Trigger Point Injection for Myofascial Pain Syndrome in the Low Back (T-PIMPS): A Randomized Controlled Trial.

Significance: Low back pain (LBP) is a common presenting complaint in the Emergency Department (ED), accounting for 2.63 million visits in the united states and 2.3 percent of ED visits annually.1 An estimated 100 billion dollars per year is lost from low back pain. One-third of this is direct costs.2 For the United States military, in 2015, 195,844 acute cases of LBP were identified, leading to significant loss of person-hours.3 The definitions of durations, or types, of LBP vary among sources. For example, the American Association of Family Physicians defines acute low back pain as six to 12 weeks of pain and chronic pain as anything more than 12 weeks.4 A more specific definition used by The American College of Physicians defines acute LBP from 0-4 weeks, subacute LBP as 5-12 weeks, and chronic low back pain as greater than 12 weeks.5 A specific definition of chronic low back pain is essential if including acute on chronic low back pain in a study. These specific definitions will not only be used for demographics, they will also aid in excluding other causes of LBP from the study such as fibromyalgia, rheumatoid arthritis, and ankylosing spondylitis.6,7 The investigators will include exacerbations of chronic LBP, but they will have to satisfy a specific definition. An excepted definition of an exacerbation of chronic low back pain is an increase of 1.5 cm above baseline pain on a 10 cm visual analog scale (VAS). The justification is that this is outside the standard deviation of typical back pain estimations.8 As this study of LBP focuses on TPIs, the investigators are narrowing the definition of LBP to myofascial pain syndrome (MPS) of the low back. The investigators chose this definition as MPS is defined by trigger points.9 Use of MPS is also consistent with prior TPI studies of LBP.10-15 The trigger points of MPS are recognized clinically by having two out of three of the following criteria: a taut band of muscle on exam, reproduction of pain upon palpation, and referred pain along a band of muscle upon palpation.16-18 The two most promising TPI studies previously conducted in the ED have been published in the last two years.19,20 They both suffered from a small sample size. Additionally, they suffered from a combination of limitations including: lack of randomization, inconsistent medical management, lack of a follow-up assessment, and lack of patient centered functional outcomes.19,20 These studies were both two armed and either compared standard medical management to TPI with local anesthetic or TPI with local anesthetic to TPI with Normal Saline (NS).19,20 One of these studies concluded that TPIs are generally beneficial.19 The other concluded that TPIs with NS are superior.20 The investigators endeavor to complete a randomized controlled trial (RCT) that definitively answers whether TPIs with local anesthetic are superior to TPIs with NS in an ED setting. The investigators will also be comparing both of these treatments to standard therapy (ST). Bupivacaine was chosen as it is the longest acting commonly available local anesthetic in most EDs.21 The investigators hypothesize that TPIs with Bupivacaine are superior to TPIs with NS or ST. If the investigators are correct this simple and inexpensive treatment could have a large impact on the financial burden and loss in person-hours caused by MPS of the low back.1-3,21

Innovation:

The invistigators will innovate by building upon lessons learned from previous TPI studies for MPS conducted in the ED.19,20 The study has also been designed with the best practices of CONSORT standards in mind.22 Unlike previous studies, this RCT will include three groups, ST, ST plus TPI with Bupivacaine, and ST plus TPI with NS. Additionally, each of these treatment arms will be highly regimented to improve the quality of evidence the investigators produce. The investigators will also follow up with study participants via telephone at 60-72 hours to determine if the treatment provided more than temporary pain relief. Lastly, the investigators will incorporate a patient centered functional score.23 A measure of functional ability is particularly relevant to MPS given its associated cost in lost person-hours.2 To date, such an endeavor to investigate TPIs in the ED has not been undertaken.

Approach:

This study will be conducted in the Emergency Department at Madigan Army Medical Center on Joint Base Lewis-McChord in Tacoma, WA. This is an academic center and level II trauma center with an annual Emergency Department census of 60,000. It is home to an Emergency Medicine Residency program and serves as a tertiary referral center for Department of Defense personnel in the Pacific Region. This study has approval from the local Institutional Review Board.