Warming reduces trophic diversity in high-latitude food webs.

The physical effects of climate warming have been well documented, but the biological responses are far less well known, especially at the ecosystem level and at large (intercontinental) scales. Global warming over the next century is generally predicted to reduce food web complexity, but this is rarely tested empirically due to the dearth of studies isolating the effects of temperature on complex natural food webs. To overcome this obstacle, we used 'natural experiments' across 14 streams in Iceland and Russia, with natural warming of up to 20°C above the coldest stream in each high-latitude region, where anthropogenic warming is predicted to be especially rapid. Using biomass-weighted stable isotope data, we found that community isotopic divergence (a universal, taxon-free measure of trophic diversity) was consistently lower in warmer streams. We also found a clear shift towards greater assimilation of autochthonous carbon, which was driven by increasing dominance of herbivores but without a concomitant increase in algal stocks. Overall, our results support the prediction that higher temperatures will simplify high-latitude freshwater ecosystems and provide the first mechanistic glimpses of how warming alters energy transfer through food webs at intercontinental scales.

Radiation-induced cerebral cavernous malformation: is it just a childhood disease?

Cerebral cavernous malformations (CCM) are clusters of dilated sinusoidal channels, lined by a single layer of endothelium. Acquired form of these lesions was related to previous radiation-therapy, and might be related to its pathophysiology, because the vascular endothelial growth factor has higher expression in the immature brain of the child. Consequently, although it occurs mainly in the paediatric population, it can happen in adults. We report a case of radiation-induced CCM in an adult patient presenting with aggressive behaviour and cerebral haemorrhage.

Minimally invasive craniotomies for lesions of the anterior and middle fossa.

Minimally invasive craniotomies are the subject of increasing attention over the last two decades in neurosurgery, following the current trend of attempting to increase patient safety by providing surgeries with less tissue disruption, blood loss, and decreased operative time. However, a significant information overlap exists among the various keyhole approaches regarding their indications and differences with more invasive techniques. Therefore, the present study aims to comprehensively review, illustrate, and describe the potential benefits and disadvantages of minimally invasive techniques to access the anterior and middle fossa, including the mini-pterional, mini orbito-zygomatic, supraorbital, lateral supraorbital, and extended lateral supraorbital approaches while comparing them to classic, more invasive approaches.

Thermal acclimation increases the stability of a predator-prey interaction in warmer environments.

Global warming over the next century is likely to alter the energy demands of consumers and thus the strengths of their interactions with their resources. The subsequent cascading effects on population biomasses could have profound effects on food web stability. One key mechanism by which organisms can cope with a changing environment is phenotypic plasticity, such as acclimation to warmer conditions through reversible changes in their physiology. Here, we measured metabolic rates and functional responses in laboratory experiments for a widespread predator-prey pair of freshwater invertebrates, sampled from across a natural stream temperature gradient in Iceland (4-18℃). This enabled us to parameterize a Rosenzweig-MacArthur population dynamical model to study the effect of thermal acclimation on the persistence of the predator-prey pairs in response to warming. Acclimation to higher temperatures either had neutral effects or reduced the thermal sensitivity of both metabolic and feeding rates for the predator, increasing its energetic efficiency. This resulted in greater stability of population dynamics, as acclimation to higher temperatures increased the biomass of both predator and prey populations with warming. These findings indicate that phenotypic plasticity can act as a buffer against the impacts of environmental warming. As a consequence, predator-prey interactions between ectotherms may be less sensitive to future warming than previously expected, but this requires further investigation across a broader range of interacting species.

Consistent temperature dependence of functional response parameters and their use in predicting population abundance.

Global warming is one of the greatest threats to the persistence of populations: increased metabolic demands should strengthen pairwise species interactions, which could destabilize food webs at the higher organizational levels. Quantifying the temperature dependence of consumer-resource interactions is thus essential for predicting ecological responses to warming. We explored feeding interactions between different predator-prey pairs in controlled-temperature chambers and in a system of naturally heated streams. We found consistent temperature dependence of attack rates across experimental settings, though the magnitude and activation energy of attack rate were specific to each predator, which varied in mobility and foraging mode. We used these parameters along with metabolic rate measurements to estimate energetic efficiency and population abundance with warming. Energetic efficiency accurately estimated field abundance of a mobile predator that struggled to meet its metabolic demands, but was a poor predictor for a sedentary predator that operated well below its energetic limits. Temperature effects on population abundance may thus be strongly dependent on whether organisms are regulated by their own energy intake or interspecific interactions. Given the widespread use of functional response parameters in ecological modelling, reconciling outcomes from laboratory and field studies increases the confidence and precision with which we can predict warming impacts on natural systems.

Regional impacts of warming on biodiversity and biomass in high latitude stream ecosystems across the Northern Hemisphere.

Warming can have profound impacts on ecological communities. However, explorations of how differences in biogeography and productivity might reshape the effect of warming have been limited to theoretical or proxy-based approaches: for instance, studies of latitudinal temperature gradients are often conflated with other drivers (e.g., species richness). Here, we overcome these limitations by using local geothermal temperature gradients across multiple high-latitude stream ecosystems. Each suite of streams (6-11 warmed by 1-15°C above ambient) is set within one of five regions (37 streams total); because the heating comes from the bedrock and is not confounded by changes in chemistry, we can isolate the effect of temperature. We found a negative overall relationship between diatom and invertebrate species richness and temperature, but the strength of the relationship varied regionally, declining more strongly in regions with low terrestrial productivity. Total invertebrate biomass increased with temperature in all regions. The latter pattern combined with the former suggests that the increased biomass of tolerant species might compensate for the loss of sensitive species. Our results show that the impact of warming can be dependent on regional conditions, demonstrating that local variation should be included in future climate projections rather than simply assuming universal relationships.

Safety of withholding perioperative steroids for patients with pituitary resection with an intact hypothalamus-pituitary-adrenal axis: A meta-analysis of randomized clinical trials.

INTRODUCTION: Several observational studies have evaluated the effects of pre-operative steroids (STER) for transsphenoidal pituitary removal in patients with an intact hypothalamus-pituitary-adrenal axis. However, a consensus built upon randomized studies has not been previously performed. PURPOSE: To comprehensively evaluate the clinical effects of patients receiving STER when compared to those not receiving steroids (NOSTER) in transsphenoidal pituitary resection, a meta-analysis of randomized clinical trials (RCT) was conducted. METHODS: A systematic review of the literature of RCTs comparing STER and NOSTER was performed in accordance with the PRISMA guidelines. Databases, including PUBMED, Cochrane Library, Web of Science, and Embase were queried. The primary outcomes were adrenal insufficiency (AI) and diabetes insipidus (DI) post-operatively. RESULTS: A total of 4 final studies were included, in which 530 total patients were analyzed. The meta-analysis suggested that there was no significant difference between STER and NOSTER groups post-operatively related to transient AI (RR= 0.83, 95% CI [0.51-1.35], p = 0.45; I² = 52%), permanent AI (RR= 0.97, 95% CI [0.41-2.31], p = 0.95; I² = 0%), and permanent DI (RR= 0.62, 95% CI [0.16-2.33], p = 0.48; I² = 0%). Nevertheless, STER group had significantly lower rates of transient DI (RR= 0.60, 95% CI [0.38-0.95], p = 0.03; I² = 5%), and post-op hyponatremia (RR = 0.49, 95% CI [0.28-0.87], p = 0.02; I² = 0%). CONCLUSION: This study demonstrates evidence from RCTs that patients receiving pre-operative STER are both safe and effective pre-operatively for resection of pituitary adenomas with an intact hypothalamus-pituitary-adrenal axis.

Intracranial ependymal cyst - A modern systematic review with a pathway to diagnosis.

BACKGROUND: Intracranial ependymal cysts (IECs) are rare, histologically benign neuroepithelial cysts that mostly occur in the cerebral parenchyma. The majority of these cysts are clinically silent and discovered incidentally, but when symptomatic they may compress surrounding structures, thus surgical intervention is needed. The current data in the literature about ECs is very scarce, and many are misdiagnosed, once they share many radiological characteristics with a variety of intracranial benign cysts. Also their terminology is confusing, and its definitive diagnosis can only be made through a thorough histopathological study, hence a detailed description about these uncommon lesions is necessary. The correct identification of the lesion lead to our better understanding of the condition and further improvement of the patient's prognosis. METHODS: A descriptive case is presented; moreover, a detailed PubMed search according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline was performed. The data found was analyzed by various criteria in order to correctly describe the characteristics of this lesion. RESULTS: The literature review gathered 9 descriptions of patients with IECs with a diverse range anatomopathological and clinical manifestations. All of the included studies found were case reports. Moreover, the authors suggest an updated classification of the lesion, involving their immunohistochemical characteristics. CONCLUSIONS: The information obtained from this study highlights IECs rarity and their inaccurately classification. We propose that the definitive diagnosis of IECs shall be made upon histopathological confirmation of an ependyma-lined cyst along with a positive glial fibrillary acidic protein (GFAP).

Implementation of Minimally Invasive Brain Tumor Resection in Rodents for High Viability Tissue Collection.

The present protocol describes a standardized paradigm for rodent brain tumor resection and tissue preservation. In clinical practice, maximal tumor resection is the standard-of-care treatment for most brain tumors. However, most currently available preclinical brain tumor models either do not include resection, or utilize surgical resection models that are time-consuming and lead to significant postoperative morbidity, mortality, or experimental variability. In addition, performing resection in rodents can be daunting for several reasons, including a lack of clinically comparable surgical tools or protocols and the absence of an established platform for standardized tissue collection. This protocol highlights the use of a multi-functional, non-ablative resection device and an integrated tissue preservation system adapted from the clinical version of the device. The device applied in the present study combines tunable suction and a cylindrical blade at the aperture to precisely probe, cut, and suction tissue. The minimally invasive resection device performs its functions via the same burr hole used for the initial tumor implantation. This approach minimizes alterations to regional anatomy during biopsy or resection surgeries and reduces the risk of significant blood loss. These factors significantly reduced the operative time (<2 min/animal), improved postoperative animal survival, lower variability in experimental groups, and result in high viability of resected tissues and cells for future analyses. This process is facilitated by a blade speed of ~1,400 cycles/min, which allows the harvesting of tissues into a sterile closed system that can be filled with a physiologic solution of choice. Given the emerging importance of studying and accurately modeling the impact of surgery, preservation and rigorous comparative analysis of regionalized tumor resection specimens, and intra-cavity-delivered therapeutics, this unique protocol will expand opportunities to explore unanswered questions about perioperative management and therapeutic discovery for brain tumor patients.

Use of transversus abdominis plane block to decrease pain scores and narcotic use following robot-assisted laparoscopic prostatectomy.

The aim of this study was to assess whether transversus abdominis plane (TAP) blocks can be utilized to decrease patient pain scores and narcotic use during the first 24 h following robot-assisted laparoscopic prostatectomy (RALP). 100 patients received a TAP block with a mixture of 1.3% liposomal bupivacaine, 0.5% Marcaine and 0.9% NaCl prior to RALP. This was in addition to an already established pain management regiment, which included preoperative PO acetaminophen (650 mg), celecoxib (200 mg), and tolterodine ER (4 mg). These patients were prospectively followed and then retrospectively compared to a 1:1 propensity matched group of 100 patients that did not receive a TAP but did receive the preoperative PO medications. Pain scores were assessed on a scale from 1-10 in the PACU, as well as the surgical floor at 8, 16, and 24-h post-surgery. Intra-/post-operative narcotic use and time to ambulation following arrival to the surgical floor were also analyzed. Patient receiving TAP blocks had immediate post-op pain scores of 2.23 vs 4.26 for those not receiving TAP blocks (p = 0.000). The pain scores at 8, 16, and 24 h for TAP patients were 2.68, 2.62, and 2.62 as compared to 2.89, 2.87, and 3.36 for non-TAP patients. The difference was statistically significant for immediate and 24-h pain scores (p = 0.000, 0.001, respectively). On average, TAP block patients ambulated faster than non-TAP patients, 2.68 vs 4.91 h (p = 0.000). Intra-operative narcotic use was decreased in the TAP group for each of the opioids that were used: fentanyl 177.5 vs 205mcg (p = 0.001), morphine 5.5 vs 10 mg (p = 0.000), and hydromorphone 0.75 vs 1.75 mg (p = 0.001). Narcotic usage in the PACU was limited to hydromorphone and TAP patients used 0.7 mg compared to 1.36 mg (p = 0.003) for non-TAP patients. Oral oxycodone/acetaminophen (5 mg/325 mg) was used for pain control on the surgical floor and on average TAP patients received less, 2.4 vs 5 tabs (p = 0.000). Average time to perform the TAP block was 3.5 min and total OR time for TAP vs non-TAP patients was 107.41 vs 106.58 min (p = 0.386). TAP blocks as part of a perioperative pain management protocol can be utilized during RALPs to decrease patient pain scores at two different time intervals, immediately post-operative and 24 h after surgery. Patients also ambulate sooner following surgery and require a decreased amount of narcotics during the intra-operative and post-operative periods. TAP blocks are quick, effective, and do not add a significant amount of OR time to RALPs.

Multi-modal hallucinations and cognitive function in Parkinson's disease.

BACKGROUND/AIMS: Hallucinations have been linked to a constellation of cognitive deficits in Parkinson's disease (PD), but it is not known whether multi-modal hallucinations are associated with greater neuropsychological dysfunction. METHODS: 152 idiopathic PD patients were categorized based on the presence or absence of hallucinations and then were further subdivided into visual-only (VHonly; n = 35) or multi-modal (VHplus; n = 12) hallucination groups. All participants underwent detailed neuropsychological assessment. RESULTS: Participants with hallucinations performed more poorly on select neuropsychological measures and exhibited more mood symptoms. There were no differences between VHonly and VHplus groups. CONCLUSIONS: PD patients with multi-modal hallucinations are not at greater risk for neuropsychological impairment than those with single-modal hallucinations.

Chemical Angioplasty with Nitroglycerin for Vasospasm after Subarachnoid Hemorrhage: Case Series and Review

Introduction Vasospasm is a common and potentially devastating complication in patients with subarachnoid hemorrhage, causing high morbidity and mortality. There is no effective and consistent way to prevent or treat cerebral vasospasm capable of altering the morbidity and mortality of this complication. Animal and human studies have attempted to show improvement in aneurysmal vasospasm. Some sought their prevention; others, the treatment of already installed vasospasm. Some achieved only angiographic improvement without clinical correlation, others achieved both, but with ephemeral duration or at the expense of very harmful associated effects. Endovascular techniques allow immediate and aggressive treatment of cerebral vasospasm and include methods such as mechanical and chemical angioplasty. These methods have risks and benefits. Objectives To analyze the results of chemical angioplasty using nitroglycerin (GTN). In addition, to performa comprehensive review and analysis of aneurysmal vasospasm. Methods We describe our series of 77 patients treated for 8 years with angioplasty for vasospasm, either mechanical (with balloon), chemical (with GTN) or both. Results Eleven patients received only balloon; 37 received only GTN; 29 received both. Forty-four patients (70.1%) evolved with delayed cerebral ischemia and 19 died (mortality of 24.7%). Two deaths were causally related to the rupture of the vessel by the balloon. The only predictors of poor outcome were the need for external ventricular drainage in the first hours of admission, and isolated mechanical angioplasty. Conclusions Balloon angioplasty has excellent results, but it is restricted to proximal vessels and is not without complications. Chemical angioplasty using nitroglycerin has reasonable but short-lived results and further research is needed about it. It is restricted to vasospasm angioplasties only in hospitals, like ours, where better and more potent vasodilator agents are not available.

Epilepsy, surgery, and the elderly.

Treatment of elderly patients with epilepsy may present unique challenges to physicians. Co-morbid conditions and drugs to treat such conditions are common in elderly patients, possibly complicating epilepsy therapies that are dependent on drugs alone. For this reason, surgical intervention may be an attractive option for elderly patients with epilepsy, particularly for medically intractable patients with key disease features, such as lateralization and precisely localized epileptic foci. Curative procedures, including lobectomy and lesionectomy, are most likely to lead to seizure freedom, but not all patients are candidates for such procedures. When a curative surgical procedure is not an option, palliative procedures, including vagus nerve stimulation and deep brain stimulation, may be viable options. Vagus nerve stimulation has been reported to reduce seizure rates and improve quality of life in elderly patients with epilepsy. Currently, widespread therapeutic application of deep brain stimulation is limited by risks, costs, and pending studies.

Tuberculoma of the brain with unknown primary infection in an immunocompetent host.

Isolated cerebral tubercular abscess is uncommon in immunocompetent hosts. Our patient had a tuberculoma with no known primary and an atypical MRI appearance. We present a 67-year-old African-American male with complex partial seizures. A CT scan of the brain revealed a new right frontal mass which was not found on imaging two years prior. In view of the patient's age and absence of any known primary malignancy, a primary brain tumor was considered to be the likely diagnosis. On MRI, the mass did not display ring enhancement or necrosis. Rather, the mass was lobulated, with near-uniform enhancement of the lesion with a surrounding high fluid-attenuated inversion recovery signal predominantly in the right frontal region, which extended inferiorly to the parietal region. The lesion showed a few punctate foci of low signal intensity on gradient echo MRI sequences, suggestive of hemorrhage. The mode of infection is unknown. However, it is important to include tuberculosis as a differential diagnosis, especially if the lesion appears to be non-primary, if a primary neoplasm or other metastases are not identified on further investigation, and in a patient of African-American ethnicity. To our knowledge, this is the first record of an isolated tubercular abscess of the brain in a developed country.

Subthalamic deep brain stimulation with a constant-current device in Parkinson's disease: an open-label randomised controlled trial.

BACKGROUND: The effects of constant-current deep brain stimulation (DBS) have not been studied in controlled trials in patients with Parkinson's disease. We aimed to assess the safety and efficacy of bilateral constant-current DBS of the subthalamic nucleus. METHODS: This prospective, randomised, multicentre controlled trial was done between Sept 26, 2005, and Aug 13, 2010, at 15 clinical sites specialising in movement disorders in the USA. Patients were eligible if they were aged 18-80 years, had Parkinson's disease for 5 years or more, and had either 6 h or more daily off time reported in a patient diary of moderate to severe dyskinesia during waking hours. The patients received bilateral implantation in the subthalamic nucleus of a constant-current DBS device. After implantation, computer-generated randomisation was done with a block size of four, and patients were randomly assigned to the stimulation or control group (stimulation:control ratio 3:1). The control group received implantation without activation for 3 months. No blinding occurred during this study, and both patients and investigators were aware of the treatment group. The primary outcome variable was the change in on time without bothersome dyskinesia (ie, good quality on time) at 3 months as recorded in patients' diaries. Patients were followed up for 1 year. This trial is registered with ClinicalTrials.gov, number NCT00552474. FINDINGS: Of 168 patients assessed for eligibility, 136 had implantation of the constant-current device and were randomly assigned to receive immediate (101 patients) or delayed (35 patients) stimulation. Both study groups reported a mean increase of good quality on time after 3 months, and the increase was greater in the stimulation group (4·27 h vs 1·77 h, difference 2·51 [95% CI 0·87-4·16]; p=0·003). Unified Parkinson's disease rating scale motor scores in the off-medication, on-stimulation condition improved by 39% from baseline (24·8 vs 40·8). Some serious adverse events occurred after DBS implantation, including infections in five (4%) of 136 patients and intracranial haemorrhage in four (3%) patients. Stimulation of the subthalamic nucleus was associated with dysarthria, fatigue, paraesthesias, and oedema, whereas gait problems, disequilibrium, dyskinesia, and falls were reported in both groups. INTERPRETATION: Constant-current DBS of the subthalamic nucleus produced significant improvements in good quality on time when compared with a control group without stimulation. Future trials should compare the effects of constant-current DBS with those of voltage-controlled stimulation. FUNDING: St Jude Medical Neuromodulation Division.

Objective tremor registration during DBS surgery for essential tremor.

Essential Tremor (ET) is characterized by a 4-12-Hz postural and kinetic tremor, most commonly affecting the upper limbs. Deep brain stimulation (DBS) of the thalamus (Vim) has been found to be highly effective in severe/refractory forms of ET. Intra-operative assessment of tremor is performed using clinical methods based on patient and physician perception of tremor intensity. We present for the first time the case of a patient whose tremor was objectively monitored/quantified pre- and intra-operatively using device-based tremor registration to supplement clinical measures. We present the case of a 76-year-old right-handed woman that received unilateral (left-sided) DBS of the ventrointermediate (Vim) nucleus of thalamus (Vim) for medically refractory ET. Tremor was monitored with an accelerometer-based Tremor Pen, which is part of a simple portable device (CATSYS 2000 System, Danish Product Development Ltd., DK, www.catsys.dk). The patient was asked to perform tasks for tremor evaluation before and during thalamic DBS. Tremor quantification revealed a significant improvement (34.7-fold) in the contralateral (right) limb following macro-stimulation. No significant improvement was registered in the ipsilateral (non-operated) side. Simple electronic tremor registration methods during DBS of the Vim nucleus of the thalamus may supplement the existing methodology that is solely based on subjective measures derived from clinical observations.