Detection of central circuits implicated in the formation of novel pain memories

Frequency-Dependent Alterations in the Amplitude of Low-Frequency Fluctuations in Patients with Acute Pericoronitis: A Resting-State fMRI Study

Background

Acute pericoronitis (AP) is a common cause of odontogenic toothache. Pain significantly affects the structure and function of the brain, but alterations in spontaneous brain activity in patients with AP are unclear.

Purpose

To apply the amplitude of low-frequency fluctuations (ALFF) method in resting-state functional magnetic resonance imaging to investigate altered spontaneous brain activity characteristics in patients with AP in different frequency bands (typical, slow-4, and slow-5 bands) and assess their correlation with clinical scores.

Patients and Methods

Thirty-four right-handed patients with AP and 31 healthy controls (HC), matched for age, sex, education, and right-handedness, were enrolled. All subjects underwent resting-state functional magnetic resonance imaging. DPABI software was used for data preprocessing and extracting the ALFF values in different frequency bands. Subsequently, differences in ALFF values in the three bands were compared between the two groups. Correlation between ALFF values in the differential brain regions and clinical scores was assessed.

Results

In the typical band, ALFF values were higher in the left insula, left superior occipital gyrus, left inferior parietal lobule, left posterior cerebellar lobule, and right postcentral gyrus in the AP than in the HC group. In the slow-4 band, ALFF values in the left superior occipital gyrus, right superior occipital gyrus, and right middle occipital gyrus were higher, and those in the right cingulate gyrus and right superior temporal gyrus were lower in the AP than in the HC group. In the slow-5 band, the ALFF values in the left insula and left superior occipital gyrus were higher in the AP than in the HC group. The ALFF values of the typical bands in the left insula, left inferior parietal lobule, and right postcentral gyrus correlated negatively, those of the slow-4 band in the right middle occipital gyrus correlated positively, and those of the slow-5 band in the left insula correlated negatively with the visual analogue scale score in the AP group.

Conclusion

Our results suggested that the intrinsic brain activity of AP patients was abnormal and frequency-dependent. This provides new insights to explore the neurophysiological mechanisms of AP.

Altered spontaneous neural activity in experimental odontogenic pain: a resting-state functional MRI study

OBJECTIVE

This study aimed to evaluate the intrinsic cerebral activity alternations in experimental odontogenic pain with resting-state functional magnetic resonance imaging (fMRI).

MATERIALS AND METHODS

Forty-nine participants in an odontogenic pain group and 49 participants in control group underwent imaging using fMRI in this prospective study. Odontogenic pain was induced by experimental tooth movement. We calculated the fractional amplitude of low-frequency fluctuation (fALFF) value to evaluate regional cerebral function and compared it between the two groups utilizing a voxel-based two-sample t-test.

RESULTS

In comparison with the healthy controls, the participants in odontogenic pain group showed increased fALFF value in the left cerebellum, right posterior cingulate gyrus, and bilateral inferior temporal gyrus, as well as decreased fALFF in the medial prefrontal cortex, the left anterior cingulate cortex, bilateral angular gyrus, left inferior parietal cortex, middle temporal gyrus, and miscellaneous cerebral regions (P < 0.001 familywise error-corrected VOXEL > 100).

CONCLUSION

The present study showed abnormal cerebral activity in odontogenic pain, and reveled that the aberrant regional functional activities were mainly located within the default mode network. The finding could provide insight into the underlying neural mechanism of odontogenic pain. Registry of clinical trials (Trial number ChiCTR1800018589) - http://www.chictr.org.cn/showproj.aspx?proj=31424.

Molecular mechanism in trigeminal nerve and treatment methods related to orthodontic pain

BACKGROUND

Orthodontic treatment is the main treatment approach for malocclusion. Orthodontic pain is an inevitable undesirable adverse reaction during orthodontic treatment. It is reported orthodontic pain has become one of the most common reason that patients withdraw from orthodontic treatment. Therefore, understanding the underlying mechanism and finding treatment of orthodontic pain are in urgent need.

AIMS

This article aims to sort out the mechanisms and treatments of orthodontic pain, hoping to provide some ideas for future orthodontic pain relief.

MATERIALS

Tooth movement will cause local inflammation. Certain inflammatory factors and cytokines stimulating the trigeminal nerve and further generating pain perception, as well as drugs and molecular targeted therapy blocking nerve conduction pathways, will be reviewed in this article.

METHOD

We review and summaries current studies related to molecular mechanisms and treatment approaches in orthodontic pain control.

RESULTS

Orthodontics pain related influencing factors and molecular mechanisms has been introduced. Commonly used clinical methods in orthodontic pain control has been evaluated.

DISCUSSION

With the clarification of more molecular mechanisms, the direction of orthodontic pain treatment will shift to targeted drugs.

Cortical representation of experimental periodontal pain: a functional magnetic resonance imaging study

The aim of this study was to investigate central pain representations during loading of the periodontium induced by orthodontic and occlusal stress. Nineteen healthy male volunteers (25.7 ± 2.8 years) were tested on two consecutive days: after phenotyping (questionnaires) and determination of warmth (WPT) and heat (HPT) pain thresholds, functional magnetic resonance imaging was performed as event-related paradigm including 36 tooth clenchings of 3 s duration, alternating with rest periods varying between 20–30 s. The task was performed in absence (T1) and 24 h after placement of an elastic separator between the second bicuspid and the first molar on the right side of the lower jaw (T2). No significant changes in WPT and HPT were observed but pain ratings were significantly elevated at T2. Significantly elevated activation at T2, as compared to T1, was found in bilateral sensorimotor cortex, bilateral secondary sensory cortex, supplementary motor area, right rolandic operculum, and bilateral insula. Our data show for the first time in humans that periodontal stimulation, as tested by tooth clenching in the presence of an elastic separator, goes along with specific expressions of pain at behavioral and neuronal network levels. Findings supplement the existing neuroimaging literature on odontogenic pain.

Physical therapist guided active intervention of chronic temporomandibular disorder presenting as ear pain: A case report

This case report describes the successful physical therapy management of a 40-year-old female who presented with left ear pain referred from the temporomandibular joint. Diagnosis was primarily based on clinical examination findings and ruling out of red flags. Guidance was given on active self-care approaches consisting of pain neuroscience education designed with individualized pain curriculum, exercise therapy, manual therapy, and breathing exercises for a period of  sixweeks. Clinically meaningful improvements were obtained in the outcome measures of Numeric Pain Rating Scale (NPRS), Patient-Specific Functional Scale (PSFS), and Global Rating of Change (GROC) scale and progress in Pain-Self Efficacy Questionnaire (PSEQ) and Tampa Scale for Kinesiophobia (TSK) scores. Positive changes were achieved with functional activities (chewing, eating, yawing, brushing teeth and physical intimacy), and the patient was pain-free on discharge, which was maintained at a six-month follow-up.

Neuroimaging investigation of memory changes in migraine: a systematic review

BACKGROUND

Individuals with migraine usually complain about lower memory performance. Diagnostic methods such as neuroimaging may help in the understanding of possible morphologic and functional changes related to the memory of those individuals. Therefore, the aim of this review is to analyze the available literature on neuroimaging changes related to memory processing in migraine.

METHODS

We searched the following databases: Pubmed/Medline, Psycinfo, Science Direct, Cochrane and Web of Science. We used articles without restriction of year of publication. The combination of descriptors used for this systematic review of literature were Neuroimaging OR Imaging OR Brain AND Migraine OR Chronic Migraine AND Memory.

RESULTS

Of the 306 articles found, nine were selected and all used magnetic resonance imaging (MRI). The studies used structural and functional MRI techniques with a predominance of 3 Tesla equipment and T1-weighted images. According to the results obtained reported by these studies, migraine would alter the activity of memory-related structures, such as the hippocampus, insula and frontal, parietal and temporal cortices, thereby suggesting a possible mechanism by which migraine would influence memory, especially in relation to the memory of pain.

CONCLUSIONS

Migraine is associated to global dysfunction of multisensory integration and memory processing. This condition changes the activity of structures in various regions related to memory of pain, prospective memory, as well as in short- and long-term verbal and visuospatial memories. However, it is necessary to perform studies with larger samples in association with cognitive tests, and without the interference of medications to verify possible alterations and to draw more concrete conclusions.

Benefits of Implicit Regulation of Instructed Fear: Evidence From Neuroimaging and Functional Connectivity

Instructed fear, which denotes fearful emotions learned from others' verbal instructions, is an important form of fear acquisition in humans. Maladaptive instructed fear produces detrimental effects on health, but little is known about performing an efficient regulation of instructed fear and its underlying neural substrates. To address this question, 26 subjects performed an instructed fear task where emotional experiences and functional neuroimages were recorded during watching, explicit regulation (calmness imagination), and implicit regulation (calmness priming) conditions. Results indicated that implicit regulation decreased activity in the left amygdala and left insula for instructed fear; however, these effects were absent in explicit regulation. The implementation of implicit regulation did not increase activity in the frontoparietal control regions, while explicit regulation increased dorsolateral prefrontal cortex activity. Furthermore, implicit regulation increased functional connectivity between the right amygdala and right fusiform gyrus, and decreased functional connectivity between the right medial temporal gyrus and left inferior frontal gyrus, which are key nodes of memory retrieval and cognitive control networks, respectively. These findings suggest a favourable effect of implicit regulation on instructed fear, which is subserved by less involvement of control-related brain mechanisms.

Effect of mobilization with movement on lateral knee pain due to proximal tibiofibular joint hypomobility

This case report describes a 45-year-old female who presented with lateral knee pain over the right proximal tibiofibular joint (PTFJ) managed unsuccessfully with rest, medications, bracing, injection, and physiotherapy. Clinical diagnosis of PTFJ hypomobility was based on concordant symptom reproduction with palpatory tenderness, accessory motion testing, and restricted anterior glide of the fibula. Intervention consisted of Mulligan's mobilization with movement and taping over the right PTFJ with immediate improvements noticed in pain, range of motion, and function. The patient was seen twice a week and was discharged after four treatment sessions. A follow-up after 6 months revealed that the patient was pain free and fully functional.

Effect of a novel mobilization with movement procedure on anterolateral ankle impingement - A case report

This case report describes a 50-year-old male who presented with right anterolateral ankle pain managed unsuccessfully with rest, medications, bracing, injection, physical therapy, and massage therapy. Clinical diagnosis of anterolateral ankle impingement was based on concordant symptom reproduction with palpatory tenderness and a positive lateral synovial impingement test. This case report is a potential first time description of the successful management of anterolateral ankle impingement utilizing a novel Mulligan's mobilization with movement procedure (consisting of internal rotation of the distal tibia) and taping with immediate improvements noted in pain, range of motion, and function. The patient was seen twice a week and was discharged after four treatment sessions. A follow-up after 4 months revealed that the patient was pain free and fully functional.