Abstract
Acute pain is one of the most common symptoms shared among patients who have suffered from an orthopedic trauma such as an isolated upper limb fracture (IULF). Development of interventions with limited side effects aiming to prevent the installation of chronic pain is critical as persistent pain is associated with an increased risk of opioid dependence, medical complications, staggering financial burdens and diminished quality of life. Theta burst stimulation (TBS), a non-invasive magnetic brain stimulation technique with minimal side effects, has shown promising results in patients experiencing various types of chronic pain conditions as it precisely targets brain regions involved in pain processing. Surprisingly, its impact on acute pain has never been investigated. This study aims to assess longitudinal effects of a 10-day continuous TBS (cTBS) protocol applied in the acute phase of an IULF on key functional outcomes.
Patients with an IULF aged between 18 to 60 years old were recruited within 7 days post-accident at a Level I Trauma Center. Exclusion criteria included a history of brain injury, neurological disorders, musculoskeletal complications, and open fractures. In order to assess longitudinal changes, questionnaires measuring intensity and characteristics of pain (Numerical Rating Scale, NRS; McGill Pain Questionnaire, MPQ) as well as functional disability (DASH) were completed by all patients at three time points, namely prior to the start of the TBS program as well as 72 hours and 3 months post-intervention. Patients were randomly attributed to the active TBS protocol (active group) or to the placebo protocol (sham group). The stimulation site for each participant corresponded to the contralateral motor cortex of the injured arm.
Fifty patients were recruited (female: 24; age: 40.38 years old), of which 25 were in the active group and 25 were in the sham group. Both groups were equivalent based on age, sex, type of injury, and surgical procedures (p>0.05). The intervention protocol was introduced on average 6.18 days post-accident. In comparison to the sham group, the active group showed a significant decrease in pain intensity (NRS) at 72h (F=6.02; p=0.02) and 3-month (F=6.37; p=0.02) post-intervention. No group difference was found early-on (72h post) in regard to pain characteristics (MPQ; F=3.90; p=0.06) and functional disabilities (DASH; F=0.48; p= 0.49). At three-month post-intervention, the active group showed statistically significant improvement on the MPQ (F=5.02; p=0.04) and the DASH (F=5.88; p=0.02) compared to the placebo group. No complications related to the treatment were reported.
Results from this study show that patients who underwent active cTBS reported less pain and better functional states shortly after the end of the TBS protocol compared to sham patients and treatment effects were maintained at three months post-intervention. Given that acute pain intensity is an excellent predictor of chronic pain development, this safe technique available in numerous centers in Canada may help prevent chronic pain development when administered during the acute post-injury phase. Future studies should continue to investigate mechanisms involved to optimize this technique among the orthopedic trauma population and to reduce opioid consumption.
