Non-assisted versus neuro-navigated and XperCT-guided external ventricular catheter placement: a comparative cadaver study

Background and purpose: Accurate placement of an external ventricular drain (EVD) for the treatment of hydrocephalus is of paramount importance for its functionality and in order to minimize morbidity and complications. The aim of this study was to compare two different drain insertion assistance tools with the traditional free-hand anatomical landmark method, and to measure efficacy, safety and precision. Methods: Ten cadaver heads were prepared by opening large bone windows centered on Kocher's points on both sides. Nineteen physicians, divided in two groups (trainees and board certified neurosurgeons) performed EVD insertions. The target for the ventricular drain tip was the ipsilateral foramen of Monro. Each participant inserted the external ventricular catheter in three different ways: 1) free-hand by anatomical landmarks, 2) neuronavigation-assisted (NN), and 3) XperCT-guided (XCT). The number of ventricular hits and dangerous trajectories; time to proceed; radiation exposure of patients and physicians; distance of the catheter tip to target and size of deviations projected in the orthogonal plans were measured and compared. Results: Insertion using XCT increased the probability of ventricular puncture from 69.2 to 90.2% (p = 0.02). Non-assisted placements were significantly less precise (catheter tip to target distance 14.3 ± 7.4mm versus 9.6 ± 7.2mm, p = 0.0003). The insertion time to proceed increased from 3.04 ± 2.06min. to 7.3 ± 3.6min. (p < 0.001). The X-ray exposure for XCT was 32.23mSv, but could be reduced to 13.9mSv if patients were initially imaged in the hybrid-operating suite. No supplementary radiation exposure is needed for NN if patients are imaged according to a navigation protocol initially. Conclusion: This ex vivo study demonstrates a significantly improved accuracy and safety using either NN or XCT-assisted methods. Therefore, efforts should be undertaken to implement these new technologies into daily clinical practice. However, the accuracy versus urgency of an EVD placement has to be balanced, as the image-guided insertion technique will implicate a longer preparation time due to a specific image acquisition and trajectory planning

Food for pollinators: quantifying the nectar and pollen resources of urban flower meadows

Planted meadows are increasingly used to improve the biodiversity and aesthetic amenity value of urban areas. Although many ‘pollinator-friendly’ seed mixes are available, the floral resources these provide to flower-visiting insects, and how these change through time, are largely unknown. Such data are necessary to compare the resources provided by alternative meadow seed mixes to each other and to other flowering habitats. We used quantitative surveys of over 2 million flowers to estimate the nectar and pollen resources offered by two exemplar commercial seed mixes (one annual, one perennial) and associated weeds grown as 300m2 meadows across four UK cities, sampled at six time points between May and September 2013. Nectar sugar and pollen rewards per flower varied widely across 65 species surveyed, with native British weed species (including dandelion, Taraxacum agg.) contributing the top five nectar producers and two of the top ten pollen producers. Seed mix species yielding the highest rewards per flower included Leontodon hispidus, Centaurea cyanus and C. nigra for nectar, and Papaver rhoeas, Eschscholzia californica and Malva moschata for pollen. Perennial meadows produced up to 20x more nectar and up to 6x more pollen than annual meadows, which in turn produced far more than amenity grassland controls. Perennial meadows produced resources earlier in the year than annual meadows, but both seed mixes delivered very low resource levels early in the year and these were provided almost entirely by native weeds. Pollen volume per flower is well predicted statistically by floral morphology, and nectar sugar mass and pollen volume per unit area are correlated with flower counts, raising the possibility that resource levels can be estimated for species or habitats where they cannot be measured directly. Our approach does not incorporate resource quality information (for example, pollen protein or essential amino acid content), but can easily do so when suitable data exist. Our approach should inform the design of new seed mixes to ensure continuity in floral resource availability throughout the year, and to identify suitable species to fill resource gaps in established mixes

Vascular relationships in right colectomy for cancer: clinical implications.

AIMS: The study aim was to provide data on pattern and length of crossing of the ileocolic artery (ICA) and right colic artery (RCA) with the superior mesenteric vein (SMV). METHODS: Specimens from 30 fresh human cadavers underwent corrosion casting. Methylacrylate was injected into the SMV and superior mesenteric artery (SMA). Length of crossing was measured with a scaleable ruler and copper wire. Values are mean (SD; range). RESULTS: ICA was present in all specimens and crossed posterior to the SMV in 19 (63.33%) of 30 specimens. Length of crossing was 17.01 (7.84; 7.09-42.89) mm. RCA was present in 19 (63.33%) of 30 specimens. RCA crossed anterior to SMV in 16 (84.21%) of 19 specimens. Length of crossing was 20.63 (8.09; 6.3-35.7) mm. CONCLUSIONS: ICA was always present, crossed posterior to SMV in 60% of specimens with a crossing length of 17 mm. RCA was present in 63% of specimens, crossed anterior to the SMV in 84% of specimens with a crossing length of 20 mm. Clinical implications include arterial length left behind with main nodes, arterial bleeding and safety of laparoscopic access

Venous anatomy of the right colon: three-dimensional topographic mapping of the gastrocolic trunk of Henle.

BACKGROUND: The gastrocolic trunk of Henle has not been described in detail in context with right hemicolectomy. The aim of this study was to define the caliber, length and three-dimensional position of the gastrocolic trunk of Henle (GTH). METHODS: We studied 10 fresh (\u3c24 \u3eh) cadavers. A corrosion cast method was employed. Cold polymerized methylacrylate was injected into the superior mesenteric vein (SMV) and artery. GTH diameter, length and point of confluence with the SMV were assessed. RESULTS: The GTH was present in all specimens originating from the confluence of the right gastroepiploic and superior-anterior pancreaticoduodenal veins. The GTH joined the SMV at an average distance of 2.2 cm (range, 1.6-3.2 cm) from the inferior pancreatic border and it coursed towards the right side in a ventral-cranial direction. The mean caliber and length of the GTH were 5.2 mm (range, 4.8-5.8 mm) and 16.1 mm (range, 10.1-20.7 mm), respectively. CONCLUSIONS: The GTH is a short, medium-sized vessel of potential clinical significance with a consistent ventral-cranial direction

Gastric varices without portal hypertension: role of left inferior vena cava?

A variant vascular anatomy was detected during regular analysis of multidetector computed tomography angiography of the abdomen in a 70 year-old female patient, referred to the department of surgery for laparoscopic right colectomy for colon cancer. The anomalous vessel was located left to the aorta, and was consistent with a persistent left inferior vena cava. It was connected by two retroaortic rootlets to the dorsal surface of the regular right inferior vena cava and had four notable tributaries - an anastomosis with the iliolumbar trunk, ovarian vein, renal vein and the inferior phrenic vein. In the upper abdomen, the left inferior vena cava took a tortuous course, passing at first between the spleen and the diaphragm, then curving below the inferior splenic border and terminating in an irregular network in the posterior region of gastric fundus and cardia, close to the splenic hilum, without supradiaphragmatic continuation. Despite this extraordinary termination, there were no signs of portal hypertension or data on previous occurrence of this condition

Gastric varices without portal hypertension: role of left inferior vena cava?

A variant vascular anatomy was detected during regular analysis of multidetector computed tomography angio - graphy of the abdomen in a 70 year-old female patient, referred to the department of surgery for laparoscopic right colectomy for colon cancer. The anomalous vessel was located left to the aorta, and was consistent with a persistent left inferior vena cava. It was connected by two retroaortic rootlets to the dorsal surface of the regular right inferior vena cava and had four notable tributaries – an anastomosis with the iliolumbar trunk, ovarian vein, renal vein and the inferior phrenic vein. In the upper abdomen, the left inferior vena cava took a tortuous course, passing at first between the spleen and the diaphragm, then curving below the inferior splenic border and terminating in an irregular network in the posterior region of gastric fundus and cardia, close to the splenic hilum, without supradiaphragmatic continuation. Despite this extraordinary termination, there were no signs of portal hypertension or data on previous occurrence of this condition

Navigating the mesentery: part II. Vascular abnormalities and a review of the literature

Aim Vascular abnormalities present advantages and/or disadvantages for the patient undergoing surgery. The aims of this study were to define, classify and demonstrate the courses, and to assess the clinical value, of arterial and venous abnormalities in the central mesentery. Method We conducted a review of the anatomy of 340 patients planned for enrolment in the ‘Safe Radical D3 Right Hemicolectomy for Cancer through Preoperative Biphasic MDCT Angiography' trial, 312 of whom were submitted to surgery. Vascular abnormalities were analysed in context with surgical notes and images. A metaanalysis of the literature was performed. Results Arterial Abnormalities were found in 28 (8.2%) of the 340 patients and were classified into the following three groups based on anticipated surgical difficulty: group 1, accessory or replaced arteries to solid organs [14 (4.1%)]; group 2, arterial shunts [11 (3.2%)] between the coeliac trunk and the superior mesenteric artery, which resulted in bleeding in three patients; and group 3, common stem abnormalities [3 (0.9%)]. Two groups of superior mesenteric vein abnormalities were noted. The first included morphological abnormalities in a single vein [4 (1.2%)]: aneurysm [1 (0.3%)]; and ring variants of principal tributaries [3 (0.9%)]. The second included double superior mesenteric vein trunks [31 (9.1%)]: genuine bifid [10 (2.9%)]; and pseudo bifid [21 (6.2%)]. The meta-analysis revealed 26 articles, including 10 series of anatomical dissections or angiographies [1970 cases with 205 (10.4%) arterial abnormalities] and 16 case reports, none of which described a clinical or surgical setting. Conclusion Vascular abnormalities occur frequently. Arterial abnormalities are a hazard when inadvertent injury occurs during surgery. Preoperative knowledge of a bifid superior mesenteric vein is useful

Evaluating Preoperative Models: A Methodologic Contribution.

Three-dimensional (3D) printed models of the human skull and parts of it are being increasingly used for surgical education and customized preoperative planning. This study, using the calvaria as a model, provides a methodologic analysis with regard to future investigations aimed at evaluating patient-specific skull replicas. Postmortem computed tomography was used for 3D reconstruction of a skull. The digital model obtained was converted to a physical replica by 3D printing. This copy was compared qualitatively and quantitatively with the original, using both a classical anthropometric and a 3D surface scanning approach. Qualitatively, the replica and the original displayed good qualitative concordance. The quantitative deviations, as measured by osteometric tools, lay partly in the submillimetric area, partly between 1 and 2 mm. The maximum difference was 3.7 mm. On the basis of the surface scans, a mean deviation of 0.2930 mm (±0.2677 mm) and a median difference of 0.2125 mm (0.0000-1.5509 mm) were observed for the inner surface. For the whole object, corresponding figures amounted to 0.9101 mm (±0.5390 mm) and 0.8851 mm (0.000-3.2647 mm). Qualitatively flawless replicas of the skull region investigated are feasible, subject to extensive manual CT image editing. However, neurosurgeons should be aware that models of one and the same patient will vary according to the production chain used by the 3D printing laboratory in charge. Methodologically, both classic anthropological and light-stripe-based comparisons are justified for use in future studies. For trials aimed at assessing mean deviations and topographic distribution patterns, optical 3D scanning technologies can be recommended

CT and operative images for evaluation of right colectomy with extended D3 mesenterectomy anterior and posterior to the mesenteric vessels

Background Surgical techniques like complete mesocolic excision (CME) and D3 mesenterectomy, D3 refering to the N3 lymph node groups central in the mesentery removed at surgery, were introduced without proper evaluation of the lymphadenectomy. The aim of this study was to measure the vascular stumps and evaluate the extent and quality of lymphadenectomy after right colectomy with extended D3 mesenterectomy anterior/posterior to the mesenteric vessels. We also compared the investigation methods. Methods Residual vascular stumps were measured using three-dimensional (3D) reconstructed anatomy from follow-up computed tomography (CT) datasets and images taken during surgery. The quality of central lymphadenectomy was evaluated on the images. Results In total, 31 patients (15 females), median age 67 years (50–78), with stage I (n=7), stage II (n= 13), and stage III (n= 11) disease, were operated. Tumor locations were: 14 (45%) in the cecum, ten (32%) in the ascending colon, three (10%) in the hepatic flexure, and four (13%) in the transverse colon. The middle colic artery (MCA) was divided at its origin (13 patients) or its right branch (18 patients). Median lengths (range) of residual vascular stumps measured on 3D reconstructed CT and photographic images taken during surgery were: right colic artery: 0.0 mm (0.0–1.8)/0.0 mm (0.0–1.1), ileocolic artery: 0.0 mm (0.0–7.2)/0.0 mm (0.0–3.0), ileocolic vein: 0.0 mm (0.0–7.5)/0.0 mm (0.0–0.0), MCA: 0.0 mm (0.0–18.1)/1.0 mm (0.0–8.0), and right branch of the MCA: 0.0 mm (0.0–1.8)/0.0 mm (0.0–2.0). There was no significant difference between average lengths measured with the two techniques. The extent of lymphadenectomy was deemed acceptable in all patients. No differences in stump lengths were found in patients with different vascular crossing patterns in the central mesentery and presumably different degree of difficulty at surgery. Conclusion The results demonstrate very short residual vascular stumps and together with operative photographs provide objective evidence for superior lymphadenectomy in right colectomy with extended D3 mesenterectomy