Selection to outsmart the germs: The evolution of disease recognition and social cognition

The emergence of providing care to diseased conspecifics must have been a turning point during the evolution of hominin sociality. On a population level, care may have minimized the costs of socially transmitted diseases at a time of increasing social complexity, although individual care-givers probably incurred increased transmission risks. We propose that care-giving likely originated within kin networks, where the costs may have been balanced by fitness increases obtained through caring for ill kin. We test a novel hypothesis of hominin cognitive evolution in which disease may have selected for the cognitive ability to recognize when a conspecific is infected. Because diseases may produce symptoms that are likely detectable via the perceptual-cognitive pathways integral to social cognition, we suggest that disease recognition and social cognition may have evolved together. Using agent-based modeling, we test 1) under what conditions disease can select for increasing disease recognition and care-giving among kin, 2) whether providing care produces greater selection for cognition than an avoidance strategy, and 3) whether care-giving alters the progression of the disease through the population. The greatest selection was produced by diseases with lower risks to the care-giver and prevalences low enough not to disrupt the kin networks. When care-giving and avoidance strategies were compared, only care-giving reduced the severity of the disease outbreaks and subsequent population crashes. The greatest selection for increased cognitive abilities occurred early in the model runs when the outbreaks and population crashes were most severe. Therefore, over the course of human evolution, repeated introductions of novel diseases into naïve populations could have produced sustained selection for increased disease recognition and care-giving behavior, leading to the evolution of increased cognition, social complexity, and, eventually, medical care in humans. Finally, we lay out predictions derived from our disease recognition hypothesis that we encourage paleoanthropologists, bioarchaeologists, primatologists, and paleogeneticists to test.

Early social environment influences the behaviour of a family-living lizard

Early social environment can play a significant role in shaping behavioural development. For instance, in many social mammals and birds, isolation rearing results in individuals that are less exploratory, shyer, less social and more aggressive than individuals raised in groups. Moreover, dynamic aspects of social environments, such as the nature of relationships between individuals, can also impact the trajectory of development. We tested if being raised alone or socially affects behavioural development in the family-living tree skink, Egernia striolata. Juveniles were raised in two treatments: alone or in a pair. We assayed exploration, boldness, sociability and aggression repeatedly throughout each juvenile's first year of life, and also assessed social interactions between pairs to determine if juveniles formed dominant-subordinate relationships. We found that male and/or the larger skinks within social pairs were dominant. Developing within this social environment reduced skink growth, and subordinate skinks were more prone to tail loss. Thus, living with a conspecific was costly for E. striolata. The predicted negative effects of isolation failed to materialize. Nevertheless, there were significant differences in behavioural traits depending on the social environment (isolated, dominant or subordinate member of a pair). Isolated skinks were more social than subordinate skinks. Subordinate skinks also became more aggressive over time, whereas isolated and dominant skinks showed invariable aggression. Dominant skinks became bolder over time, whereas isolated and subordinate skinks were relatively stable in their boldness. In summary, our study is evidence that isolation rearing does not consistently affect behaviour across all social taxa. Our study also demonstrates that the social environment plays an important role in behavioural development of a family-living lizard.

Incomplete Circle of Willis: A risk factor for mesial temporal sclerosis?

OBJECTIVE

The aim of this study was to investigate whether there may be a correlation between the anatomical variants of Circle of Willis (CoW) and presence/laterality of mesial temporal sclerosis (MTS).

METHODS

We retrospectively identified the CoW variants on Wada angiograms in 71 patients with pathologically proven MTS. Angiograms were interpreted by two radiologists independently and blinded to clinical data. We divided the anterior and posterior components of the CoW into functionally complete and functionally incomplete groups. We then sought its correlation with the presence and laterality of MTS.

RESULTS

No statistically significant relationship was found between the functional status of the anterior circulation and the laterality of the MTS (p=0.657). Relationship of the posterior incomplete circle to MTS was statistically significant on both sides (p=0.023 for the left, p=0.04 for the right), with an effect size moderate to large for the left side and moderate for the right side. Although the fetal variant appeared to be related to the ipsilateral MTS, it did not reach to a level of statistical significance (p=0.15).

SIGNIFICANCE

The study demonstrates a statistically significant association of the incomplete posterior circulation of the CoW to the presence of ipsilateral MTS. Further studies in larger patient populations may be needed to seek whether an incomplete circulation may facilitate development of MTS, especially affecting the watershed zones.

Chimpanzee uses manipulative gaze cues to conceal and reveal information to foraging competitor

Tactical deception has been widely reported in primates on a functional basis, but details of behavioral mechanisms are usually unspecified. We tested a pair of chimpanzees (Pan troglodytes) in the informed forager paradigm, in which the subordinate saw the location of hidden food and the dominant did not. We employed cross-correlations to examine temporal contingencies between chimpanzees' behavior: specifically how the direction of the subordinate's gaze and movement functioned to manipulate the dominant's searching behavior through two tactics, withholding, and misleading information. In Experiment 1, not only did the informed subordinate tend to stop walking toward a single high value food, but she also refrained from gazing toward it, thus, withholding potentially revealing cues from her searching competitor. In a second experiment, in which a moderate value food was hidden in addition to the high value food, whenever the subordinate alternated her gaze between the dominant and the moderate value food, she often paused walking for 5 s; this frequently recruited the dominant to the inferior food, functioning as a "decoy." The subordinate flexibly concealed and revealed gaze toward a goal, which suggests that not only can chimpanzees use visual cues to make predictions about behavior, but also that chimpanzees may understand that other individuals can exploit their gaze direction. These results substantiate descriptive reports of how chimpanzees use gaze to manipulate others, and to our knowledge are the first quantitative data to identify behavioral mechanisms of tactical deception.

RESEARCH HIGHLIGHTS

Cross correlations show a subordinate chimpanzee tactically deceived a dominant by not gazing toward a valuable food (withholding), and recruiting to a "decoy" food (misleading). Chimpanzees understand that others can exploit their gaze direction.

Cortical stimulation parameters for functional mapping

PURPOSE

There is significant variation in how patients respond to cortical electrical stimulation. It has been hypothesized that individual demographic and pathologic factors, such as age, sex, disease duration, and MRI findings, may explain this discrepancy. The purpose of our study is to identify specific patient characteristics and their effect on cortical stimulation, and discover the extent of variation in behavioral responses that exists among patients with epilepsy.

METHOD

We retrospectively analyzed data from 92 patients with medically intractable epilepsy who had extra-operative cortical electrical stimulation. Mapping records were evaluated and information gathered about demographic data, as well as the thresholds of stimulation for motor, sensory, speech, and other responses; typical seizure behavior; and the induction of afterdischarges.

RESULTS

Ninety-two patient cortical stimulation mapping reports were analyzed. The average of the minimum thresholds for motor response was 4.15mA±2.67. The average of the minimum thresholds for sensory response was 3.50mA±2.15. The average of the minimum thresholds for speech response was 4.48mA±2.42. The average of the minimum thresholds for afterdischarge was 4.33mA±2.37. Most striking were the degree of variability and wide range of thresholds seen between patients and within the different regions of the same patient.

CONCLUSION

Wide ranges of thresholds exist for the different responses between patients and within different regions of the same patient. With multivariate analysis in these series, no clinical or demographic factors predicted physiological response or afterdischarge threshold levels.

The gestural repertoire of the wild bonobo (Pan paniscus): a mutually understood communication system

In animal communication, signallers and recipients are typically different: each signal is given by one subset of individuals (members of the same age, sex, or social rank) and directed towards another. However, there is scope for signaller–recipient interchangeability in systems where most signals are potentially relevant to all age–sex groups, such as great ape gestural communication. In this study of wild bonobos (Pan paniscus), we aimed to discover whether their gestural communication is indeed a mutually understood communicative repertoire, in which all individuals can act as both signallers and recipients. While past studies have only examined the expressed repertoire, the set of gesture types that a signaller deploys, we also examined the understood repertoire, the set of gestures to which a recipient reacts in a way that satisfies the signaller. We found that most of the gestural repertoire was both expressed and understood by all age and sex groups, with few exceptions, suggesting that during their lifetimes all individuals may use and understand all gesture types. Indeed, as the number of overall gesture instances increased, so did the proportion of individuals estimated to both express and understand a gesture type. We compared the community repertoire of bonobos to that of chimpanzees, finding an 88 % overlap. Observed differences are consistent with sampling effects generated by the species’ different social systems, and it is thus possible that the repertoire of gesture types available to Pan is determined biologically.

Communication in the second and third year of life: Relationships between nonverbal social skills and language

We aimed to investigate developmental continuities between a range of early social and communicative abilities (including gestural communication) and language acquisition in children aged between 11 and 41 months. Initiation of joint attention and imitation were strongly correlated to language comprehension and production. Moreover, the analysis of different communicative gestures revealed significant relationships between language development and the production of symbolic gestures, declarative pointing (declarative informative pointing in particular), and head nodding. Other gestures such as imperative pointing, showing, and head shaking were not found to correlate with language level. Our results also suggest that distinct processes are involved in the development of language comprehension and production, and highlight the importance of considering various characteristics of children's early communicative skills.

Learning curve for the transsphenoidal endoscopic endonasal approach to pituitary tumors

INTRODUCTION

The transsphenoidal endoscopic approach is a relatively new procedure compared to the microscopic approach in pituitary adenoma resection. The endoscopic approach has shown to significantly decrease the rate of complications, time in the operating room and hospital, and patient post-op discomfort. However, this procedure requires the surgeon to make use of different visual and tactile clues that must be developed with experience. Therefore, it is important to understand the learning curve that the surgeon must overcome to become proficient with the endoscopic approach.

METHODS

Retrospective review of a single-surgeon consecutive series of 78 patients undergoing endoscopic pituitary tumor surgery from 2006 to 2012 at Rush University Medical Center has been used in this study. Patients were grouped according to an early (n = 9) and late group (n = 68) determined by a significant difference in outcomes. Our primary outcome measures were: duration of operation, CSF leak, hospital length of stay, visual field improvement, diabetes insipidus, panhypopituitarism, and subtotal resection.

RESULTS

There was a significant reduction in OR time and intraoperative CSF leaks between the early and late groups. There was no difference in hospital LOS or visual field improvement between the groups. With regards to complication rates, there was no difference found for DI, panhypopituitarism, lumbar drain placement, sinusitis, or subtotal resection between the two groups.

CONCLUSION

This study indicates that there may be a learning curve of approximately 9 cases before a surgical team can decrease OR times and reduce the rate of intraoperative CSF leaks for the endonasal endoscopic approach to pituitary adenoma resection.

A rare intracranial tumor consisting of malignant anaplastic and papillary meningioma subtypes

Background:

Intracranial tumors with heterogeneous histopathology are a well-described pathologic entity. Pathologically, distinct tumors in direct contact with one another, also known as collision tumors are exceptionally rare, and collision between meningioma subtypes has not been previously described in the literature.

Case Description:

A 79-year-old female with a history of breast carcinoma presenting with visual and motor deficits and imaging/intraoperative findings consistent with separate, distinct lesions. Histopathologic findings provided evidence for a collision between World Health Organization Grade III anaplastic and papillary meningioma.

Conclusion:

We report a possible collision tumor between two separate meningioma subtypes based on the unique radiologic, intraoperative, and histopathologic findings. Submission of multiple pathologic specimens during surgical resection is key for accurate histopathologic diagnosis.

Age-dependent social learning in a lizard

Evidence of social learning, whereby the actions of an animal facilitate the acquisition of new information by another, is taxonomically biased towards mammals, especially primates, and birds. However, social learning need not be limited to group-living animals because species with less interaction can still benefit from learning about potential predators, food sources, rivals and mates. We trained male skinks (Eulamprus quoyii), a mostly solitary lizard from eastern Australia, in a two-step foraging task. Lizards belonging to 'young' and 'old' age classes were presented with a novel instrumental task (displacing a lid) and an association task (reward under blue lid). We did not find evidence for age-dependent learning of the instrumental task; however, young males in the presence of a demonstrator learnt the association task faster than young males without a demonstrator, whereas old males in both treatments had similar success rates. We present the first evidence of age-dependent social learning in a lizard and suggest that the use of social information for learning may be more widespread than previously believed.

African elephants (Loxodonta africana) recognize visual attention from face and body orientation

How do animals determine when others are able and disposed to receive their communicative signals? In particular, it is futile to make a silent gesture when the intended audience cannot see it. Some non-human primates use the head and body orientation of their audience to infer visual attentiveness when signalling, but whether species relying less on visual information use such cues when producing visual signals is unknown. Here, we test whether African elephants (Loxodonta africana) are sensitive to the visual perspective of a human experimenter. We examined whether the frequency of gestures of head and trunk, produced to request food, was influenced by indications of an experimenter's visual attention. Elephants signalled significantly more towards the experimenter when her face was oriented towards them, except when her body faced away from them. These results suggest that elephants understand the importance of visual attention for effective communication.

The what as well as the why of animal fun

Fun is functional: play is evolution's way of making sure animals acquire and perfect valuable skills in circumstances of relative safety. Yet precisely what animals find fun has seldom been examined for what it can potentially reveal about how they represent and think about the world.

Wild chacma baboons (Papio ursinus) remember single foraging episodes

Understanding animal episodic-like memory is important for tracing the evolution of the human mind. However, our knowledge about the existence and nature of episodic-like memory in non-human primates is minimal. We observed the behaviour of a wild male chacma baboon faced with a trade-off between protecting his stationary group from aggressive extra-group males and foraging among five out-of-sight platforms. These contained high-priority food at a time of natural food shortage. In 10 morning and eight evening trials, the male spontaneously visited the platforms in five and four different sequences, respectively. In addition, he interrupted foraging sequences at virtually any point on eight occasions, returning to the group for up to 2 h. He then visited some or all of the remaining platforms and prevented revisits to already depleted ones, apparently based on his memory for the previous foraging episode about food value, location, and time. Efficient use of memory allowed him to keep minimal time absent from his group while keeping food intake high. These findings support the idea that episodic-like memory offers an all-purpose solution to a wide variety of problems that require flexible, quick, yet precise decisions in situations arising from competition for food and mates in wild primates.

Apes in the Anthropocene: flexibility and survival

We are in a new epoch, the Anthropocene, and research into our closest living relatives, the great apes, must keep pace with the rate that our species is driving change. While a goal of many studies is to understand how great apes behave in natural contexts, the impact of human activities must increasingly be taken into account. This is both a challenge and an opportunity, which can importantly inform research in three diverse fields: cognition, human evolution, and conservation. No long-term great ape research site is wholly unaffected by human influence, but research at those that are especially affected by human activity is particularly important for ensuring that our great ape kin survive the Anthropocene.

Fostering and assessing professionalism and communication skills in neurosurgical education

INTRODUCTION

Incorporation of the 6 ACGME core competencies into surgical training has proven a considerable challenge particularly for the two primarily behavioral competencies, professionalism and interpersonal and communication skills. We report on experience with two specific interventions to foster the teaching and continuous evaluation of these competencies for neurosurgery residents.

MATERIAL AND METHODS

In 2010, the Society of Neurological Surgeons (SNS) organized the first comprehensive Neurosurgery Boot Camp courses, held at six locations throughout the US and designed to assess and teach not only psychomotor skills but also components of all six Accreditation Council for Graduate Medical Education (ACGME) core competencies. These courses are comprised of various educational methodologies, including online material, faculty lectures, clinical scenario and group discussions, manual skills stations, and pre- and post-course assessments. Resident progress in each of the 6 ACGME competencies is now tracked using the neurosurgical Milestones, developed by the ACGME in collaboration with the SNS. In addition, the Milestones drafting group for neurosurgery has formulated a milestone-compatible evaluation system to directly populate Milestone reports. These evaluations utilize formative, summative, and 360-degree evaluations that are considered by a faculty core competency committee in finalizing milestones levels for each resident.

RESULTS

Initial attendance at the 2010 Boot Camp course was 94% of the incoming resident class and in subsequent years, 100%. Pre- and post-course surveys demonstrated a significant and sustained increase in knowledge. The value of these courses has been recognized by the ACGME, which requires Boot Camp or equivalent participation prior to acting with indirect supervision during clinical activities. Neurosurgery was one of 7 early Milestone adopter specialties, beginning use in July, 2013. Early milestone data will establish benchmarks prior to utilization for "high stake" decisions such as promotion, graduation, and termination.

CONCLUSIONS

The full impact of the neurosurgical Boot Camps and Milestones on residency education remains to be measured, although published data from the first years of the Boot Camp Courses demonstrate broad acceptance and early effectiveness. A complementary junior resident course has now been introduced for rising second-year residents. The Milestones compatible evaluation system now provides for multi-source formative and summative evaluation of neurosurgical residents within the new ACGME reporting rubric. Combined with consensus milestone assignments, this system provides new specificity and objectivity to resident evaluations. The correlation of milestone level assignments with other measurements of educational outcome awaits further study.

Magnetic resonance imaging characteristics of typical and atypical/anaplastic meningiomas - Case series and literature review

OBJECTIVE

The histologic grades of meningiomas have a significant impact on the risk of recurrence, prognosis, and the need for adjuvant treatment such as radiation therapy. The purpose of this study is to investigate the magnetic resonance imaging (MRI) characteristics of typical and atypical/anaplastic meningiomas.

METHODS

The medical records of 32 consecutive patients who underwent meningioma resections between April 2004 and November 2006 were retrospectively reviewed. Preoperative MR studies were reviewed by board-certified neuroradiologists. Both univariate and multivariate analyses were used to analyze the MR characteristics of the typical and atypical/anaplastic meningiomas. A review of pertinent literature was also conducted.

RESULTS

Thirty-two patients were identified during the study period. Histopathologic examination of the surgical specimens revealed 27 (84.4% - Group I) typical meningiomas and 5 (15.6% - Group 2) atypical/anaplastic meningiomas. The chi-square test showed that restricted diffusion was much more likely to be present in Group 2 (p < 0.01), and the choline-to-creatinine (Cho/Cr) ratio was significantly higher in Group 2 (8.8 vs. 5.1, p = 0.01). The multivariate analysis confirmed that the atypical/anaplastic group is much more likely to have restricted diffusion (p = 0.02) and higher Cho/Cr ratios (p = 0.03).

CONCLUSION

Meningiomas with restricted diffusion and higher Cho/Cr ratio on MR spectroscopy are more likely to be atypical/anaplastic types. Preoperative MRI utilizing these sequences can provide important information which can be valuable to counsel patients regarding prognosis, risk of recurrence and the need for adjuvant radiation in addition to surgical resection.

Chiari I malformation associated with atlanto-occipital assimilation presenting as orthopnea and cough syncope: a case report and review of literature

Although it is not uncommon for patients with Chiari I malformations to present with respiratory complaints, cough syncope is a rare presenting symptom. We report an adult patient who harbored both a Chiari I malformation and atlanto-occipital assimilation who complained of cough syncope, orthopnea, and central sleep apnea. The patient underwent decompressive craniectomy of the posterior fossa and cervical level 2 laminectomy. However, due to a possible initial underappreciation of the profound narrowing of the foramen magnum as a result of these concomitant pathologies, the patient may have had continued impaired cerebrospinal fluid flow, leading to a symptomatic pseudomeningocele and requiring a more extensive decompression that included a cervical level 3 laminectomy as well as a temporary lumbar drain. On 2-year follow-up, he has remained asymptomatic.

Interpretation of human pointing by African elephants: generalisation and rationality

Factors influencing the abilities of different animals to use cooperative social cues from humans are still unclear, in spite of long-standing interest in the topic. One of the few species that have been found successful at using human pointing is the African elephant (Loxodonta africana); despite few opportunities for learning about pointing, elephants follow a pointing gesture in an object-choice task, even when the pointing signal and experimenter's body position are in conflict, and when the gesture itself is visually subtle. Here, we show that the success of captive African elephants at using human pointing is not restricted to situations where the pointing signal is sustained until the time of choice: elephants followed human pointing even when the pointing gesture was withdrawn before they had responded to it. Furthermore, elephants rapidly generalised their response to a type of social cue they were unlikely to have seen before: pointing with the foot. However, unlike young children, they showed no sign of evaluating the 'rationality' of this novel pointing gesture according to its visual context: that is, whether the experimenter's hands were occupied or not.

Amygdalohippocampectomy for epilepsy in a patient with prior ipsilateral deep brain stimulator lead placement

In light of failed medical therapy for movement disorders, the use of deep brain stimulation (DBS) has increased the last two decades. Many complications may transpire; however, to our knowledge, the literature does not mention the phenomena of brain shift from a second unrelated neurosurgical procedure and its theoretical effect on lead displacement and lead function. We present a patient with a left sided DBS for essential tremor and subsequent left amygdalohippocampectomy for temporal lobe epilepsy with minimal radiographic distortion of the DBS lead and without clinical or functional complications. A 47-year-old woman presented with bitemporal epilepsy secondary to a brain injury acquired in childhood in addition to a comorbid bilateral essential tremor, both refractory to medical intervention. A successful left-sided DBS placement was performed with satisfactory resolution of her essential tremor. The patient subsequently developed deterioration of seizure control, becoming refractory to anti-epileptic medications, requiring surgical intervention. A left-sided selective amygdalohippocampectomy and techniques to minimize brain shift were performed without complications. Postoperative imaging suggested minimal distortion of the DBS lead. This did not correspond with reemergence of her essential tremor, implying that the lead maintained functional utility. Brain shift secondary to a craniotomy may cause DBS lead displacement. This phenomenon should be considered when planning operative approaches and can be limited by selective resections. With the growing propensity for placement of DBS leads and the risk of lead displacement, it is important to consider operative approaches to minimize brain shift.

Chronic unlimited recording electrocorticography–guided resective epilepsy surgery: technology-enabled enhanced fidelity in seizure focus localization with improved surgical efficacy

Object

Epilepsy surgery is at the cusp of a transformation due to the convergence of advancements in multiple technologies. Emerging neuromodulatory therapies offer the promise of functionally correcting neural instability and obviating the need for resective or ablative surgery in select cases. Chronic implanted neurological monitoring technology, delivered as part of a neuromodulatory therapeutic device or as a stand-alone monitoring system, offers the potential to monitor patients chronically in their normal ambulatory setting with outpatient medication regimens. This overcomes significant temporal limitations, pharmacological perturbations, and infection risks inherent in the present technology comprising subacute percutaneous inpatient monitoring of presurgical candidates in an epilepsy monitoring unit.

Methods

As part of the pivotal study for the NeuroPace Responsive Neurostimulation (RNS) System, the authors assessed the efficacy of the RNS System to control seizures in a group of patients with medically refractory epilepsy. Prior to RNS System implantation, these patients were not candidates for further resective surgery because they had temporal lobe epilepsy with bilateral temporal sources, frontal lobe reflex epilepsy with involvement of primary motor cortex, and occipital lobe epilepsy with substantial involvement of eloquent visual cortex. Without interfering with and beyond the scope of the therapeutic aspect of the RNS System study, the authors were able to monitor seizure and epileptiform activity from chronically implanted subdural and depth electrodes in these patients, and, in doing so, they were able to more accurately localize the seizure source. In 5 of these study patients, in whom the RNS System was not effective, the notion of resective surgery was revisited and considered in light of the additional information gleaned from the chronic intracranial recordings obtained from various permutations of electrodes monitoring sources in the frontal, temporal, parietal, and occipital lobes.

Results

Through long-term analysis of chronic unlimited recording electrocorticography (CURE) from chronically implanted electrodes, the authors were able to further refine seizure source localization and sufficiently increase the expected likelihood of seizure control to the extent that 4 patients who had previously been considered not to be candidates for surgery did undergo resective surgery, and all have achieved seizure freedom. A fifth patient, who had a double-band heterotopia, underwent surgery but did not achieve significant seizure reduction.

Conclusions

Chronic unlimited recording electrocorticography–guided resective epilepsy surgery employs new monitoring technology in a novel way, which in this small series was felt to improve seizure localization and consequently the potential efficacy of resective surgery. This suggests that the CURE modality could improve outcomes in patients who undergo resective surgery, and it may expand the set of patients in whom resective surgery may be expected to be efficacious and therefore the potential number of patients who may achieve seizure freedom. The authors report 4 cases of patients in which this technique and technology had a direct role in guiding surgery that provided seizure freedom and that suggest this new approach warrants further study to characterize its value in presurgical evaluation. Clinical trial no.: NCT00572195 (ClinicalTrials.gov).

Relevance of early head CT scans following neurosurgical procedures: an analysis of 892 intracranial procedures at Rush University Medical Center

OBJECT

Early postoperative head CT scanning is routinely performed following intracranial procedures for detection of complications, but its real value remains uncertain: so-called abnormal results are frequently found, but active, emergency intervention based on these findings may be rare. The authors' objective was to analyze whether early postoperative CT scans led to emergency surgical interventions and if the results of neurological examination predicted this occurrence.

METHODS

The authors retrospectively analyzed 892 intracranial procedures followed by an early postoperative CT scan performed over a 1-year period at Rush University Medical Center and classified these cases according to postoperative neurological status: baseline, predicted neurological change, unexpected neurological change, and sedated or comatose. The interpretation of CT results was reviewed and unexpected CT findings were classified based on immediate action taken: Type I, additional observation and CT; Type II, active nonsurgical intervention; and Type III, surgical intervention. Results were compared between neurological examination groups with the Fisher exact test.

RESULTS

Patients with unexpected neurological changes or in the sedated or comatose group had significantly more unexpected findings on the postoperative CT (p < 0.001; OR 19.2 and 2.3, respectively) and Type II/III interventions (p < 0.001) than patients at baseline. Patients at baseline or with expected neurological changes still had a rate of Type II/III changes in the 2.2%-2.4% range; however, no patient required an immediate return to the operating room.

CONCLUSIONS

Over a 1-year period in an academic neurosurgery service, no patient who was neurologically intact or who had a predicted neurological change required an immediate return to the operating room based on early postoperative CT findings. Obtaining early CT scans should not be a priority in these patients and may even be cancelled in favor of MRI studies, if the latter have already been planned and can be performed safely and in a timely manner. Early postoperative CT scanning does not assure an uneventful course, nor should it replace accurate and frequent neurological checks, because operative interventions were always decided in conjunction with the neurological examination.

Using cross correlations to investigate how chimpanzees (Pan troglodytes) use conspecific gaze cues to extract and exploit information in a foraging competition

In a dyadic informed forager task, chimpanzees (Pan troglodytes) are known to exploit the knowledge of informed subordinates; however, the behavioral mechanisms they employ are unknown. It is tempting to interpret outcome measures, such as which individual obtained the food, in a cognitively richer way than the outcomes may justify. We employed a different approach from prior research, asking how chimpanzees compete by maneuvering around each other, whether they use gaze cues to acquire information from others, and what information they use in moment-to-moment decision-making. We used cross correlations, which plot the correlation between two variables as a function of time, systematically to examine chimpanzee interactions in a series of dyadic informed forager contests. We used cross correlations as a "proof of concept" so as to determine whether the target actions were contingent on, or occurred in a time-locked pattern relative to, the referent actions. A subordinate individual was given privileged knowledge of food location. As expected, an ignorant dominant followed the informed subordinate's movement in the enclosure. The dominant also followed the subordinate's gaze direction: after she looked at the subordinate, she was more likely to gaze toward this same direction within one second. In contrast, the subordinate only occasionally followed the dominant's movement and gaze. The dominant also changed her own direction of movement to converge on the location to which the subordinate directed her gaze and movement. Cross correlation proves an effective technique for charting contingencies in social interactions, an important step in understanding the use of cognition in natural situations.

Impact of therapeutic regimen and clinical presentation on overall survival in CNS lymphoma

BACKGROUND

The authors present a retrospective analysis of 45 patients who underwent treatment of CNS lymphoma (both primary and secondary) at a single institution between 2005 and 2012.

METHODS

This study involves 21 female and 24 male patients with a mean age of 59.2 years. All medical records and pathology reports were reviewed for each patient. Univariate and multivariate analyses of overall survival were performed.

RESULTS

Presentation with altered mental status was a significant risk factor for worse overall survival. An HIV infection, deep lesion location, and age over 60 did not impact survival. A survival benefit was demonstrated with the use of systemic therapy, specifically rituximab, and radiation. The CNS Lymphoma Score was derived from this cohort, which proved a powerful predictive tool for overall survival. The surgical complication rate in this series was 17.8 %.

CONCLUSIONS

This study highlights the prognostic importance of presenting mental status on outcomes in CNS lymphoma and demonstrates a summative benefit of rituximab and whole brain radiation therapy. Considering these factors together provides an easily applicable and meaningful stratification for this patient population. The surgical complication rate in this patient population is not negligible. The high percentage of wound-related surgical complications suggests the need for a waiting period between surgery and initiation of chemotherapy to allow for wound healing.

Application of Novel CO2 Laser-Suction Device

Background Development of the flexible CO2 fiber has presented new opportunities for the use of precision laser cutting in cranial procedures. The efficacy of the CO2 scalpel is further enhanced by combining it with a fluid removal suction capability. Objectives We report our experience with a novel CO2 laser-suction device. Methods The novel laser-suction device was designed in conjunction with OmniGuide Inc. (Cambridge, Massachusetts, USA). We performed a case review of its use in firm tumors that were resistant to resection by bipolar, suction, and ultrasonic aspirator. Results The laser-suction device was applied in three tumors where resection with ultrasonic aspiration failed. Tumor resection using the laser-suction device was successful in all three cases. There were no complications related to the laser-suction device. There were no instances of intraoperative device malfunction. Discussion The CO2 laser combined with suction is a useful instrument for resection of firm tumors that prove to be resistant to ultrasonic aspiration. We also find it to be useful in settings where precise tissue incisions are desired with minimal manipulation. In our experience, the surgical efficiency of the CO2 laser is improved by the laser-suction device. This device allows the surgeon to utilize a suction device and laser in a single hand and enables concurrent use of bipolar electrocautery without repeated instrument changes.

Microsurgical anatomy of the transsylvian translimen insula approach to the mediobasal temporal lobe: Technical considerations and case illustration

Background:

Various vascular, neoplastic, and epileptogenic pathologies occur in the mediobasal temporal region. A transsylvian translimen insula (TTI) approach can be used as an alternative to temporal transcortical approach to the mediobasal temporal region. The aim of this study was to demonstrate the surgical anatomy of the TTI approach, including the gyral, sulcal, and vascular anatomy in and around the limen insula. The use of this approach is illustrated in the resection of a complex arteriovenous malformation.

Methods:

The TTI approach to the mediobasal temporal region was performed on three silicone-injected cadaveric heads. The gyral, sulcal, and arterial anatomy of the limen insula was studied in six formalin-fixed injected hemispheres.

Results:

The TTI approach provided access to the anterior and middle segments of the mediobasal temporal lobe region as well as allowing access to temporal horn of the lateral ventricle. Using this approach we were able to successfully resect an arteriovenous malformation of the dominant medial temporal lobe.

Conclusion:

The TTI approach provides a viable surgical route to the region of mediobasal temporal lobe region. This approach offers an advantage over the temporal transcortical route in that there is less risk of damage to optic radiations and speech area in the dominant hemisphere.

Retrosigmoid approach for resection of an extraventricular choroid plexus papilloma in the cerebellopontine angle

Choroid plexus papillomas (CPP) are uncommon benign brain tumors that usually arise in the fourth ventricle in adults and lateral ventricles in children. Extraventricular CPPs are rare and can be found primarily in the cerebellopontine angle (CPA). We present a case of primary extraventricular CPP in the right CPA successfully resected with retrosigmoid approach. Detailed surgical techniques of retrosigmoid craniotomy and tumor dissection are presented in high definition video with narration. The video can be found here: http://youtu.be/6591en3nWlY .

Large cerebellar mass lesion: A rare intracranial manifestation of blastomycosis

BACKGROUND

Blastomyces dermatitidis is a dimorphic fungus found endemically in the Mississippi and Ohio River basins and in the Midwestern and Canadian provinces that border the Great Lakes. Unlike other fungal infections, it most commonly affects immunocompetent hosts. Blastomycosis typically manifests as pulmonary infection, but may affect nearly any organ, including the skin, bone, and genitourinary system. Central nervous system (CNS) blastomycosis is rare, but potentially fatal manifestation of this disease. When it does occur, it most commonly presents as acute or chronic meningitis.

CASE DESCRIPTION

We present a case of a patient who suffered intractable nausea and vomiting for several months before discovery of a large cerebellar blastomycoma causing mass effect and obstructive hydrocephalus. The enhancing lesion with unusual peripheral cystic structures is a unique radiographic appearance of CNS blastomycosis.

CONCLUSION

We review this patient's purely intraparenchymal manifestation of CNS blastomycosis and describe the unique imaging characteristics encountered.

Differentiating ictal panic with low-grade temporal lobe tumors from psychogenic panic attacks

OBJECTIVE

Indolent low-grade temporal lobe tumors may present with ictal panic that may be difficult to differentiate from psychogenic panic attacks. The current study aims to demonstrate the differences between the two disorders and help physicians generate a diagnostic paradigm.

METHOD

This was a retrospective study of 43 patients who underwent a temporal lobectomy between 1981 and 2008 for the treatment of intractable temporal lobe epilepsy secondary to low-grade neoplasms at Rush University Medical Center. A total of 10 patients in this group presented with ictal panic who were previously being treated for psychogenic panic attacks. Medical records were reviewed for age at seizure onset, duration of symptoms, lateralization of the epileptogenic zone, pathological diagnosis, and postsurgical seizure outcome according to the modified Engel classification.

RESULTS

Neuropathologic findings of the 10 tumors were pleomorphic xanthoastrocytoma, ganglioglioma, oligodendroglioma, and dysembryoplastic neuroepithelial. The mean age of the patients undergoing surgery was 28 years (range, 15-49). The mean duration of panic symptoms prior to surgery was 9.8 years (range, 3-23). All patients had unprovoked ictal panic. None had symptoms suggestive of a brain tumor, such as signs of increased intracranial pressure or any focal neurologic deficit. In 5 of the patients, other symptoms associated with the ictal panic, including unusual sounds, nausea, automatism, uprising gastric sensation, and déjà vu were identified. Gross total resection of the lesion resulted in improved seizure outcome in all patients undergoing surgery. Patient follow-up was, on average, 7.4 years (range, 2-14) from time of surgery.

CONCLUSIONS

Although similar, ictal panic from epilepsy and classic panic attacks are clinically distinguishable entities with different modalities of treatment. A careful history may help differentiate patients with ictal panic from those with psychogenic panic attacks and determine for which patients to obtain neuroimaging studies.

Deictic gesturing in wild chimpanzees (Pan troglodytes)? Some possible cases

Referential pointing is important in the development of language comprehension in the child and is often considered a uniquely human capacity. Nonhuman great apes do point in captivity, usually for a human audience, but this has been interpreted as an interaction pattern learned from human caretakers, not indicative of natural deictic ability. In contrast, spontaneous pointing for other apes is almost unknown among wild ape populations, supporting doubts as to whether apes naturally have any capacity to point referentially. Here the authors describe and illustrate 4 cases of gestures by juvenile chimpanzees in the Sonso chimpanzee community in Budongo, Uganda, that, at some level, may appear to be deictic and referential. The authors discuss the possible reasons why chimpanzees, if they possess a capacity for referential pointing, do not use it more frequently.

Titi monkey call sequences vary with predator location and type

Animal alarm calls can encode information about a predator's category, size, distance or threat level. In non-human primates, alarm calls typically refer to broad classes of disturbances, in some instances to specific predators. Here, we present the results of a field experiment with a New World primate, the black-fronted titi monkey (Callicebus nigrifrons), designed to explore the information conveyed by their alarm call system. Adults produced sequences consisting of two main alarm call types that conveyed, in different parts of the utterance, information about a predator's type and location. In particular, sequence compositions differed depending on whether the predator was a mammalian carnivore or a raptor, and whether it was detected in a tree or on the ground. This is the first demonstration of a sequence-based alarm call system in a non-human animal that has the capacity to encode both location and type of predatory threat.

Chronic epilepsy due to low grade temporal lobe tumors and due to hippocampal sclerosis: do they differ in post-surgical outcome?

Chronic seizures as a presenting feature of low grade temporal lobe gliomas and hippocampal sclerosis (HS) are reported to have similar outcomes although the prognostic indicators may not be the same. This study seeks to identify the variables that are associated with poor surgical outcome in both conditions. A retrospective analysis from our epilepsy data base was performed. All low-grade temporal lobe gliomas were selected and relevant variables were compared to the same variables in HS patients. There were 34 tumors (out of 233 cases of chronic temporal lobe epilepsy = 14.6 %) with a mean age of onset of 19 years, and the preoperative duration was 12.3 years. When compared to 120 HS patients both of these factors were significantly different (p < 0.001). Age at the time of surgery for tumors was 31.08 (p = 0.5). Tumors were left sided in 20 patients. In tumor cases amygdala resection was complete in 75 %, for hippocampus 24 % were complete and 39 % partial. Astrocytoma, ganglioglioma and oligodendroglioma constituted 80 % of tumor cases. Good outcome (Engel's Class I) was achieved in 88.2 % of tumor cases and 71 % of HS cases while poor outcome (Class III + IV) was seen in 5.9 and 16.7 % respectively. The follow up period for the two groups was not significantly different. In multivariate logistic regression analysis, the groups differed significantly in preoperative delay (between diagnosis and surgery) and in epilepsy outcome. Chronic temporal lobe epilepsy due to low-grade tumors had significantly better surgical outcome with considerably less preoperative delay. The age of onset of seizures was younger in HS patients but a delay in surgical treatment was significantly longer. Given that the diagnosis of treatment-resistant TLE secondary to HS can be established after two failed AED trials at optimal doses, shortening the interval between diagnosis and surgery may improve epilepsy outcome.

Change point analysis of travel routes reveals novel insights into foraging strategies and cognitive maps of wild baboons

Efficient space use is a critical challenge for animals relying on stationary resources. It is often difficult with purely observational methods to gain unambiguous insight into any ability of primates to manage and process spatial information. Investigating the visible signs of the decision processes underlying space use often leaves open important issues. We applied the change point test [Byrne et al. (2009). Anim Behav 77: 619-631], a statistical tool to objectively determine change points (CPs) in animal travel paths, to investigate to what degree directional changes in our study group's (Papio ursinus) dry season ranging were associated with important resources and prominent landmarks. One-third of directional changes were associated with fruit feeding, 1/3 with traveling, and 1/3 with dry matter feeding, travel feeding and with drinking. When directional changes were associated with traveling, the subsequent directional changes were likely to result in fruit feeding. Fruit feeding mostly occurred at the apex of the day journeys, while drinking, dry matter feeding, and travel feeding often occurred along straight travel segments. The majority of directional changes did not occur in clusters at distinctive locations, but at distances of more than 120 m apart from each other, many of them along prominent landmarks. We conclude that the CPs do not represent nodes or route bends of a network map. Rather, they represent (1) locations where the decision to turn back to their sleeping site was taken, and (2) locations next to important landmarks (changes of slope, car tracks) where slight adjustment of a movement direction was possible. We found no evidence for a Euclidean map and discuss our findings in the light of a network map representation of space.