The impact of levamisole and alcohol on white matter microstructure in adult chronic cocaine users.

Previous brain imaging studies with chronic cocaine users (CU) using diffusion tensor imaging (DTI) mostly focused on fractional anisotropy to investigate white matter (WM) integrity. However, a quantitative interpretation of fractional anisotropy (FA) alterations is often impeded by the inherent limitations of the underlying tensor model. A more fine-grained measure of WM alterations could be achieved by measuring fibre density (FD). This study investigates this novel DTI metric comparing 23 chronic CU and 32 healthy subjects. Quantitative hair analysis was used to determine intensity of cocaine and levamisole exposure-a cocaine adulterant with putative WM neurotoxicity. We first assessed the impact of cocaine use, levamisole exposure and alcohol use on group differences in WM integrity. Compared with healthy controls, all models revealed cortical reductions of FA and FD in CU. At the within-patient group level, we found that alcohol use and levamisole exposure exhibited regionally different FA and FD alterations than cocaine use. We found mostly negative correlations of tract-based WM associated with levamisole and weekly alcohol use. Specifically, levamisole exposure was linked with stronger WM reductions in the corpus callosum than alcohol use. Cocaine use duration correlated negatively with FA and FD in some regions. Yet, most of these correlations did not survive a correction for multiple testing. Our results suggest that chronic cocaine use, levamisole exposure and alcohol use were all linked to significant WM impairments in CU. We conclude that FD could be a sensitive marker to detect the impact of the use of multiple substances on WM integrity in cocaine but also other substance use disorders.

The debate on apraxia and the supplementary motor area in the twentieth century.

Hand function and apraxia are equally relevant to neurosurgeons: as a symptom, as well as through the functional anatomy of "praxis" which underlies the dexterity needed for neurosurgical practice. The supplementary motor area is crucial for its understanding. Historically, Hugo Liepmann dominated the apraxia debate at the beginning of the twentieth century, a debate that has remained influential until today. Kurt Goldstein, a contemporary of Liepmann, is regularly mentioned as the first to have described the alien hand syndrome in 1909. Wilder Penfield was a key figure in exploring the role of the fronto-mesial cortex in human motor control and coined the term "supplementary motor area". It was Goldstein who not only contributed substantially to the apraxia debate more than 100 years ago; he also established the link between the dysfunction of the fronto-mesial cortex and abnormal higher motor control in humans.

Neurologists, neurosurgeons, and psychiatrists' personality traits: a comparison.

BACKGROUND: Clinicians in neuroscientific disciplines may present distinct personality profiles. Despite of potential relevance to clinical practice, this has not yet been studied. We therefore aimed to compare personality profiles of physicians working in the three main disciplines of clinical neuroscience, i.e., neurologists, neurosurgeons, and psychiatrists, between each other, across levels of training and to other specialties. METHODS: An online survey using the Ten-Item Personality Inventory (TIPI), an internationally validated measure of the five-factor model of personality dimensions, was distributed to board-certified physicians, residents, and medical students in several European countries and Canada. Differences in personality profiles were analyzed using multivariate analysis of variance and canonical linear discriminant analysis on age- and sex-standardized z-scores of personality traits. Single personality traits were analyzed using robust t tests. RESULTS: Of the 5148 respondents who completed the survey, 723 indicated the specialties neurology, neurosurgery, or psychiatry. Compared to all other specialties, personality profiles of training and trained physicians in these three main clinical neuroscience disciplines ("NN&P") significantly differed, with significantly higher scores in openness to experience. Within NN&P, there were significant differences in personality profiles, driven by lower neuroticism in neurosurgeons, higher conscientiousness in neurosurgeons and neurologists, and higher agreeableness in psychiatrists. Across levels of training, NN&P personality profiles did not differ significantly. CONCLUSION: The distinct clinical neuroscience personality profile is characterized by higher levels of openness to experience compared to non-neuroscience specialties. Despite high variability within each discipline, moderate, but solid differences in the personality profiles of neurologists, neurosurgeons and psychiatrists exist.

Sigmund Freud-early network theories of the brain.

Since the early days of modern neuroscience, psychological models of brain function have been a key component in the development of new knowledge. These models aim to provide a framework that allows the integration of discoveries derived from the fundamental disciplines of neuroscience, including anatomy and physiology, as well as clinical neurology and psychiatry. During the initial stages of his career, Sigmund Freud (1856-1939), became actively involved in these nascent fields with a burgeoning interest in functional neuroanatomy. In contrast to his contemporaries, Freud was convinced that cognition could not be localised to separate modules and that the brain processes cognition not in a merely serial manner but in a parallel and dynamic fashion-anticipating fundamental aspects of current network theories of brain function. This article aims to shed light on Freud's seminal, yet oft-overlooked, early work on functional neuroanatomy and his reasons for finally abandoning the conventional neuroscientific "brain-based" reference frame in order to conceptualise the mind from a purely psychological perspective.

The influence of lunar phases and zodiac sign 'Leo' on perioperative complications and outcome in elective spine surgery.

BACKGROUND: Many people believe that the moon has an influence on daily life, and some even request elective surgery dates depending on the moon calendar. The aim of this study was to assess the influence of 'unfavorable' lunar or zodiac constellations on perioperative complications and outcome in elective surgery for degenerative disc disease. METHODS: Retrospective database analysis including 924 patients. Using uni- and multivariate logistic regression, the likelihood for intraoperative complications and re-do surgeries as well as the clinical outcomes at 4 weeks was analyzed for surgeries performed during the waxing moon, full moon, and dates when the moon passed through the zodiac sign 'Leo.' RESULTS: In multivariate analysis, patients operated on during the waxing moon were 1.54 times as likely as patients who were operated on during the waning moon to suffer from an intraoperative complication (OR 1.54, 95 % CI 1.07-2.21, p = 0.019). In contrast, there was a trend toward fewer re-do surgeries for surgery during the waxing moon (OR 0.51, 95 % CI 0.23-1.16, p = 0.109), while the 4-week responder status was similar (OR 0.73, 95 % CI 0.47-1.14, p = 0.169). A full moon and the zodiac sign Leo did not increase the likelihood for complications, re-do surgeries or unfavorable outcomes. CONCLUSIONS: We found no influence of 'unfavorable' lunar or zodiac constellations on the 4-week responder status or the revision rate that would justify a moon calendar-based selection approach to elective spine surgery dates. However, the fact that patients undergoing surgery during the waxing moon were more likely to suffer from an intraoperative complication is a surprising curiosity and defies our ability to find a rational explanation.

The evolution of brain surgery on awake patients.

In the early days of modern neurological surgery, the inconveniences and potential dangers of general anesthesia by chloroform and ether using the so-called "open-drop technique" led to the quest for alternative methods of anesthesia. Besides preventing the feared side effects, the introduction of regional anesthesia revealed another decisive advantage over general anesthesia in neurosurgery: While intraoperative direct cortical stimulation under general anesthesia could only delineate the motor area (by evocation of contralateral muscular contraction), now, the awake patients were able to report sensations elicited by this method. These properties advanced regional anesthesia to the regimen of choice for cranial surgeries in the first half of the 20th century. While technical advances and new drugs led to a progressive return to general anesthesia for neurosurgical procedures, the use of regional anesthesia for epilepsy surgery has only decreased in recent decades. Meanwhile, awake craniotomies regained popularity in oncologically motivated surgeries, especially in craniotomies for diffuse low-grade gliomas. Intraoperative mapping of brain functions using electrical stimulation in awake patients enables not only for increased tumor removal while preserving the functional status of the patients but also opens a window to cognitive neuroscience. Observations during such interventions and their correlation with both pre - and postoperative neuropsychological examinations and functional neuroimaging is progressively leading to new insights into the complex functional anatomy of the human brain. Furthermore, it broadens our knowledge on cerebral network reorganization in the presence of disease-with implications for all disciplines of clinical neuroscience.

Georg Büchner, Sigmund Freud and the "Schädelnerven" (cranial nerves) - research on the brain and soul in the 19th century.

BACKGROUND: One of the authors' encounter with one of Sigmund Freud's original works about the anatomy of the human brain stem and his interest in the scientist, anatomist, philosopher, writer and revolutionary Georg Büchner led to re-examination and review of the original writings of two major 19th century protagonists of brain anatomy research. The aim of the authors is to highlight the achievements of both Freud and Büchner in the field of comparative brain morphology. METHODS: The medical and philosophical publications of Georg Büchner were reviewed with reference to the historical-critical edition of his complete works and writings (the so-called Marburg edition). Evaluation of the neuroanatomical achievements of Sigmund Freud was based on a summary of his publications and also partially on his autobiographical writings. RESULTS: After careful review of their publications both Freud and Büchner should be acknowledged as brain scientists focusing particularly on comparative morphology. Both chose fish as the subject of their macroscopic (Büchner) and microscopic (Freud) neuroanatomical studies, and both cut across their own language and cultural space by continuing their work in France. In interpreting their findings both were influenced by their respective contemporary methodological schools of thought. Büchner became a soul scientist/psychologist by turning to the writing of literary texts, heralding the end of his idealistic and metaphysical interpretation of life. Likewise, Freud increasingly devoted himself to the destiny of man and his "conditio humana," eventually turning away from anatomical brain research. CONCLUSION: Review of the biographies and medical-scientific, as well as philosophical publications, of Georg Büchner and Sigmund Freud reveal striking parallels between the two researchers in addition to common insights that have generally been ignored or only marginally addressed in the past. Both should be appreciated and remembered as forerunners of today's neuroscientific community.

Hans Brun: a Swiss pioneer in the surgery of the spinal cord, brain and herniated lumbar disc.

INTRODUCTION: Toward the end of the nineteenth century, it was Gowers, Horsley and Macewen who first reported successful surgical procedures for the treatment of subdural extramedullary tumors. Following this, Church and Eisendrath as well as Putnam and Warren reported unsuccessful attempts to treat subpial spinal pathologies in their patients. Only at the beginning of the twentieth century did reports of successful interventions of this type accumulate. In the analysis of these case reports, the authors noticed a certain lack of accuracy about the anatomical allocations and descriptions of intra- and extramedullary spinal lesions. From this, the question of who actually carried out the pioneering works in the early twentieth century in the field of surgery of intramedullary pathologies arose. METHODS: Analysis of the relevant original publications of Hans Brun and research on the poorly documented information about his life history by personally contacting contemporary relatives. RESULTS: The literature analysis showed that the Swiss neurologist Otto Veraguth and surgeon Hans Brun made fundamental contributions to subpial spinal cord surgery at the very beginning of the last century that remain valid today. According to our research, Hans Brun should be remembered as the third surgeon (after von Eiselsberg and Elsberg) who successfully removed an intramedullary lesion in a patient. CONCLUSION: Brun should be remembered as an early and successful surgeon in this specialized field. His operative work is described in detail in this article. At the same time, his achievements in the fields of brain and disc herniation surgery are presented.

Von Bergmann, Kocher, and Krönlein--a triumvirate of pioneers with a common neurosurgical concept.

BACKGROUND: The rise of a neurosurgical subspecialisation in general surgery was strongly influenced by some key surgeons. In the German-speaking regions of Europe, Ernst von Bergmann, Emil Theodor Kocher and Rudolf Ulrich Krönlein have to be especially highlighted. METHODS: This article describes their contributions to the neurosurgical field and their personal interactions. For this, the numerous publications on cranial neurosurgery of von Bergmann were reviewed. They are presented in chronological order. Kocher's and Krönlein's contributions to early neurosurgery have been valued recently by the authors and are briefly summarized. RESULTS: All three developed early interest in the neurosurgical field and conducted clinical and experimental research at the turn of the twentieth century. It becomes evident that von Bergmann, Kocher and Krönlein provided a basis for a transnational neurosurgical school. CONCLUSION: This triumvirate developed a common neurosurgical concept that was grounded in the physiological experiments and scientific evidence.

Distribution of Psychological Instability Among Surgeons.

BACKGROUND: High emotional instability (i.e., neuroticism) is associated with poor mental health. Conversely, traumatic experiences may increase neuroticism. Stressful experiences such as complications are common in the surgical profession, with neurosurgeons being particularly affected. We compared the personality trait neuroticism between physicians in a prospective cross-sectional study. METHODS: We used an online survey using the Ten-Item Personality Inventory, an internationally validated measure of the 5-factor model of personality dimensions. It was distributed to board-certified physicians, residents, and medical students in several European countries and Canada (n = 5148). Multivariate linear regression was used to model differences between surgeons, nonsurgeons, and specialties with occasional surgical interventions with respect to neuroticism, adjusting for sex, age, age squared, and their interactions, then testing equality of parameters of adjusted predictions separately and jointly using Wald tests. RESULTS: With an expected variability within disciplines, average levels of neuroticism are lower in surgeons than nonsurgeons, especially in the first part of their career. However, the course of neuroticism across age follows a quadratic pattern, that is, an increase after the initial decrease. The acceleration of neuroticism with age is specifically significant in surgeons. Levels of neuroticism are lowest towards mid-career, but exhibit a strong secondary increase towards the end of the surgeon's career. This pattern seems driven by neurosurgeons. CONCLUSIONS: Despite initially lower levels of neuroticism, surgeons suffer a stronger increase of neuroticism together with age. Because, beyond well-being, neuroticism influences professional performance and health care systems costs, explanatory studies are mandatory to enlighten causes of this burden.

Predictors of outcomes after surgery for medically intractable insular epilepsy: A systematic review and individual participant data meta-analysis.

Insular epilepsy (IE) is an increasingly recognized cause of drug-resistant epilepsy amenable to surgery. However, concerns of suboptimal seizure control and permanent neurological morbidity hamper widespread adoption of surgery for IE. We performed a systematic review and individual participant data meta-analysis to determine the efficacy and safety profile of surgery for IE and identify predictors of outcomes. Of 2483 unique citations, 24 retrospective studies reporting on 312 participants were eligible for inclusion. The median follow-up duration was 2.58 years (range, 0-17 years), and 206 (66.7%) patients were seizure-free at last follow-up. Younger age at surgery (≤18 years; HR = 1.70, 95% CI = 1.09-2.66, P = .022) and invasive EEG monitoring (HR = 1.97, 95% CI = 1.04-3.74, P = .039) were significantly associated with shorter time to seizure recurrence. Performing MR-guided laser ablation or radiofrequency ablation instead of open resection (OR = 2.05, 95% CI = 1.08-3.89, P = .028) was independently associated with suboptimal or poor seizure outcome (Engel II-IV) at last follow-up. Postoperative neurological complications occurred in 42.5% of patients, most commonly motor deficits (29.9%). Permanent neurological complications occurred in 7.8% of surgeries, including 5% and 1.4% rate of permanent motor deficits and dysphasia, respectively. Resection of the frontal operculum was independently associated with greater odds of motor deficits (OR = 2.75, 95% CI = 1.46-5.15, P = .002). Dominant-hemisphere resections were independently associated with dysphasia (OR = 13.09, 95% CI = 2.22-77.14, P = .005) albeit none of the observed language deficits were permanent. Surgery for IE is associated with a good efficacy/safety profile. Most patients experience seizure freedom, and neurological deficits are predominantly transient. Pediatric patients and those requiring invasive monitoring or undergoing stereotactic ablation procedures experience lower rates of seizure freedom. Transgression of the frontal operculum should be avoided if it is not deemed part of the epileptogenic zone. Well-selected candidates undergoing dominant-hemisphere resection are more likely to exhibit transient language deficits; however, the risk of permanent deficit is very low.

Estimating multimodal brain variability in schizophrenia spectrum disorders: A worldwide ENIGMA study.

Objective: Schizophrenia is a multifaceted disorder associated with structural brain heterogeneity. Despite its relevance for identifying illness subtypes and informative biomarkers, structural brain heterogeneity in schizophrenia remains incompletely understood. Therefore, the objective of this study was to provide a comprehensive insight into the structural brain heterogeneity associated with schizophrenia. Methods: This meta- and mega-analysis investigated the variability of multimodal structural brain measures of white and gray matter in individuals with schizophrenia versus healthy controls. Using the ENIGMA dataset of MRI-based brain measures from 22 international sites with up to 6139 individuals for a given brain measure, we examined variability in cortical thickness, surface area, folding index, subcortical volume and fractional anisotropy. Results: We found that individuals with schizophrenia are distinguished by higher heterogeneity in the frontotemporal network with regard to multimodal structural measures. Moreover, individuals with schizophrenia showed higher homogeneity of the folding index, especially in the left parahippocampal region. Conclusions: Higher multimodal heterogeneity in frontotemporal regions potentially implies different subtypes of schizophrenia that converge on impaired frontotemporal interaction as a core feature of the disorder. Conversely, more homogeneous folding patterns in the left parahippocampal region might signify a consistent characteristic of schizophrenia shared across subtypes. These findings underscore the importance of structural brain variability in advancing our neurobiological understanding of schizophrenia, and aid in identifying illness subtypes as well as informative biomarkers.

Emil Theodor Kocher--valve surgery for epilepsy.

Emil Theodor Kocher (1841-1917) was a pioneering and versatile Swiss surgeon who played a decisive role in the surgical evolution on the threshold to the 20th century. Apart from conducting intense research and fostering the development of the surgical treatment of thyroid gland diseases (honored with a Nobel Prize in 1909), he remained a generalist and was active in orthopedic, genitourinary, and neurologic surgery. Even today, many surgical techniques and instruments are still named after him, thus providing evidence of his great impact. His neurosurgical ambitions included, in particular, cerebral and spinal trauma, the pathophysiology of elevated intracranial pressure, as well as etiological considerations and the operative treatment of epilepsy. This article aims to shed light on Kocher's work on epilepsy, published exclusively in German, and illustrates the development of his idea on valve surgery for recurrent general convulsions.

Emil Theodor Kocher: the first Swiss neurosurgeon.

BACKGROUND: Emil Theodor Kocher (1841-1917) was elected as head of the university clinic for surgery in Berne, Switzerland at the age of 31 years. During the 45 years of his professorship he became one of the outstanding surgeons of Europe by using surgical techniques based predominately on physiological and biological ideas. The aim of this article was to highlight his neurosurgical achievements published in the German language. METHODS: The illustrations of Kocher's works in the field of neurosurgery are exclusively based on his publications and works published by his co-workers. RESULTS: Kocher received the Nobel Prize in Physiology or Medicine in 1909 because he devoted himself to intense research and development in the pathophysiology and surgical treatment of diseases of the thyroid gland. His particular neurosurgical interests were in cerebral and spinal trauma, operative treatment of epilepsy and the pathophysiology of elevated intracranial pressure. CONCLUSION: Studies of Kocher's contributions, published exclusively in the German language, lead to the conclusion that Kocher must be designated as the first Swiss neurosurgeon.

The combination of subdural and depth electrodes for intracranial EEG investigation of suspected insular (perisylvian) epilepsy.

PURPOSE: We present two methods of implantation for the investigation of suspected insular and perisylvian epilepsy that combine depth and subdural electrodes to capitalize on the advantages of each technique. METHODS: Retrospective study of all intracranial EEG studies that included insular electrodes from 2004-2010. Patients were divided according to the implantation scheme. The first method (type 1) consisted of a craniotomy, insertion of insular electrodes after microdissection of the sylvian fissure, orthogonal implantation of mesiotemporal structures with neuronavigation, and coverage of the adjacent lobes with subdural electrodes. The second method (type 2) consisted of magnetic resonance imaging (MRI)-stereotactic frame-guided depth electrode implantation into insula and hippocampus using sagittal axes, and insertion of subdural electrodes through burr holes to cover the adjacent lobes. The combined implantations were developed and performed by one neurosurgeon (AB). KEY FINDINGS: Nineteen patients had an intracranial study that sampled the insula, among other regions. Sixteen patients were implanted using the first method, which allowed a mean of 4, 5, 20, 15, and 42 contacts per patient to be positioned into/over the insular, mesial temporal, neocortical temporal, parietal, and frontal areas, respectively. The second method (three patients) allowed a mean of 8, 7, 16, 6, and 9 contacts per patient to sample the same areas, respectively. The four patients in whom transient neurologic deficits occurred were investigated with use of type 1 implantation. SIGNIFICANCE: Combined depth and subdural electrodes can be used safely to investigate complex insular/perisylvian refractory epilepsy. Choice of implantation scheme should be individualized according to presurgical data and the need for functional localization.

A case of aphasia due to temporobasal edema: Contemporary models of language anatomy are clinically relevant.

BACKGROUND: Understanding the anatomy of language in the human brain is crucial for neurosurgical decision making and complication avoidance. The traditional anatomical models of human language, relying on relatively simple and rigid concepts of brain connectivity, cannot explain all clinical observations. The clinical case reported here illustrates the relevance of more recent concepts of language networks involving white matter tracts and their connections. CASE DESCRIPTION: Postoperative edema of the ventral occipitotemporal cortex, where modern network models locate a crucial language hub, resulted in transient severe aphasia after a subtemporal approach. Both verbal comprehension and expression were lost. The resolution of edema was associated with complete recovery from phonetic and semantic dysfunction. CONCLUSION: Complete aphasia due to a functional disturbance remote from the areas of Broca and Wernicke could be explained by contemporary neuroanatomical concepts of white matter connectivity. Knowledge of network-based models is relevant in brain surgery complication avoidance.

Anatomical integrity within the inferior fronto-occipital fasciculus and semantic processing deficits in schizophrenia spectrum disorders.

The core symptoms of schizophrenia spectrum disorders (SSD) include abnormal semantic processing which may rely on the ventral language stream of the human brain. Thus, structural disruption of the ventral language stream may play an important role in semantic deficits observed in SSD patients. Therefore, we compared white matter tract integrity in SSD patients and healthy controls using diffusion tensor imaging combined with probabilistic fiber tractography. For the ventral language stream, we assessed the inferior fronto-occipital fasciculus [IFOF], inferior longitudinal fasciculus, and uncinate fasciculus. The arcuate fasciculus and corticospinal tract were used as control tracts. In SSD patients, the relationship between semantic processing impairments and tract integrity was analyzed separately. Three-dimensional tract reconstructions were performed in 45/44 SSD patients/controls ("Bern sample") and replicated in an independent sample of 24/24 SSD patients/controls ("Basel sample"). Multivariate analyses of fractional anisotropy, mean, axial, and radial diffusivity of the left IFOF showed significant differences between SSD patients and controls (p(FDR-corr) < 0.001, ηp2 = 0.23) in the Bern sample. Axial diffusivity (AD) of the left UF was inversely correlated with semantic impairments (r = -0.454, p(FDR-corr) = 0.035). In the Basel sample, significant group differences for the left IFOF were replicated (p < .01, ηp2 = 0.29), while the correlation between AD of the left IFOF and semantic processing decline (r = -0.376, p = .09) showed a statistical trend. No significant effects were found for the dorsal language stream. This is direct evidence for the importance of the integrity of the ventral language stream, in particular the left IFOF, in semantic processing deficits in SSD.

Conscious Experience and Psychological Consequences of Awake Craniotomy.

BACKGROUND: Experiencing cranial surgery under awake conditions may expose patients to considerable psychological strain. METHODS: This study aimed to investigate the occurrence and course of psychological sequelae following awake craniotomy (AC) for brain tumors in a series of 20 patients using a broad, validated psychological assessment preoperatively, intraoperatively, postoperatively and a standardized follow-up of 3 months. In addition, the association of the preoperative psychological condition (including, but not limited to, anxiety and fear) with perioperative pain perception and interference was assessed. RESULTS: AC did not induce any shift in the median levels of anxiety, depression, and stress symptoms already present prior to the procedure. Furthermore, anxiety and depression were all moderately to strongly associated over time (all P < 0.05). Stress symptoms also correlated positively over all times of measurement. Stress 3 days after surgery was strongly associated with stress 3 months after surgery (P < 0.001), whereas the correlation between preoperative and immediate postoperative stress showed a statistical trend (P = 0.07). Preoperative fear was not related to intraoperative pain, but to pain and its interference with daily activity on the third postoperative day (P < 0.001 and P < 0.01, respectively). CONCLUSIONS: Postoperative psychological symptoms clearly correlated with their corresponding preoperative symptoms. Thus, mental health was not negatively affected by the AC experience in our series. Intraoperative fear and pain were not related to the preoperative psychological condition. However, preoperative fear and anxiety were positively related with pain and its interference with daily activity in the immediate postoperative period.

Different but similar: personality traits of​ surgeons and internists-results of a cross-sectional observational study.

OBJECTIVES: Medical practice may attract and possibly enhance distinct personality profiles. We set out to describe the personality profiles of surgical and medical specialties focusing on board-certified physicians. DESIGN: Prospective, observational. SETTING: Online survey containing the Ten-Item Personality Inventory (TIPI), an internationally validated measure of the Five Factor Model of personality dimensions, distributed to board-certified physicians, residents and medical students in several European countries and Canada. Differences in personality profiles were analysed using multivariate analysis of variance and Canonical Linear Discriminant Analysis on age-standardised and sex-standardised z-scores of the personality traits. Single personality traits were analysed using robust t-tests. PARTICIPANTS: The TIPI was completed by 2345 board-certified physicians, 1453 residents and 1350 medical students, who also provided demographic information. RESULTS: Normal population and board-certified physicians' personality profiles differed (p<0.001). The latter scored higher on conscientiousness, extraversion and agreeableness, but lower on neuroticism (all p<0.001). There was no difference in openness to experience. Board-certified surgical and medical doctors' personality profiles were also different (p<0.001). Surgeons scored higher on extraversion (p=0.003) and openness to experience (p=0.002), but lower on neuroticism (p<0.001). There was no difference in agreeableness and conscientiousness. These differences in personality profiles were reproduced at other levels of training, that is, in students and training physicians engaging in surgical versus medical practice. CONCLUSION: These results indicate the existence of a distinct and consistent average 'physician personality'. Despite high variability within disciplines, there are moderate but solid and reproducible differences between surgical and medical specialties.