Effect of gender and hand laterality on pain processing in human neonates

Clinical application of repetitive transcranial magnetic stimulation in the treatment of chronic pelvic pain syndrome: a scoping review

Introduction

Chronic pelvic pain syndrome is a common condition characterized by persistent symptoms that are difficult to treat. Repetitive transcranial magnetic stimulation (rTMS) is considered a safe treatment option for alleviating chronic pelvic pain, but different stimulation protocols can affect pain relief outcomes. Establishing an optimal stimulation protocol can enhance the uniformity and consistency of rTMS to provide a potentially effective therapeutic intervention. This review sought to systematically review and assess the existing literature on transcranial magnetic stimulation in patients experiencing chronic pelvic pain syndrome, evaluate the therapeutic efficacy, and determine the most effective stimulation protocol.

Methods

A comprehensive search was conducted across three databases, supplemented by manual searches. Two researchers independently reviewed and extracted relevant studies and subsequently performed a thorough analysis of all available clinical data.

Results

A total of eight studies were ultimately incorporated into the analysis. These comprised two randomized controlled trials, one self-controlled trial, two case reports, and three prospective studies. All studies demonstrated a notable reduction in pain scores post-treatment.

Conclusion

rTMS has demonstrated efficacy in alleviating pain in individuals suffering from chronic pelvic pain syndrome. It is regarded as a safe intervention with minimal adverse effects. Nonetheless, the variability observed across studies hindered our ability to conclusively determine the most effective stimulation sites and parameters. Additional research is essential to reduce bias, enhance methodological rigor, and ascertain the optimal conditions and indications for brain stimulation to optimize the therapeutic effectiveness of rTMS.

Systematic Review Registration

https://inplasy.com/projects/, identifier INPLASY2023120112.

Functional near-infrared spectroscopy to assess pain in neonatal circumcisions

INTRODUCTION

Pain assessment is challenging in neonates. Behavioral and physiological pain scales do not assess neocortical nociception, essential to pain encoding and central pain pathway development. Functional near-infrared spectroscopy (fNIRS) can assess neocortical activation to noxious stimuli from changes in oxy-(HbO) and total-hemoglobin concentrations (HbT). This study aims to assess fNIRS nociceptive functional activation in the prefrontal cortex of neonates undergoing circumcision through changes in HbO and HbT, and the correlation between changes in fNIRS and Neonatal Infant Pain Scale (NIPS), a behavioral pain assessment scale.

METHODS

In healthy term neonates, HbO, HbT, and NIPS were recorded during sequential circumcision events 1-Prep before local anesthetic injection; 2-Local anesthetic injection; 3-Prep before incision; 4-Oral sucrose; 5-Incision; 6-Gomco (hemostatic device) attached; 7-Gomco twisted on; and 8-Gomco removed. fNIRS and NIPS changes after each event were assessed with Wilcoxon signed-rank test and summarized as median and interquartile range (IQR). Changes in fNIRS vs. NIPS were correlated with Spearman coefficient.

RESULTS

In 31 neonates fNIRS increased (median [IQR] µmol/L) with noxious events: Local injection (HbO: 1.1 [0.5, 3.1], p < .001; HbT: 2.3 [0.2, 7.6], p < .001), Gomco attached (HbO: 0.7 [0.1, 1.7], p = .002; HbT: 0.7 [-0.2, 2.9], p = .02), and Gomco twisted on (HbO: 0.5 [-0.2, 1.7], p = .03; HbT: 0.8 [-0.1, 3.3], p = .02). fNIRS decreased with non-noxious event: Prep before incision (HbO: -0.6 [-1.2, -0.2] p < .001; HbT: -1 [-1.8, -0.4], p < .001). Local anesthetic attenuated fNIRS increases to subsequent sharp stimuli. NIPS increased with subsequent sharp stimuli despite local anesthetic. Although fNIRS and NIPS changed in the same direction, there was not a strong correlation between them.

CONCLUSIONS

During neonatal circumcision, changes in fNIRS differed between different types of painful stimuli, which was not the case for NIPS, suggesting that fNIRS may complement NIPS to assess the quality of pain.

Shedding light on pain for the clinic: a comprehensive review of using functional near-infrared spectroscopy to monitor its process in the brain

ABSTRACT

Pain is a complex experience that involves sensation, emotion, and cognition. The subjectivity of the traditional pain measurement tools has expedited the interest in developing neuroimaging techniques to monitor pain objectively. Among noninvasive neuroimaging techniques, functional near-infrared spectroscopy (fNIRS) has balanced spatial and temporal resolution; yet, it is portable, quiet, and cost-effective. These features enable fNIRS to image the cortical mechanisms of pain in a clinical environment. In this article, we evaluated pain neuroimaging studies that used the fNIRS technique in the past decade. Starting from the experimental design, we reviewed the regions of interest, probe localization, data processing, and primary findings of these existing fNIRS studies. We also discussed the fNIRS imaging's potential as a brain surveillance technique for pain, in combination with artificial intelligence and extended reality techniques. We concluded that fNIRS is a brain imaging technique with great potential for objective pain assessment in the clinical environment.

The effect of eye dominancy on patients' cooperation and perceived pain during photorefractive keratectomy

PURPOSE

To find a possible association between patients' cooperation, perceived pain, and ocular dominance in patients who undergo photorefractive keratectomy (PRK).

METHODS

One hundred-one eligible candidates for PRK refractive surgery were recruited. Preoperative exams were performed for all patients, and the dominant eye was specified. The surgeon was unaware about which eye was dominant. After surgery, the surgeon completed a cooperation score form for each patient. Ocular cyclotorsion, cooperation, and perceived pain scores were compared between the first-second eye surgeries and between dominant-non-dominant eyes surgeries.

RESULTS

The dominant eye was the right eye in 68 patients and the left eye in 33 patients. First, eye surgery was performed on the dominant eye in 56 patients and on the non-dominant eye in 45 patients. Cooperation score and perceived pain were not significantly different between the first and second eye surgeries (P = 0.902 and P = 0.223, respectively), but cyclotorsion was more in the second eye (P = 0.031). Cooperation score, pain score, and cyclotorsion were not significantly different between dominant and non-dominant eye surgeries (P = 0.538, P = 0.581, and P = 0.193, respectively). Also, there was no correlation between cooperation score and duration of the surgery for the first or second eye (P = 0.12 and P = 0.78).

CONCLUSION

During PRK surgery, the patients' cooperation and perceived pain did not seem to be associated with eye laterality or dominancy.

Investigation of the Pattern of the Hemodynamic Response as Measured by Functional Near-Infrared Spectroscopy (fNIRS) Studies in Newborns, Less Than a Month Old: A Systematic Review

It has been 20 years since functional near-infrared spectroscopy (fNIRS) was first used to investigate the evoked hemodynamic response to a stimulus in newborns. The hemodynamic response to functional activation is well-established in adults, with an observed increase in concentration change of oxygenated hemoglobin (Δ[HbO2]) and decrease in deoxygenated hemoglobin (Δ[HHb]). However, functional studies in newborns have revealed a mixed response, particularly with Δ[HHb] where an inconsistent change in direction is observed. The reason for this heterogeneity is unknown, with potential explanations arising from differing physiology in the developing brain, or differences in instrumentation or methodology. The aim of this review is to collate the findings from studies that have employed fNIRS to monitor cerebral hemodynamics in term newborn infants aged 1 day-1 month. A total of 46 eligible studies were identified; some studies investigated more than one stimulus type, resulting in a total of 51 reported results. The NIRS parameters reported varied across studies with 50/51 cases reporting Δ[HbO2], 39/51 reporting Δ[HHb], and 13/51 reporting total hemoglobin concentration Δ[HbT] (Δ[HbO2] + Δ[HHb]). However, of the 39 cases reporting Δ[HHb] in graphs or tables, only 24 studies explicitly discussed the response (i.e., direction of change) of this variable. In the studies where the fNIRS responses were discussed, 46/51 cases observed an increase in Δ[HbO2], 7/51 observed an increase or varied Δ[HHb], and 2/51 reported a varied or negative Δ[HbT]. An increase in Δ[HbO2] and decrease or no change in Δ[HHb] was observed in 15 studies. By reviewing this body of literature, we have identified that the majority of research articles reported an increase in Δ[HbO2] across various functional tasks and did not report the response of Δ[HHb]. Confirming the normal, healthy hemodynamic response in newborns will allow identification of unhealthy patterns and their association to normal neurodevelopment.

Neurophysiological assessment of acute pain in infants: a scoping review of research methods

A systematic scoping search to describe the neurophysiological methods used in infant acute pain assessment research was conducted. Of the 2411 abstracts screened, 19 articles were retained. Nine studies utilised near-infrared spectroscopy (NIRS), two utilised functional magnetic resonance imaging (fMRI), and eight utilised electroencephalography (EEG). There was methodological variability in studies utilising NIRS, whereas EEG and fMRI studies reported consistent methods. Of the eight EEG studies, six identified a nociceptive-specific event-related potential.

CONCLUSION

While more methodologically rigorous studies are needed, ERPs appear to hold some promise as indicators of infant nociception during clinical procedures to supplement existing measures.

Pain and cooperation in patients having dominant-side or nondominant-side phacoemulsification

PURPOSE

To evaluate the relationship between laterality and perceived pain and cooperation during phacoemulsification under combined topical and intracameral anesthesia.

SETTING

University ophthalmology clinic and eye hospital, Kahramanmaraş, Turkey.

DESIGN

Cohort study.

METHODS

Seventy-eight patients with senile cataracts who had ocular surgery were included prospectively. The dominant side was determined with the Edinburg Handedness Inventory. Phacoemulsification and intraocular lens implantation were performed. The surgeon graded the patient's cooperation from 0 (best) to 3 (worst). The duration of surgery was recorded. Another researcher rated perceived pain from 0 (no pain) to 10 (unbearable pain) using a visual analogue scale (VAS). Pain scores and the degree of cooperation for dominant-side and nondominant-side surgery were the primary outcomes.

RESULTS

Forty-six patients had surgery in the dominant eye and 32 in the nondominant eye. The 2 groups were similar in age, sex, and severity and type of cataract. The mean VAS score was significantly higher in patients having dominant-side surgery than in those having nondominant-side surgery (P<.01). Similarly, the mean cooperation score was significantly poorer in the patients having dominant-side surgery (P<.05). Visual analogue scores were correlated with patient cooperation (r = 0.890, P<.0001).

CONCLUSION

Pain scores were higher in dominant-side surgery for cataract under topical and intracameral anesthesia, which should be kept in mind when selecting anesthesia and in studies in which pain is scored.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Frequency of counterstrain tender points in osteopathic medical students

CONTEXT

Counterstrain is 1 osteopathic manipulative treatment technique taught to osteopathic medical students, but teaching all 300 counterstrain tender points is not feasible at most colleges of osteopathic medicine (COMs) because of time limitations.

OBJECTIVE

To identify high-yield tender points in osteopathic medical students for teaching and to assess for correlations between tender points and demographic information, weight, and history of pain or trauma.

METHODS

First- and second-year osteopathic medical students at 5 COMs were surveyed regarding the presence and absence of tender points found on themselves by fellow students. Demographic information, weight, and history of pain and trauma data were collected. The McNemar test was used to compare the frequency of positive tender points between the right and left sides. Multiple logistic regression models were fit to the data to determine if participant characteristics were related to having 1 or more positive tender points in a tender point group. Wilcoxon signed rank tests were used to compare the percentage of positive anterior vs posterior tender points. Multiple logistic regression models were used to test for differences between COMs after accounting for differences in participant characteristics.

RESULTS

Frequency of 78 tender point groups was obtained. Forty tender point groups (51%) were positive for the presence of 1 or more tender points by 50% or more of the participants. Positive tender points were more common on the right side for 23 groups (all P<.001). Female participants were more likely to have tender points for 22 groups (all P<.001). The 20- to 25-year-olds had more tender points for 6 groups (all P≤.03). Tender points were more common in participants with a history of pain for 29 groups (all P<.001) and with a history of trauma for 4 groups (all P≤.05). Anterior tender points were more common for cervical, thoracic, rib, and lumbar body regions (P<.001). Differences were found between COMs for all tender point groups (P≤.02).

CONCLUSION

Nearly half of the tender point groups surveyed were reported positive by 50% or more of participants, and high-yield tender points were found in each body region. Ultimately, these results may guide counterstrain curricula for COMs.

Her versus his migraine: multiple sex differences in brain function and structure

Migraine is twice as common in females as in males, but the mechanisms behind this difference are still poorly understood. We used high-field magnetic resonance imaging in male and female age-matched interictal (migraine free) migraineurs and matched healthy controls to determine alterations in brain structure. Female migraineurs had thicker posterior insula and precuneus cortices compared with male migraineurs and healthy controls of both sexes. Furthermore, evaluation of functional responses to heat within the migraine groups indicated concurrent functional differences in male and female migraineurs and a sex-specific pattern of functional connectivity of these two regions with the rest of the brain. The results support the notion of a 'sex phenotype' in migraine and indicate that brains are differentially affected by migraine in females compared with males. Furthermore, the results also support the notion that sex differences involve both brain structure as well as functional circuits, in that emotional circuitry compared with sensory processing appears involved to a greater degree in female than male migraineurs.