Altered central sensitization in subgroups of women with vulvodynia

Vestibulodynia Presentation is Differentiated by the Presence of Additional Chronic Primary Pain Conditions

Vestibulodynia (VBD) is a common chronic primary pain condition (CPPC) defined by the presence of recurrent vulvovaginal pain with no obvious root cause. As many as 3 in 4 women with VBD may have co-occurring CPPCs, such as episodic migraine, fibromyalgia, irritable bowel syndrome, and temporomandibular disorder. The purpose of the present study was to compare pain and pain-related factors in women with VBD alone and those with VBD and co-occurring CPPCs (VBD+). We enrolled 45 women with VBD, 106 with VBD+, and 198 pain-free controls, who underwent a highly specific gynecological examination, quantitative sensory testing at remote body sites, and completed an extensive array of questionnaires assessing various physical and psychological experiences. Blood samples were also collected for genome-wide association study (GWAS). Results demonstrated that women with VBD+ had distinct patterns of heightened local vulvovaginal pain intensity and increased pain sensitivity at remote body site compared to those with VBD. Further women with VBD+ reported taking more medications indicated for pain and greater adverse mood states, somatic and psychological symptoms, and pain catastrophizing. Finally, case-control GWAS analysis identified distinct genetic variants associated with VBD and VBD+ subtypes. Variants associated with VBD were located in genes that regulate reproductive and nervous system development, while those associated with VBD+ were located in genes implicated in synaptic transmission and related CPPC pathophysiology. Together, these findings emphasize the critical need for accounting for CPPC status in VBD diagnostic, mechanistic, and therapeutic methodologies. Perspective This study identifies co-occurring chronic primary pain conditions as a differentiating factor in vestibulodynia presentation, highlighting the need for precise diagnostic criteria and personalized treatment approaches to address heightened symptom burden and complexity.

Impact of deep or ovarian endometriosis on pelvic pain and quality of life: prospective cross-sectional ultrasound study

OBJECTIVE

To assess whether premenopausal women diagnosed with deep or ovarian endometriosis on transvaginal sonography (TVS) were more likely to suffer from dyspareunia and pelvic pain symptoms, and have a lower quality of life, compared to women without sonographically diagnosed deep or ovarian endometriosis.

METHODS

This was a prospective, cross-sectional study carried out between February 2019 and October 2020 at the general gynecology clinic at University College London Hospital, London, UK. All premenopausal women aged 18-50 years, who were examined consecutively by a single experienced examiner and underwent a detailed TVS scan, were eligible for inclusion. Pregnant women and those who had received a previous diagnosis of endometriosis or who had experienced a hysterectomy or unilateral/bilateral oophorectomy were excluded. Sonographic findings consistent with deep or ovarian endometriosis were noted. All women completed the British Society of Gynaecological Endoscopy pelvic pain questionnaire. The primary outcome was to determine whether women with sonographic evidence of endometriosis were more likely to experience moderate-to-severe levels of dyspareunia (score of ≥ 4 on an 11-point numerical rating scale (NRS)). Secondary outcomes included assessing moderate-to-severe levels of other pelvic pain symptoms (NRS score of ≥ 4), bowel symptoms (score of ≥ 2 on a 5-point Likert scale) and quality of life, which was measured using the EuroQol-5D-3L (EQ-5D) questionnaire. The number of women with pain scores ≥ 4 and bowel scores ≥ 2, as well as the mean EQ-5D scores, were compared between the group with and that without sonographic evidence of endometriosis using logistic regression analysis, and multivariable analysis was used to adjust for demographic and clinical variables.

RESULTS

A total of 514 women were included in the final study population, of whom 146 (28.4%) were diagnosed with deep or ovarian endometriosis on TVS. On multivariable analysis, the presence of moderate-to-severe dyspareunia was not found to be associated with endometriosis. Moderate-to-severe dyspareunia was significantly associated with lower age (odds ratio (OR), 0.70 (95% CI, 0.56-0.89); P = 0.003) and a history of migraine (OR, 3.52 (95% CI, 1.42-8.77); P = 0.007), and it occurred significantly less frequently in women with non-endometriotic ovarian cysts (OR, 0.47 (95% CI, 0.28-0.78); P = 0.003). There was also a trend towards a positive association between anxiety/depression and moderate-to-severe dyspareunia (OR, 1.94 (95% CI, 0.93-4.03); P = 0.08). Following multivariable analysis, the only symptoms that were significantly more common in women with endometriosis compared to those without were menstrual dyschezia (OR, 2.44 (95% CI, 1.59-3.78); P < 0.001) and difficulty emptying the bladder (OR, 2.56 (95% CI, 1.52-4.31); P < 0.001). Although not reaching statistical significance on multivariable analysis, dysmenorrhea (OR, 1.72 (95% CI, 0.92-3.20); P = 0.09) and lower EQ-5D score (mean ± SD, 0.67 ± 0.33 vs 0.72 ± 0.28; P = 0.06) also occurred more frequently in women with sonographic evidence of endometriosis.

CONCLUSIONS

The majority of pelvic pain symptoms did not differ significantly between women with and those without sonographic evidence of endometriosis, indicating that endometriosis may not always be the source of pelvic pain, even if present. This highlights the need to rule out other causes of pain in symptomatic endometriosis patients before considering surgical procedures, and to provide appropriate patient counseling. © 2024 The Author(s). Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Central sensitization symptoms in vulvodynia: exploring the role of temperament, personality traits, childhood adverse events, defense mechanisms, and mental pain on quality of life

BACKGROUND

Vulvodynia is a chronic pain syndrome characterized by persistent vulvar pain, occurring without clinically identifiable disorders. Central sensitization (CS) is suggested to play a role in the pathophysiology of vulvodynia, as for other nociplastic pain conditions.

AIM

This study delves into the complex interplay between psychosocial factors and CS burden in women with vulvodynia, aiming to identify potential predictors (temperament, personality traits, childhood adverse events, defense mechanisms, and mental pain) and understand their impact on quality of life (QoL).

METHODS

A cohort-based cross-sectional web survey of 357 women with vulvodynia.

OUTCOMES

Outcomes included 8 self-report measures to assess the Central Sensitization Inventory (CSI) and psychological variables, including sensory processing sensitivity, traumatic experiences, personality traits, defense mechanisms, and mental pain.

RESULTS

Hierarchical multiple regression analyses were conducted in study 1, revealing that the following predicted higher CSI scores in women with vulvodynia: higher emotional overexcitability, decreased low sensory threshold, increased bodily threat experiences, elevated psychoticism, greater use of immature and neurotic defense mechanisms, and heightened mental pain. The final regression model identified the following as the strongest predictors of CS: low sensory threshold (β = 0.316), bodily threat experiences (β = 0.145), neurotic defenses (β = 0.210), and mental pain (β = 0.269). In study 2, the model presented interactions among these psychological factors in predicting CSI values explaining 48.9% of the variance in CS, 30.3% in psychological QoL, and 57.1% in physical QoL.

CLINICAL TRANSLATION

This model opens discussion for tailored psychological interventions aimed to improve overall QoL in women with vulvodynia.

STRENGTHS AND LIMITATIONS

Strengths of the study include innovative insights into the interplay between psychological variables and the construct of CS and quality of life. As a limitation, the research was conducted as a cross-sectional study with self-reported measures.

CONCLUSION

The study calls for comprehensive assessments that consider physical and mental aspects, paving the way for holistic health care approaches in the management of vulvodynia.

6-Methoxyflavone antagonizes chronic constriction injury and diabetes associated neuropathic nociception expression

Neuropathy is a disturbance of function or a pathological change in nerves causing poor health and quality of life. A proportion of chronic pain patients in the community suffer persistent neuropathic pain symptoms because current drug therapies may be suboptimal so there is a need for new therapeutic modalities. This study investigated the neuroprotective flavonoid, 6-methoxyflavone (6MF), as a potential therapeutic agent and gabapentin as the standard comparator, against neuropathic models. Thus, neuropathic-like states were induced in Sprague-Dawley rats using sciatic nerve chronic constriction injury (CCI) mononeuropathy and systemic administration of streptozotocin (STZ) to induce polyneuropathy. Subsequent behaviors reflecting allodynia, hyperalgesia, and vulvodynia were assessed and any possible motoric side-effects were evaluated including locomotor activity, as well as rotarod discoordination and gait disruption. 6MF (25-75 mg/kg) antagonized neuropathic-like nociceptive behaviors including static- (pressure) and dynamic- (light brushing) hindpaw allodynia plus heat/cold and pressure hyperalgesia in the CCI and STZ models. 6MF also reduced static and dynamic components of vulvodynia in the STZ induced polyneuropathy model. Additionally, 6MF reversed CCI and STZ suppression of locomotor activity and rotarod discoordination, suggesting a beneficial activity on motor side effects, in contrast to gabapentin. Hence, 6MF possesses anti-neuropathic-like activity not only against different nociceptive modalities but also impairment of motoric side effects.

Immunohistochemical staining with CD117 and PGP9.5 of excised vestibular tissue from patients with neuroproliferative vestibulodynia

BACKGROUND

Neuroproliferative vestibulodynia (NPV), a provoked genital pain characterized by severe allodynia and hyperalgesia, is confirmed in excised vestibular tissue by immunohistochemical staining (>8 CD117-positive immunostained cells/100× microscopic field) rather than by hematoxylin and eosin staining.

AIM

In this study we sought to assess immunostaining of tissue samples obtained during vestibulectomy surgery and to correlate results with patient outcomes.

METHODS

Patients (n = 65) meeting criteria for NPV who underwent vestibulectomy during the period from June 2019 through December 2022 formed the study cohort. We performed assessment of pathology of vestibular tissues by use of immunohistochemical staining, including quantitation of mast cells by CD117 (mast cell marker) and nerve fibers by protein gene product (PGP) 9.5 (neuronal marker). We analyzed 725 photomicrographs of immunostained tissue sections (100× and 200×) by manual counting and computer-assisted histometry and correlated these data to clinical assessments.

OUTCOMES

Outcomes included density of CD117 and PGP9.5 immunostaining in the 1:00-11:00 o'clock and 12:00 o'clock vestibular regions, and patient-reported outcomes assessing sexual function, pain, distress, and symptom improvement.

RESULTS

All 65 NPV patients (median age 26 years), 45 with lifelong and 20 with acquired NPV, had severe pain documented by PROs and vulvoscopy and had >8 CD117-immunopositive cells/100× microscopic field. Median cell count values were similar in the 1:00-11:00 o'clock and 12:00 vestibular regions (28.5 and 29.5/100× field, respectively). Likewise, the marker) and nerve fibers by protein gene product (PGP) 9.5 (neuronal marker). We analyzed 725 photomicrographs of immunostained tissue sections (100× and 200×) by manual counting and computer-assisted histometry and correlated these data to clinical assessments.

OUTCOMES

Outcomes included density of CD117 and PGP9.5 immunostaining in the 1:00-11:00 o'clock and 12:00 o'clock vestibular regions, and patient-reported outcomes assessing sexual function, pain, distress, and symptom improvement.

RESULTS

All 65 NPV patients (median age 26 years), 45 with lifelong and 20 with acquired NPV, had severe pain documented by PROs and vulvoscopy and had >8 CD117-immunopositive cells/100× microscopic field. Median cell count values were similar in the 1:00-11:00 o'clock and 12:00 vestibular regions (28.5 and 29.5/100× field, respectively). Likewise, the median area of CD117 immunostaining was similar in both regions (0.69% and 0.73%). The median area of PGP9.5 immunostaining was 0.47% and 0.31% in these same regions. Pain scores determined with cotton-tipped swab testing were nominally higher in lifelong vs acquired NPV patients, reaching statistical significance in the 1:00-11:00 o'clock region (P < .001). The median score for the McGill Pain Questionnaire affective subscale dimension was also significantly higher in lifelong vs acquired NPV patients (P = .011). No correlations were observed between hematoxylin and eosin results and density of mast cells or neuronal markers. Of note, 63% of the patient cohort reported having additional conditions associated with aberrant mast cell activity.

CLINICAL IMPLICATIONS

The pathology of NPV is primarily localized to the vestibular epithelial basement membrane and subepithelial stroma with no visible vulvoscopic findings, making clinical diagnosis challenging.

STRENGTHS AND LIMITATIONS

Strengths of this study include the large number of tissues examined with what is to our knowledge the first-ever assessment of the 12:00 vestibule. Major limitations are specimens from a single timepoint within the disease state and lack of control tissues.

CONCLUSIONS

Performing immunohistochemical staining of excised vestibular tissue with CD117 and PGP9.5 led to histometric confirmation of NPV, indications that NPV is a field disease involving all vestibular regions, validation for patients whose pain had been ignored and who had experienced negative psychosocial impact, and appreciation that such staining can advance knowledge.

A conceptual model for managing sexual pain with somatocognitive therapy in women with provoked vestibulodynia and implications for physiotherapy practice

Somatocognitive therapy is a multimodal physiotherapy treatment developed in the early 2000s to alleviate the burden of chronic pelvic pain. In recent years, somatocognitive therapy has been further developed to treat women with provoked vestibulodynia. This prevalent gynecological pain condition is a subgroup of chronic pelvic pain and the most common form of vulvodynia. Provoked vestibulodynia is a neglected multifactorial pain condition of unknown cause, adversely affecting women's sexual life, relation to their partners and their psychological health. Pain is located at the vulvar vestibule and is provoked by touch or pressure such as sexual intercourse. In the management of sexual pain, somatocognitive therapy combines bodily exploration, pain education, cognitive coping strategies and structured homework to improve sexual function and reduce pain. To support these processes, developing a sound therapeutic alliance with the patient is essential. The aim of this article is to provide a conceptual model for managing provoked vestibulodynia with somatocognitive therapy, including a theoretical rational for this treatment. We base our conceptual model on the biopsychosocial model, i.e., considering the complex interplay of biomedical, emotional/cognitive, psychosexual and interpersonal factors in provoked vestibulodynia management. In addition, implications for practice and a detailed description of somatocognitive therapy for provoked vestibulodynia will be provided, to allow replication in clinical practice and in clinical trials.

Central Sensitization in Vulvodynia and Endometriosis: What Have We Been Overlooking So Far?

Importance

Women experience more frequent and greater pain than men, although they receive less adequate treatment and are perceived as more anxious than males. Recent clinical research has lead to hypothesize a common etiology for overlapping chronic pain conditions and mood disorders, namely, central sensitization, which originates from an alteration of pain processing pathways in the central nervous system.

Objective

The aim of this review was to collect all available evidence regarding the potential role of central sensitization in vulvodynia and endometriosis.

Evidence Acquisition

A systematic literature search was performed between July and August 2022 using the electronic database PubMed. The extracted data were summarized using a narrative approach.

Results

Ten articles were chosen for the review. Participants' mean age was 39.2 years (SD = 5.1). Among serum markers of central sensitization, nitric oxide levels were greater in women with endometriosis than in controls, whereas brain-derived neurotrophic factor and S100B levels differed among pain conditions with structural anomalies and those without. Functional magnetic resonance imaging showed different resting state networks between patients with endometriosis and controls. In neurophysiology studies, cases had reduced pain thresholds, compared with healthy controls. Lastly, self-reported questionnaires suggested a central component of pain in women with endometriosis-related dyspareunia and associated bladder/pelvic floor tenderness.

Conclusions and Relevance

The management of vulvodynia and endometriosis may benefit from a new perspective, which considers their possible central etiology. It is compelling that treatment of pain starts to be considered a therapeutic goal in its own right.

Treatment of Vestibulodynia with Submucosal Injections of IncobotulinumtoxinA into Targeted Painful Points: An Open-Label Exploratory Study

The studies carried out to date on vulvodynia treatment with botulinum neurotoxin type A (BoNT/A) have followed generic injection protocols and reported contradictory outcomes on its effects. The aim of the present study was thus to propose a protocol for injecting BoNT/A into targeted painful points, to comprehensively assess the clinical effect of BoNT/A treatment and identify the risk/protective factors for successful treatment. Thirty-five vestibulodynia patients were treated with submucosal injections of incobotulinumtoxinA and assessed 8, 12 and 24 weeks after their treatment. Their clinical and pelvic statuses were assessed from self-reported questionnaires (Visual Analogue Scale (VAS), Female Sexual Function Index (FSFI), Marinoff's Dyspareunia Scale (MDS), Hospital Anxiety and Depression Scale (HADS), Catastrophizing Scale (CS)), physical examinations and surface electromyography (sEMG). The patients reported a reduction in provoked vestibulodynia (FSFI, p < 0.01; Collapse

Key Words

• algometer
• botulinum toxin A
• sexual function
• surface electromyography
• vestibulodynia
• vulvodynia

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MESH Headings

• Humans
• Female
• Vulvodynia/drug therapy
• Botulinum Toxins, Type A/therapeutic use
• Pain
• Pain Threshold

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Grants Collapse

Affiliation(s)

Paula Villa-Muñoz Servicio De Ginecología Y Obstetricia, Hospital Universitari I Politècnic La Fe, 46026 Valencia, Spain; (P.V.-M.); (F.J.N.-A.)
Monica Albaladejo-Belmonte Centro De Investigación E Innovación En Bioingeniería (CI2B), Universitat Politècnica De València, 46022 Valencia, Spain;
Francisco J. Nohales-Alfonso Servicio De Ginecología Y Obstetricia, Hospital Universitari I Politècnic La Fe, 46026 Valencia, Spain; (P.V.-M.); (F.J.N.-A.)
Jose Alberola-Rubio Sonda Devices S.L., 46004 Valencia, Spain;
Javier Garcia-Casado Centro De Investigación E Innovación En Bioingeniería (CI2B), Universitat Politècnica De València, 46022 Valencia, Spain;

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Collaborators Collapse

Exploratory Study on Central Sensitization and Bioelectrical Activity of the Selected Masticatory Muscles in Subjects with Myopia

BACKGROUND

Myopia is one of the most common eye disorders involving abnormal focusing of light rays. The studies recognize the association between the stomatognathic and visual systems. This compound may have a neurological basis associated with disorders such as central sensitization. The main aim of this study was to evaluate the influence of central sensitization on the bioelectrical activity of selected muscles of the masticatory organ in subjects with myopia.

METHODS

Selected masticatory and cervical spine muscles were analyzed using an eight-channel BioEMG III electromyograph. Central sensitization was analyzed using the central sensitization inventory.

RESULTS

Statistical analysis revealed significantly higher scores on the central sensitization inventory in subjects with axial myopia compared to subjects without refractive error. Repeated positive correlations were observed in the sternocleidomastoid muscle activity and negative correlations in the digastric muscle activity during open and closed eyes in myopic subjects.

CONCLUSIONS

Subjects with myopia have an increased score in the central sensitization inventory. The increase in the central sensitization inventory score is connected with the changes within the electromyographic activity of the masticatory and neck muscles. The effect of central sensitization on masticatory muscle activity in myopic subjects requires further study.

Methodology of the INVestigating traIning assoCiated blasT pAthology (INVICTA) study

BACKGROUND

Subconcussive blast exposure during military training has been the subject of both anecdotal concerns and reports in the medical literature, but prior studies have often been small and have used inconsistent methods.

METHODS

This paper presents the methodology employed in INVestigating traIning assoCiated blasT pAthology (INVICTA) to assess a wide range of aspects of brain function, including immediate and delayed recall, gait and balance, audiologic and oculomotor function, cerebral blood flow, brain electrical activity and neuroimaging and blood biomarkers.

RESULTS

A number of the methods employed in INVICTA are relatively easy to reproducibly utilize, and can be completed efficiently, while other measures require greater technical expertise, take longer to complete, or may have logistical challenges.

CONCLUSIONS

This presentation of methods used to assess the impact of blast exposure on the brain is intended to facilitate greater uniformity of data collection in this setting, which would enable comparison between different types of blast exposure and environmental circumstances, as well as to facilitate meta-analyses and syntheses across studies.

Vulvodynia: Pain Management Strategies

Background: Vulvodynia is defined in this international consensus as persistent vulvar pain that occurs for >3 months without an identifiable cause and with several potential associated factors. At present there is no univocal consensus in the therapeutic treatment of vulvodynia. The methods of intervention are based on various aspects including, above all, the management of painful symptoms. Methods: a research on scientific database such as “Pubmed”, “Medline Plus”, “Medscape” was conducted, using the words “women’s genital pain” and “vulvodynia” for the review of the scientific evidence on the assessment and treatment of women’s genital pain. Results: Among the drugs with pain-relieving action, the most effective in the treatment of vulvodynia would seem to be those with antidepressant and anticonvulsant action, even if their mechanisms of action are not known and there are still insufficient studies able to demonstrate their real validity. Among the least effective are non-steroidal anti-inflammatory drugs (NSAIDs) and corticosteroids. However, the ideal would seem to use a combined treatment with multiple types of drugs. Conclusions: Future studies are needed to draw up a unique therapeutic action plan that considers the stratification of patients with vulvodynia and the variability of the symptom.

Characterization of Early Inflammatory Events Leading to Provoked Vulvodynia Development in Rats

Background

Provoked vulvodynia (PV) is the main cause of vulvar pain and dyspareunia. The etiology of PV has not yet been elucidated. However, PV is associated with a history of recurrent inflammation, and its often accompanied by increases in the numbers of mast cells (MCs) and sensory hyperinnervation in the vulva. Therefore, this study aimed to examine the role of MCs and the early inflammatory events in the development of chronic vulvar pain in a rat model of PV.

Methods

Mechanical and thermal vulvar sensitivity was measured for 5 months following zymosan vulvar challenges. Vulvar changes in glutamate and nerve growth factor (NGF) were analyzed using ELISA. Immunofluorescence (IF) staining of the vulvar section after 20, 81, and 160 days of the zymosan challenge were performed to test MCs accumulation, hyperinnervation, and expression of pain channels (transient receptor potential vanilloid/ankyrin-1-TRPV1 & TRPA1) in vulvar neurons. Changes in the development of vulvar pain were evaluated following the administration of the MCs stabilizer ketotifen fumarate (KF) during zymosan vulvar challenges.

Results

Zymosan-challenged rats developed significant mechanical and thermal vulvar sensitivity that persisted for over 160 days after the zymosan challenge. During inflammation, increased local concentrations of NGF and glutamate and a robust increase in MCs degranulation were observed in zymosan-challenged rats. In addition, zymosan-challenged rats displayed sensory hyperinnervation and an increase in the expression of TRPV1 and TRPA1. Treatment with KF attenuated the upregulated level of NGF during inflammation, modulated the neuronal modifications, reduced MCs accumulation, and enhanced mechanical hypersensitivity after repeated inflammation challenges.

Conclusion

The present findings suggest that vulvar hypersensitivity is mediated by MCs accumulation, nerve growth, and neuromodulation of TRPV1 and TRPA1. Hence, KF treatment during the critical period of inflammation contributes to preventing chronic vulvar pain development.

An Experimental Animal Model that Parallels Neurosensory Assessments of Concussion

INTRODUCTION

Tactile-based quantitative sensory assessments have proven successful in differentiating concussed vs. non-concussed individuals. One potential advantage of this methodology is that an experimental animal model can be used to obtain neurophysiological recordings of the neural activity in the somatosensory cortex evoked in response to the same tactile stimuli that are used in human sensory assessments and establish parallels between various metrics of stimulus-evoked cortical activity and perception of the stimulus attributes.

MATERIALS AND METHODS

Stimulus-evoked neural activity was recorded via extracellular microelectrodes in rat primary somatosensory cortex (S1) in response to vibrotactile stimuli that are used in two particular human sensory assessments (reaction time (RT) and amplitude discrimination). Experiments were conducted on healthy control and brain-injured (BI) rats.

RESULTS

Similar to the effects of mild traumatic brain injuries (mTBI) on human neurosensory assessments, comparable experimentally induced brain injuries in rats resulted in the following: (1) elevation of S1 responsivity to vibrotactile stimulation that depended nonlinearly on stimulus amplitude, significantly reducing its capacity to discriminate between stimuli of different amplitudes; (2) 50% reduction in S1 signal-to-noise ratios, which can be expected to contribute to elevation of RT in BI rats; and (3) 60% increase in intertrial variability of S1 responses to vibrotactile stimulation, which can be expected to contribute to elevation of RT variability in BI rats.

CONCLUSIONS

The results demonstrate suggestive similarities between neurophysiological observations made in the experimental rat mTBI model and observations made in post-concussion individuals with regard to three sensory assessment metrics (amplitude discrimination, RT, and RT variability). This is the first successful model that demonstrates that perceptual metrics obtained from human individuals are impacted by mTBI in a manner consistent with neurophysiological observations obtained from rat S1.

Chronic Neurophysiological Effects of Repeated Head Trauma in Retired Australian Male Sport Athletes

Aim: This study investigated the somatosensory and corticomotor physiology of retired contact sport athletes with a history of repeated concussion/subconcussion head trauma. Methods: Retired male athletes with a history of playing contact sports and repeated head trauma (n = 122) were divided into two groups: those who expressed concerns regarding their mental and cognitive health ("symptomatic": n = 83), and those who did not express any ongoing concerns ("asymptomatic": n = 39). Both groups were compared to age-matched male controls (n = 50) with no history of concussions or participation in contact sports, an absence of self-reported cognitive, or mood impairments. Transcranial magnetic stimulation (TMS) and vibrotactile stimulation were used to assess corticomotor and somatosensory pathways respectively. TMS and vibrotactile stimulation were correlated to self-reported responses using the Fatigue and Related Symptom Survey. Linear regression was used to associate concussion history with TMS, somatosensory variables. Results: Significant differences were found in symptom survey scores between all groups (p < 0.001). TMS showed significant differences between the "symptomatic" and control groups for intracortical inhibition and paired pulse TMS measures. Somatosensory measures showed significant differences for reaction time (p < 0.01) and reaction time variability (p < 0.01) between the "symptomatic" group to the "asymptomatic" and control groups. For other somatosensory measures, the "symptomatic" measures showed differences to the "control" group. Correlations showed significant associations between severity of symptom reporting with TMS and somatosensory measure, and regression revealed the number of concussions reported was shown to have significant relationships to increased intracortical inhibition and poorer somatosensory performance. Conclusion: This study shows that retired contact sport athletes expressing chronic symptoms showed significant pathophysiology compared to those with no ongoing concerns and non-concussed controls. Further, there is a linear dose-response relationship between number of reported concussions and abnormal neurophysiology. Neurophysiological assessments such as TMS and somatosensory measures represent useful and objective biomarkers to assess cortical impairments and progression of neuropsychological impairment in individuals with a history of repeated head trauma.

An Accurate Measure of Reaction Time can Provide Objective Metrics of Concussion

There have been numerous reports of neurological assessments of post-concussed athletes and many deploy some type of reaction time assessment. However, most of the assessment tools currently deployed rely on consumer-grade computer systems to collect this data. In a previous report, we demonstrated the inaccuracies that typical computer systems introduce to hardware and software to collect these metrics with robotics (Holden et al, 2020). In that same report, we described the accuracy of a tactile based reaction time test (administered with the Brain Gauge) as approximately 0.3 msec and discussed the shortcoming of other methods for collecting reaction time. The latency errors introduced with those alternative methods were reported as high as 400 msec and the system variabilities could be as high as 80 msec, and these values are several orders of magnitude above the control values previously reported for reaction time (200-220msec) and reaction time variability (10-20 msec). In this report, we examined the reaction time and reaction time variability from 396 concussed individuals and found that there were significant differences in the reaction time metrics obtained from concussed and non-concussed individuals for 14-21 days post-concussion. A survey of the literature did not reveal comparable sensitivity in reaction time testing in concussion studies using alternative methods. This finding was consistent with the prediction put forth by Holden and colleagues with robotics testing of the consumer grade computer systems that are commonly utilized by researchers conducting reaction time testing on concussed individuals. The significant difference in fidelity between the methods commonly used by concussion researchers is attributed to the differences in accuracy of the measures deployed and/or the increases in biological fidelity introduced by tactile based reaction times over visually administered reaction time tests. Additionally, while most of the commonly used computerized testing assessment tools require a pre-season baseline test to predict a neurological insult, the tactile based methods reported in this paper did not utilize any baselines for comparisons. The reaction time data reported was one test of a battery of tests administered to the population studied, and this is the first of a series of papers that will examine each of those tests independently.  

Repeated Vaginal Exposures to the Common Cosmetic and Household Preservative Methylisothiazolinone Induce Persistent, Mast Cell-Dependent Genital Pain in ND4 Mice

A history of allergies doubles the risk of vulvodynia—a chronic pain condition of unknown etiology often accompanied by increases in numbers of vulvar mast cells. We previously established the biological plausibility of this relationship in mouse models where repeated exposures to the allergens oxazolone or dinitrofluorobenzene on the labiar skin or inside the vaginal canal of ND4 Swiss Webster outbred mice led to persistent tactile sensitivity and local increases in mast cells. In these models, depletion of mast cells alleviated pain. While exposure to cleaning chemicals has been connected to elevated vulvodynia risk, no single agent has been linked to adverse outcomes. We sensitized female mice to methylisothiazolinone (MI)—a biocide preservative ubiquitous in cosmetics and cleaners—dissolved in saline on their flanks, and subsequently challenged them with MI or saline for ten consecutive days in the vaginal canal. MI-challenged mice developed persistent tactile sensitivity, increased vaginal mast cells and eosinophils, and had higher serum Immunoglobulin E. Therapeutic and preventive intra-vaginal administration of Δ⁹-tetrahydrocannabinol reduced mast cell accumulation and tactile sensitivity. MI is known to cause skin and airway irritation in humans, and here we provide the first pre-clinical evidence that repeated MI exposures can also provoke allergy-driven genital pain.

Quantification of Mild Traumatic Brain Injury via Cortical Metrics: Analytical Methods

Mild traumatic brain injuries are difficult to diagnose or assess with commonly used diagnostic methods. However, the functional state of cerebral cortical networks can be rapidly and effectively probed by measuring tactile-based sensory percepts (called cortical metrics), which are designed to exercise various components of cortical machinery. In this study, such cortical metrics were obtained from 52 college students before and after they experienced sports-related concussions by delivering vibrotactile stimuli to the index and middle fingertips. Performance on four of the sensory test protocols is described: reaction time, amplitude discrimination, temporal order judgment, and duration discrimination. The collected test performance data were analyzed using methods of uni- and multivariate statistics, receiver operated characteristic (ROC) curves, and discriminant analysis. While individual cortical metrics vary extensively in their ability to discriminate between control and concussed subjects, their combined discriminative performance greatly exceeds that of any individual metric, achieving cross-validated 93.0% sensitivity, 92.3% specificity, 93.0% positive predictive value, and 92.3% negative predictive value. The cortical metrics vector can be used to track an individual's recovery from concussion. The study thus establishes that cortical metrics can be used effectively as a quantitative indicator of central nervous system health status.

Neurophysiological abnormalities in individuals with persistent post-concussion symptoms

Concussion injury results in a rapid onset of transient neurological impairment that can resolve quickly, or sometimes evolve over time, but usually resolve within seven to 10 days. However, a small but noticeable cohort (~10%) of individuals continues to experience persistent lingering effects, particularly fatigue, recognized as post-concussion symptoms (PCS). This study explored neurophysiological mechanisms in people with persistent PCS. Studies involved using self-report post-concussion fatigue scale, transcranial magnetic stimulation (TMS) and somatosensory stimulation in those with diagnosed PCS (n = 20; 36.1 ± 14.0 yr., 4 female; mean time post-concussion 15.4 ± 7.6 months) to fully recovered individuals (n = 20; 33.8 ± 6.6 yr., 2 female; post-concussion 12.9 ± 6.6 months) and healthy controls (n = 20; 37.7 ± 8.0 yr., 3 female). PCS participants demonstrated a significantly higher self-report fatigue (score: PCS 20.2 [95% CI 17.4-22.9], Recovered 6.2 [3.1-9.3], Control 2.75 [0.6-4.8]). PCS participants showed a worsening of reaction time (F_2,57 = 4.214; p = 0.020) and increased reaction time variability (F_2,57 = 5.505; p = 0.007). Somatosensory differences were observed for amplitude discrimination (F_2,57 = 5.166; p = 0.009), temporal order judgment (F_2,57 = 4.606; p = 0.014) and duration discrimination (F_2,57 = 6.081; p = 0.004). Increased intracortical inhibition in TMS single pulse suprathreshold stimulation (110%: F_2,57 = 6.842; p = 0.002; 130%: F_2,57 = 4.900; p = 0.011; 150%: F_2,57 = 4.638; p = 0.014; 170%: F_2,57 = 9.845; p < 0.001) and paired pulse protocols was also seen (SICI: F_2,57 = 23.390; p < 0.001, and LICI: F_2,57 = 21.603; p < 0.001). Using non-invasive stimulation techniques, this novel study showed increased cortical inhibition and compromised central information processing, suggesting neural mechanisms underpinning ongoing fatigue, allowing for potential clinical rehabilitation strategies.

Deep Dyspareunia: Review of Pathophysiology and Proposed Future Research Priorities

INTRODUCTION

Dyspareunia has been traditionally divided into superficial (introital) dyspareunia and deep dyspareunia (pain with deep penetration). While deep dyspareunia can coexist with a variety of conditions, recent work in endometriosis has demonstrated that coexistence does not necessarily imply causation. Therefore, a reconsideration of the literature is required to clarify the pathophysiology of deep dyspareunia.

AIMS

To review the pathophysiology of deep dyspareunia, and to propose future research priorities.

METHODS

A narrative review after appraisal of published frameworks and literature search with the terms (dyspareunia AND endometriosis), (dyspareunia AND deep), (dyspareunia AND (pathophysiology OR etiology)).

MAIN OUTCOME VARIABLE

Deep dyspareunia (present/absent or along a pain severity scale).

RESULTS

The narrative review demonstrates potential etiologies for deep dyspareunia, including gynecologic-, urologic-, gastrointestinal-, nervous system-, psychological-, and musculoskeletal system-related disorders. These etiologies can be classified according to anatomic mechanism, such as contact with a tender pouch of Douglas, uterus-cervix, bladder, or pelvic floor, with deep penetration. Etiologies of deep dyspareunia can also be stratified into 4 categories, as previously proposed for endometriosis specifically, to personalize management: type I (primarily gynecologic), type II (nongynecologic comorbid conditions), type III (central sensitization and genito-pelvic pain/penetration disorder), and type IV (mixed). We also identified gaps in the literature, such as lack of a validated patient-reported questionnaire or an objective measurement tool for deep dyspareunia and clinical trials not powered for sexual outcomes.

CONCLUSION

We propose the following research priorities for deep dyspareunia: deep dyspareunia measurement tools, inclusion of the population avoiding intercourse due to deep dyspareunia, nongynecologic conditions in the generation of deep dyspareunia, exploration of sociocultural factors, clinical trials with adequate power for deep dyspareunia outcomes, partner variables, female sexual response, pathways between psychological factors and deep dyspareunia, and personalized approaches to deep dyspareunia. Orr N, Wahl K, Joannou A, et al. Deep Dyspareunia: Review of Pathophysiology and Proposed Future Research Priorities. Sex Med Rev 2020;8:3-17.

Central sensitization in chronic pain and medically unexplained symptom research: A systematic review of definitions, operationalizations and measurement instruments

OBJECTIVE

Central sensitization (CS), a mechanism explaining the persistence of symptoms, has been the focus of many research projects. Explanations given to patients with chronic pain are often based on this mechanism. It is hypothesized that CS also plays an important role in the persistence of medically unexplained symptoms (MUS). However, definitions and operationalizations of CS vary. We conducted a systematic review of definitions, operationalizations and measurement instruments of CS.

METHODS

We searched in PubMed, EMBASE, PsycINFO, Cinahl and The Cochrane Library till September 2017 and included papers that addressed CS in relation to chronic pain and/or MUS. Two reviewers independently selected, analysed and classified information from the selected publications. We performed a thematic analysis of definitions and operationalizations. We listed the measurement instruments.

RESULTS

We included 126 publications, 79 publications concerned chronic pain, 47 publications concerned MUS. Definitions of CS consistently encompass the theme hyperexcitability of the central nervous system (CNS). Additional themes are variably present: CNS locations, nature of sensory input, reduced inhibition and activation and modulation of the NDMA receptor. Hyperalgesia and allodynia are widely mentioned as operationalizations of CS. Quantitative sensory testing (QST) and (f)MRI are the most reported measurement instruments.

CONCLUSIONS

There is consensus that hyperexcitability is the central mechanism of CS. Operationalizations are based on this mechanism and additional components. There are many measurement instruments available, whose clinical value has still to be determined. There were no systematic differences in definitions and operationalizations between the publications addressing MUS and those addressing chronic pain.

Quantitative Sensory Testing, Antihistamines, and Beta-Blockers for Management of Persistent Breast Pain: A Case Series

BACKGROUND

It is not uncommon for mothers to have persistent pain with breastfeeding beyond the first few weeks after birth. Persistent pain can be multifactorial, with neuropathic pain maintained by central sensitization being one dimension. Our knowledge in delineating categories of persistent pain is simple and not very sophisticated.

METHODS

We have developed and tested a Lactation Quantitative Sensory Test (L-QST) to quantify the neuropathic component of persistent breastfeeding pain. We present three case reports of neuropathic breastfeeding pain and treatment, and we discuss the potential role of histamine and catecholamines in persistent breastfeeding-associated pain.

CONCLUSIONS

The L-QST can be a useful tool to quantify neuropathic pain. Further studies are needed to test inter-observer reliability and reproducibility of this tool. Antihistamines can be considered for treating persistent pain in breastfeeding women with a history of allergy or atopy, and beta-blockers may be helpful in women with multiple pain disorders.

Antenatal Vulvar Pain Management, Labour Management, and Postpartum Care of Women With Vulvodynia: A Survey of Physicians and Midwives

OBJECTIVE

To examine maternity providers' recommendations for pregnant women with vulvodynia regarding management of vulvar pain and postpartum care, and to examine if, and how, a woman's chronic vulvar pain affects providers' examination and management during labour.

METHODS

This research was part of a larger study that invited physicians and midwives to answer a questionnaire regarding pregnancy and childbirth care in women with vulvodynia. To achieve the current objectives, the questionnaire included both dichotomous (yes or no) and open-ended items. The current sample (n = 116) consisted of 75 physicians and 41 midwives.

RESULTS

Over 60% of the sample reported making recommendations for vulvar pain management during pregnancy, and 32.8% of providers reported making special postpartum care recommendations for women with vulvodynia. Differences between physicians and midwives were noted for some of these recommendations. For example, to manage vulvar pain, only physicians recommended the use of/change in medications (P <0.001) and only midwives recommended complementary medicines (P = 0.02) and the use of lubricants (P = 0.006) and made recommendations for sexual well-being (P = 0.02). The majority of the sample (75%) reported that a woman having vulvodynia affected labour examination and management; providers most frequently reported minimizing exams and early use of epidural. Over 80% of midwives and 54% of physicians minimized exams during labour for women with vulvodynia (P= 0.01).

CONCLUSION

Further research is needed to understand the optimal provision of care for pregnant and postpartum women with vulvodynia. We advocate for increased education of vulvodynia aimed at providers of antenatal, labour, and postnatal care.

Disease-Related Microstructural Differences in the Brain in Women With Provoked Vestibulodynia

Provoked vestibulodynia (PVD) is a chronic pelvic pain disorder affecting 16% of the female population. Neuroimaging studies have highlighted central abnormalities in PVD, similar to other chronic pelvic pain disorders, including brain regions involved in sensory processing and modulation of pain. The aim of the study was to determine alterations in the subvoxel, microstructural organization within tissues in PVD compared with healthy control participants (HCs) and a disease control group (irritable bowel syndrome [IBS]). Diffusion tensor imaging magnetic resonance imaging was conducted in 87 age-matched premenopausal women (29 PVD, 29 HCs, 29 IBS). Statistical parameter mapping of fractional anisotropy (FA) and mean diffusivity (MD) maps were used to identify microstructural difference in the brain specific to PVD or shared with IBS. PVD alterations in microstructural organization of the brain were predominantly observed in fibers associated with sensorimotor integration and pain processing that relay information between the thalamus, basal ganglia, sensorimotor, and insular cortex. PVD, compared with HCs, showed extensive increases in the FA of somatosensory and basal ganglia regions. In contrast, PVD and IBS subjects did not show any FA-related group differences. PVD subjects showed greater MD in the basal ganglia compared with HCs (higher MD in the internal capsule and pallidum) and IBS (higher MD in the putamen and pallidum). Increases in MD were associated with increased vaginal muscle tenderness and vulvar pain. The current findings highlight possible shared mechanisms between 2 different pelvic pain disorders, but also highlight the widespread alterations observed specifically in PVD compared with HCs.

PERSPECTIVE

Alterations in microstructure in PVD were observed in fibers associated with sensorimotor integration and pain processing, which were also associated with increased vaginal muscle tenderness and vulvar pain. These alterations may be contributing to increased pain sensitivity and tenderness, highlighting the need for new therapies targeting the central nervous system.

Efficacy of transcranial direct-current stimulation in women with provoked vestibulodynia

BACKGROUND

Provoked vestibulodynia is a highly prevalent condition characterized by acute recurrent pain located at the vaginal entrance in response to pressure application or attempted vaginal penetration. Despite a wide variety of treatments offered to women with provoked vestibulodynia, a high proportion of women are refractory to conventional treatment. Transcranial direct-current stimulation is a noninvasive brain stimulation technique that has been shown effective for improving various chronic pain conditions. Growing evidence suggests that the central nervous system could play a key role in provoked vestibulodynia. Targeting the central nervous system could therefore be a promising treatment for women with provoked vestibulodynia.

OBJECTIVE

The purpose of this study was to evaluate and compare the efficacy of active and sham transcranial direct-current stimulation in reducing pain intensity during intercourse in patients with provoked vestibulodynia.

STUDY DESIGN

We conducted a triple-blind, parallel-group, randomized controlled trial. Women aged 17-45 years diagnosed with provoked vestibulodynia by a gynecologist using a validated protocol were randomized to 10 sessions of either active transcranial direct-current stimulation (intensity = 2 mA) or 10 sessions of sham transcranial direct-current stimulation, over a 2-week period. Both active and sham transcranial direct-current stimulation were applied for 20 minutes, with the anode positioned over the primary motor cortex, and the cathode over the contralateral supraorbital area. Outcome measures were collected at baseline, 2 weeks after treatment, and at 3-month follow-up by an evaluator blinded to group assignment. The primary objective was to assess pain intensity during intercourse, using a numerical rating scale. Secondary outcomes focused on sexual function and distress, vestibular sensitivity, psychological distress, treatment satisfaction, and patient impression of change. Statistical analyses were conducted on the intention-to-treat basis, and treatment effects were evaluated using a mixed linear model for repeated measures.

RESULTS

A total of 40 patients were randomly assigned to receive either active (n = 20) or sham (n = 20) transcranial direct-current stimulation treatments from November 2014 through February 2016. Baseline characteristics were similar between the active and sham transcranial direct-current stimulation groups. In full compliance with the study protocol, every participant followed all courses of the study treatment, including assessments at 2-week and 3-month follow-up. Pain during sexual intercourse was not significantly different between active and sham treatment groups 2 weeks after treatment (P = .84) and at follow-up (P = .09). Mean baseline and 2-week assessment pain intensity were, respectively, 6.8 (95% confidence interval, 5.9-7.7) and 5.6 (95% confidence interval, 4.7-6.5) for active transcranial direct-current stimulation (P = .03) vs 7.5 (95% confidence interval, 6.6-8.4) and 5.7 (95% confidence interval, 4.8-6.6) for sham transcranial direct-current stimulation (P = .001). Nonsignificant differences between the 2 groups were also found in their sexual function and distress after treatment (P > .20) and at follow-up (P > .10). Overall, at 2-week assessment 68% assigned to active transcranial direct-current stimulation reported being very much, much, or slightly improved compared to 65% assigned to sham transcranial direct-current stimulation (P = .82), and still comparable at follow-up: 42% vs 65%, respectively (P = .15).

CONCLUSION

Findings suggest that active transcranial direct-current stimulation is not more effective than sham transcranial direct-current stimulation for reducing pain in women with provoked vestibulodynia. Likewise, no significant effects were found on sexual function, vestibular sensitivity, or psychological distress.

What Does Electromyography Tell Us About Dyspareunia?

INTRODUCTION

Emergent evidence suggests that pelvic floor muscle (PFM) dysfunction contributes to dyspareunia, the experience of pain on vaginal penetration. Electromyography (EMG) is a valuable tool for the assessment of neuromuscular control and could be very useful in enhancing our understanding of PFM involvement in sexual function and in conditions such as dyspareunia. However, PFM EMG must be interpreted within the context of the many factors that can influence findings.

AIM

To outline the main factors to consider when evaluating PFM EMG for female sexual function and dyspareunia and to synthesize the literature in which EMG has been acquired and interpreted appropriately in this context.

METHODS

Standards for the acquisition and interpretation of EMG were retrieved and consulted. An exhaustive search of four electronic databases (Embase, CINAHL, PubMed, and PsycLit) and hand searching references from relevant articles were performed to locate articles relevant to PFM involvement in sexual function and in dyspareunia in which EMG was used as a primary outcome. Study outcomes were evaluated within the context of the appropriate application and interpretation of EMG and their contribution to knowledge.

MAIN OUTCOME MEASURES

A synthesis of the evidence was used to present the current state of knowledge on PFM involvement in sexual function and in dyspareunia.

RESULTS

Few standards documents and no practice guidelines for the acquisition and interpretation of PFM EMG are available. Some cohort studies with small samples of women have described the role of the PFMs in female sexual function. The literature on PFM involvement in dyspareunia also is limited, with outcomes suggesting that higher than normal tonic activation and higher than normal reflex responses might be present in the superficial PFM layer and might be characteristic features of dyspareunia. The data are less clear on the involvement of the deep layer of the PFMs in dyspareunia.

CONCLUSION

Guidelines for the application and interpretation of PFM EMG in the context of sexual function and dyspareunia are needed. When interpreted within the context of their strengths and limitations, EMG data have contributed valuable information to our understanding of PFM involvement in dyspareunia. The literature to date suggests that the superficial PFMs might have higher than normal tone and exaggerated responses to tactile or penetrative provocation in at least some women with dyspareunia. McLean L, Brooks K. What Does Electromyography Tell Us About Dyspareunia? Sex Med Rev 2017;5:282-294.

Do Vulvodynia TCM Patterns Differ by Pain Types? Beginning Evidence Supporting the Concept

INTRODUCTION

Vulvodynia affects a maximum of 14 million U.S. women; however, it has not been adequately characterized. Traditional Chinese Medicine (TCM) offers pattern diagnoses that may be considered vulvodynia phenotypes and may guide the development of more targeted treatments.

OBJECTIVES

In women with vulvodynia, to explore relationships between the TCM patterns and pain.

DESIGN/METHODS

In an exploratory study, 36 women diagnosed with vulvodynia had a TCM assessment and completed the Short Form McGill Pain Questionnaire (SF-MPQ).

RESULTS

All 36 women were diagnosed with one of the two TCM patterns (excess heat [n = 28] or excess cold [n = 8]). Although not statistically significant, (1) the excess heat pattern group had a higher mean sensory score (14.4 ± 6.0) and mean affective pain score (4.1 ± 2.8) (more pain) compared with the mean sensory score (13.3 ± 5.9) and mean affective score (3.3 ± 1.8) of the excess cold pattern group; (2) there was a higher mean score for neuropathic sensory descriptors in the excess heat pattern group (1.55 ± .58) compared with the excess cold pattern group (1.16 ± 0.72); and (3) there was a higher mean score for nociceptive sensory descriptors in the excess cold pattern group (1.23 ± 0.45) compared with the excess heat pattern group (1.14 ± 0.62). The difference in the hot-burning mean score between the two TCM pattern groups was statistically significant (t [34] = 6.55, p < 0.0001).

CONCLUSION

Intriguing trends were observed in the pain scores for the two TCM pattern groups. The possibility that TCM pattern groups have different types of pain (neuropathic vs. nociceptive) deserves further research in larger samples. If these exploratory findings are confirmed, the characterization of TCM patterns could lead to new treatments for vulvodynia.

Presence of Spontaneous Pain and Comorbid Pain Conditions Identifies Vulvodynia Subgroups

OBJECTIVE

The aims of the study were to define the heterogeneity of vulvodynia by determining data-driven subgroups within the vulvodynia diagnosis using exploratory cluster analysis and to characterize the subgroups identified.

MATERIALS AND METHODS

Included were participants in the longitudinal population-based study of vulvodynia in southeast Michigan who screened positive for vulvodynia at least once during the study. A cluster analysis using variables reflecting vulvar pain characteristics and comorbid pain conditions was conducted. Variables reflecting best separation of clusters were used to assign participants to subgroup categories. Demographic, psychiatric, general health, and other vulvar pain characteristics were summarized for each subgroup, followed by multinomial regression and pairwise comparisons of subgroups on these factors.

RESULTS

Of 441 women screening positive for vulvodynia during the course of the study, 393 were eligible on the basis of data requirements. Cluster analysis suggested that best subgroup separation was based on the following 2 variables: (1) presence or absence of spontaneous vulvar pain and (2) presence or absence of other comorbid pain conditions. Subgroups did not differ by age or ethnicity. The subgroup having spontaneous pain and other comorbid conditions demonstrated greatest morbidity in general health measures, psychiatric disorders, and other vulvar pain measures. Primary versus secondary vulvodynia did not vary between subgroups and did not assist in subgroup separation in the cluster analysis.

DISCUSSION

Subgroups based on exploratory cluster analysis demonstrated that presence of spontaneous pain and the presence of comorbid pain conditions resulted in best separation of groups. Presence of both spontaneous pain and other comorbid pain conditions identified the group with greatest morbidity.

6-Methoxyflavanone attenuates mechanical allodynia and vulvodynia in the streptozotocin-induced diabetic neuropathic pain

BACKGROUND

Diabetic neuropathy is the most prevalent, persistent and debilitating complication of diabetes mellitus often coupled with vulvodynia that may present as an isolated symptom or as a part of constellation of other neuropathic abnormalities.

OBJECTIVE

Flavonoids have selective affinity for GABA receptors and 6-methoxyflavanone (6-MeOF) is a positive allosteric modulator of GABA responses at human recombinant GABA_A receptors. GABAergic and opioidergic system inhibition have been shown to facilitate neuropathic pain.

METHODS

6-MeOF was evaluated for analgesic effect in the hot plate test and streptozotocin-induced diabetic neuropathic pain in female rats using von Frey hairs. The possible involvement of opioidergic and GABAergic mechanisms was investigated using naloxone and pentylenetetrazole (PTZ) antagonists, respectively. The biodistribution of 6-MeOF in plasma and CNS was examined using a validated HPLC/UV analytical method. The binding affinity of 6-MeOF with opioid and GABA receptors was studied using molecular docking simulation approach.

RESULTS

6-MeOF (10 and 30mg/kg) attenuated the acute phasic thermal nociception in the hot plate test while in the case of streptozotocin-induced diabetic neuropathy model, 6-MeOF (10 and 30mg/kg) produced static/dynamic anti-allodynic (increased paw withdrawal threshold and latency) as well as static/dynamic anti-vulvodynic effects (increased flinching response threshold and latency), when compared to the vehicle and standard gabapentin (75mg/kg). In silico studies depicted the preference of 6-MeOF for the delta- and kappa-opioid and GABA_A receptors. Moreover, the pharmacokinetic profile revealed a quick appearance of 6-MeOF in the systemic circulation and brain areas with maximum concentration observed after 30min in the amygdala, brain stem and cerebral cortex.

CONCLUSION

6-MeOF readily crosses the blood brain barrier and may be effective in attenuating the diabetes-induced allodynia as well as vulvodynia, probably through interactions with the GABAergic and opioidergic systems.

An Undergraduate Laboratory Exercise that Demonstrates the Difference Between Peripherally and Centrally Mediated Measures

One of the first concepts that students of neuroscience are exposed to is the overall organization of the nervous system and the two principle divisions of it: the Peripheral Nervous System (PNS) and the Central Nervous System (CNS). In sensory systems, this fundamental division plays a particularly prominent role in the information processing stream that integrates and processes information from the external environment to the CNS. To better understand the differences between the roles that the PNS and CNS play in information processing, we developed a relatively simple in-class laboratory exercise. The experimental methods used to determine several aspects of a subject's discriminative capacity (threshold detection, amplitude discrimination, duration discrimination) are described. These methods were used either under control conditions or after the students altered their skin sensitivity (i.e., the PNS) by cold water immersion. At the conclusion of the lab exercise, students will thoroughly understand the principle of the PNS vs. CNS, as well as a fundamental understanding of quantitative sensory testing. This fundamental understanding of sensory testing provides a foundation for students to pursue or investigate other aspects of sensory information processing in either independent studies or subsequent lab exercises.

Vulvar vestibulodynia: strategies to meet the challenge

Vulvodynia is a condition that affects approximately 8% to 12% of women during their lifetimes. Vulvar vestibulodynia (VVD), the most common form of this condition, is characterized by pain with touch at the vulvar vestibule and resulting entryway dyspareunia. Studies suggest a multifactorial etiology; hormonal effects, muscle dysfunction, personality, psychosocial factors, and inflammatory mediators may all play some role in the development of this condition. Both peripheral and central sensitization to pain have been implicated in the development of enhanced pain experienced by women with VVD. Recommendations for the treatment of this condition exist; however, treatments of this condition have not been well studied. Few prospective placebo-controlled trials exist, and many of those that do have failed to show clinically relevant efficacy associated with traditional therapies. New studies into the etiology of this condition, as well as potential new therapies, are emerging, but the optimal approach has yet to be defined. Proper vulvar hygiene is recommended, and traditional therapies such as topical medications and centrally acting oral medications may continue to play a role in treatment. Newer studies elucidating the effects of personality and cognitive factors as well as pelvic floor muscle dysfunction in the development of this condition lend support for the inclusion of cognitive behavioral therapy and physical therapy/surface electromyographic biofeedback in the treatment regimen. Surgery for this condition exists, with success rates of 60% to 90%; however, it is recommended only in cases that have failed to respond to traditional therapy.

Site-specific mesenchymal control of inflammatory pain to yeast challenge in vulvodynia-afflicted and pain-free women

Fibroblast strains were derived from 2 regions of the lower genital tract of localized provoked vulvodynia (LPV) cases and pain-free controls. Sixteen strains were derived from 4 cases and 4 controls, age and race matched, after presampling mechanical pain threshold assessments. Strains were challenged with 6 separate stimuli: live yeast species (Candida albicans, Candida glabrata, Candida tropicalis, and Saccharomyces cerevisiae), yeast extract (zymosan), or inactive vehicle. Production of prostaglandin E2 (PGE2) and interleukin 6 (IL-6) were proinflammatory response measures. Highest IL-6 and PGE2 occurred with vestibular strains after C albicans, C glabrata, and zymosan challenges, resulting in the ability to significantly predict IL-6 and PGE2 production by genital tract location. After C albicans and C glabrata challenge of all 16 fibroblast strains, adjusting for dual sampling of subjects, PGE2 and IL-6 production significantly predicted the presampling pain threshold from the genital tract site of sampling. At the same location of pain assessment and fibroblast sampling, in situ immunohistochemical (IHC)(+) fibroblasts for IL-6 and Cox-2 were quantified microscopically. The correlation between IL-6 production and IL-6 IHC(+) was statistically significant; however, biological significance is unknown because of the small number of IHC(+) IL-6 fibroblasts identified. A low fibroblast IL-6 IHC(+) count may result from most IL-6 produced by fibroblasts existing in a secreted extracellular state. Enhanced, site-specific, innate immune responsiveness to yeast pathogens by fibroblasts may be an early step in LPV pathogenesis. Fibroblast strain testing may offer an attractive and objective marker of LPV pathology in women with vulvodynia of inflammatory origin.

Long-term assessment of effectiveness and quality of life of OnabotulinumtoxinA injections in provoked vestibulodynia

BACKGROUND

Provoked vestibulodynia is a relatively common condition that affects sexual activity. Multidisciplinary care is indicated and OnabotulinumtoxinA injections are safe and effective treatment in this indication.

AIMS

To assess the long-term efficacy of OnabotulinumtoxinA in provoked vestibulodynia.

MATERIALS AND METHODS

Twenty-one patients treated with OnabotulinumtoxinA injections (50U in each bulbospongiosus muscle) 24 months prior to the study were included. Data on pain [assessed using a visual analogue scale (VAS)], quality of life [measured by the Dermatology Life Quality Index (DLQI)] and quality of sex life [assessed using the Female Sexual Function Index (FSFI)] were collected before treatment, and 3 and 24 months after injection.

RESULTS

Nineteen patients participated in the study and 37% had no pain after 24 months. Significant improvements were noted in the VAS, DLQI and FSFI scores between baseline and 24 months post treatment (P < 0.0001). After 24 months, 18 patients (95%) were able to have sexual intercourse. This study was open and non-controlled.

DISCUSSION AND CONCLUSION

100U OnabotulinumtoxinA injections constitute an effective treatment in provoked vestibulodynia with results maintained after 2 years. They significantly improve pain, and have a positive impact on patient quality of life and sex life. Beneficial effects continue in the long-term, allowing patients to resume sexual activity.

Stimulating somatosensory psychophysics: a double-blind, sham-controlled study of the neurobiological mechanisms of tDCS

The neuromodulation technique transcranial direct current stimulation (tDCS) is thought to produce its effects on behavior by altering cortical excitability. Although the mechanisms underlying the observed effects are thought to rely on the balance of excitatory and inhibitory neurotransmission, the physiological principles of the technique are not completely understood. In this study, we examine the influence of tDCS on vibrotactile adaptation, using a simple amplitude discrimination paradigm that has been shown to exhibit modifications in performance due to changes in inhibitory neurotransmission. Double-blind tDCS (Anodal/Sham) of 1 mA was delivered for 600 s to electrodes positioned in a somatosensory/contralateral orbit montage. Stimulation was applied as part of a pre/post design, between blocks of the behavioral tasks. In accordance with previous work, results obtained before the application of tDCS indicated that amplitude discrimination thresholds were significantly worsened during adaptation trials, compared to those achieved at baseline. However, tDCS failed to modify amplitude discrimination performance. Using a Bayesian approach, this finding was revealed to constitute substantial evidence for the null hypothesis. The failure of DC stimulation to alter vibrotactile adaptation thresholds is discussed in the context of several factors that may have confounded the induction of changes in cortical plasticity.

Percept of the duration of a vibrotactile stimulus is altered by changing its amplitude

There have been numerous studies conducted on time perception. However, very few of these have involved tactile stimuli to assess a subject’s capacity for duration discrimination. Previous optical imaging studies in non-human primates demonstrated that increasing the duration of a vibrotactile stimulus resulted in a consistently longer and more well defined evoked SI cortical response. Additionally, and perhaps more interestingly, increasing the amplitude of a vibrotactile stimulus not only evoked a larger magnitude optical intrinsic signal (OIS), but the return to baseline of the evoked response was much longer in duration for larger amplitude stimuli. This led the authors to hypothesize that the magnitude of a vibrotactile stimulus could influence the perception of its duration. In order to test this hypothesis, subjects were asked to compare two sets of vibrotactile stimuli. When vibrotactile stimuli differed only in duration, subjects typically had a difference limen (DL) of approximately 13%, and this followed Weber’s Law for standards between 500 and 1500 ms, as increasing the value of the standard yielded a proportional increase in DL. However, the percept of duration was impacted by variations in amplitude of the vibrotactile stimuli. Specifically, increasing the amplitude of the standard stimulus had the effect of increasing the DL, while increasing the amplitude of the test stimulus had the effect of decreasing the DL. A pilot study, conducted on individuals who were concussed, found that increasing the amplitude of the standard did not have an impact on the DL of this group of individuals. Since this effect did not parallel what was predicted from the optical imaging findings in somatosensory cortex of non-human primates, the authors suggest that this particular measure or observation could be sensitive to neuroinflammation and that neuron-glial interactions, impacted by concussion, could have the effect of ignoring, or not integrating, the increased amplitude.

Prevalence and use of complementary health approaches among women with chronic pelvic pain in a prospective cohort study

OBJECTIVE

The aim of this study was to examine the prevalence of and factors associated with use of complementary health approaches among women with chronic pelvic pain (CPP).

DESIGN

We analyzed data from the Study of Pelvic Problems, Hysterectomy, and Intervention Alternatives, a prospective cohort study of women seeking care for noncancerous pelvic problems with intact uteri at enrollment. Among a subset of 699 participants who reported having CPP, we analyzed the prevalence of complementary health approaches used and associated patient sociodemographic and clinical characteristics, health-related quality of life, attitudes and beliefs, and conventional health care practices.

RESULTS

At baseline, slightly over one-half (51%) of women with CPP used at least one complementary health approach in the past year, including acupuncture (8%), special foods or diets (22%), herbs (27%), and vitamins and minerals (29%). During follow-up surveys conducted annually for 4 years, a substantial proportion of women (44.8%) used complementary health approaches at more than half of the assessments. Users of complementary health approaches were more likely to undergo a hysterectomy or oophorectomy or to use gonadotropin-releasing hormone agonists or opioids during the study compared with nonusers. Women with CPP who used complementary health approaches also had more optimal health-related quality of life measured by the Pelvic Problem Impact Questionnaire (31.6 vs 25.6, P < 0.001).

CONCLUSION(S)

Many women with CPP consistently use complementary health approaches. The substantial interest in and high prevalence of complementary health approaches used alongside conventional medical approaches highlight the need for better understanding of multimodal approaches to address the complex condition of CPP.

Vibrotactile discriminative capacity is impacted in a digit-specific manner with concurrent unattended hand stimulation

A number of perceptual and neurophysiological studies have investigated the effects of delivering unilateral versus bilateral tactile sensory stimulation. While a number of studies indicate that perceptual discrimination degrades with opposite-hand stimulation, there have been no reports that examined the digit specificity of cross-hemispheric interactions to discriminative capabilities. The purpose of this study was to determine whether unattended hand (UH) stimulation significantly degraded or improved amplitude discriminative capacity on the attended hand (AH) in a digit-specific manner. The methods are based on a sensory perceptual task (vibrotactile amplitude discriminative capacity on the tips of the fingers D2 and D3 of the left hand) in the absence and presence of conditioning stimuli delivered to D2 and D3 of the right hand. Non-specific equal-amplitude stimulation to D2 and D3 of the UH significantly worsened amplitude discrimination (AD) performance, while delivering unequal-amplitude stimuli to D2 and D3 of the UH worsened task performance only under the condition in which the unattended stimuli failed to appropriately match the stimulus parameters on the AH. Additionally, delivering single-site stimuli to D2 or D3 of the UH resulted in degraded performance on the AD task when the stimulus amplitude did not match the amplitude of the stimulus applied to homologous digits of the AH. The findings demonstrate that there is a reduction in performance under conditions where UH stimulation least matched stimulation applied to the AH, while there was little or no change in performance when stimulus conditions on the homologous digit(s) of the contralateral sites were similar. Results suggest that bilateral interactions influence perception in a context-dependent manner that is digit specific.

Functional deficits in carpal tunnel syndrome reflect reorganization of primary somatosensory cortex

Carpal tunnel syndrome, a median nerve entrapment neuropathy, is characterized by sensorimotor deficits. Recent reports have shown that this syndrome is also characterized by functional and structural neuroplasticity in the primary somatosensory cortex of the brain. However, the linkage between this neuroplasticity and the functional deficits in carpal tunnel syndrome is unknown. Sixty-three subjects with carpal tunnel syndrome aged 20-60 years and 28 age- and sex-matched healthy control subjects were evaluated with event-related functional magnetic resonance imaging at 3 T while vibrotactile stimulation was delivered to median nerve innervated (second and third) and ulnar nerve innervated (fifth) digits. For each subject, the interdigit cortical separation distance for each digit's contralateral primary somatosensory cortex representation was assessed. We also evaluated fine motor skill performance using a previously validated psychomotor performance test (maximum voluntary contraction and visuomotor pinch/release testing) and tactile discrimination capacity using a four-finger forced choice response test. These biobehavioural and clinical metrics were evaluated and correlated with the second/third interdigit cortical separation distance. Compared with healthy control subjects, subjects with carpal tunnel syndrome demonstrated reduced second/third interdigit cortical separation distance (P < 0.05) in contralateral primary somatosensory cortex, corroborating our previous preliminary multi-modal neuroimaging findings. For psychomotor performance testing, subjects with carpal tunnel syndrome demonstrated reduced maximum voluntary contraction pinch strength (P < 0.01) and a reduced number of pinch/release cycles per second (P < 0.05). Additionally, for four-finger forced-choice testing, subjects with carpal tunnel syndrome demonstrated greater response time (P < 0.05), and reduced sensory discrimination accuracy (P < 0.001) for median nerve, but not ulnar nerve, innervated digits. Moreover, the second/third interdigit cortical separation distance was negatively correlated with paraesthesia severity (r = -0.31, P < 0.05), and number of pinch/release cycles (r = -0.31, P < 0.05), and positively correlated with the second and third digit sensory discrimination accuracy (r = 0.50, P < 0.05). Therefore, reduced second/third interdigit cortical separation distance in contralateral primary somatosensory cortex was associated with worse symptomatology (particularly paraesthesia), reduced fine motor skill performance, and worse sensory discrimination accuracy for median nerve innervated digits. In conclusion, primary somatosensory cortex neuroplasticity for median nerve innervated digits in carpal tunnel syndrome is indeed maladaptive and underlies the functional deficits seen in these patients.

An undergraduate laboratory exercise to study sensory inhibition

Sensory inhibition was first described by von Békésy as a process in which excitation of a field of sensory neurons leads to the reduction of activity of surrounding neurons and thus promotes contrast enhancement of the excited field. In the context of somatosensory cortex, the cortical neurons excited by touch or vibration will suppress excitation of neurons from surrounding receptive fields. USING TACTILE STIMULATORS BOTH DESIGNED AND FABRICATED AT THE UNIVERSITY OF NORTH CAROLINA AT CHAPEL HILL, WE CONDUCTED TWO SIMPLE EXPERIMENTS IN WHICH SENSORY INHIBITION PLAYS A ROLE IN INFORMATION PROCESSING: a unilateral study in which stimuli are delivered to the digits of one hand, and a bilateral study in which stimuli are delivered to the digits of both hands. In the unilateral study, we demonstrated that threshold detection on the third digit (D3) is impacted by conditioning stimuli delivered to adjacent digits 2 (D2) and digits 4 (D4). In the bilateral study, we delivered different conditions of bilateral stimulation in order to investigate the impact that conditioning stimulation of the right hand had on amplitude discriminative capacity of the left hand. The results demonstrated that conditioning stimulation on the right hand had a significant impact on the discriminative capacity of the left hand, and this alteration in discriminative capacity was consistent with previous animal studies in which somatosensory cortical responses evoked by stimulus conditions of unilateral vs. bilateral stimulation were compared. At the conclusion of this exercise, students will appreciate the fundamentals of sensory inhibition as well as the logistics of obtaining and analyzing data from human subjects. This study is designed to help students prepare for studying other facets of sensory processing by providing a firm foundation in the experimental methods and procedures.

Neurosensory assessments of migraine

Headache medicine is primarily dependent on patients' subjective reports of pain, which are assessed at diagnosis and throughout the duration of treatment. There is a need for an objective, quantitative biological measurement of headache pain severity. In this study, quantitative sensory testing (QST) was conducted via multi-site vibrotactile stimulation in patients with migraine. The purpose was to investigate the sensitivity of the method and to determine if the metrics obtained from migraineurs could be differentiated from controls. Metrics reflecting sensory percepts of baseline measures of stimulus amplitude discrimination, temporal order judgment, and duration discrimination were significantly different. Additional measures previously demonstrated to be sensitive to alterations in centrally-mediated information processing features such as adaptation and synchronization were also significantly different from control values. In contrast, reaction times and vibrotactile detection thresholds of migraineurs failed to differentiate them from controls, indicating that the results are not due to peripheral neuropathy or some other primary afferent mechanism. The long-term objective of the study is to develop methods that can improve diagnosis and enable more accurate assessments of treatment efficacy in migraine.

Centrally-mediated sensory information processing is impacted with increased alcohol consumption in college-aged individuals

Alcohol consumption can have an impact on a variety of centrally-mediated functions of the nervous system, and some aspects of sensory perception can be altered as a result of long-term alcohol use. In order to assess the potential impact of alcohol intake on sensory information processing, metrics of sensory perception (simple and choice reaction time; static and dynamic threshold detection; amplitude discrimination with and without pre-exposure to conditioning stimulation) were tested in college-aged subjects (18 to 26 years of age) across a broad range of levels of alcohol consumption. The analysis indicated no detectable associations between reaction time and threshold measures with alcohol consumption. However, measures of adaptation to short duration (0.5s) conditioning stimuli were significantly associated with alcohol consumption: the impact of a confounding conditioning stimulus on amplitude discriminative capacity was comparable to values reported in previous studies on healthy controls (28.9±8.6) for light drinkers while the same adaptation metric for heavy drinkers (consuming greater than 60 drinks per month) was significantly reduced (8.9±7.1). The results suggest that while some of the sensory perceptual metrics which are normally impacted in chronic alcoholism (e.g., reaction time and threshold detection) were relatively insensitive to change with increased alcohol consumption in young non-alcoholic individuals, other metrics, which are influenced predominantly by centrally-mediated mechanisms, demonstrate a deviation from normative values with increased consumption. Results of this study suggest that higher levels of alcohol consumption may be associated with alterations in centrally-mediated neural mechanisms in this age group.