EEG theta activity and pain insensitivity in self-injurious borderline patients

The principal aim of this study was to investigate possible neurophysiological underpinnings of self-injurious behavior in women with borderline personality disorder (BPD). Pain report and EEG power spectrum density during a laboratory pain procedure, a 4-min 10 degrees C cold pressor test (CPT), were compared among four groups; female inpatients with BPD who do (BPD-P group, n = 22) and do not (BPD-NP group, n = 19) report pain during self-injury, female inpatients with major depression (n = 15), and normal women (n = 20). The BPD-NP group reported less pain intensity during the CPT compared to the other groups. Total absolute theta power was significantly higher in the BPD-NP group compared to the Depressed (P = 0.0074) and Normal (P = 0.0001) groups, with a trend toward being significantly higher compared to the BPD-P group (P = 0.0936). Dissociative Experience Scale scores were significantly higher in the BPD-NP group compared to the Depressed and Normal groups (maximum P = 0.0004), and significantly higher in the BPD-P group compared to the Normal group (P = 0.0016). Beck Depression Inventory and Sheehan Patient Rated Anxiety Scale scores were significantly lower in the Normal group compared to all patient groups. Theta activity was significantly correlated with pain rating (Pearson partial r = -0.43, P = 0.0001) and Dissociative Experiences Scale score (Pearson partial r = 0.32, P = 0.01).     

Pain assessment in self-injurious patients with borderline personality disorder using signal detection theory

Signal detection theory measures of thermal responsivity were examined to determine whether differences in reported pain experienced during self-injurious behavior in female patients with borderline personality disorder (BPD) are explained by neurosensory factors and/or attitudinal factors (response bias). Female patients with BPD who do not experience pain during self-injury (BPD-NP group) were found to discriminate more poorly between noxious thermal stimuli of similar intensity, low P(A), than female patients with BPD who experience pain during self-injury (BPD-P group), female patients with BPD who do not have a history of self-injury (BPD-C group), and age-matched normal women. The BPD-NP group also had a higher response criterion, B (more stoical) than the BPD-C group. These findings suggest that ‘analgesia' during self-injury in patients with BPD is related to both neurosensory and attitudinal/psychological abnormalities. © 1997 Elsevier Science Ireland Ltd.     

Nonsuicidal self-injury and diminished pain perception: the role of emotion dysregulation

Nonsuicidal self-injury (NSSI) is the deliberate destruction of one's own body tissue in the absence of suicidal intent (e.g., cutting or burning the skin). Previous studies have found that people with a history of NSSI display diminished pain perception. However, it remains unclear why this effect occurs. In the present study, we used a sample of participants with (n = 25) and without (n = 47) a history of NSSI to test the hypothesis that emotion dysregulation partially explains why NSSI is associated with diminished pain perception. Pain perception was quantified as pain threshold, pain tolerance, and pain intensity ratings assessed during the cold pressor task. Nonsuicidal self-injury was associated with increased emotion dysregulation and diminished pain perception. Results showed that emotion dysregulation was correlated with diminished pain perception within both groups, demonstrating that this association exists regardless of NSSI history. Results also specified that emotion dysregulation partially accounted for the association between NSSI and pain tolerance but not other pain variables. Overall, results were consistent with the hypothesis that emotion dysregulation may increase NSSI risk in part by increasing the willingness to experience the pain involved in self-injury. Studies are needed to more directly investigate this hypothesis.     

Coffee drinking enhances the analgesic effect of cigarette smoking

Nicotine (from cigarette smoke) and caffeine (from coffee) have analgesic effects in humans and experimental animals. We investigated the combined effects of coffee drinking and cigarette smoking on pain experience in a group of moderate nicotine-dependent, coffee drinking, young smokers. Pain threshold and pain tolerance were measured during cold pressor test following the habitual nocturnal deprivation of smoking and coffee drinking. Smoking increased pain threshold and pain tolerance in both men and women. Coffee drinking, at a dose that had no independent effect, doubled the increase in pain threshold induced by smoking. The effect could not be explained by a cumulative raise in blood pressure. Our data suggest that caffeine enhances the analgesic effect of nicotine.     

The effect of modeling and selective attention on pain tolerance

The present study assessed the separate and combined effects of selective attention and modeling on college student's tolerance for pain as measured by a cold pressor test (duration of keeping the hand in ice water). There were four treatment groups: selective attention (A), modeling (M), selective attention and modeling combined (AM), and selective attention plus modeling with cognitions (AMC). In addition, there were three control groups: no treatment (C), experimenter demand (D), and expectancy (E). Using pre-test to post-test difference scores, the four treatment conditions generally produced more pain tolerance than the control conditions, with the possible exception of the E group. The AMC group resulted in the greatest increase in pain tolerance but it was not significantly greater than the M group. There were no differences between the seven groups in their ratings of discomfort following the cold pressor test.     

Both pain and EEG response to cold pressor stimulation occurs faster in fibromyalgia patients than in control subjects

Pain-evoked brain potentials elicited by laser stimulation have been repeatedly shown to be abnormal in fibromyalgia syndrome. However, to our knowledge this is the first study assessing enduring (cold pressor) pain and correlated EEG changes in fibromyalgia. EEG power and subjective pain ratings during the cold pressor test were analyzed and contrasted with tasks not involving sensory stimulation (rest, mental arithmetic and pain imagery) in 20 patients with fibromyalgia and 21 healthy control subjects. Fibromyalgia patients both perceived pain and judged pain as intolerable earlier than control subjects, while pain intensity ratings and EEG power changes during subjective awareness of pain were similar in both groups. In patients and control subjects, pain was correlated with a rise in delta, theta and beta power. EEG power spectra during pain imagery and mental arithmetic were significantly different from those observed during the cold pressor test. In conclusion, fibromyalgia patients seem to process painful stimuli abnormally in a quantitative sense, thus producing both the sensation of pain, as well as the associated EEG patterns, much earlier than control subjects. However, the quality of the pain-associated EEG changes seems similar.     

Anger management style moderates effects of emotion suppression during initial stress on pain and cardiovascular responses during subsequent pain-induction

Background: Suppression of emotion, anger in particular, may be linked to heightened pain intensity during a subsequent painful event, but it is not clear whether an individual’s anger management style (trait anger-out or trait anger-in) moderates effects on pain intensity and cardiovascular responses during pain.Purpose: To determine whether (a) trait anger-out and/or trait anger-in moderate effects of Emotion-Induction (anger, anxiety)×Emotion Suppression (nonsuppression, experiential, expressive) manipulations during mental arithmetic on pain intensity and cardiovascular responses during and following a cold pressor pain task, such that “mismatch” relationships emerge (preferred anger management style is discrepant from situation demands), and (b) general emotional expressivity accounts for these effects.Method: Healthy nonpatients (N=187) were assigned to 1 of 6 conditions for a mental arithmetic task. Cells were formed by crossing 2 Emotion-Induction (anxiety, anger)×3 Emotion Suppression (non-suppression, experiential, expressive) conditions. After mental arithmetic, participants underwent a cold pressor followed by recovery. Systolic blood pressure (SBP), diastolic BP (DBP), heart rate (HR), and pain intensity ratings were recorded. Spielberger Anger Expression Inventory tapped anger management style.Results: General Linear Model procedures tested Emotion-Induction×Emotion Suppression×Anger-Out or Anger-In (continuous)×Period (baseline, cold pressor, recovery) effects on pain intensity, SBP, DBP, and HR. A 4-way interaction emerged for pain intensity: Only for those in the anger-induction/experiential suppression condition, anger-out was related significantly to pain recovery. Three-way interactions emerged for SBP and DBP: Only for those in expressive suppression condition, anger-out was related significantly to SBP during and following cold pressor and to DBP following cold pressor. General emotion expressivity did not account for anger-out effects.Conclusions: A mismatch situation may apply for high anger-out people who suppress emotion in a certain circumstance and thus may suffer greater discomfort and physiological responsiveness to subsequent pain than high anger-out people not having to suppress. This research was supported in part by Grants NS37164 from the National Institute of Neurological Disorders and Stroke (John W. Burns, Ph.D.), MH071260 from the National Institute of Mental Health (John W. Burns, Ph.D. and Stephen Bruehl, Ph.D.), NS046694 from the National Institute of Neurological Disorders and Stroke (Stephen Bruehl, Ph.D.), and by Grant F31 NS051200-01A1 from the National Institute of Neurological Disorders and Stroke (Phillip J. Quartana, M.S.).     

How positive and negative expectations shape the experience of visceral pain: an experimental pilot study in healthy women

Background In order to elucidate placebo and nocebo effects in visceral pain, we analyzed the effects of positive and negative expectations on rectal pain perception, rectal pain thresholds, state anxiety and cortisol responses in healthy women. Methods Painful rectal distensions were delivered at baseline, following application of an inert substance combined with either positive instructions of pain relief (placebo group, N = 15), negative instructions of pain increase (nocebo group, N = 17), or neutral instructions (control, N = 15). Perceived pain intensity, unpleasantness/aversion and urge‐to‐defecate, state anxiety and serum cortisol were determined at baseline, immediately following group‐specific instructions and on a second study day after the same instructions (test day). Rectal pain thresholds were determined at baseline and on the test day. Key Results Whereas perceived pain intensity was significantly decreased in the placebo group, the nocebo group revealed significantly increased pain intensity ratings, along with significantly greater anticipatory anxiety on the test day (all P < 0.05 vs controls). Cortisol concentrations were significantly increased in the nocebo group following treatment but not on the test day. Conclusions & Inferences The experience of abdominal pain can be experimentally increased or decreased by inducing positive or negative expectations. Nocebo effects involve a psychological stress response, characterized by increased anticipatory anxiety. These findings further underscore the role of cognitive and emotional factors in the experience of visceral pain, which has implications for the pathophysiology and treatment of patients with chronic abdominal complaints.     

Pain avoidance in rheumatoid arthritis

Forty-eight patients with rheumatoid arthritis were compared to 52 pain-free controls in terms of tolerance/avoidance and rated intensity of cold pressor pain. The patients had lower thresholds and tolerated the cold pressor pain for a shorter period, although not significantly so. However, the patients rated the novel nociceptive cold stimulus as significantly more painful. The results demonstrate that arthritis patients report novel pain experiences as being more painful, which necessitates special attention to their post-operative analgesic demands needs. Tolerance/avoidance of the cold pressor pain had different correlates in the more and less chronic patient groups, and was respectively related to the affective and sensory qualities of the pain stimulus. The results confirmed qualitative similarities between different chronic pain populations, suggesting that chronicity of the pain problem may be a more important factor in determining pain experience and pain-related behaviours than the specific locus of the pain.     

Pain perception during self-reported distress and calmness in patients with borderline personality disorder and self-mutilating behavior

Self-mutilation occurs in 70-80% of patients who meet DSM-IV criteria for borderline personality disorder. Approximately 60% of these patients report that they do not feel pain during acts of self-mutilation such as cutting or burning. Findings of recent studies measuring pain perception in patients with BPD are difficult to interpret since variables such as distress, dissociation or relevant psychotropic medication have not been controlled. The Cold Pressor Test (CPT) and the Tourniquet Pain Test (TPT) were administered to 12 female patients with BPD who reported analgesia during self-mutilation and 19 age-matched healthy female control subjects. All subjects were free of psychotropic medication. The patients were studied on two occasions: during self-reported calmness and during intensive distress (strong urge to cut or burn themselves). Even during self-reported calmness, patients with BPD showed a significantly reduced perception of pain compared to healthy control subjects in both tests. During distress, pain perception in BPD patients was further significantly reduced as compared with self-reported calmness. The present findings show that self-mutilating patients with BPD who experience analgesia during self-injury show an increased threshold for pain perception even in the absence of distress. This may reflect a state-independent increased pain threshold which is further elevated during stress. Interpretation of these findings is limited by their reliance upon self-reports.     

Safety and acceptability of the research lumbar puncture

Three hundred forty-two subjects underwent 428 research lumbar punctures for studies of cerebrospinal fluid (CSF) biomarkers. Subjects were 67 Alzheimer disease or mild cognitive impairment (AD/MCI) patients and 275 cognitively normal adults aged 21 to 88. Lumbar puncture was performed in the lateral decubitus or sitting position using the Sprotte 24 g atraumatic spinal needle. Up to 34 ml of cerebrospinal fluid were collected. Anxiety and pain experienced during lumbar puncture were rated on a visual analog scale. The frequency of any adverse event (11.7%), clinically significant adverse events (3.97%), and typical post-lumbar puncture headache (PLPHA) (0.93%) was low. Risk of post-lumbar puncture headache was unrelated to age, gender, position during lumbar puncture, ml of cerebrospinal fluid collected, or minutes of recumbent rest following lumbar puncture. The frequency of post-lumbar puncture headache was lower in AD/MCI (P = 0.03) than any other subject group. Anxiety and pain ratings were low. Younger subjects reported more anxiety than old (P = 0.001) and AD/MCI subjects (P = 0.008) and more pain than older normal subjects (P = 0.013). Pain ratings for women were higher than those for men (P = 0.006). Using the Sprotte 24 g spinal needle, research lumbar puncture can be performed with a very low rate of clinically significant adverse events and with good acceptability in cognitively impaired persons and cognitively normal adults of all ages.     

Evaluation of the Efficacy of Musical Vibroacupuncture in Pain Relief: A Randomized Controlled Pilot Study

ObjectivesTo investigate if skin vibration employing consonant frequencies emitted by skin transducers attached to a combination of acupuncture points and according to musical harmony (musical chord) produces more significant pain relief compared to just a single frequency.Materials and MethodsSkin vibrostimulation produced by five electromagnet transducers was applied at five acupoints traditionally used to pain relief and anxiety in 13 pain-free healthy volunteers using the cold pressor test (CPT). The study consisted of three randomized sessions conducted on alternate days, with participants receiving either simultaneous frequencies of 32, 48, and 64 Hz that equate those used in a musical chord, hereby defined as musical vibroacupuncture (MVA), a single frequency of 32 Hz, set as vibroacupuncture (VA) and sham procedure (SP). CPT scores for pain thresholds and pain tolerance were assessed using repeated-measures ANOVAs. Pain intensity was evaluated using a numerical rating scale (NRS), while sensory and affective aspects of pain were rated using the short-form McGill Pain Questionnaire (SF-MPQ) and State-Trait Anxiety Inventory (STAI) Y-Form.ResultsPain thresholds did not vary significantly between trials. Pain tolerance scores were markedly higher in MVA compared to baseline (p = 0.0043) or SP (p = 0.006) but not for VA. Pain intensity for MVA also differed significantly from the baseline (p = 0.007) or SP (p = 0.027), but not for VA. No significant differences were found in SF-MPQ and STAI questionnaires.ConclusionsThese results suggest that MVA effectively increased pain tolerance and reduced pain intensity when compared with all groups, although not significant to the VA group.     

Pain increases during sympathetic arousal in patients with complex regional pain syndrome

OBJECTIVE: To investigate the effect of sympathetic arousal on pain and vasomotor responses in healthy control subjects and patients with complex regional pain syndrome (CRPS), and to determine whether pain increases in patients with particular symptoms. METHODS: In experiments 1 and 2, capsaicin was applied to the forearm of 24 healthy subjects to induce thermal hyperalgesia. Vascular responses were monitored and subjects rated thermal hyperalgesia before and after being startled (experiment 1), and before, during, and after mental arithmetic, breath holding, forehead cooling, the Valsalva maneuver, and a cold pressor test in experiment 2. In a third experiment, sensitivity to heat, cold, and mechanical stimulation was investigated in 61 patients with CRPS. Pain ratings and vascular and electrodermal responses were recorded after patients were startled and during forehead cooling. RESULTS: In experiment 1, thermal hyperalgesia decreased in healthy control subjects after they were startled, and digital blood vessels constricted symmetrically. In experiment 2, thermal hyperalgesia decreased during and after other forms of sympathetic arousal. However, in experiment 3, ratings of clinical pain increased during forehead cooling or after being startled in over 70% of patients with CRPS. Pain increased most consistently during forehead cooling in patients with cold allodynia or punctate allodynia. Digital blood vessels constricted more intensely on the symptomatic than the nonsymptomatic side in patients with CRPS during sympathetic arousal. CONCLUSIONS: Normal inhibitory influences on pain during sympathetic arousal are compromised in the majority of patients with CRPS. The augmented vasoconstrictor response in the symptomatic limb during sympathetic arousal is consistent with adrenergic supersensitivity. An adrenergic sensitivity in nociceptive afferents might contribute to pain and hyperalgesia during sympathetic arousal in certain patients with CRPS.     

Reproducibility of the cold pressor test: studies in normal subjects

The reproducibility of the cold pressor test was studied in healthy subjects. A non-invasive method was utilized for estimating beat-to-beat arterial blood pressure (BP) and heart rate (HR). The study population of 17 healthy volunteers consisted of two groups. In the first group (Group 1, n=11), a 1-min test was performed three times during the same day. In the second group (Group 2, n=6), a 2-min test was repeated at the same time of the day on three consecutive days. In both groups, the test response was defined as the 46- to 60-s mean, minus the prestimulus 15 s baseline mean. In Group 1, a fair test-retest reliability was observed for the systolic BP response (intraclass correlation coefficient R=0.57). Large intraindividual HR and diastolic BP variabilities were found. The intraindividual testretest difference in Group 1 ranged from ?8 to 11 beats/min (SD=4.3, R=0.49) for the HR, from ?16 to 13 mm Hg (SD=6.3) for systolic BP, and from ?21 to 20 mm Hg (SD=9.7, R=0.23) for diastolic BP. Even larger variability was observed when the test was repeated on different days (Group 2). Thus, the maxim that the response pattern to the cold pressor test is fairly constant for each individual may not be true. It does not seem to be advisable to use the results from one solitary cold pressor test. The use of replicated measurements and large sample sizes in comparative studies to compensate for the low to moderate reliability of the cold pressor test is recommended.     

Nociceptive brain activation in patients with neuropathic pain related to Parkinson's disease

BackgroundPatients suffering from Parkinson's disease (PD) frequently experience painful sensations that may be due to central modification of nociception in PD. We compared pain thresholds and cerebral activity in nociceptive areas using Positron Emission Tomography (PET) during nociceptive stimulation before (OFF condition) and after (ON condition) levodopa challenge between nine PD patients with and nine PD patients without neuropathic pain.MethodsPain thresholds were determined using a cold pressor test in the two conditions. We used H₂¹⁵O PET to study the regional cerebral blood flow changes in subjects while they received alternate randomized noxious and innocuous cold stimuli during OFF and ON periods.ResultsPain thresholds were not significantly different between PD patients with and without pain in either condition (OFF and ON). In both groups of PD patients, levodopa significantly raised pain threshold (F _1,16 = 26.71; p < 0.0001) with a mean variation of ?2.7 (±2.3 °C). In the OFF condition, PD patients with pain had a lower pain activation in the right prefrontal cortex and posterior insula and a higher pain activation in the right anterior cingulate cortex (BA32/8) than pain-free patients. Levodopa significantly reduced pain-induced-activation in the right insula and in the anterior cingulate cortex in both groups.ConclusionLevodopa decreased nociceptive perception in both PD patients with and without pain. In PD patients with neuropathic pain the medial affective pathway was preferentially recruited whereas pain-free PD patients exhibited a greater activation in lateral discriminative nociceptive areas.     

Perceived control over anxiety-related events as a predictor of pain behaviors in a cold pressor task

The extent to which perceived control over anxiety-related events contributes to the experience of pain was investigated. It was hypothesized that perceived control over anxiety-related events would predict pain behaviors induced via a cold pressor task because perceived control may alter the meaning of a pain-inducing stimulus. Eighty undergraduate students completed the Anxiety Control Questionnaire, Pain Anxiety Symptoms Scale, State-Trait Anxiety Inventory, and Penn State Worry Questionnaire. Heart rate was assessed prior to hand immersion. Participants then immersed their dominant hand in ice water and rated pain intensity at their pain threshold and tolerance times. Results indicate that perceived control over anxiety-related events predicts pain tolerance and endurance (i.e., overt pain response) but not pain intensity, threshold, or heart rate. It appears that the psychological process variable of perceived control over anxiety-related events uniquely influences participants’ ability to cope with the experience of pain by altering the perceived threat of the acute pain induced via a cold pressor task.     

Acupuncture effects on autonomic responses to cold pressor and handgrip exercise in healthy humans

Abstract. Acupuncture at P6, Liv 3 and Li 4 attenuates the increase in blood pressure during mental stress in healthy humans. The purpose of this study was to test the hypothesis that acupuncture at these points has a generalized depressor effect seen during other stimuli to the autonomic nervous system. Thirty-eight healthy humans (mean age 33 ± 13 years) performed handgrip exercise (n = 20) or the cold pressor test (n = 18) before and after acupuncture at P6, Liv 3 and Li4. To control for repeated interventions, subjects underwent an identical protocol on a different day, during which acupuncture was replaced by quiet rest. Blood pressure and heart rate increased similarly during the first and repeat intervention (handgrip or cold pressor test). Acupuncture did not attenuate the increase in blood pressure (delta mean arterial pressure [MAP] 9.3 ± 1.8 vs 7.3 ± 3.1 mmHg) or the increase in heart rate (delta heart rate [HR] 6.7 ± 2.1 vs 6.0 ± 2.0 bpm) during handgrip exercise. Similarly, acupuncture did not attenuate the increase in blood pressure (delta mean arterial pressure [MAP] 14.8 ± 5.0 vs 14.8 ± 4.8 mmHg) or the increase in heart rate (delta heart rate [HR] 5.3 ± 2.1 vs 8.7 ± 3.6 bpm) during the cold pressor test. In summary, in normal healthy humans, acupuncture at P6, Liv 3 and Li 4 does not attenuate the blood pressure or heart rate responses during handgrip exercise or the cold pressor test.     

Olfactory influences on mood and autonomic, endocrine, and immune function

Despite aromatherapy's popularity, efficacy data are scant, and potential mechanisms are controversial. This randomized controlled trial examined the psychological, autonomic, endocrine, and immune consequences of one purported relaxant odor (lavender), one stimulant odor (lemon), and a no-odor control (water), before and after a stressor (cold pressor); 56 healthy men and women were exposed to each of the odors during three separate visits. To assess the effects of expectancies, participants randomized to the "blind" condition were given no information about the odors they would smell; "primed" individuals were told what odors they would smell during the session, and what changes to expect. Experimenters were blind. Self-report and unobtrusive mood measures provided robust evidence that lemon oil reliably enhances positive mood compared to water and lavender regardless of expectancies or previous use of aromatherapy. Moreover, norepinephrine levels following the cold pressor remained elevated when subjects smelled lemon, compared to water or lavender. DTH responses to Candida were larger following inhalation of water than lemon or lavender. Odors did not reliably alter IL-6 and IL-10 production, salivary cortisol, heart rate or blood pressure, skin barrier repair following tape stripping, or pain ratings following the cold pressor.     

Long-term effects of a brief distraction intervention on children's laboratory pain reactivity

This 2-year follow-up study examined the effects of a brief behavioral intervention on task-based coping and pain reactivity to the cold pressor task (CPT). In the original study by Fanurik et al. (1993), 64 children (aged 8 to 10) whose coping style was categorized as "attender" or "distracter," based on primary coping strategy during baseline CPT trials, received a 5-minute intervention (attention-focusing, distraction training, or control, randomly assigned). In the present study, 51 (32 female) of the original sample were readministered the CPT, and their coping style and pain responsivity were reassessed. Both distracters and attenders given distraction training preferred use of distraction at follow-up. The distraction training group also demonstrated greater tolerance at follow-up compared to controls, although pain ratings did not differ by intervention group. Our findings suggest that a brief distraction intervention has long-term effects on task-based coping and experimental pain reactivity.     

Autonomic cardiovascular control and responses to experimental pain stimulation in fibromyalgia syndrome

Objective

This study involves a comprehensive investigation of autonomic cardiovascular regulation in fibromyalgia syndrome (FMS) at rest and during painful stimulation and its association with pain indices.

Methods

In 35 patients and 29 healthy controls, electrocardiography, impedance cardiography, and finger continuous blood pressure measurements were conducted. For the purpose of experimental pain induction, a cold pressor test was applied.

Results

FMS patients showed lower pain threshold and tolerance, as well as higher ratings of pain intensity and unpleasantness on visual analogue scales. Resting stroke volume, myocardial contractility, R-R interval, heart rate variability, and sensitivity of the cardiac baroreflex were reduced in the patients, and increases in stroke volume and myocardial contractility during cold pressor stimulation were less pronounced. In the whole sample as well as in the FMS group, baroreflex sensitivity was inversely associated with subjective pain intensity, and a higher number of baroreflex operations per unit of time predicted higher pain tolerance.

Conclusions

The data suggest impaired autonomic cardiovascular regulation in FMS in terms of reduced sympathetic and parasympathetic influences, as well as blunted sympathetic reactivity to acute stress. The association between baroreflex function and pain experience reflects the pain inhibition mediated by the baroreceptor system. Given the reduced baroreflex sensitivity in FMS, one may assume deficient ascending pain inhibition arising from the cardiovascular system, which may contribute to the exaggerated pain sensitivity of FMS.