Print version ISSN 1806-0013
Rev. dor vol.13 no.2 São Paulo Apr./June 2012
Pulsed radiofrequency to treat low back pain*
Alexandra Jesus de SouzaI; Márcia Carla MoreteII
and Student of the Pain Specialization Course, School of Nursing, Hospital
Israelita Albert Einstein. São Paulo, SP, Brazil
IIPain Specialist Nurse and Advisor of the Pain and Palliative Care Specialization Course, Institute of Teaching and Research, Hospital Israelita Albert Einstein. São Paulo, SP, Brazil
AND OBJECTIVES: Low back pain treatment may be either conservative or surgical. Current
guidelines recommend conservative treatment for most cases, with drugs and
rehabilitation, including physical medicine and psychological assistance.
Invasive procedures may be justified if there are evidences of short and long
term benefits, and minimally invasive techniques, such as radiofrequency, are
modern and effective to relieve this pain. This study aimed at searching
Brazilian literature about the use of pulsed radiofrequency to treat low back
CONTENTS: A literature survey was carried out with articles published from 2004 to 2010 in Portuguese and Spanish in LILACS, Scielo and Cochrane, Cinahl and Medline databases.
CONCLUSION: Pulsed radiofrequency is an effective method to treat chronic low back pain, with low incidence of complications.
Keywords: Low back pain, Pulsed radiofrequency treatment, Spine.
Low back pain is one of the most frequent reasons for general Orthopedics and Traumatology consultation. Chronic low back pain is defined as lasting for at least three months. Seventy percent to 80% of adults will have some low back pain episode along life, which is one of the most important medical and socio-economic problems of industrialized countries1-3.
Treatment of these patients should be individualized, based on an accurate diagnosis obtained through detailed history, adequate physical and neurological evaluation and with complementary tests when needed. Disc or discogenic pain is among the most frequent causes of chronic low back pain, along with facet arthritis, sacroiliitis and nonspecific radiculopathies.
Low back pain may be conservatively or surgically treated. In addition to treating the reason for pain whenever possible, some additional resources may be useful. Current guidelines recommend that initial treatment should be conservative for most cases, with drugs including anti-inflammatory and non-opioid analgesics, and mild and strong opioids, in general associated to a multidisciplinary rehabilitation program, including physical medicine and psychological assistance4.
Invasive procedures may be justified when there are evidences of short and long term benefits. Minimally invasive techniques are extremely current and have huge future perspectives1,4,5.
Radiofrequency is nothing more than an electromagnetic wave with frequency between 30 thousand and 3 million cycles/sec (30 Khz to 3000 Khz), that is, within radio waves frequency spectrum. Radiofrequency is applied by a 27 G electrode inserted through a special 22 G needle which exposes only its most distal part. The metal part not distally insulated is called active tip and its length may vary from 2 to 15 mm. The electric current is produced by a specialized generator on its terminals. Patient is connected to a dispersive plate, which sends the current back to the radiofrequency generator; so, the amount of current entering patient's body through the injury electrode should be equal to the current that will leave through the dispersive plate. This way, patient's body works as one element of the electric circuit4,6.
Shealy was the first to use radiofrequency to treat spinal pain in 1975. He injured the medial branch for facet pain in the lumbar or cervical region. The year 1980 was a landmark when small diameter electrodes started to be used to treat spinal pain, allowing injuries to be more circumscribed and making the procedure significantly less painful6.
The Idea of pulsed radiofrequency was developed in 1997. It is very similar to conventional radiofrequency in terms of producing and distributing energy to neighbor tissues. Its fundamental difference is that the generator, rather than emitting continuous waves, generates pulses of waves at defined intervals. A classic exposure to pulsed radiofrequency emits waves lasting 20 milliseconds, followed by 480 milliseconds of rest (2 active cycles/sec). During active periods, a wave frequency of approximately 500,00 Hz is fired. This way, the heat wave offered by the short exposure time is compensated by a prolonged wash-out period, enough to prevent significant temperature increase. Seldom the temperature goes beyond 42º C in this type of procedure, thus not causing neuronal injury. Its application field is neuropathic pain and its action mechanism is the persistent blockade of nociceptive transmission at medullar level7,8.
Radiofrequency treatment has been widely used in recent years. It is in general a minimally invasive procedure with selective targets, in general performed in outpatient settings and with very low incidence of complications and adverse effects, when performed by qualified and duly trained professionals6.
The understanding of how pulsed radiofrequency and its applications impact low back pain treatment and act on patients' quality of life may be a very important starting point for the search for further information about existing procedures to treat low back pain with minimally invasive techniques.
This study aimed at identifying national and international literature publications about the use of pulsed radiofrequency to treat low back pain.
This is a descriptive and retrospective literature review, following stages recommended for studies of such nature. Articles published between 2004 and 2010 in Portuguese and Spanish were included. The following databases were queried: LILACS, Scielo, Cochrane, Cinahl and Medline. Narrative literature reviews, systematic literature reviews, field research, experience reports and case reports were included, regardless of authors' qualification. Keywords used were: Low back pain, Pain and Radiofrequency.
The authors have developed a semi-structured scheme, as follows: article identification data, methodological features, sample, results and conclusions.
PICO methodology was used, which allows clarifying the issue, identifying needed information to give the answer, translating it in researchable terms, developing and refininge the research strategy and also recognizing some types of studies more adequate for each analyzed situation: P Patient/population/problem; I - Intervention; C - Comparison and O - Outcomes.
Data were collected throughout the year 2010. After identifying the articles, we have first evaluated their abstracts and then the whole article. After reading the articles and deciding to include them in the study, the scheme was filled out with research data.
Only complete studies addressing pulsed radiofrequency to treat low back pain were selected.
From 10 selected publications, eight were selected to give information about pulsed radiofrequency to treat low back pain.
From six evaluated articles, three were published in the last three years, which shows the increasing interest on the subject, and two were published in the international literature, which shows the need for more Brazilian studies on the subject. In terms of studies design, we have found two literature reviews, one comparative study, one prospective and comparative study, one observational perspective study and one retrospective analysis.
Chart 1 shows the summary of articles included in this research.
In evaluated studies, low back pain is mentioned as the most frequent cause of permanent disability in adults around 45 years of age, and as the second most common cause for looking for medical assistance. In some studies, the causes of chronic low back pain are imprecise and controversial when diagnosed only by physical evaluation, simple X-rays, CT, MRI and electroneuromyography. Diagnostic blocks are critical for the accurate diagnosis of low back pain, such as discographies or diagnostic block of the L2 root ganglion, indicated to confirm nonspecific discogenic pain.
Chronic low back pain specialists should accurately understand the anatomy of the region to identify potential sources of different painful syndromes affecting the back, such as sympathetic nervous system, dorsal root ganglion, lumbo-sacral roots, post-primary posterior branches, radicular veins and arteries, peri-radicular and epidural venous plexuses, upper bone marrow levels, vertebral ligaments and bone components of each mobile segment3,5,6.
A study from 2004 reports the inexistence in the literature of that time of studies using pulsed radiofrequency to treat lumbar radiculopathy. The selection of ten studies identified in this search shows the increasing interest in interventionist low back pain treatment with pulsed radiofrequency1.
Some studies classify pulsed radiofrequency as a non neurodestructive technique where tissues are exposed to an established temperature of 42 degrees and to a high-voltage magnetic field of 45 V, resulting in an intracellular biological effect affecting less myelinated fibers, such as sensory fibers. All evaluated studies, in comparative or randomized character, describe pulsed radiofrequency as an effective method to treat chronic low back pain with few complications2,3.
This survey shows the increasing interest in understanding interventionist procedures for low back pain through pulsed radiofrequency, however there is the need for further Brazilian studies on this technique to relief chronic low back pain.
Pulsed radiofrequency is an effective method to treat chronic low back pain, with few complications.
1. Abejón D, Delgado C, Nieto C, et al. Tratamiento de La radiculopatía lumbar com radiofrecuencia pulsada. Rev Soc Esp Dolor 2004;11(6):345-52. [ Links ]
2. Assis F, Amaral C, Tucci C, et al. Uso terapêutico da radiofreqüência pulsátil no gânglio dorsal da raiz de L2 na lombalgia discogênica. Columna 2009;;8(2):139-42. [ Links ]
3. Barreras-Tejeda M, Rodriguez-Celaya C, Santillana-Macedo MA. Tratamiento de dolor lumbar crónico mediante radiofrecuencia pulsada y aplicación de esteroides em forma epidural. Estudio comparativo. Columna 2011;29;9(1):24-9. [ Links ]
4. Almeida DB. Radiofreqüência: conceitos técnicos e aplicações. Rev Dor 2007;8(4): 1117-21. [ Links ]
5. Padrón F. Síndrome postlaminectomía lumbar I. Tratamiento del dolor mediante técnicas intervencionistas. Rev Neuroc 2007;18(6):468-77. [ Links ]
6. Braun Filho JL, Braun LM. Radiofrequência na dor crônica. Columna 2009;8(2):200-5. [ Links ]
7. Cánovas L, Castro M, Martínez-Salgado J, et al. Ciática: tratamiento con ozono intradiscal y radiofrecuencia del gânglio de la raíz dorsal frente a cada una de estas dos técnicas. Rev Soc Esp Dolor 2009;16(3):141-6. [ Links ]
8. Gutiérrez-Cruz AR, Hernández-Santos JR, Tenopala S, et al. Anuloplastia en el dolor lumbar de origen discógeno, experiência a corto plazo en el C.M.N. "20 de Novembre"; Reporte de 10 casos. Rev Soc Esp Dolor 2011;15(4):234-40. [ Links ]
9. Mailis A, Furlan A. Simpatectomía para el dolor neuropático (Revisión Cochrane traducida). En: La Biblioteca Cochrane Plus, 2008 Número 2. Oxford: Update Software Ltd. [ Links ]
Correspondence to: Submitted
in April 26, 2011. * Received from Hospital
Israelita Albert Einstein. São Paulo, SP.
Márcia Carla Morete
Rua Paraná, 291, Casa 03
11045-320 Santos, SP.
Accepted for publication in June 08, 2012.
in April 26, 2011.
* Received from Hospital Israelita Albert Einstein. São Paulo, SP.