Corridor Size Research Articles

A magnetic resonance imaging-based morphometric analysis of bilateral L1-L5 oblique lumbar interbody fusion corridor: feasibility of safe surgical approach and influencing factors.

Retrospective cross-sectional study. To investigate the size and local anatomy of the right and the left-sided oblique corridors between L1-L5 levels and identify the potential impact of increasing age and sex on corridor size. The oblique lumbar interbody fusion (OLIF) was introduced by Silvestre and his colleagues as a solution to the approach-related complications associated with anterior lumbar interbody fusion and lateral lumbar interbody fusion. Limited data were available describing the local anatomy and morphology of this approach. Imaging data of 300 patients (150 males and 150 females) who underwent 1.5T magnetic resonance imaging (MRI) scans of the lumbar spine at Indian Spinal Injuries Centre, New Delhi, India between January 2023 and January 2024 were retrospectively reviewed. The cohort was stratified into six age groups (21-30, 31-40, 41-50, 51-60, 61-70, and >70 years) with 25 patients in each age group for both sexes. T2 weighted axial MRI images were analyzed from the L1-L5 level at the mid-disc level to calculate the corridor size. The local anatomical differences were recorded. At L1-L2, L2-L3, L3-L4, and L4-L5 levels, the mean corridor sizes in males were 17.48, 15.50, 13.41, and 9.32 mm on the left side, and 11.48, 7.12, 4.34, and 1.64 mm on the right side, respectively. The corresponding mean corridor sizes in females were 10.34, 12.94, 12.64, and 7.22 mm on the left side and 2.66, 3.52, 3.69, and 1.64 mm on the right side, respectively. For both sides, the corridor size was significantly affected by sex, increased with age, and decreased at the lower lumbar disc levels. A left-sided OLIF approach is more feasible for both sexes. The right-sided approach is less likely to be performed effectively.

Sacropelvic Fixation with Porous Fusion/Fixation Screws: A Technical Note and Retrospective Review

ObjectiveThe goal of this study was to analyze our initial experience using a novel porous fusion/fixation screw (PFFS) for pelvic fixation, and to determine our rate of screw malposition requiring intraoperative repositioning. MethodsWe reviewed 83 consecutive patients who underwent sacropelvic fixation with PFFS at our institution from 6/1/2022-6/30/2023 using intraoperative CT-based computer-assisted navigation (CAN) via an open posterior approach. Following PFFS insertion, intraoperative CT scans were obtained to assess screw positioning. Demographic data was collected, and operative reports and patient images were reviewed to determine what implants were used and if any PFFS required repositioning. Results74 patients (26M:48F) were included, and 57 (77.0%) had a prior sacroiliac joint or lumbar spine surgery. A stacked screw configuration was used in 62/74 cases (83.8%). A total of 235 PFFS were used and six (2.6%) were malpositioned. Of 88 cephalic screws placed in stacked configuration, 4 were malpositioned (4.5%); and 1/123 caudal screws were malpositioned (0.8%). One of 24 SAI screws placed in a stand-alone configuration was malpositioned (4.2%). Malpositions included four medial, one lateral, and one inferior; and all were revised intraoperatively without major sequela. ConclusionsAlthough PFFS are larger than traditional sacropelvic fixation screws, stacked SAI instrumentation can be done safely with CAN. We found a low malposition rate in our initial series of patients, the majority being the cephalad screw in a stacked configuration. This isn’t surprising, as these are placed after the caudal screws which reduces the available corridor size and increases the placement difficulty.

Attractive combinations of female gingival displays, buccal corridor sizes, and facial heights according to orthodontists, dentists, and laypeople of different ages and sexes: a psychometric study

IntroductionEsthetics plays a crucial role in orthodontics and many other dental and medical fields. To date, no study has assessed the combined effects of the 3 facial features ‘facial height, gingival display (GD), and buccal corridor size (BC)’ on facial/smile beauty. Therefore, this study was conducted for the first time.MethodsIn this psychometric diagnostic study, beauty of 27 randomized perceptometric images of a female model with variations in facial heights (short, normal, long), gingival displays (0, 2, 4, 6 mm), and buccal corridor sizes (2%, 10%, 15%, 20%, 25%) were evaluated by 108 judges (36 orthodontists, 36 dentists, 36 laypeople) using a 5-scale Likert scale (1 to 5). Combined effects of facial heights, GDs, BCs, judges’ sexes, ages, and jobs, and their 2-way interactions were tested using a mixed-model multiple linear regression and a Bonferroni test. Zones of ideal features were determined for all judges and also for each group using repeated-measures ANOVAs and the Bonferroni test (α=0.05).ResultsJudges’ sex but not their age or expertise might affect their perception of female beauty: men gave higher scores. The normal face was perceived as more beautiful than the long face (the short face being the least attractive). Zero GD was the most attractive followed by 4 mm; 6 mm was the least appealing. BCs of 15% followed by 10% were the most attractive ones, while 25% BC was the worst. The zone of ideal anatomy was: long face + 0mm GD + 15% BC; normal face + 2mm GD + 15% BC; long face + 2mm GD + 15% BC; normal face + 0mm GD + 15% BC.ConclusionsNormal faces, zero GDs, and 15% BCs may be the most appealing. Facial heights affect the perception of beauty towards GDs but not BCs.

Investigating expert and lay judgments of pathogen transmission risk in urban and architectural environments

ABSTRACT The threat of infection posed by the COVID-19 virus forced the general public to use the visible cues within urban and architectural environments as a ‘lens’ through which pathogen transmission risk could be inferred. This study presents a model that quantifies associations between (1) the visible cues of urban and architectural environments and lay ratings of pathogen transmission risk, (2) the same relationship for experts (i.e. Infection Control Practitioners), and (3) the association between the lay ratings and the expert ratings. A series of urban and architectural environments were rated on twenty visible architectural cues and for their perceived pathogen transmission risk by lay and expert raters. Correlational analyses between the two groups yielded considerable consensus between risk ratings, as well as between which cues were significantly associated with risk ratings, which included the space’s crowdedness, the potential for crowds, and cleanliness. Expert risk ratings were also significantly associated with corridor size, and marginally significantly associated with the number of touchable surfaces, the number of furniture/seating, and access to fresh air. In this way, expert cue utilization is more complex than lay assessments. Implications for public health policy makers and designers of the built environment are discussed.

Perception of smile attractiveness among laypeople and orthodontists regarding the buccal corridor space, as it is defined by the eyes. An innovated technique.

To investigate whether there is a relationship between the distance between the iris and pupil with the ideal size of buccal corridors. A full-portrait image of a male Caucasian was used to create a set of 11 digitally modified images with different buccal corridor space. A web-based cross-sectional study was designed and distributed via an online survey to 200 laypeople and 200 orthodontists to assess image attractiveness, using a Visual analogue scale. For the statistical analysis, Wilcoxon signed-rank and Mann-Whitney U tests were used. The significance level was set at p < 0.05. The response rate for laypeople was 70% (n=139), while the rate for orthodontists was 73% (n=146). For the layperson group, the maximum smile attractiveness score was 10% of buccal width reduction, compared to the iris-pupillary distance, while for the orthodontists, it was 20%. The attractiveness of the smile was significantly reduced in both groups when the buccal corridor width was increased in comparison to the iris-pupillary distance. The length between the mesial part of the iris and the distal of the pupil, may constitutes a landmark for the estimation of the desired width of the buccal corridor. Inter iris-pupillary distance can be the starting point in the smile designing process, in order to perform a facial driven selection of buccal corridor size.

The geometrical properties of fracture corridors

Fracture corridors are densely fractured zones that may form preferential drains for fluids in the surface and subsurface. Their accurate characterization and modeling are of utmost importance to predictive hydrodynamic models. This paper details their key geometrical attributes and shows that they can be predicted, based on a comprehensive study of surface and subsurface data.The spacing, length and width of fracture corridors all exhibit multifractal characteristics, with a very good consistency between the different data sources. Their width appears to be limited to a maximum of ∼250–300 m, while their fracture density is correlated to their width by a negative power law relationship, but with a significant variability at all scales. The constitutive fractures in the corridors also show multifractal properties. The fracture spacings typically fall in the cm-m range regardless of the corridor size, and moderately increase with increasing corridor size. The fracture heights increase more significantly with increasing corridor size, but with a constant distribution when normalized to the corridor height. All these elements are indicative of typically scale-independent fracture corridor development mechanisms, consistent with a recent model.The data acquired form a key resource from which a new method and tools are proposed for the modeling of fracture corridors in surface and subsurface contexts, with applications to aquifers, hydrocarbon reservoirs or underground CO2 storage sites.

Defining Sacral Dysmorphism: What Size Corridor Precludes Transsacral Screw Placement.

To determine what size S1-transsacral (TS) corridor is amenable to TS screw placement, as this is commonly used to identify sacral dysmorphism, and to determine if gender, ethnicity, or screw breach is associated with narrow corridors. Retrospective review. Urban level-1 trauma center. Two hundred ninety patients with pelvic ring injuries and preoperative computed tomography (CT) scans. Percutaneous posterior pelvic ring fixation. The width of the S1-TS corridor was measured on the axial (inlet) and coronal (outlet) reformatted CT images. Patients with S1-TS screw fixation and postoperative CT scans were identified. Corridor size, gender, ethnicity, and screw breach were documented. S1-TS screws were placed in 55 of the 290 patients. No S1-TS screws were placed in corridors less than 8 mm. Corridors of &lt;8 mm were present in 114 (39%) of the 290 patients and were not associated with gender or ethnicity. S1-TS screws placed in small (&lt;10 mm) versus large (≥10 mm) corridors did not have a detectable difference in screw breaches (5 of 8, 62% versus 19 of 47 40%; difference, 22%, 95% confidence interval -14% to 52%) or median (interquartile range) screw breach distance [3 mm (2.5-4.8) versus 3 mm (1.2-4.8); difference, 0.9 mm; confidence interval -1.6 to 2.2]. These data are useful for the standardization of sacral dysmorphism reporting based on corridor size. Screw breaches were common irrespective of TS corridor size, emphasizing the small degree of error allowed by this procedure. Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Risk factors for screw breach and iatrogenic nerve injury in percutaneous posterior pelvic ring fixation

BackgroundPercutaneous screw fixation of the posterior pelvic ring is technically demanding and can result in cortical breach. The purpose of this study was to examine risk factors for screw breach and iatrogenic nerve injury. MethodsA retrospective review at a single level-one trauma center identified 245 patients treated with 249 screws for pelvic ring injuries with postoperative computed tomography (CT) scans. Cortical screw breach, iatrogenic nerve injury, and associated risk factors were evaluated. ResultsThere were 86 (35%) breached screws. The breach rate was similar between screw types (33% S1-iliosacral (S1-IS), 44% S1-transsacral (S1-TS), 31% S2-IS, and 30% S2-TS) and was not associated with patient characteristics, Tile C injuries, or corridor size or angle. The overall rate of screw revision for screw malpositioning was 1.2% (3/249). Iatrogenic nerve injuries occurred in 8 (3.2%) of the 249 screws. Screws that caused iatrogenic nerve injuries had greater screw breach distances (5.4 vs. 0 mm, MD 5, CI 2.3 to 8.7, p < 0.0001), were more likely to be S1-IS screws (88% vs. 47%, PD 40%, CI 7 to 58%, p = 0.006), more likely to be placed in Tile C injuries (75% vs. 44%, PD 31%, CI -3 to 55%, p = 0.04), and there was a trend for having a screw corridor size <10 mm (75% vs. 47%, PD 28, CI -6 to 52%, p = 0.06). Of the 7 iatrogenic nerve injuries adjacent to screw breaches, two nerve injuries recovered after screw removal, three recovered with screw retention, and two did not recover with screw retention. ConclusionScrew breaches were common and iatrogenic nerve injuries were more likely with S1-IS screws. Surgeons should maintain a high degree of caution when placing these screws and consider removal of any breached screw associated with nerve injury.

Iliac dysmorphism: defining radiographic characteristics and association with pelvic osseous corridor size.

Insertion of iliac wing implants requires understanding of the curvilinear shape of the ilium. This study serves to quantitatively identify the area of iliac inner-outer table convergence (IOTC), characterize the iliac wing osseous corridor, and define the gluteal pillar osseous corridor. Computed tomography scans of 100 male and 100 female hemipelves were evaluated. The iliac wing was studied using manual best-fit analysis of the bounds of the inner and outer cortices. The IOTC was defined as the location of the iliac wing with an intercortical width less than 5mm. The shortest distance from the apex of the iliac crest to the superior border of the IOTC was defined as the iliac wing osseous corridor. Finally, the width of the gluteal pillar corridor from the gluteus medius tubercle to the ischial tuberosity was measured. The IOTC is an elliptical area measuring 22.3 cm2. All ilia had an area where the inner and outer cortices converged to an intercortical width of less than 5mm; 48% converged to a single cortex. The shortest mean distance from the superior edge of the iliac crest to the beginning of the IOTC was 20.3mm in men and 13.8mm in women (p < 0.001). The gluteal pillar diameter averaged 5.3mm in men and 4.3mm in women (p < 0.001). All ilia converge to a thin and frequently unicortical central region. A 4.5mm iliac wing lag screw will not breach the cortex if it remains within 20mm or 14mm distal to the cranial aspect of the iliac crest in males and females, respectively. Not only is the gluteal pillar smaller than previously thought, in 41% of males and 73% of females, it is not be large enough for 5mm implants. This study quantitatively assesses the dimensions of the IOTC, the iliac crest osseous corridor, and the gluteal pillar. Overall, our findings provide improved understanding of the limits for implant use in the iliac wing as well as better appreciation of the complex osteology of the ilium. This will help surgeons to identify safe areas for implant placement and avoid inadvertent cortical penetration.

Real-time tracking of a moving target in an indoor corridor of the hospital building using RSSI signals received from two reference nodes.

In this paper, implementation and validation of a target tracking system based on the received signal strength indicator (RSSI) for an indoor corridor environment of the hospital is presented. Six tracking methods of a moving target (i.e., equipment, robot, or human) using RSSI signals measured from two stationary reference nodes located at the different sides of the corridor are proposed. A filter with its optimal weight value is also applied to smoothen and increase the accuracy of estimated position results (i.e., the x-position in the corridor). Additionally, a determination approach for finding the optimal parameters assigned for the proposed tracking methods and the filter are also introduced. The proposed methods are implemented in MATLAB/Simulink, and experiments using a 2.4 GHz, IEEE 802.15.4/ZigBee wireless network have been carried out in the indoor corridor of the hospital building. Experimental results obtained from the corridor size of 22 m demonstrate that our proposed methods can automatically and efficiently track the moving target in real time. The average distance errors, in the case of varying and manual tuning the optimal parameters of the proposed methods and the filter, reduce from 5.14 to 1.01 m and 4.55 to 0.86 m (i.e., two test cases; slow moving speed and double moving speed). Here, the errors decrease by 80.35% and 81.10%, respectively. For the case using the optimal parameters determined by the optimization approach, the average errors can reduce to 0.97 m for the first test case and 0.78 m for the second test case, respectively.Graphical abstractAn RSSI-based real-time tracking system for a moving target in an indoor corridor of the hospital building

ESTUDO DO DIÂMETRO DO CORREDOR OBLÍQUO EM DECÚBITO LATERAL E DECÚBITO DORSAL: ESTUDO RADIOLÓGICO

ABSTRACT Introduction: Degenerative intervertebral disc disease and its impact on quality of life when associated with sagittal misalignmentis a current topic in the literature. The technique known as OLIF derives from the need to use anterior cage stop romote stabilization of the affected segment, indirect decompression, restoration of segmental lordosis, and sagittal balance. Methods: Single-center, non-randomized, comparative, observational study. The following variables were measured using magnetic resonance imaging of the lumbar spine in dorsal and lateral decubitus, establishing a comparison between the size of the OLIF corridor in the L3L4 and L4L5 segments, as well as a comparison of corridor size between the different positions. Results: There was no difference incorridor size in the comparison between decubitus. However, when the L3L4 and L4L5 levels were compared, there was a significant difference in the size of the corridor in both the lateral and dorsal positions. Conclusion: The present study did not show any difference between the size of the OLIF corridor in L3L4 and L4L5 in the different decubitus, suggesting that thee valuation of the corridor in convention al magnetic resonance images appearstobe safe andreflects the actual size when positio ned for performing the OLIF technique. Level of evidence III; Retrospective study.

Variability in the size of the retroperitoneal oblique corridor: A magnetic resonance imaging-based analysis.

Background:A minimally invasive approach to the L2-S1 disc spaces through a single, left-sided, retroperitoneal oblique corridor has been previously described. However, the size of this corridor varies, limiting access to the disc space in certain patients. Here, the authors retrospectively reviewed lumbar spine magnetic resonance imaging (MRI) in 300 patients to better define the size and variability of the retroperitoneal oblique corridor.Methods:Lumbar spine MRI from 300 patients was reviewed. The size of the retroperitoneal oblique corridor from L2-S1 was measured. It was defined as the (1) distance between the medial aspect of the aorta and the lateral aspect of the psoas muscle from L2-L5 and (2) the distance between the midpoint of the L5-S1 disc and the medial aspect of the nearest major vessel on the left at L5-S1. In addition, the rostral-caudal location of the iliac bifurcation was measured.Results:The size of the retroperitoneal oblique corridor at L2/3, L3/4, L4/5, and L5/S1 was, respectively, 17.3 ± 6.4 mm, 16.2 ± 6.3 mm, 14.8 ± 7.8 cm, and 13.0 ± 8.3 mm. The incidence of corridor size <1 cm at L2/3, L3/4, L4/5, and L5/S1 was 10.3%, 16.0%, 30.0%, and 39.3%, respectively. The iliac bifurcation was most commonly found behind the L4 vertebral body (n = 158, 52.67%) followed by the L4/5 disc space (n = 74, 24.67%).Conclusion:The size of the retroperitoneal oblique corridor diminishes in a rostral-caudal direction, often limiting access to the L4/5 and L5/S1 disc spaces.

Changes in the Operative Corridor in Oblique Lumbar Interbody Fusion Between Preoperative Imaging and Intraoperative Cone-Beam Computed Tomography Using Morphometric Analysis

Abstract INTRODUCTION Oblique lumbar interbody fusion (OLIF) is a minimally-invasive technique that relies on a sufficient corridor anterior to the psoas and posterior to vascular structures.This intraoperative corridor is evaluated on preoperative computed tomography (CT) and/or magnetic resonance (MR) imaging to guide patient selection.Previous cadaveric studies and preoperative MR imaging analysis have examined this corridor to determine corridor variations along right- and left-sided approaches and among patient characteristics.This is the first study that directly evaluates the true intraoperative corridor in the lateral decubitus position based on intraoperative 3D imaging. METHODS We performed a retrospective evaluation identifying patients &gt; 18 yr old who had undergone an OLIF via a left-sided approach at 2 tertiary care centers from 2016 to 2018. Patients with scoliosis greater than 20 degrees, transitional anatomy, and psoas abnormalities were excluded.We recorded demographics and the intraoperative corridor defined by the distance between the left lateral border of the aorta or iliac vessels and anteromedial border of the psoas from L1-L2 through L4-5 disc spaces.This corridor was measured on supine, preoperative MR axial imaging and subsequent intraoperative 3D cone beam CT acquired in the right lateral decubitus position. RESULTS A total of 33 patients, 15 of whom were female, were included in this study.The average age was 65.4 and body mass index (BMI) was 31 kg/m2.There was a statistically significant increase (P &lt; .05) in the intraoperative corridor from supine to lateral decubitus positioning at all levels.The greatest increase in corridor size was noted at L1-2 (3.1 cm) and least at L4-5 (2.1 cm).There was no statistically significant difference between age, BMI, or gender in the preoperative versus intraoperative corridor. CONCLUSION This is the first study to provide objective evidence to support that lateral decubitus positioning increases the intraoperative corridor for anterior to the psoas techniques.This information should increase confidence with an anterior to the psoas approach if there is adequate corridor size on supine preoperative imaging evaluation.

Assessment of Aerocapture for Orbit Insertion of Small Satellites at Mars

Small satellites may provide a low-cost platform for targeted science investigations in the Mars system. With current technology, small satellites require ride shares with larger orbiters to capture into orbit, limiting the range of orbits available to small satellite mission designers. Successful development of an independent orbit insertion capability for small satellites, using aerocapture, would allow small satellite mission designers to choose the orbit most appropriate for a science investigation while enabling small satellite ride shares on any mission to Mars. A generic small satellite drag-modulation aerocapture system is assessed for use at Mars across a range of approach trajectories and destinations in the Mars system. Analyses include assessment of the sensitivity of the entry corridor size over different atmospheric conditions, a comparison of velocity-trigger and numerical predictor-corrector guidance schemes for drag modulation, and aerocapture flight performance assessment via Monte Carlo techniques. A special focus is placed on four baseline missions: a low-altitude Mars mapping orbit, Phobos and Deimos flyby/rendezvous, and areosynchronous orbit. Results indicate that aerocapture may decrease the orbit insertion system mass fraction by 30% or more with respect to fully propulsive options.

Roadside Safety Recovery Zone Corridor Widths Derived from Live Field Experiments and Comparison to Past Accidents Records

The increasing number of run-off-road accidents has driven institutions to study and introduce roadside geometric design guidelines to reduce the number of fatalities and severe injuries. Providing the right configuration and dimensions of a roadside slope cross section would allow travel lane motorists who have strayed off the travel lane with a safe way of traversing back into driving lanes and can reduce run-off-road fatal accidents or severe injuries. American Association of Highway and Transportation Official (AASHTO) introduced roadside safety clear zone derived from a set of past accident records. Unfortunately, most of other countries do not keep the same past accident records. Alternatively, safety clear zone can be derived from live field experiments. The 180 live field experiments were safely performed by five drivers with three motorcars at ten locations having various roadside slope gradients and ground surface conditions. The motorcar tires’ printed marks on the turfed roadside were measured, recorded, and analyzed to establish a safety clear zone corridor size. Comparatively, the American figures are higher as they have accounted for additional widths of non-recovery zone and turn out area, the justifiable difference confirms that deriving roadside safety recovery zone corridor widths by the method of live field experiments is a sound engineering practice. The study concludes that the live field experiment method can be applied in place of past accident records in establishing the size of roadside safety clear zones.

Smile attractiveness perception regarding buccal corridor size among different facial types.

The width of the buccal corridor (BC) is one of the factors affecting smile attractiveness. The aim of this study was to determine the effects of the BC size on the smile attractiveness of individuals with short, normal and long faces from the viewpoint of laypersons, general dentists and orthodontists. Smiling photographs of male and female subjects who met the inclusion criteria were digitally altered to create 3 BC sizes (narrow: 2%; normal: 15%; wide: 28%) and 3 facial types defined by the facial index (FI) (short face: FI ≤ 83.9; normal face: 84.0 ≤ FI ≤ 87.9; long face: FI ≥ 88.0). Nine different combinations were made and the evaluators rated the overall attractiveness and acceptability of each smile on a 10-millimeter visual analog scale (VAS). A total of 53 raters (22 laypersons, 16 general dentists and 15 orthodontists) participated in this study. The orthodontists and general dentists had similar viewpoints and they preferred narrow and normal BCs over the wide ones in all facial types. Laypersons preferred normal BC for normal faces, while they did not distinguish different BCs in short faces. Variations in the BC size affect smile attractiveness in different facial types and wide BCs are attributed to the least attractive smiles. Due to the different viewpoints of laypersons and professionals in this regard, there is no justification for expanding the maxillary arch to achieve more attractive smiles.

Thermal Performance of a High-Rise Residential Building with Internal Courtyard in Tropical Climate

Natural ventilation is an effectual passive design approach to create a better indoor thermal condition as well as energy efficiency. The primary goal of building design is providing a healthy and comfortable indoor environment titled as sustainable architecture. Literature suggests that the significant feature that alteration has to take place on for better energy performance is the envelope design. This paper aims to augment the Window to Wall Ratio (WWR), orientation and courtyard corridor size for improving the design of naturally ventilated courtyard high-rise residential buildings. Briefly, the findings indicate that contending with WWR, orientation and courtyard corridor size could increase the potential of improving its natural ventilation and thus, thermal performance.

Narrow anthropogenic corridors direct the movement of a generalist boreal butterfly.

Ecological and anthropogenic corridors are becoming more common worldwide, but little is known about how corridor size (width) affects species' movements, and thus their effects. Here we investigated whether 4- and 8-m wide anthropogenic corridors (seismic lines) cleared for petroleum (oil sands) exploration in boreal forests in Alberta, Canada, act on altering the behaviour of a habitat generalist butterfly, the Arctic fritillary (Boloria chariclea). Specifically, we captured 539 Arctic fritillaries and released them in seismic line corridor or control sites with no structural directionality (i.e. forests and clearings), and recorded both their initial direction (along the seismic line or not) and persistence in directional movements. Arctic fritillaries moved inside these lines twice as often as they left them, and maintained their initial direction more often, regardless of line size and independently of forest structure or sex of individuals. Thus, anthropogenic corridors as narrow as 4 m can affect insect movements. Given the vast area of boreal forests disturbed from seismic assessments, investigating if the effects of these dense, localized lines affect population dynamics and species interactions would provide important insights to managing this ecosystem and identifying restoration actions.

Morphometric MRI Imaging Study of the Corridor for the Oblique Lumbar Interbody Fusion Technique at L1-L5.

Anterior lumbar interbody fusion and lateral lumbar interbody fusion are associated with approach-related disadvantages. Oblique lumbar interbody fusion (OLIF) is the proposed solution, especially for upper lumbar levels. We analyzed the size and regional anatomy of the corridor used in the OLIF technique between levels L1 and L5. This is a morphometric study of 200 randomly selected magnetic resonance imaging (MRI) studies with features of lumbar degenerative disease. On MRI, the oblique corridor was defined as the smallest distance between the psoas major muscle and aorta or inferior vena cava (or common iliac artery) and measured at the L1/L2, L2/L3, L3/L4, and L4/L5 disc levels on both the left and right on the axial images at the mid-disc level. Mean distances of the oblique corridor on theleft side were L1/L2= 18.90 mm, L2/L3= 15.50 mm; L3/L4= 12.75 mm, and L4/L5= 8.92 mm; on the right side,they were L1/L2= 14.80 mm, L2/L3= 5.50 mm, L3/L4= 3.00 mm, and L4/L5= 1.46 mm. For both sides, the corridor size was not significantly affected by sex, and it increased with age and decreased at the inferior lumbar disc levels. The L1/L2 and L2/L3 levels may be obstructed by the ipsilateral kidney and renal vasculature on both sides and the liver on the right side. A left-sided OLIF approach is viable for both sexes. Oblique access to the L1/L2 and L2/L3 disc levels is feasible regardless of age, whereas the L3/L4 and L4/L5 levels may be more suitable in older patients, especially for male patients. The right-sided approach is less likely to be performed effectively.

Is the chiasm-pituitary corridor size important for achieving gross-total resection during endonasal endoscopic resection of craniopharyngiomas?

OBJECTIVE Craniopharyngiomas arise from the pituitary stalk, and in adults they are generally located posterior to the chiasm extending up into the third ventricle. The extended endonasal approach (EEA) can provide an ideal corridor between the bottom of the optic chiasm and the top of the pituitary gland (chiasm-pituitary corridor [CPC]) for their removal. A narrow CPC in patients with a prefixed chiasm and a large tumor extending up and behind the chiasm has been considered a contraindication to EEA, with a high risk of visual deterioration and subtotal resection. METHODS A database of all patients treated in the authors' center (Weill Cornell Medical College, NewYork-Presbyterian Hospital) between July 2004 and August 2016 was reviewed. Patients with craniopharyngiomas who underwent EEA with the goal of gross-total resection (GTR) were included in the study. Patients with postfixed chiasm or limited available preoperative imaging were excluded. Using preoperative contrast-enhanced T1-weighted sagittal midline MR images, the authors calculated the CPC as well as the distance from the chiasm to the top of the tumor (CTOT). From these numbers, they calculated a ratio of the CPC to the CTOT as a measure of difficulty in removing the tumors through the EEA and called this ratio the corridor index (CI). The relationship between the CI and the ability to achieve GTR and visual outcome were measured. RESULTS Thirty-four patients were included in the study. The mean CPC was 10.1 mm (range 5.2-19.1 mm). The mean CTOT was 12.8 mm (range 0-28.3 mm). The median CI was 0.8; the CI ranged from 0.4 to infinity (for tumors with a CTOT of 0). Thirty-two patients had GTR (94.1%) and 2 had subtotal resection. The CPC value had no relationship with our ability to achieve GTR and no effect on visual or endocrine outcome. CONCLUSIONS EEA for craniopharyngioma is generally considered the first-line surgical approach. Although a narrow corridor between the top of the pituitary gland and the bottom of the chiasm may seem to be a relative contraindication to surgery for larger tumors, the authors' data do not bear this out. EEA appears to be a successful technique for the majority of midline craniopharyngiomas.