Background & Aims

High frequency repetitive transcranial magnetic stimulation (rTMS) has been shown to produce analgesic effects in chronic pain populations (Wasserman et al, 2012). Recent studies on otherwise healthy individuals experiencing sustained pain induced by intramuscular injection of nerve growth factor (NGF) have shown analgesic effects of 5 consecutive days of 10Hz rTMS delivered after pain has peaked (Cavaleri et al. 2019). One unexplored question is whether rTMS delivered before pain begins can influence pain severity. This is an important question, as it would provide preliminary evidence as to whether rTMS can be used as a preventative pain intervention (e.g. for post-operative pain). The present study aimed to investigate whether individuals who receive 5 consecutive days of active rTMS prior to NGF-induced temporomandibular pain, subsequently experience lower pain severity, , functional limitation and muscle soreness, compared to those who receive sham rTMS.

Methods

A longitudinal, parallel design was used to follow 40 healthy individuals for a period of 26 days. On each day from Day 0-4, participants received a single session of active (n = 21) or sham (n = 19) rTMS over the left primary motor cortex (10Hz, 30 trains, 3000 pulses). An intramuscular injection of NGF was administered to the right masseter muscle after the final rTMS session. From Days 5-25, participants completed twice daily electronic dairies comprising measures of pain, functional limitation of jaw movement and muscle soreness.

Results

A mixed-model analysis of variance (ANOVA) with factors time (Day 5-25) and group (active vs. sham) demonstrated significantly lower pain during chewing, F(1, 38) = 5.24, p = .028, and yawning , F(1, 38) = 9.65, p = .004, in the active group compared to the sham group. Further, compared to those in the sham group , participants in the active rTMS group demonstrated expedited recovery of pain (i.e. significant group x time interaction) for pain while chewing, F(41,1558) = 4.174, p < 0.001, yawning, F(41,1558) = 3.457, p < 0.001, and talking, F(41, 1558) = 1.73, p = .003 and expedited recovery of functional impairment in jaw mobility, F(41, 1558) = 2.43, p<.001.

Conclusions

The delivery of 5 consecutive daily sessions of rTMS prior to the experience of sustained, experimentally induced orofacial pain led to reduced pain and expedited recovery from pain and functional impairment. These preliminary data suggest rTMS may have potential as a preventative intervention. This has implications for contexts such as post-surgical pain, such that rTMS delivered prior to surgery could have subsequent analgesic effects and improve patient recovery.

References

Wassermann, E. and T. Zimmermann, Transcranial magnetic brain stimulation: therapeutic promises and scientific gaps. Pharmacology & Therapeutics, 2012. 133(1): p. 98–107.

Cavaleri, R., et al., Repetitive transcranial magnetic stimulation of the primary motor cortex expedites recovery in the transition from acute to sustained experimental pain: a randomised, controlled study. Pain, 2019. 160(11): p. 2624-2633.

Presenting Author

Nahian Chowdhury

Poster Authors

Nahian Chowdhury, PhD

PhD

University of Sydney

Lead Author

E-mail

Khandoker Taseen (B. Science Hons)

Neuroscience Research Australia

Lead Author

E-mail

Alan K.I. Chiang

PhD

Neuroscience Research Australia, Sydney, Australia

Lead Author

E-mail

Wei-Ju Chang

PhD

Universidy of Newcastle, Callaghan, Australia

Lead Author

E-mail

Samantha Millard (PhD)

Aalborg University

Lead Author

E-mail

David Seminowicz (PhD)

University of Western Ontario

Lead Author

E-mail

Siobhan Schabrun

University of Western Ontario

Lead Author

E-mail

Topics

  • Mechanisms: Biological-Systems (Physiology/Anatomy)