The Relationship Between Corticomotor Reorganization and Acute Pain Severity: A Randomized, Controlled Study Using Rapid Transcranial Magnetic Stimulation Mapping

Abstract Objective Although acute pain has been shown to reduce corticomotor excitability, it remains unknown whether this response resolves over time or is related to symptom severity. Furthermore, acute pain research has relied upon data acquired from the cranial “hotspot,” which do not provide valuable information regarding reorganization, such as changes to the distribution of a painful muscle’s representation within M1. Using a novel, rapid transcranial magnetic stimulation (TMS) mapping method, this study aimed to 1) explore the temporal profile and variability of corticomotor reorganization in response to acute pain and 2) determine whether individual patterns of corticomotor reorganization are associated with differences in pain, sensitivity, and somatosensory organization. Methods Corticomotor (TMS maps), pain processing (pain intensity, pressure pain thresholds), and somatosensory (two-point discrimination, two-point estimation) outcomes were taken at baseline, immediately after injection (hypertonic [n = 20] or isotonic saline [n = 20]), and at pain resolution. Follow-up measures were recorded every 15 minutes until 90 minutes after injection. Results Corticomotor reorganization persisted at least 90 minutes after pain resolution. Corticomotor depression was associated with lower pain intensity than was corticomotor facilitation (r = 0.47 [P = 0.04]). These effects were not related to somatosensory reorganization or peripheral sensitization mechanisms. Conclusions Individual patterns of corticomotor reorganization during acute pain appear to be related to symptom severity, with early corticomotor depression possibly reflecting a protective response. These findings hold important implications for the management and potential prevention of pain chronicity. However, further research is required to determine whether these adaptations relate to long-term outcomes in clinical populations.

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Sterile water; a novel and promising human experimental muscle pain model

10.21203/rs.3.rs-26494/v1 ◽

2020 ◽

Author(s):

Sofia Louca Jounger ◽

Johanna Svedenlöf ◽

Reija Elenius ◽

Christoffer Källkrans ◽

Emil Scheid ◽

...

Keyword(s):

Pain Intensity ◽

Hypertonic Saline ◽

Intramuscular Injection ◽

Isotonic Saline ◽

Controlled Study ◽

Sterile Water ◽

Pain Model ◽

Pain Drawing ◽

Pressure Pain Thresholds ◽

Pain Duration

Abstract Background Intramuscular injection of hypertonic saline evokes pain with similar characteristics as clinical myalgia and is thus, considered a valid human experimental model. The aim of this study was to investigate if intramuscular injection of sterile water can be used as a human experimental pain model by comparing it with hypertonic and isotonic saline, and to analyze if the effects differ between men and women. Methods This randomized double blind and placebo-controlled study included 15 healthy women and 15 healthy age-matched men (mean (SD) age of 23.6 (2.4) years). The study comprised of three separate sessions, with at least one week of wash out between each session. Sterile water (i.e. the test-substance), hypertonic saline (active control), and isotonic saline (passive control) were injected intramuscularly into one of the masseter muscles in a randomized order. Pain intensity (VAS) was assessed every 15 th s after the injection and pain duration (s) as well as pain drawing area (au) were recorded. Pressure pain thresholds (kPa) were assessed every 5 min after injection during 30 min. Results All substances evoked pain ( P < 0001), but sterile water and hypertonic saline induced pain with higher intensity ( P < 0.001), longer duration ( P < 0.001), and larger pain drawing area ( P < 0.001) than isotonic saline. The pain intensity was higher for hypertonic saline than sterile water 45-165 s after injection ( P < 0.015), but there were no significant differences between them regarding maximum pain intensity, pain duration or pain drawing area. There was no significant difference in PPT values with time or between substances. The pain duration was longer in the men compared to the women for all substances ( P < 0.006), while the pain drawing area was larger in women after injection of hypertonic saline ( P < 0.003), but not after injection of the other substances. No other sex differences were found. Conclusion Injection of sterile water had similar effects as hypertonic saline on pain variables, but no effect on PPT. Hence, the model mimics clinical myalgia and may offer a novel and simpler alternative to hypertonic saline injections.

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Repeated buffered acidic saline infusion in the human masseter muscle as a putative experimental pain model

Scientific Reports ◽

10.1038/s41598-019-51670-3 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 1

Author(s):

Sofia Louca Jounger ◽

Niklas Eriksson ◽

Helena Lindskog ◽

Anna Oscarsson ◽

Vivian Simonsson ◽

...

Keyword(s):

Pain Intensity ◽

Muscle Pain ◽

Saline Solution ◽

Isotonic Saline ◽

Mouth Opening ◽

Saline Infusion ◽

Controlled Study ◽

Solution Ph ◽

Pressure Pain Thresholds ◽

Masseter Muscles

Abstract This study investigated if repeated buffered acidic saline infusions into the masseter muscles induced muscle pain and mechanical sensitization. Fourteen healthy men participated in this double-blind, randomized, and placebo-controlled study. Two repeated infusions (day 1 and 3) were given in the masseter muscles with either a buffered acidic saline solution (pH 5.2) or an isotonic saline solution (pH 6) as control. After 10 days of wash-out, the experiment was repeated with the other substance. Pressure pain thresholds (PPT), pain intensity, maximum unassisted mouth opening (MUO), and pain drawings were assessed before, directly following, and after each infusion at 5, 15, and 30 min and on day 4 and 7. Fatigue and pain intensity were assessed after a one-minute chewing test 30 min after infusions and day 4 and 7. Acidic saline induced higher pain intensity than control day 3 up to 5 min after infusions, but did not affect PPT. The chewing test did not evoke higher fatigue during chewing or MUO or after acidic saline infusion compared to control. Repeated acidic saline infusions in the masseter muscles induced a short-lasting muscle pain without mechanical hyperalgesia or functional pain. Hence, this model might not be superior to already existing experimental muscle pain models.

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A 3-Month, Follow-up, Randomized, Placebo-Controlled Study of Repetitive Transcranial Magnetic Stimulation in Depression

Yearbook of Psychiatry and Applied Mental Health ◽

10.1016/s0084-3970(08)70189-0 ◽

2006 ◽

Vol 2006 ◽

pp. 193-194

Author(s):

J.C. Ballenger

Keyword(s):

Transcranial Magnetic Stimulation ◽

Magnetic Stimulation ◽

Repetitive Transcranial Magnetic Stimulation ◽

Controlled Study

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Repetitive transcranial magnetic stimulation as a prophylactic treatment in migraine

The Egyptian Journal of Neurology Psychiatry and Neurosurgery ◽

10.1186/s41983-020-00254-4 ◽

2021 ◽

Vol 57 (1) ◽

Author(s):

Azza B. Hammad ◽

Rasha E. Elsharkawy ◽

Ghada S. Abdel Azim

Keyword(s):

Transcranial Magnetic Stimulation ◽

Serum Level ◽

Pain Intensity ◽

Magnetic Stimulation ◽

Prophylactic Treatment ◽

Repetitive Transcranial Magnetic Stimulation ◽

Low Frequency ◽

Control Group ◽

Neurokinin A ◽

Abortive Treatment

Abstract Background Clinical applications of transcranial magnetic stimulation (TMS) have shown promising results in the treatment of headache disorders, with migraine being one of the most encountered. Objective To assess the role of low-frequency repetitive transcranial magnetic stimulation as a preventive treatment of migraine (with and without aura) and correlate the results with the serum level of the inflammatory biomarker (neurokinin A). Methods Forty patients, with age ranging from 15 to 55 years, diagnosed with migraine (30 migraine without aura and 10 with aura) and 20 apparently healthy individuals, who were age and sex matched with the patient group, were included in this study. A low-frequency (1 Hz) rTMS protocol was applied for all patients for five consecutive days interictally. Assessment of pain intensity using visual analogue scale and frequency and duration of attacks as well as number of pills taken by patients as an abortive treatment according to the Basic Diagnostic Headache Diary for 4 weeks before and 4 weeks after TMS sessions was done. In addition, the Migraine Disability Assessment scale (MIDAS) was applied to assess the severity and degree of disability caused by migraine. Measurement of neurokinin A serum level was done by using ELISA for all patients before and after TMS and for control group once. Results There was a significant reduction in pain intensity, frequency and duration of migraine attacks, migraine disability scores, and number of pills taken as abortive treatment for attacks after rTMS (P < 0.001). Also, serum level of neurokinin A in the patients was significantly reduced after rTMS (P < 0.001). Conclusion Low-frequency rTMS is an effective prophylactic treatment for migraine with and without aura.

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