Lesson of the month (2). Is that your arm or mine?

We report a case of a 45-year-old man presenting with asomatognosia, or loss of body part ownership, when he experienced difficulty acknowledging that his arm was his own. His symptoms might easily have been considered to be of psychiatric origin. Instead they turned out to be due to highly focal stroke secondary to carotid dissection, an important and often missed cause of stroke in younger patients.

Gender bias in the observation of experimental pain.

The aim of this study was to examine how men and women observe experimentally induced pain in male and female participants and to specifically determine the accuracy of observed pain ratings, the possible interactions between the sex of the viewer and the sex of the individual being observed, and the influence of gender role expectations on observed pain ratings. The sample comprised 29 participants (15 females). They each completed a battery of psychological questionnaires and viewed a presentation of 10 randomly ordered video clips. Each presentation consisted of 10 video clips, lasting 30s, of a participant (five males and five females) in the cold pressor task. The participants viewing the videos were asked to provide several ratings, including observed pain intensity and gender role related characteristics of the individual in the video. In terms of sex of the video participant, results indicated that viewers rated male videos as having less pain than female videos although the effect was small. Regarding sex of the viewer, results indicated that for both male and female videos, female viewers rated observed pain intensity significantly higher than did male viewers. In terms of accuracy, results indicated that on average, female video participants' pain was underestimated by 14 points, while male videos participants' pain was underestimated by 22 points (on a 0-100-point scale). Pain intensity ratings and pain tolerance from the participants in the videos did not differ significantly with respect to sex, though women had shorter tolerance times and higher pain ratings than men. Hierarchical regression analyses indicated that expectations of gender related 'endurance of pain' significantly predicted ratings of both male and female videos. When endurance expectations were controlled, sex of the viewer no longer significantly predicted observed pain ratings. The 'willingness to report pain' variable was not a significant predictor of observed pain ratings. Our results show that women are perceived to have more pain than men, that there was a tendency by both sexes to underestimate pain in others, but men showed even greater underestimation, and that gender role expectations of pain endurance given by the video observers accounted for substantial variance in their ratings of pain in the videos.

A meta-analytic review of pain perception across the menstrual cycle.

The purpose of this article is to review the sixteen published studies that examine associations between the perception of experimentally induced pain across menstrual cycle phases of healthy females. We also performed a meta-analysis to quantitatively analyze the data and attempt to draw conclusions. The results suggest that there are relatively consistent patterns in the sensitivity to painful stimulation. These patterns are similar across stimulus modality with the exception of electrical stimulation. The magnitude of the effect was approximately 0.40 across all stimulation. For pressure stimulation, cold pressor pain, thermal heat stimulation, and ischemic muscle pain, a clear pattern emerges with the follicular phase demonstrating higher thresholds than later phases. When the effect size was pooled across studies (excluding electrical) comparisons involving the follicular phase were small to moderate (periovulatory phase, d(thr) = 0.34; luteal phase, d(thr) = 0.37; premenstrual phase, d(thr) = 0.48). The pattern of effects was similar for tolerance measures. Electrical stimulation was different than the other stimulus modalities, showing the highest thresholds for the luteal phase. When the effect size was pooled across studies for electrical stimulation, effect sizes were small to moderate (menstrual (d(thr) = -0.37), follicular d(thr) = -0.30) periovulatory d(thr) = -0.61), and premenstrual d(thr) = 0.35) phases. This paper raises several important questions, which are yet to be answered. How much and in what way does this menstrual cycle effect bias studies of female subjects participating in clinical trials? Furthermore, how should studies of clinical pain samples control for menstrual related differences in pain ratings and do they exist in clinical pain syndromes? What this paper does suggest is that the menstrual cycle effect on human pain perception is too large to ignore.

Gender role expectations of pain: relationship to experimental pain perception.

The primary purpose of this study was to investigate the influence of an individual's Gender Role Expectations of Pain (GREP) on experimental pain report. One hundred and forty-eight subjects (87 females and 61 males) subjects underwent thermal testing and were asked to report pain threshold, pain tolerance, VAS ratings of pain intensity and unpleasantness, and a computerized visual analogue scales (VAS) rating of pain intensity during the procedure. Subjects completed the GREP questionnaire to assess sex-related stereotypic attributions of pain sensitivity, pain endurance, and willingness to report pain. Consistent with previous research, significant sex differences emerged for measures of pain threshold, pain tolerance, and pain unpleasantness. After statistically controlling for age, GREP scores were significant predictors of threshold, tolerance, and pain unpleasantness, accounting for an additional 7, 11, and 21% of the variance, respectively. Sex remained a significant predictor of pain tolerance in hierarchical regression analyses after controlling for GREP scores. Results provide support for two competing but not mutually exclusive hypotheses related to the sex differences in experimental pain. Both psychosocial factors and first-order, biological sex differences remain as viable explanations for differences in experimental pain report between the sexes. It appears that GREP do play a part in determining an individual's pain report and may be contributing to the sex differences in the laboratory setting.

Prior pain experience: influence on the observation of experimental pain in men and women.

UNLABELLED: Research examining perceptions of subjects participating in an experimental pain task has not been widely studied. The primary purpose of this study was to examine the influence of prior experience with the cold pressor on subsequent perceptions of others experiencing this same pain task. Furthermore, to replicate our previous work, we examined how individuals observe experimentally induced pain in male and female participants. Possible interactions between order of cold pressor experience, sex of the viewer, sex of the individual being observed, and characteristics attributed to the individuals in the videos were also analyzed. The sample was composed of 57 participants. They were each randomized to 1 of 2 conditions: (1) participate in cold pressor task before viewing a presentation of 10 video clips (of subjects in cold pressor task), rate videos, and complete battery of questionnaires or (2) cold pressor participation after completion of the same questionnaires, and viewing/rating videos. Participants viewing the videos provided ratings including observed pain and emotional characteristics they attributed to the individuals. These results replicated and extended our previous work by demonstrating a gender bias (ie, a stereotypical belief about an individual on the basis of their sex) in the observation of pain, such that participants rated female subjects as experiencing greater pain intensity when undergoing a cold pressor task compared to male subjects. Furthermore, experiencing the cold pressor before watching the videos increased a participant's pain ratings of observed pain. There were also several significant interactions between cold pressor condition, sex of video participant, sex of viewer, and emotional/behavioral characteristics attributed to the video participant. PERSPECTIVE: Results of this study demonstrate that prior experience with pain increases accuracy of estimating others' pain. Gender role expectations also influence observer's ratings of pain, and prior experience of pain influences men and women differently.

Influences of gender role and anxiety on sex differences in temporal summation of pain.

UNLABELLED: Previous research has consistently shown moderate to large differences between pain reports of men and women undergoing experimental pain testing. These differences have been shown for a variety of types of stimulation. However, only recently have sex differences been demonstrated for temporal summation of second pain. This study examined sex differences in response to temporal summation of second pain elicited by thermal stimulation of the skin. The relative influences of state anxiety and gender role expectations on temporal summation were investigated. Asymptomatic undergraduates (37 women and 30 men) underwent thermal testing of the thenar surface of the hand in a temporal summation protocol. Our results replicated those of Fillingim et al indicating that women showed increased temporal summation compared to men. We extended those findings to demonstrate that temporal summation is influenced by anxiety and gender role stereotypes about pain responding. When anxiety and gender role stereotypes are taken into account, sex is no longer a significant predictor of temporal summation. These findings highlight the contribution of social learning factors in the differences between sexes' pain perception. PERSPECTIVE: Results of this study demonstrate that psychosocial variables influence pain mechanisms. Temporal summation was related to gender role expectations of pain and anxiety. These variables explain a significant portion of the differences between men and women's pain processing, and may be related to differences in clinical presentation.

Equestrian injury is costly, disabling, and frequently preventable: the imperative for improved safety awareness.

Horse-related injury can be severe and disabling. We investigated the causes, severity, and costs of equestrian injury with the goal of injury prevention. A retrospective review of horse-related injuries from 2001 to 2008 identified 231 patients with a mean age of 38 years and a mean Injury Severity Score of 11 (range, 1 to 45). Mean length of stay was 5.5 days. Fifty-nine patients (25%) required 84 surgeries. Helmet use was 20 per cent and of the 172 patients not wearing a helmet while mounted, 38 per cent received potentially preventable head injuries. There were three deaths of which two were the result of intracranial hemorrhage in riders not wearing a helmet. Mean hospital charge was $29,800 for a total of $6.9 million. Ninety-one patients completed a survey regarding causation and disability. Thirty-four per cent reported wearing a helmet at the time of injury. Forty per cent reported that poor environmental factors contributed, 30 per cent reported poor horse and rider pairing, and 9 per cent reported equipment failure. Fifty-nine per cent reported long-term disabilities. Compared with the general population, respondents had diminution in their ability to perform usual daily activities associated with physical problems, diminution in social function, and higher bodily pain. We conclude that equestrian injury is costly, disabling, and frequently preventable.

Monitoring toxicity associated with parenteral sodium stibogluconate in the day-case management of returned travellers with New World cutaneous leishmaniasis [corrected].

BACKGROUND: Patients with New World cutaneous leishmaniasis (NWCL) caused by Leishmania Viannia are treated with parenteral sodium stibogluconate (SbV) to reduce the risk of development of mucocutanous leishmaniasis. Our centre manages patients with NWCL on an outpatient-basis. This study was conducted to assess the safety and efficacy of this approach. METHODOLOGY: We reviewed records of 67 consecutive NWCL patients, aged 17-61 years, treated as day-cases with 20 mg/kg/day SbV for up to 28 days at our UK centre. Data had been collected in a standardised format at the time of treatment using a care-record tool. Patients reported adverse-effects daily using a structured questionnaire. Blood tests and electrocardiograms were performed twice weekly to monitor for toxicity. PRINCIPAL FINDINGS: Parenteral SbV treatment was associated with an early, significant suppression of mean lymphocyte and platelet counts. By day four of treatment, lymphocytes reduced by 0.53×10(9)/L (CI 0.29×10(9)/L to 0.76×10(9)/L, p<0.001), and platelets by 31,000/µL (CI 16,000/µL to 46,000/µL, p<0.001). SbV was further associated with significant elevation of serum alanine transaminase concentrations, with a mean peak rise of 107 iu/L by day 13 (CI 52 iu/L to 161 iu/L, p<0.001). These disturbances were temporary and did not result in adverse clinical events. Patient-described symptoms were cumulative and at three weeks of treatment, 59.6% of patients experienced myalgia and 29.8% malaise. Treatment adherence and clinical outcomes were comparable to inpatient treatment studies. A total of 1407 individual doses of SbV resulted in only 26 nights' hospital admission, a saving of 1381 bed-days compared to inpatient treatment. CONCLUSIONS/SIGNIFICANCE: In specialist centres, NWCL patients aged below 65 years and without co-morbidities can be safely and effectively treated without hospital admission. This reduces the cost of treatment, and is much preferred by patients. Twice weekly blood and electrocardiographic monitoring may be surplus to requirement in clinically well, low-risk patients.

Clinical pearl: comedone extraction for persistent macrocomedones while on isotretinoin therapy.

In the past, the safety of performing procedures while patients are on isotretinoin has been questioned. Macrocomedones are traditionally resistant to treatment with isotretinoin alone. The authors present a technique that is safe to employ while patients are on isotretinoin to effectively eliminate macrocomedones without complication.

Rates of skin cancer screening and prevention counseling by US medical residents.

OBJECTIVE: To determine factors related to residents' self-reported skill level for the skin cancer examination (SCE). DESIGN: Survey of residents in November 2003. SETTING: Four US residency programs. PARTICIPANTS: Medical residents in family medicine, pediatrics, obstetrics and gynecology, and internal medicine and specialists. MAIN OUTCOME MEASURE: Proportion of residents reporting their current skill level for the performance of the SCE. RESULTS: Of 454 surveys distributed, 342 residents completed the survey (75.3% response rate). Clinical training for the SCE during residency was infrequent. During residency, 75.8% were never trained in the SCE, 55.3% never observed an SCE, and 57.4% never practiced the examination. Only 15.9% of residents reported being skilled in the SCE. However, the conduct of 4 SCEs (or slightly more than 1 per each year of residency) was associated with manifold increases in self-reported skill levels. CONCLUSIONS: Information now collected from 7 medical schools and 4 residency programs underscores the need for more supervised opportunities to enable physicians in training to perform an SCE during routine patient examinations.