Off-road vehicle crashes: dangers of alcohol and drug impairment

BACKGROUND

Impaired driving is a public health issue, yet little is known concerning the prevalence of substance use in drivers involved in off-road vehicle crashes. The goal of the present study was to describe the demographics and prevalence of alcohol and drug use in drivers of off-road vehicle crashes.

METHODS

In this observational substudy, we collected clinical and toxicological data on all moderately or severely injured off-road vehicle drivers who had blood samples obtained within 6 h of the crash. Clinical data were extracted from patients' medical charts and toxicology analyses were performed for blood alcohol, cannabinoids, recreational drugs, and impairing medications.

RESULTS

Thirty-three injured drivers met the inclusion criteria. The mean age was 37.6 ± 13.4 years and 79% were male. Blood alcohol was detected in 58% of drivers and 42% of these were above the legal limit. Tetrahydrocannabinol was positive in 12% of drivers, and 18% were positive for recreational drugs. Opiates were detected in 21% of drivers. Overall, 85% were positive for at least one substance and 39% tested positive for multiple substances.

CONCLUSION

This study presents the first evidence of alcohol and drug use in off-road vehicle drivers after cannabis legalization in Canada. Our results show that over half of drivers in off-road vehicle crashes test positive for alcohol and 30% tested positive for THC, cocaine, or amphetamines. Opiates are also commonly detected in off-road vehicle drivers. Emergency department (ED) visits resulting from drug driving of off-road vehicles serve as an opportunity for screening, initiating treatment, and connecting patients to interventions for substance use disorders.

Spatial Hotspots and Sociodemographic Profiles Associated With Traumatic Brain Injury in Nova Scotia

Traumatic brain injury (TBI) is a leading cause of death and disability, primarily caused by falls and motor vehicle collisions (MVCs). Although many TBIs are preventable, there is a notable lack of studies exploring the association of geographically defined TBI hotspots with social deprivation. Geographic information systems (GIS) can be used to identify at-risk neighborhoods (hotspots) for targeted interventions. This study aims to determine the spatial distribution of TBI by major causes and to explore the sociodemographic and economic characteristics of TBI hotspots and cold spots in Nova Scotia. Patient data for TBIs from 2003 to 2019 were obtained from the Nova Scotia Trauma Registry. Residential postal codes were geocoded and assigned to dissemination areas (DA). Area-based risk factors and deprivation status (residential instability [RI], economic dependency [ED], ethnocultural composition [EC], and situational vulnerability [SV]) from the national census data were linked to DAs. Spatial autocorrelation was assessed using Moran's I, and hotspot analysis was performed using Getis-Ord Gi* statistic. Differences in risk factors between hot and cold spots were evaluated using the Mann-Whitney U test for numerical variables and the χ2 test or Fisher's exact test for categorical variables. A total of 5394 TBI patients were eligible for inclusion in the study. The distribution of hotspots for falls exhibited no significant difference between urban and rural areas (p = 0.71). Conversely, hotspots related to violence were predominantly urban (p = 0.001), whereas hotspots for MVCs were mostly rural (p < 0.001). Distinct dimensions of deprivation were associated with falls, MVCs, and violent hotspots. Fall hotspots were significantly associated with areas characterized by higher RI (p < 0.001) and greater ethnocultural diversity (p < 0.001). Conversely, the same domains exhibited an inverse relationship with MVC hotspots; areas with low RI and ethnic homogeneity displayed a higher proportion of MVC hotspots. ED and SV exhibited a strong gradient with MVC hotspots; the most deprived quintiles displayed the highest proportion of MVC hotspots compared with cold spots (ED; p = 0.002, SV; p < 0.001). Areas with the highest levels of ethnocultural diversity were found to have a significantly higher proportion of violence-related hotspots than cold spots (p = 0.005). This study offers two significant contributions to spatial epidemiology. First, it demonstrates the distribution of TBI hotspots by major injury causes using the smallest available geographical unit. Second, we disentangle the various pathways through which deprivation impacts the risk of main mechanisms of TBI. These findings provide valuable insights for public health officials to design targeted injury prevention strategies in high-risk areas.

Blood-Brain Barrier Dysfunction and Exposure to Head Impacts in University Football Players

OBJECTIVE

To investigate the link between dysfunction of the blood-brain barrier (BBB) and exposure to head impacts in concussed football athletes.

DESIGN

This was a prospective, observational pilot study.

SETTING

Canadian university football.

PARTICIPANTS

The study population consisted of 60 university football players, aged 18 to 25. Athletes who sustained a clinically diagnosed concussion over the course of a single football season were invited to undergo an assessment of BBB leakage.

INDEPENDENT VARIABLES

Head impacts detected using impact-sensing helmets were the measured variables.

MAIN OUTCOME MEASURES

Clinical diagnosis of concussion and BBB leakage assessed using dynamic contrast-enhanced MRI (DCE-MRI) within 1 week of concussion were the outcome measures.

RESULTS

Eight athletes were diagnosed with a concussion throughout the season. These athletes sustained a significantly higher number of head impacts than nonconcussed athletes. Athletes playing in the defensive back position were significantly more likely to sustain a concussion than remain concussion free. Five of the concussed athletes underwent an assessment of BBB leakage. Logistic regression analysis indicated that region-specific BBB leakage in these 5 athletes was best predicted by impacts sustained in all games and practices leading up to the concussion-as opposed to the last preconcussion impact or the impacts sustained during the game when concussion occurred.

CONCLUSIONS

These preliminary findings raise the potential for the hypothesis that repeated exposure to head impacts may contribute to the development of BBB pathology. Further research is needed to validate this hypothesis and to test whether BBB pathology plays a role in the sequela of repeated head trauma.

Memantine inhibits cortical spreading depolarization and improves neurovascular function following repetitive traumatic brain injury

Cortical spreading depolarization (CSD) is a promising target for neuroprotective therapy in traumatic brain injury (TBI). We explored the effect of NMDA receptor antagonism on electrically triggered CSDs in healthy and brain-injured animals. Rats received either one moderate or four daily repetitive mild closed head impacts (rmTBI). Ninety-three animals underwent craniectomy with electrocorticographic (ECoG) and local blood flow monitoring. In brain-injured animals, ketamine or memantine inhibited CSDs in 44 to 88% and 50 to 67% of cases, respectively. Near-DC/AC-ECoG amplitude was reduced by 44 to 75% and 52 to 67%, and duration by 39 to 87% and 61 to 78%, respectively. Daily memantine significantly reduced spreading depression and oligemia following CSD. Animals (N = 31) were randomized to either memantine (10 mg/kg) or saline with daily neurobehavioral testing. Memantine-treated animals had higher neurological scores. We demonstrate that memantine improved neurovascular function following CSD in sham and brain-injured animals. Memantine also prevented neurological decline in a blinded, preclinical randomized rmTBI trial.

Joint pain, physical function, and balance self-confidence in acromegaly versus non-functioning pituitary adenoma patients

CONTEXT

Patients with acromegaly experience balance issues, despite achieving biochemical remission, that may significantly impair their quality of life.

OBJECTIVE

We sought to assess the prevalence of falls and balance self-confidence in patients with acromegaly in comparison with a control group. Furthermore, we investigated the effect of joint pain and function as predictors for their balance self-confidence.

DESIGN

Cross-sectional, case-controlled.

SETTING

Tertiary care centres.

PATIENTS OR OTHER PARTICIPANTS

In this case-control study, we surveyed patients with acromegaly (PWA; n = 94) and non-functioning pituitary adenoma (PNA; n = 82) with similar age, sex, and BMI from two Canadian centres.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Data were obtained on number of falls during the past 12 months, self-confidence to maintain balance, joint pain, joint surgery, pain medication usage, and upper and lower extremity musculoskeletal disability.

RESULTS

While both PWA and PNA had a similarly high risk of falls, PWA had lower self-confidence to maintain balance (p < 0.01). PWA had higher joint pain scores and more functional impairment in upper extremity, hip, knee, and ankle joints (all p < 0.01). In both groups, age, sex, and ankle functional score were predictors of balance self-confidence. For PWA, hip functional score was also a predictor of balance self-confidence in contrast to knee and back pain scores being predictors for the PNA group.

CONCLUSIONS

We confirmed an increased prevalence of falls in both groups with diminished balance confidence in PWA. This reduced balance self-confidence seems to be related to their increased hip functional impairment in comparison to PNA.

Association between traumatic brain injury and mental health care utilization: evidence from the Canadian Community Health Survey

BACKGROUND

Mental health disorders are a common sequelae of traumatic brain injury (TBI) and are associated with worse health outcomes including increased mental health care utilization. The objective of this study was to determine the association between TBI and use of mental health services in a population-based sample.

METHODS

Using data from a national Canadian survey, this study evaluated the association between TBI and mental health care utilization, while adjusting for confounding variables. A log-Poisson regression model was used to estimate unadjusted and adjusted prevalence ratios (PR) and 95% confidence intervals (CI).

RESULTS

The study sample included 158,287 TBI patients and 25,339,913 non-injured individuals. Compared with those were not injured, TBI patients reported higher proportions of chronic mental health conditions (27% vs. 12%, p < 0.001) and heavy drinking (33% vs. 24%, p = 0.005). The adjusted prevalence of mental health care utilization was 60% higher in patients with TBI than those who were not injured (PR = 1.60, 95%; CI 1.05-2.43).

CONCLUSIONS

This study suggests that chronic mental health conditions and heavy drinking are more common in individuals with TBI. The prevalence of mental health care utilization is 60% higher in TBI patients compared with those who are not injured after adjusting for sociodemographic factors, mental health conditions, and heavy drinking. Future longitudinal research is required to examine the temporality and direction of the association between TBI and the use of mental health services.

Intraosseous Cavernous Hemangioma of the Middle Turbinate: A Case Report

BACKGROUND

We report a case of an intraosseous cavernous hemangioma originating from the middle turbinate that expanded into the anterior skull base, without traversing the cribriform plate.

METHODS

The mass was found incidentally after a computed tomography head was ordered for unrelated reasons. On questioning, the patient denied any nasal symptoms. Magnetic resonance imaging showed an enhancing mass and the radiological imaging supported a broad differential.

RESULTS

The lesion was removed by endoscopic image-guided surgery, and the pathology was that of a benign intraosseous cavernous hemangioma. There was no residual hemangioma on postoperative imaging and the nasal mucosa healed well. This is the first report of an intraosseous cavernous hemangioma of the middle turbinate showing superior expansion to the anterior skull base.

CONCLUSION

This case demonstrates the extent to which cavernous hemangiomas may expand into surrounding tissues. While these lesions are uncommon, they can be considered as part of a broad differential diagnosis of sinonasal tumors.

Concussion susceptibility is mediated by spreading depolarization-induced neurovascular dysfunction

The mechanisms underlying the complications of mild traumatic brain injury, including post-concussion syndrome, post-impact catastrophic death, and delayed neurodegeneration remain poorly understood. This limited pathophysiological understanding has hindered the development of diagnostic and prognostic biomarkers and has prevented the advancement of treatments for the sequelae of mild traumatic brain injury.

We aimed to characterize the early electrophysiological and neurovascular alterations following repetitive mild traumatic brain injury and sought to identify new targets for the diagnosis and treatment of individuals at risk of severe post-impact complications. We combined behavioural, electrophysiological, molecular, and neuroimaging techniques in a rodent model of repetitive mild traumatic brain injury. In humans, we used dynamic contrast-enhanced MRI to quantify blood–brain barrier dysfunction after exposure to sport-related concussive mild traumatic brain injury.

Rats could clearly be classified based on their susceptibility to neurological complications, including life-threatening outcomes, following repetitive injury. Susceptible animals showed greater neurological complications and had higher levels of blood–brain barrier dysfunction, transforming growth factor β (TGFβ) signalling, and neuroinflammation compared to resilient animals. Cortical spreading depolarizations were the most common electrophysiological events immediately following mild traumatic brain injury and were associated with longer recovery from impact. Triggering cortical spreading depolarizations in mild traumatic brain injured rats (but not in controls) induced blood–brain barrier dysfunction. Treatment with a selective TGFβ receptor inhibitor prevented blood–brain barrier opening and reduced injury complications. Consistent with the rodent model, blood–brain barrier dysfunction was found in a subset of human athletes following concussive mild traumatic brain injury.

We provide evidence that cortical spreading depolarization, blood–brain barrier dysfunction, and pro-inflammatory TGFβ signalling are associated with severe, potentially life-threatening outcomes following repetitive mild traumatic brain injury. Diagnostic-coupled targeting of TGFβ signalling may be a novel strategy in treating mild traumatic brain injury.

Staged reflexive artificial intelligence driven testing algorithms for early diagnosis of pituitary disorders

BACKGROUND

Sellar masses (SM) frequently present with insidious hormonal dysfunction. We previously showed that, by utilizing a combined reflex/reflecting approach involving a laboratory clinician (LC) on common endocrine test results requested by non-specialists, and subsequently adding further warranted tests, previously undiagnosed pituitary disorders can be identified. However, manually employing these strategies by an LC is not feasible for wider screening of pituitary disorders.

OBJECTIVE

The aim of this study was to compare the accuracy and financial impact of an Artificial Intelligence (AI) based, fully computerized reflex protocol with manual reflex/reflective intervention protocol led by an LC.

METHODS

We developed a proof-of-concept AI-based framework to fully computerize multi-stage reflex testing protocols for pituitary dysfunction using automated reasoning methods. We compared the efficacy of this AI-based protocol with a reflex/reflective protocol based on manually curated retrospective data in identifying pituitary dysfunction based on 12 months of laboratory testing.

RESULTS

The AI-based reflex protocol, as compared with the manual protocol, would have identified laboratory tests for add-on that either directly matched or included all manual add-on tests in 92% of cases, and recommended a similar specialist referral in 90% of the cases. The AI-based protocol would have issued 2.8 times the total number of manual add-on laboratory tests at an 85% lower operation cost than the manual protocol when considering marginal test costs, technical staff and specialist salary.

CONCLUSION/DISCUSSION

Our AI-based reflex protocol can successfully identify patients with pituitary dysfunction, with lower estimated laboratory cost. Future research will focus on enhancing the protocol's accuracy and incorporating the AI-based reflex protocol into institutional laboratory and hospital information systems for the detection of undiagnosed pituitary disorders.

Knowledge transfer and retention of simulation-based learning for neurosurgical instruments: a randomised trial of perioperative nurses

Introduction

Previous studies have shown that simulation is an acceptable method of training in nursing education. The objectives of this study were to determine the effectiveness of tablet-based simulation in learning neurosurgical instruments and to assess whether skills learnt in the simulation environment are transferred to a real clinical task and retained over time.

Methods

A randomised controlled trial was conducted. Perioperative nurses completed three consecutive sessions of a simulation. Group A performed simulation tasks prior to identifying real instruments, whereas Group B (control group) was asked to identify real instruments prior to the simulation tasks. Both groups were reassessed for knowledge recall after 1 week.

Results

Ninety-three nurses completed the study. Participants in Group A, who had received tablet-based simulation, were 23% quicker in identifying real instruments and did so with better accuracy (93.2% vs 80.6%, p<0.0001) than Group B. Furthermore, the simulation-based learning was retained at 7 days with 97.8% correct instrument recognition in Group A and 96.2% in Group B while maintaining both speed and accuracy.

Conclusion

This is the first study to assess the effectiveness of tablet-based simulation training for instrument recognition by perioperative nurses. Our results demonstrate that instrument knowledge acquired through tablet-based simulation training results in improved identification and retained recognition of real instruments.

Preclinical Evaluation of the Stealth Autoguide Robotic Guidance Device for Stereotactic Cranial Surgery: A Human Cadaveric Study

INTRODUCTION

Stereotactic procedures are routinely performed for brain biopsies, deep brain stimulation, and placement of stereoelectroencephalography (SEEG) electrodes for epilepsy. The recently developed Stealth Autoguide (Medtronic, Minneapolis, MN, USA) device does not require patients to don a stereotactic frame. In this preclinical study, we sought to quantitatively compare the Stealth Autoguide robotic system to 2 devices commonly used in clinical practice: the Navigus biopsy system (Medtronic) and the Leksell stereotactic frame (Elekta Ltd., Stockholm, Sweden).

METHODS

In the first experimental setup, we compared target accuracy of the Stealth Autoguide to the Navigus system by using phantom heads filled with gelatin to simulate the brain tissue. In the second experimental setup, we inserted SEEG electrodes to targets within cadaveric heads in a simulated operating room environment.

RESULTS

Using a homogeneous gelatin-filled phantom 3D reconstruction of a human head, we found that using the Stealth Autoguide system, while maintaining accuracy, was faster to use than the Navigus system. In our simulated operating room environment using nonliving human cadaveric heads, we found the accuracy of the Stealth Autoguide robotic device to be comparable to that of the Leksell frame.

DISCUSSION/CONCLUSION

These results compare the use of the Stealth Autoguide robotic guidance system with commonly used stereotactic devices, and this is the first study to compare its use and accuracy with the Leksell frame. These findings provide mounting evidence that Stealth Autoguide will have potential clinical uses in various stereotactic neurosurgical procedures.

Secondary pituitary hormonal dysfunction patterns: tumor size and subtype matter

PURPOSE

Patients with sellar masses (SM) frequently have secondary hormonal deficiency (SHD) at initial presentation. While larger SM are more likely to present with SHD, it is unclear whether SHD at presentation is influenced by the type of SM.

METHODS

We conducted a retrospective analysis of patients with SM prospectively enrolled in our comprehensive provincial neuropituitary registry between November 2005 and December 2018. SM were subdivided based on size: < 1 cm, 1-1.9 cm, 2-2.9 cm, and > 3 cm.

RESULTS

A total of 914 patients met the inclusion criteria, including: 346 nonfunctioning adenomas (NFA), 261 prolactinomas (PRLoma), 51 growth hormone adenomas, 36 adrenocorticotropic adenomas, 93 Rathke's cleft cysts, 70 craniopharyngiomas and 57 meningiomas. The overall rate of SHD at presentation was highest in PRLoma (62.8%) and craniopharyngiomas (64.3%) and lowest in meningiomas (14%). While larger SM were significantly more likely to have SHD, the rate of SHD within each group was significantly different despite similar size (p < 0.001). Of the two largest groups of SM (NFA and PRLoma), NFA had significantly higher odds ratio (3.34, CI 1.89-5.89) of having multiple SHDs when compare with PRLoma, even when corrected for age, gender and size of tumor (p < 0.001).

CONCLUSION

Our study shows that the rate and distribution of SHD in SM vary dependent upon the size of the tumor and specific pathology; in particular, NFA are more likely to present with multiple SHDs. Our data will help clinicians in determining adequate hormonal testing strategy for different SM.

Polysialylated - neural cell adhesion molecule (PSA-NCAM) promotes recovery of vision after the critical period

Vision loss has long since been considered irreversible after a critical period; however, there is potential to restore limited vision, even in adulthood. This phenomenon is particularly pronounced following complete loss of vision in the dominant eye. Adult neural cell adhesion molecule (NCAM) knockout mice have an age-related impairment of visual acuity. The underlying cause of early deterioration in visual function remains unknown. Polysialylated (PSA) NCAM is involved in different forms of neural plasticity in the adult brain, raising the possibility that NCAM plays a role in the plasticity of the visual cortex, and therefore, in visual ability. Here, we examined whether PSA-NCAM is required for visual cortical plasticity in adult C57Bl/6J mice following deafferentation and long-term monocular deprivation. Our results show that elevated PSA in the contralateral visual cortex of the reopened eye is accompanied by changes in other markers of neural plasticity: increased brain-derived neurotrophic factor (BDNF) levels and degradation of perineuronal nets (PNNs). The removal of PSA-NCAM in the visual cortex of these mice reduced BDNF expression, decreased PNN degradation, and resulted in impaired recovery of visual acuity after optic nerve transection and chronic monocular deprivation. Collectively, our results demonstrate that PSA-NCAM is necessary for the reactivation of visual cortical plasticity and recovery of visual function in adult mice. It also offers a potential molecular target for the therapeutic treatment of cortically based visual impairments.

Securing the position of the nasoseptal flap in endoscopic transsphenoidal surgery: No need for a Foley catheter (technical report)

BACKGROUND

The pedicled nasoseptal mucoperiosteal flap is currently widely used for the reconstruction of a skull base defect following transsphenoidal surgery. The flap is generally secured in position by a Foley catheter balloon. We describe an alternative technique using cylinders of Gelfoam™ (Pfizer Incorporated) to buttress the flap in place, obviating the need for a balloon catheter.

MATERIAL AND METHODS

A review of our database identified patients who underwent endoscopic transsphenoidal surgery for a pituitary macroadenoma with nasoseptal flap, secured with small rolls of Gelfoam™ (Pfizer Incorporated) rather than a nasal Foley catheter. Minimum follow-up clinical and MRI assessments: 3 months.

RESULTS

73 patients (mean follow-up: 22 months) met the inclusion criteria: 56 non-functioning and 17 functioning pituitary adenomas. 36 patients had an intraoperative CSF leak: 30 high flow and 6 low flow leaks. The surgical repair in 35 patients included fat +/- fascia graft. One patient had a post-operative CSF leak repaired by subsequent surgery without the use of a Foley catheter.

CONCLUSION

Securing the nasoseptal flap using rolls of Gelfoam™ (Pfizer Incorporated) as described can be achieved without the use of a nasal Foley catheter.

Complete recovery following transorbital penetrating head injury traversing the brainstem: case report

Transorbital penetration accounts for one-quarter of the penetrating head injuries (PHIs) in adults and half of those in children. Injuries that traverse (with complete penetration of) the brainstem are often fatal, with survivors rarely seen in clinical practice. Here, the authors describe the case of a 16-year-old male who suffered and recovered from an accidental transorbital PHI traversing the brainstem-the first case of complete neurological recovery following such injury. Neuroimaging captured the trajectory of the initial injury. A delayed-onset carotid cavernous fistula and the subsequent development of internal carotid artery pseudoaneurysms were managed by endovascular embolization.The authors also review the relevant literature. Sixteen cases of imaging-confirmed PHI traversing the brainstem have been reported, 14 involving the pons and 12 penetrating via the transorbital route. Management and outcome of PHI are informed by object velocity, material, entry point, trajectory, relationship to neurovascular structures, and the presence of a retained foreign body. Trauma resuscitation is followed by a careful neurological examination and appropriate neuroimaging. Ophthalmological examination is performed if transorbital penetration is suspected, as injuries may be occult; the potential for neurovascular complications highlights the value of angiography. The featured case shows that complete recovery is possible following injury that traverses the brainstem.

Cavernous sinus involvement in human papillomavirus associated oropharyngeal squamous cell carcinoma: case report of an atypical site of distant metastasis

BACKGROUND

HPV-associated OSCC (HPV-OSCC) has been determined to be a distinct disease entity from non-HPV associated OSCC. Patients affected by HPV-OSCC generally have a more favourable prognosis, with improved rates of locoregional control and survival compared with their non-HPV counterparts. Despite this, HPV-OSCC has a similar rate of distant metastases. Interestingly, recent evidence has emerged that demonstrates more frequent atypical metastasis patterns when compared to non-HPV associated disease. To the best of our knowledge, this report describes the first case of a confirmed HPV-OSCC with distant metastasis to the cavernous sinus.

CASE PRESENTATION

A 62-year-old non-smoking male presented to the head and neck oncology clinic with a five-month history of enlarging right neck mass causing neck pain, dysphagia, and dysphonia. HPV-associated base of tongue squamous cell carcinoma (cT4aN2c) was diagnosed, and he was treated with primary chemoradiation. Shortly after treatment, he presented with progressive bilateral cranial nerve palsies including left cranial nerve III and right cranial nerve VI involvement. Imaging identified masses in the left cavernous sinus with extension of tumor into the sella and in the right cavernous sinus at the level of Dorello's canal. Endoscopic Image Guided Transsphenoidal biopsy of the left sellar mass confirmed distant metastases from the previously treated HPV-OSCC primary to the cavernous sinus. The patient was palliated with carboplatin and paclitaxel.

CONCLUSION

The presented report is the first documented case of confirmed HPV-associated oropharyngeal squamous cell carcinoma metastasizing to the cavernous sinus, and the only HPV confirmed head and neck cancer case to present with metastasis to the cavernous sinus and limited extracranial disease. This case demonstrates the importance of recognizing presentations of atypical metastasis that are possible in HPV-associated oropharyngeal cancer. Given the rarity of metastasis to this region, vigilance in follow up is instrumental in early identification and treatment for these patients.

A comparative, population-based analysis of pituitary incidentalomas vs clinically manifesting sellar masses

PURPOSE

Sellar masses may present either with clinical manifestations of mass effect/hormonal dysfunction (CMSM) or incidentally on imaging (pituitary incidentaloma (PI)). This novel population-based study compares these two entities.

METHODS

Retrospective analysis of all patients within a provincial pituitary registry between January 2006 and June 2014.

RESULTS

Nine hundred and three patients were included (681 CMSM, 222 PI). CMSM mainly presented with secondary hormone deficiencies (SHDs) or stalk compression (29.7%), whereas PIs were found in association with neurological complaints (34.2%) (P < 0.0001). PIs were more likely to be macroadenomas (70.7 vs 49.9%; P < 0.0001). The commonest pathologies among CMSM were prolactinomas (39.8%) and non-functioning adenomas (NFAs) (50%) in PI (P < 0.0001). SHDs were present in 41.3% CMSM and 31.1% PI patients (P < 0.0001) and visual field deficit in 24.2 and 29.3%, respectively (P = 0.16). CMSM were more likely to require surgery (62.9%) than PI (35.8%) (P < 0.0005). The commonest surgical indications were impaired vision and radiological evidence of optic nerve compression. Over a follow-up period of 5.7 years for CMSM and 5.0 years for PI, tumour growth/recurrence occurred in 7.8% of surgically treated CMSM and 2.6% without surgery and PI, 0 and 4.9%, respectively (P = 1.0). There were no significant differences in the risk of new-onset SHD in CMSM vs PI in those who underwent surgery (P = 0.7) and those who were followed without surgery (P = 0.58).

CONCLUSIONS

This novel study compares the long-term trends of PI with CMSM, highlighting the need for comprehensive baseline and long-term radiological and hormonal evaluations in both entities.

Reflex and reflective testing strategies for early detection of pituitary dysfunction

OBJECTIVE

The clinical presentation of pituitary dysfunction is typically variable and may often be insidious, resulting in delayed diagnosis by up to decades. The complexity of presentation and difficulty in pattern recognition of first line hormone tests result in challenges in early diagnosis of this condition. The aim of this study was to determine the impact of reflective testing and interpretive commenting on the early detection and management of such cases from primary care.

METHODS

Prospective audit over 12 months in which first line pituitary target organ hormones were identified via a reflex algorithm in the laboratory information system. Selected tests were reviewed by a laboratory clinician and decision made on reflective testing and interpretive commenting based on available clinical information and previous result trends. Patients who had a laboratory intervention were followed up to determine the clinical outcome.

RESULTS

Out of 1099 patients identified, additional testing was made for 214. Interpretative comments were subsequently added to reports of 196 patients, 48 (25%) of whom were referred to endocrinology and 35 (73%) of these were directly related to the laboratory intervention. Eleven other patients had outcomes related to the intervention. Pituitary related conditions (insufficiency and/or adenoma) were found in 29 patients, 24 of which were identified as a result of laboratory intervention.

CONCLUSIONS

This study highlights the clinical value of laboratory intervention in aiding early detection of pituitary dysfunction and may avoid the disease burden of delayed management.

Unusual AIP mutation and phenocopy in the family of a young patient with acromegalic gigantism

Early-onset acromegaly causing gigantism is often associated with aryl-hydrocarbon-interacting receptor protein (AIP) mutation, especially if there is a positive family history. A15y male presented with tiredness and visual problems. He was 201 cm tall with a span of 217 cm. He had typical facial features of acromegaly, elevated IGF-1, secondary hypogonadism and a large macroadenoma. His paternal aunt had a history of acromegaly presenting at the age of 35 years. Following transsphenoidal surgery, his IGF-1 normalized and clinical symptoms improved. He was found to have a novel AIP mutation destroying the stop codon c.991T>C; p.*331R. Unexpectedly, his father and paternal aunt were negative for this mutation while his mother and older sister were unaffected carriers, suggesting that his aunt represents a phenocopy.

Long-Term Effects of Education and Legislation Enforcement on All-Age Bicycle Helmet Use: A Longitudinal Study

Bicycle-related injuries are a leading cause of child and youth hospitalizations in Canada. The use of helmets while bicycling reduces the risk of brain injuries. This study investigated the long-term effect of legislation coupled with enforcement to improve helmet use rates. We conducted a longitudinal observational study of helmet use at 9, 11, and 14 years after bicycle helmet legislation was enacted. Data were compared to baseline observations collected after legislation was passed in 1997. A comprehensive enforcement and educational diversion program, Operation Headway-Noggin Knowledge (OP-NK), was developed and implemented in partnership with regional police during the study period. Helmet use was sustained throughout the post-legislation period, from 75.3 % in the year legislation was enacted to 94.2 % 14 years post-legislation. The increase in helmet use was seen among all age groups and genders. Helmet legislation was not associated with changes in bicycle ridership over the study years. OP-NK was associated with improved enforcement efforts as evidenced by the number of tickets issued to noncompliant bicycle riders. This observational study spans a 16-year study period extending from pre-legislation to 14 years post all-age bicycle helmet legislation. Our study results demonstrate that a comprehensive approach that couples education and awareness with ongoing enforcement of helmet legislation is associated with long-term sustained helmet use rates. The diversion program described herein is listed among best practices by the Public Health Agency of Canada.

Virtual Reality Surgical Simulation: Implications for Resection of Intracranial Gliomas

Surgical simulation has the potential to play important roles in surgical training and preoperative planning. The advent of virtual reality (VR) with tactile haptic feedback has revolutionized surgical simulation, creating a novel environment for residents to learn manual skills without compromising patient safety. This concept is particularly relevant in neurosurgical training where the acquired skill set demands performance of technically challenging tasks under pressure and where the consequences of error are significant. The evolution of VR simulation is discussed here within the context of neurosurgical training and its implications for resection of intracranial gliomas. VR holds the promise of providing a useful educational tool for neurosurgical residents to hone their surgical skills and for neurosurgeons to rehearse specific segments of the surgery prior to the actual operation. Also discussed are several important issues related to simulation and simulation-based training that will need to be addressed before widespread adoption of VR simulation as a useful technology.

Exploring the effects of state highway safety laws and sociocultural characteristics on fatal crashes

OBJECTIVE

Distinguished from the traditional perspectives in crash analyses, which examined the effects of geometric design features, traffic factors, and other relevant attributes on the crash frequencies of roadway entities, our study focuses on exploring the effects of highway safety laws, as well as sociocultural characteristics, on fatal crashes across states.

METHODS

Law and regulation related data were collected from the Insurance Institute for Highway Safety, State Highway Safety Offices, and Governors Highway Safety Association. A variety of sociodemographic characteristics were obtained from the U.S. Census Bureau. In addition, cultural factors and other attributes from a variety of resources are considered and incorporated in the modeling process. These data and fatal crash counts were collected for the 50 U.S. states and the District of Columbia and were analyzed using zero-truncated negative binomial (ZTNB) regression models.

RESULTS

The results show that, in law and regulation-related factors, the use of speed cameras, no handheld cell phone ban, limited handheld cell phone ban, and no text messaging ban are found to have significant effects on fatal crashes. Regarding sociocultural characteristics, married couples with both husband and wife in the labor force are found to be associated with lower crash frequencies, the ratios of workers traveling to work by carpool, those driving alone, workers working outside the county of residence, language other than English and limited English fluency, and the number of licensed drivers are found to be associated with higher crash frequencies.

CONCLUSIONS

Through reviewing and modeling existing state highway safety laws and sociocultural characteristics, the results reveal new insights that could influence policy making. In addition, the results would benefit amending existing laws and regulations and provide testimony about highway safety issues before lawmakers consider new legislation.

Polysialylated Neural Cell Adhesion Molecule Protects Against Light-Induced Retinal Degeneration

Purpose

We previously demonstrated that neural cell adhesion molecule (NCAM) plays an important role in supporting the survival of injured retinal ganglion cells. In the current study, we used light-induced retinal degeneration (LIRD) as a model to investigate whether NCAM plays a functional role in neuroprotection and whether NCAM influences p75^NTR signaling in modulating retinal cell survival.

Methods

Retinas from wild-type (WT) and NCAM deficient (−/−) mice were tested by electroretinogram before and after LIRD, and changes in the protein expressions of NCAM, polysialic acid (PSA)-NCAM, p75^NTR, and active caspase 3 were measured by immunoblot from 0 to 4 days after light induction. The effects of NCAM and PSA-NCAM on p75^NTR were examined by intraocular injections of the p75^NTR function-blocking antibody and/or the removal of PSA with endoneuraminidase-N prior to LIRD.

Results

In WT mice, low levels of active caspase 3 activation were detected on the first day, followed by increases up to 4 days after LIRD. Conversely, in NCAM^−/− mice, higher cleaved caspase 3 levels along with rapid reductions in electroretinogram amplitudes were found earlier at day 1, followed by reduced levels by day 4. The removal of PSA prior to LIRD induced earlier onset of retinal cell death, an effect delayed by the coadministration of endoneuraminidase-N and the p75^NTR function-blocking antibody antiserum.

Conclusions

These results indicate that NCAM protects WT retinas from LIRD; furthermore, the protective effect of NCAM is, at least in part, attributed to its effects on p75^NTR.

Recovery of adrenal function after chronic secondary adrenal insufficiency in patients with hypopituitarism

OBJECTIVE

Previous studies have reported recovery of secondary adrenal insufficiency (SAI) in patients with pituitary disorders, generally immediately after pituitary surgery; however, data regarding recovery of long-term SAI are lacking. We conducted a study to assess the longer term recovery rate of SAI in patients with pituitary disorders.

METHODS

We identified all SAI patients in the Halifax Neuropituitary Database from 1 November 2005 to 30 September 2014, who had required glucocorticoid therapy for ≥3 months, and had a minimum follow-up of 6 months. Patients with ACTH-secreting adenomas, those receiving glucocorticoids only in the routine peri-operative period for pituitary surgery and those on glucocorticoids for nonpituitary conditions were excluded. SAI was defined as either basal serum cortisol < 130 nm and/or a subnormal cortisol response to ACTH-(1-24) stimulation test or insulin tolerance test response.

RESULTS

Fifty-one patients fulfilled the criteria. Nine (17·6%) patients had complete recovery of SAI over a median of 20 months (range: 8-51) after initiating glucocorticoid replacement. Patients with smaller tumour size had increased likelihood of hypothalamic-pituitary-adrenal (HPA) axis recovery, whereas those with secondary hypogonadism or growth hormone deficiency were less likely to recover. Those with initial cortisol >175 nm had an almost one in two chance of recovery.

CONCLUSION

Results from our study show that approximately one in six patients with SAI recover adrenal function, even up to 5 years after diagnosis. We recommend that patients with SAI undergo regular testing to assess recovery in order to prevent unnecessary glucocorticoid therapy.

Analysis and natural history of pituitary incidentalomas

OBJECTIVES

Pituitary incidentalomas (PI) are frequently found on brain imaging. Despite their high prevalence, little is known about their long-term natural history and there are limited guidelines on how to monitor them.

METHODS

We conducted a retrospective study to compare epidemiological characteristics at presentation and the natural history of PI in population-based vs referral-based registries from two tertiary-care referral centers in Canada.

RESULTS

A total of 328 patients with PI were included, of whom 73% had pituitary adenomas (PA) and 27% had non-pituitary sellar masses. The commonest indications for imaging were headache (28%), dizziness (12%) and stroke/transient ischemic attack (TIA) (9%). There was a slight female preponderance (52%) with a median age of 55 years at diagnosis; 71% presented as macroadenomas (>10mm). Of PA, 25% were functioning tumors and at presentation 36% of patients had evidence of secondary hormonal deficiency (SHD). Of the total cohort, 68% were treated medically or conservatively whereas 32% required surgery. Most tumors (87% in non-surgery and 68% in post-surgery group) remained stable during follow-up. Similarly, 84% of patients in the non-surgery and 73% in the surgery group did not develop additional SHD during follow-up. The diagnosis of non-functioning adenoma was a risk factor for tumor enlargement and a change in SHD status was associated with a change in tumor size.

CONCLUSIONS

Our data suggest that most PI seen in tertiary-care referral centers present as macroadenomas and may frequently be functional, often requiring medical or surgical intervention.

Simulation-based training for burr hole surgery instrument recognition

BACKGROUND

The use of simulation training in postgraduate medical education is an area of rapidly growing popularity and research. This study was designed to assess the impact of simulation training for instrument knowledge and recognition among neurosurgery residents.

METHODS

This was a randomized control trial of first year residents from neurosurgery residency training programs across Canada. Eighteen neurosurgery trainees were recruited to test two simulation-based applications: PeriopSim™ Instrument Trainer and PeriopSim™ for Burr Hole Surgery. The intervention was game-based simulation training for learning neurosurgical instruments and applying this knowledge to identify correct instruments during a simulated burr hole surgery procedure.

RESULTS

Participants showed significant overall improvement in total score (p < 0.0005), number of errors (p = 0.019) and time saved (p < 0.0005), over three testing sessions when using the PeriopSim™ Instrument Trainer. Participants demonstrated further performance-trained improvements when using PeriopSim™ Burr Hole Surgery.

CONCLUSIONS

Training in the recognition and utilization of simulated surgical instruments by neurosurgery residents improved significantly with repetition when using PeriopSim™ Instrument Trainer and PeriopSim™ for Burr Hole Surgery.

Improving fMRI reliability in presurgical mapping for brain tumours

PURPOSE

Functional MRI (fMRI) is becoming increasingly integrated into clinical practice for presurgical mapping. Current efforts are focused on validating data quality, with reliability being a major factor. In this paper, we demonstrate the utility of a recently developed approach that uses receiver operating characteristic-reliability (ROC-r) to: (1) identify reliable versus unreliable data sets; (2) automatically select processing options to enhance data quality; and (3) automatically select individualised thresholds for activation maps.

METHODS

Presurgical fMRI was conducted in 16 patients undergoing surgical treatment for brain tumours. Within-session test-retest fMRI was conducted, and ROC-reliability of the patient group was compared to a previous healthy control cohort. Individually optimised preprocessing pipelines were determined to improve reliability. Spatial correspondence was assessed by comparing the fMRI results to intraoperative cortical stimulation mapping, in terms of the distance to the nearest active fMRI voxel.

RESULTS

The average ROC-r reliability for the patients was 0.58±0.03, as compared to 0.72±0.02 in healthy controls. For the patient group, this increased significantly to 0.65±0.02 by adopting optimised preprocessing pipelines. Co-localisation of the fMRI maps with cortical stimulation was significantly better for more reliable versus less reliable data sets (8.3±0.9 vs 29±3 mm, respectively).

CONCLUSIONS

We demonstrated ROC-r analysis for identifying reliable fMRI data sets, choosing optimal postprocessing pipelines, and selecting patient-specific thresholds. Data sets with higher reliability also showed closer spatial correspondence to cortical stimulation. ROC-r can thus identify poor fMRI data at time of scanning, allowing for repeat scans when necessary. ROC-r analysis provides optimised and automated fMRI processing for improved presurgical mapping.

Effect of NCAM on aged-related deterioration in vision

The neural cell adhesion molecule (NCAM) is involved in developmental processes and age-associated cognitive decline; however, little is known concerning the effects of NCAM in the visual system during aging. Using anatomical, electrophysiological, and behavioral assays, we analyzed age-related changes in visual function of NCAM deficient (-/-) and wild-type mice. Anatomical analyses indicated that aging NCAM -/- mice had fewer retinal ganglion cells, thinner retinas, and fewer photoreceptor cell layers than age-matched controls. Electroretinogram testing of retinal function in young adult NCAM -/- mice showed a 2-fold increase in a- and b-wave amplitude compared with wild-type mice, but the retinal activity dropped dramatically to control levels when the animals reached 10 months. In behavioral tasks, NCAM -/- mice had no visual pattern discrimination ability and showed premature loss of vision as they aged. Together, these findings demonstrate that NCAM plays significant roles in the adult visual system in establishing normal retinal anatomy, physiology and function, and in maintaining vision during aging.

Morphometric changes correlate with poor psychological outcomes in patients with acromegaly

OBJECTIVE

Acromegaly is frequently associated with altered facial appearance at the time of diagnosis. Furthermore, acromegaly is also associated with adverse psychological outcomes. We conducted a single-centre, cross-sectional study comparing patients with growth hormone vs non-functioning pituitary adenomas (NFA) to assess the association between morphometric changes and psychological outcomes and illness perception of patients with acromegaly.

METHODS

A seven-step scale was developed to grade morphometric changes based on facial photographs. In addition, all patients were asked to draw an image of their own body and an image of what they considered to be an average healthy body and complete seven psychological questionnaires. We recruited 55 consecutive patients in each of the two groups who had undergone surgery with or without radiation therapy (RT).

RESULTS

Our data showed that the clinician-rated morphometric scale was highly reliable in assessing facial changes, with 93/99 (Intraclass correlation coefficient (ICC)=0.95 (0.93-0.97)) graded as similar by independent raters. The mean (s.d.) grading for Acro and NFA patients on the clinician-rated morphometric scale were 3.5 (1.3) and 0.41 (0.35) respectively (P<0.0001). A higher clinician-rated morphometric score was also predictive of a poorer score on the drawing test.

CONCLUSIONS

Our study demonstrates a correlation between physical changes associated with acromegaly and poor psychological outcomes, whereas no such correlation existed with modes of therapy, disease control status, RT, malignancy, initial or recent GH/IGF1 or secondary hormonal deficiency. Our data support the utility of the morphometric scale as a clinical tool for grading facial changes.

Implementation of an all-ages mandatory helmet policy for ice skating

Ice skaters sustain a significant number of head injuries each winter. We are the first to implement an all-ages helmet policy at a university-based Canadian arena. We report our experience from a cross-sectional observational study as well as the policy's consequences on helmet use and skating participation. Educational programming was provided prior to policy implementation. Observations of helmet use, falls and skater demographics were conducted prior to education/implementation and after policy implementation. The number of skaters observed was essentially unchanged by the policy; 361 skaters were observed pre-implementation, while 358 were observed post-implementation during the same number of observation-hours. Pre-implementation, helmet use ranged from 97% among children under 12 to 10% among adults; post-implementation use in all skaters was 99%. Falls were observed among all age groups, with preponderance among those aged 4-12. An all-ages helmet policy was successful both in achieving helmet use among all skaters and in maintaining participation rates.

Multivariate random-parameters zero-inflated negative binomial regression model: an application to estimate crash frequencies at intersections

Crash data are collected through police reports and integrated with road inventory data for further analysis. Integrated police reports and inventory data yield correlated multivariate data for roadway entities (e.g., segments or intersections). Analysis of such data reveals important relationships that can help focus on high-risk situations and coming up with safety countermeasures. To understand relationships between crash frequencies and associated variables, while taking full advantage of the available data, multivariate random-parameters models are appropriate since they can simultaneously consider the correlation among the specific crash types and account for unobserved heterogeneity. However, a key issue that arises with correlated multivariate data is the number of crash-free samples increases, as crash counts have many categories. In this paper, we describe a multivariate random-parameters zero-inflated negative binomial (MRZINB) regression model for jointly modeling crash counts. The full Bayesian method is employed to estimate the model parameters. Crash frequencies at urban signalized intersections in Tennessee are analyzed. The paper investigates the performance of MZINB and MRZINB regression models in establishing the relationship between crash frequencies, pavement conditions, traffic factors, and geometric design features of roadway intersections. Compared to the MZINB model, the MRZINB model identifies additional statistically significant factors and provides better goodness of fit in developing the relationships. The empirical results show that MRZINB model possesses most of the desirable statistical properties in terms of its ability to accommodate unobserved heterogeneity and excess zero counts in correlated data. Notably, in the random-parameters MZINB model, the estimated parameters vary significantly across intersections for different crash types.

Differences in passenger car and large truck involved crash frequencies at urban signalized intersections: an exploratory analysis

The influence of intersection features on safety has been examined extensively because intersections experience a relatively large proportion of motor vehicle conflicts and crashes. Although there are distinct differences between passenger cars and large trucks-size, operating characteristics, dimensions, and weight-modeling crash counts across vehicle types is rarely addressed. This paper develops and presents a multivariate regression model of crash frequencies by collision vehicle type using crash data for urban signalized intersections in Tennessee. In addition, the performance of univariate Poisson-lognormal (UVPLN), multivariate Poisson (MVP), and multivariate Poisson-lognormal (MVPLN) regression models in establishing the relationship between crashes, traffic factors, and geometric design of roadway intersections is investigated. Bayesian methods are used to estimate the unknown parameters of these models. The evaluation results suggest that the MVPLN model possesses most of the desirable statistical properties in developing the relationships. Compared to the UVPLN and MVP models, the MVPLN model better identifies significant factors and predicts crash frequencies. The findings suggest that traffic volume, truck percentage, lighting condition, and intersection angle significantly affect intersection safety. Important differences in car, car-truck, and truck crash frequencies with respect to various risk factors were found to exist between models. The paper provides some new or more comprehensive observations that have not been covered in previous studies.

The Role of Morning Basal Serum Cortisol in Assessment of Hypothalamic Pituitary-Adrenal Axis

Purpose: The use of morning basal serum cortisol levels as an alternative to dynamic testing for assessment of hypothalamic-pituitary-adrenal (HPA) axis has previously been reported. The purpose of this study was to determine the lower and upper cutoff values that would obviate subsequent HPA axis testing. Methods: A single-centre, retrospective study from a tertiary care endocrinology clinic was conducted, analyzing data from 106 adult individuals referred for HPA axis testing who had undergone a 0800-0900 morning basal serum cortisol test followed by a standard dose (250 μg) adrenocorticotropin (ACTH) stimulation test. The ability of morning basal serum cortisol values to predict post-ACTH 30 or 60 minute peak cortisol value of > 500 or > 550 nmol/L was investigated. Results: A morning basal cutoff of < 128 nmol/L is sufficient for predicting a post-ACTH value < 550 nmol/L, and morning basal cutoff levels of > 243 nmol/L and > 266 nmol/L predict peak post-ACTH values of > 500 and > 550 nmol/L respectively, obviating the need for dynamic testing. Regression analysis further demonstrated the log-linear relationship between morning basal and peak levels, while also finding a significant decrease in peak post-ACTH levels for patients diagnosed with secondary hypothyroidism (76 nmol/L lower, p=0.003) or secondary hypogonadism (61 nmol/L lower, p=0.02). These data suggest that the risk of cortisol deficiency is significantly higher in individuals with additional pituitary insufficiencies. The odds ratios for cortisol deficiency in patients with history of isolated secondary hypothyroidism was 3.41 (p=0.015), with isolated secondary hypogonadism was 4.77 (p=0.002) and with both was 7.45 (p=0.0002). Conclusion: Morning basal serum cortisol levels show promise as an effective screening test for HPA insufficiency for most patients. Clinicians should consider the high probability of HPA insufficiency in patients with one or more pituitary insufficiencies.

Virtual Reality Simulator

Background. The overriding importance of patient safety, the complexity of surgical techniques, and the challenges associated with teaching surgical trainees in the operating room are all factors driving the need for innovative surgical simulation technologies. Technical development. Despite these issues, widespread use of virtual reality simulation technology in surgery has not been fully implemented, largely because of the technical complexities in developing clinically relevant and useful models. This article describes the successful use of the NeuroTouch neurosurgical simulator in the resection of a left frontal meningioma. Conclusion. The widespread application of surgical simulation technology has the potential to decrease surgical risk, improve operating room efficiency, and fundamentally change surgical training.

Management of prolactinomas during pregnancy – A survey of four Canadian provinces

Purpose: The guidelines for management of prolactinomas during pregnancy are mostly based on retrospective evidence or expert opinion. We conducted a survey to assess the current trends in management of prolactinomas during pregnancy. Methods: A case-based electronic questionnaire was sent in January 2011 to all practicing endocrinologists, in four Canadian provinces: Nova Scotia, New Brunswick, Prince Edward Island and British Columbia with three cases of varying severity; ranging from a microprolactinomas to a large macroprolactinomas compressing the optic chiasm. Result: There was a considerable diversity among endocrinologists with regards to monitoring and managing prolactinomas during pregnancy. In case of microprolactinomas, 94% of specialists would discontinue dopamine agonist (DA) therapy upon confirmation of pregnancy, 79% would discontinue serum prolactin measurement during pregnancy, and 94% would not perform routine pituitary imaging in the absence of new symptoms whereas 32% would perform regular formal visual field (VF) testing throughout pregnancy. In the case of macroprolactinomas, 65% chose to discontinue DA therapy upon confirmation of pregnancy, 30% would either perform regular MRI during pregnancy or, if serum prolactin was thought to be elevated out of proportion, with clinical judgment and 40% would not perform regular formal VF monitoring during pregnancy. In management of large macroprolactinomas, 82% elected to continue DA therapy whereas 18% chose surgical excision as the treatment of choice. Forty nine percent would perform regular MRI during pregnancy and 94% would perform regular formal VF monitoring during pregnancy. Conclusion: Among endocrinologists there is considerable diversity in management of prolactinomas during pregnancy, indicating a need for better consensus and clearer guidelines.

Spatial MEG laterality maps for language: clinical applications in epilepsy

Functional imaging is increasingly being used to provide a noninvasive alternative to intracarotid sodium amobarbitol testing (i.e., the Wada test). Although magnetoencephalography (MEG) has shown significant potential in this regard, the resultant output is often reduced to a simplified estimate of laterality. Such estimates belie the richness of functional imaging data and consequently limit the potential value. We present a novel approach that utilizes MEG data to compute "complex laterality vectors" and consequently "laterality maps" for a given function. Language function was examined in healthy controls and in people with epilepsy. When compared with traditional laterality index (LI) approaches, the resultant maps provided critical information about the magnitude and spatial characteristics of lateralized function. Specifically, it was possible to more clearly define low LI scores resulting from strong bilateral activation, high LI scores resulting from weak unilateral activation, and most importantly, the spatial distribution of lateralized activation. We argue that the laterality concept is better presented with the inherent spatial sensitivity of activation maps, rather than being collapsed into a one-dimensional index.

Effects of epidermal growth factor and erythropoietin on Müller glial activation and phenotypic plasticity in the adult mammalian retina

Retinal Müller glia have received considerable attention with regard to their potential to function as quiescent retinal precursors. Various activation strategies induce characteristic features of retinal progenitor cells in Müller glia; however, these are often accompanied by hallmark features of reactive gliosis. We investigated the effects of an intravitreal injection of epidermal growth factor (EGF), a known mitogen, and erythropoietin (EPO) on activation and expression of developmental phenotypes within the adult retina. Using thymidine-analogue labeling as well as immunocytochemical and confocal analyses, we assayed the responses of retinal cells exposed to intravitreal administration of either EGF or EPO. We report that adult Müller glia incorporate bromodeoxyuridine (BrdU) and undergo a process of nuclear translocation to ectopic retinal layers following exposure to EGF. These cells survive within the retina for at least 23 days and express the developmental markers Pax6 and Chx10 as well as nestin and glial fibrillary acidic protein. Furthermore, we demonstrate that cotreatment with EGF and EPO suppresses aspects of EGF-induced glial reactivity, alters the retinal distribution of BrdU-positive nuclei, and serves to regulate the expression of developmental phenotypes seen in these cells. These data further our understanding of Müller cell responsiveness to intravitral, combinatorial growth factor treatments.

Differential expression of organic cation transporters in normal and polyps human nasal epithelium: implications for in vitro drug delivery studies

The aim of this study was to compare the expression of organic cation transporters (OCTs) in normal and polyps nasal epithelium. Primary cell cultures of human nasal epithelium (polyps and normal tissues) were compared by investigating the uptake of a fluorescent organic cation, [4-dimethylaminostyryl-N-methylpyridinium (4-Di-1-ASP)]. The effect of concentration, temperature, pH and competing inhibitors were investigated. Quantitative polymerase chain reaction (qPCR) was used to compare the OCTs gene expression levels in the cells. The K(m) (μM) and V(max) (μM/mg protein/15 min) for 4-Di-1-ASP uptake were higher in normal (K(m)=3031 ± 559.6, V(max)=70.8 ± 8.8) cells compared to polyps (K(m)=952.4 ± 207.8, V(max)=30.9 ± 2.1). qPCR results showed that OCT1-3 and organic cation/carnitine transporter 1-2 gene transcripts (OCTN1-2) were expressed in both normal and polyps cells at comparable levels, with OCT-3 having the highest expression level in both cultures. Kruskal-Wallis ANOVA showed that pH and specific inhibitors had similar effects on both normal and polyps cells (p>0.5). Similarly, OCTs and OCTNs gene expression levels were similar. This study showed that polyps biopsies can be used for isolating cells to study organic cation transporters in human nasal epithelium as no major functional or molecular differences relative to normal cells could be found.

Carotid artery visualization during anterior skull base surgery: a novel protocol for neuronavigation

Detailed knowledge of the vascular anatomy of the anterior skull base is critical to successful surgery in this area. Whereas conventional neuronavigational approaches combine MRI (+/- contrast) for tumor visualization and CT (+/- C) for bony and vascular anatomy, we describe the Canadian and Austrian experiences using a novel protocol integrating MR angiography (MRA) into surgical neuronavigation to provide superior visualization of the carotid arteries. The pre-operative imaging protocol employs a T1-weighted, 3D fast spoiled gradient echo MRI (+/- C) for soft tissue anatomy, a plain CT for bony anatomy, and a 3D time-of-flight MR angiography for carotid anatomy. The series are imported into the Medtronic StealthStation((R)) TREON((R)) Treatment Guidance System; during intra-operative neuronavigation, each series (MRI, CT, MRA) can be viewed individually, or layered and viewed as a composite image. Our protocol has important advantages. First, it provides detailed tissue, tumor, vascular and bony anatomy. Second, a contrast CT is not necessary; this is important, as numerous reports have highlighted the nephrotoxic nature of radiographic contrast material. Third, visualization of the carotid system is superior than can be obtained from CT angiography. We use this unique imaging protocol routinely for our endoscopic transsphenoidal surgeries to provide superior visualization of the carotid arteries during anterior skull base surgery.