

Evaluar la eficacia de las técnicas no invasivas de estimulación cerebral para el dolor crónico.

Estrategia de búsqueda

Se realizaron búsquedas en CENTRAL, MEDLINE, EMBASE, CINAHL, PsycINFO, LILACS, el Registro de ensayos del Grupo Cochrane PaPaS y los registros de ensayos clínicos.

Criterios de selección

Estudios con asignación aleatoria y cuasialeatorios de estimulación magnética transcraneal repetitiva, estimulación craneal con electroterapia o estimulación transcraneal por corriente directa si usaron un grupo control de estimulación simulada, incluyeron pacientes mayores de 18 años con dolor de tres meses o más de duración y midieron el dolor como un resultado primario.

Obtención y análisis de los datos

Dos autores, de forma independiente, extrajeron y verificaron los datos. De ser posible, se introdujeron los datos en los metanálisis. Se excluyeron del análisis los estudios considerados de alto riesgo de sesgo.

Resultados principales

Se incluyeron 33 ensayos en la revisión (con 937 participantes) (19 de estimulación magnética transcraneal repetitiva, ocho de estimulación craneal con electroterapia y seis de estimulación transcraneal por corriente directa). Sólo un estudio se consideró con bajo riesgo de sesgo.

Los estudios de estimulación magnética transcraneal repetitiva (con 368 participantes) mostraron una heterogeneidad significativa. Los análisis de subgrupos preespecificados indican que la estimulación de baja frecuencia no es efectiva. Se sugirió un efecto a corto plazo en el dolor a partir de la estimulación activa de alta frecuencia de la corteza motora en los estudios de dosis única (diferencia de medias estandarizada [DME] −0,40, intervalo de confianza [IC] del 95%: −0,26 a −0,54; p < 0,00001). Esto equivale a una reducción de 15% (IC del 95%: 10% a 20%) del dolor que claramente no excede los criterios prestablecidos para una diferencia mínima y clínicamente importante (> 15%).

Para la estimulación craneal con electroterapia (cuatro estudios, 133 participantes), no se encontraron diferencias estadísticamente significativas entre la estimulación activa y la simulada. El análisis de los estudios de estimulación transcraneal por corriente directa (cinco estudios, 83 participantes) mostró heterogeneidad significativa y no encontró una diferencia significativa entre la estimulación activa y la simulada. El análisis de subgrupos preespecificado de estimulación transcraneal por corriente directa aplicada a la corteza motora indicó superioridad de la estimulación activa sobre la simulada (DME −0,59; IC del 95%: −1,10 a −0,08).

La estimulación cerebral no invasiva parece asociarse con efectos secundarios menores y transitorios.

Conclusiones de los autores

Las dosis únicas de estimulación magnética transcraneal repetitiva de alta frecuencia de la corteza motora pueden tener efectos a corto plazo pequeños en el dolor crónico. Los efectos no exceden claramente el umbral predeterminado de significación clínica mínima. La estimulación magnética transcraneal repetitiva de baja frecuencia no es efectiva para el tratamiento del dolor crónico. No existen pruebas suficientes para establecer conclusiones sólidas con respecto a la eficacia de la estimulación craneal con electroterapia o la estimulación transcraneal por corriente directa. Las pruebas disponibles indican que la estimulación transcraneal por corriente directa aplicada a la corteza motora puede tener efectos a corto plazo en el dolor crónico y que la estimulación craneal con electroterapia posiblemente no sea efectiva. Se necesitan más estudios rigurosamente diseñados de todos los tipos de estimulación.

Traducción

Traducción realizada por el Centro Cochrane Iberoamericano

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