Secondary hyperalgesia in chronic nonspecific low back pain Fabio Marcon Alfieri1, Karoline Mayara de Aquiles Bernardo2 ORIGINAL ARTICLE ABSTRACT Objective:Secondary hyperalgesia may be present in chronic nonspecific low back pain. The study compared pressure pain threshold (PPT) in the lumbar and thoracic paravertebral muscles in indi- viduals with non-specific chronic low back pain correlating them with disability, functional mobil- ity, age and body mass index. Method: This is a cross-sectional study involving individuals of both sexes diagnosed with non-specific chronic low back pain, aged between 18 and 65 years, with pain of moderate to severe intensity and with pain time of ≥ 12 weeks. The volunteers were evaluated for pain intensity through the Visual Analogue Scale (VAS), disability by the Roland Morris ques- tionnaire, functional mobility by the Timed Up and Go test, and pressure pain threshold (PPT) by algometry. We used the t-test and made Pearson’s correlation for data analysis that was done in the Graph Pad Instat program. Results: Fifty individuals (53.75 ± 13.65 years) participated in the study, and when comparing PPT values between the thoracic and lumbar regions, no significant difference was observed (p = 0.19). Moderate correlation was observed only between lumbar and thoracic PPT (r = 0.65). Other correlations, though some significant, were all weak. Conclusion: The data from this study allow us to conclude that individuals with chronic low back pain may pres- ent with secondary hyperalgesia, since the individuals presented similar values between the lum- bar and thoracic PPTs, in addition to having a significant correlation between these two measures. Keywords: Hyperalgesia, Low Back Pain, Pain Measurement 1 Docente, Coordenador do Curso de Mestrado em Promoção da Saúde, Centro Universitário Adventista de São Paulo – UNASP. 2 Discente, Curso de Fisioterapia, Centro Universitário Adventista de São Paulo – UNASP. Mailing address: Centro Universitário Adventista de São Paulo Fábio Marcon Alfieri Estrada de Itapecerica, 5859 São Paulo – SP CEP 05858-001 E-mail: [email protected] Received on April 27, 2017. Accepted on May 23, 2017. DOI: 10.5935/0104-7795.20170008 40 Acta Fisiatr. 2017;24(1):40-43 Bernardo KMA, Alfieri FM Secondary hyperalgesia in chronic nonspecific low back pain INTRODUCTION the disability assessed by the Roland Morris The functionality of the lumbar spine was questionnaire among individuals with chronic verified using the Roland Morris question- Considered a public health problem, low low back pain. These authors analyzed several naire. This questionnaire has 24 affirmative back pain can be defined as pain, tension sen- structures such as hip and lumbar spine mus- phrases, which are marked if they are applica- sation, stiffness located below the marginal cles, as well as the cutaneous regions repre- ble to the subjects’ daily life. Punctuation was ribs and above the lower gluteal fold. 1,2,3,4 Ac- sented. However, according to our knowledge, assigned to each sentence, with a minimum cording to the Global Burden of Disease Study, none of them evaluated the lumbar and tho- score of zero and a maximum, that is, total low back pain is the disease that occurs with racic paravertebral musculature. functional disability of 24 points.22 more frequency in the years lived with some The Timed Up & Go Test (TUG) was used kind of disability.5 Yet, it is complex and mul- to assess functional mobility. This test eval- tifactorial, which explains why 85-90% of pa- OBJECTIVE uates the level of mobility of the individual, tients with this disease do not have well-de- measuring in seconds the time spent by the fined pathological diagnoses.6,7,8,9 This study compared the threshold of pain volunteer to get up from a chair, without the Regarding the pathophysiology of chronic tolerance to pressure in the lumbar and tho- help of the arms; walk at a distance of 3 me- pain, central sensitization has been proposed racic paravertebral muscles in individuals with ters; turn around and return. At the beginning as a pathophysiological mechanism for its non-specific chronic low back pain correlating of the test, the volunteer was leaning against explanation. It refers to pain that persists or them with functionality, functional mobility, the back of the chair and, in the end, should arises as a result of processes and/or hyper- age and body mass index. lean back. The volunteer received the “go” in- sensitivity within diffuse neural networks of struction to perform the test; time was timed the central nervous system involved in noci- from the command voice to the moment the ception. This type of sensitization implies in METHOD volunteer rested his back on the back of the alterations of the peripheral impulses, occur- chair. The test was performed once for famil- ing reduction of the threshold or increase of The study was approved by the Research iarization and a second time for taking the the response to the stimuli. Ethics Committee of the Adventist University time spent.23 Thus, there is support for chronic condi- Center of São Paulo under number 1,221,945 Pressure pain threshold (PPT) was as- tions such as low back pain to alter the high and developed according to the resolutions sessed using the J Tech algometer (JTech Med- sensitivity of pain to painful stimuli.15 The sen- presented in Resolution 466 of the National ical, Salt Lake City, UT, USA). The algometer is sation of pressure pain may be important to Health Council. a hand device formed by a piston that contains determine the development of chronic mus- It is a cross-sectional observational study at its end a rubber of 1 cm2 in diameter, able culoskeletal disorders, therefore individuals in which 50 individuals of both sexes partic- to register, through the electronic device, the with non-specific chronic low back pain may ipated. Persons with a diagnosis of non-spe- pressure applied on a surface. Its reliability be with a lower threshold of pain tolerance cific chronic low back pain, aged between 18 was previously demonstrated. 24,25 than healthy individuals.16,17 A way of measur- and 65 years, with pain of moderate to severe For this evaluation, a pressure was ap- ing these painful points under pressure is by intensity on the visual analogue scale (VAS) ≥ plied at a constant velocity of 1kg/sec to the menas of a dolorimetry, which is the veritifica- 4 cm and with duration of ≥ 12 weeks were level where pain or discomfort was reported tion of the pain sensitivity throguh a minimal included in the study. This study did not in- by the volunteer who was in the ventral de- pressure that causes pain or discomfort in a clude those with: neurological deficits, equine cubitus position. The evaluated muscles were: certain region of the body18,19 This measure tail compression; previous history of trauma in paravertebral 2 centimeters distal lateral of can determine the pressure pain threshold the spine region; lumbar spine surgery; pelvic the vertebral column in the lumbar region at (PPT). 3,20 pain; pregnancy; associated rheumatic, onco- the level of the L4-L5 vertebral segment. To This technique has been used in studies logical or infectious diseases; severe psychi- evaluate the thoracic paravertebrae, the spine that seek to assess PPT in low back pain, such atric disorders; degenerative neuromuscular of the scapula was found and distanced 2cm as the study by Imamura et al.17 that com- diseases; metabolic diseases such as diabetes from its border. pared individuals with and without chronic and hyperthyroidism; coagulopathies (such as The reading was expressed in kg/cm². low back pain and found that those with low hemophilia and use of anticoagulants) and fe- During the evaluation the volunteer was in- back pain had lower PPT values ​​than those in- brile condition. structed to say “stop” as soon as the feeling dividuals considered healthy in almost all eval- The volunteers who agreed to participate of pressure went from unpleasant to painful. uated structures. signed the two-way informed consent form The final amount of applied pressure was re- Farasyn et al.20 found that there may be and were submitted to the evaluation of pain corded. muscular disorder in the lumbar region in intensity, functionality, functional mobility patients with non-specific chronic low back and pressure tolerance threshold. To verify Data analysis pain. Schenck et al.3 concluded that chronic the intensity of the pain, the visual analogue low back pain is not strongly associated with scale was applied, which consists of the evalu- The data were analyzed with the aid of the a generalized increase in the sensitivity of the ation of the pain intensity. To do this, we used statistical package Graphy Pad In Stat. (Gra- muscles and ligaments of the lumbar region. a 10 cm ruler, graduated as absence of pain ph Pad Software, San Diego, California, USA, Recently, Imamura et al.21 verified that (0) and pain of maximum intensity (10). The www.graphpad.com). Data are expressed as there are negative correlations between the volunteers were instructed to mark, in the mean and standard deviation. To compare the PPT and the pain intensity analyzed by the vi- mentioned rule, the place that showed the in- PPT between the thoracic and lumbar region, sual analogue scale and between the PPT and tensity of the pain, in a scale of 0-10. Student’s t test was used and to verify the 41 Acta Fisiatr. 2017;24(1):40-43 Bernardo KMA, Alfieri FM Secondary hyperalgesia in chronic nonspecific low back pain correlations between age, TUG, body mass in- Table 1. Sample general characteristics dex (BMI), PPT in the thoracic and lumbar re- Variables n 50 gions, Roland Morris Questionnaire and VAS, Age (years) 53.75±13.65 was made Pearson’s correlation, following Gender M/F 11/39 the following criteria: 0.0 <r <0.2: very weak correlation, 0.2 <r <0.4: weak correlation, 0.4 BMI (Kg/m²) 27.40±5.53 <r <0.6: moderate correlation, 0 , 6 <r <0.8: VAS (cm) 6.45±2.51 strong correlation, 0.8 <r ≤ 1.0: very strong TUG (s) 12.99±4.65 correlation.