Surgical Target Area Research Articles

The anterolateral triangle as window on the foramen lacerum from transorbital corridor: anatomical study and technical nuances

ObjectiveNeurosurgical indications for the superior eyelid transorbital endoscopic approach (SETOA) are rapidly expanding over the last years. Nevertheless, as any new technique, a detailed knowledge of the anatomy of the surgical target area, the operative corridor, and the specific surgical landmark from this different perspective is required for a safest and successful surgery. Therefore, the aim of this study is to provide, through anatomical dissections, a detailed investigation of the surgical anatomy revealed by SETOA via anterolateral triangle of the middle cranial fossa. We also sought to define the relevant surgical landmarks of this operative corridor.MethodsEight embalmed and injected adult cadaveric specimens (16 sides) underwent dissection and exposure of the cavernous sinus and middle cranial fossa via superior eyelid endoscopic transorbital approach. The anterolateral triangle was opened and its content exposed. An extended endoscopic endonasal trans-clival approach (EEEA) with exposure of the cavernous sinus content and skeletonization of the paraclival and parasellar segments of the internal carotid artery (ICA) was also performed, and the anterolateral triangle was exposed. Measurements of the surface area of this triangle from both surgical corridors were calculated in three head specimens using coordinates of its borders under image-guide navigation.ResultsThe drilling of the anterolateral triangle via SETOA unfolds a space that can be divided by the course of the vidian nerve into two windows, a wider “supravidian” and a narrower “infravidian,” which reveal different anatomical corridors: a “medial supravidian” and a “lateral supravidian,” divided by the lacerum segment of the ICA, leading to the lower clivus, and to the medial aspect of the Meckel’s cave and terminal part of the horizontal petrous ICA, respectively. The infravidian corridor leads medially into the sphenoid sinus. The arithmetic means of the accessible surface area of the anterolateral triangle were 45.48 ± 3.31 and 42.32 ± 2.17 mm2 through transorbital approach and endonasal approach, respectively.ConclusionSETOA can be considered a minimally invasive route complementary to the extended endoscopic endonasal approach to the anteromedial aspect of the Meckel’s cave and the foramen lacerum. The lateral loop of the trigeminal nerve represents a reliable surgical landmark to localize the lacerum segment of the ICA from this corridor. Nevertheless, as any new technique, a learning curve is needed, and the clinical feasibility should be proven.

Machine Learning-Derived Multimodal Neuroimaging of Presurgical Target Area to Predict Individual's Seizure Outcomes After Epilepsy Surgery.

Objectives: Half of the patients who have tailored resection of the suspected epileptogenic zone for drug-resistant epilepsy have recurrent postoperative seizures. Although neuroimaging has become an indispensable part of delineating the epileptogenic zone, no validated method uses neuroimaging of presurgical target area to predict an individual’s post-surgery seizure outcome. We aimed to develop and validate a machine learning-powered approach incorporating multimodal neuroimaging of a presurgical target area to predict an individual’s post-surgery seizure outcome in patients with drug-resistant focal epilepsy. Materials and Methods: One hundred and forty-one patients with drug-resistant focal epilepsy were classified either as having seizure-free (Engel class I) or seizure-recurrence (Engel class II through IV) at least 1 year after surgery. The presurgical magnetic resonance imaging, positron emission tomography, computed tomography, and postsurgical magnetic resonance imaging were co-registered for surgical target volume of interest (VOI) segmentation; all VOIs were decomposed into nine fixed views, then were inputted into the deep residual network (DRN) that was pretrained on Tiny-ImageNet dataset to extract and transfer deep features. A multi-kernel support vector machine (MKSVM) was used to integrate multiple views of feature sets and to predict seizure outcomes of the targeted VOIs. Leave-one-out validation was applied to develop a model for verifying the prediction. In the end, performance using this approach was assessed by calculating accuracy, sensitivity, and specificity. Receiver operating characteristic curves were generated, and the optimal area under the receiver operating characteristic curve (AUC) was calculated as a metric for classifying outcomes. Results: Application of DRN–MKSVM model based on presurgical target area neuroimaging demonstrated good performance in predicting seizure outcomes. The AUC ranged from 0.799 to 0.952. Importantly, the classification performance DRN–MKSVM model using data from multiple neuroimaging showed an accuracy of 91.5%, a sensitivity of 96.2%, a specificity of 85.5%, and AUCs of 0.95, which were significantly better than any other single-modal neuroimaging (all p ˂ 0.05). Conclusion: DRN–MKSVM, using multimodal compared with unimodal neuroimaging from the surgical target area, accurately predicted postsurgical outcomes. The preoperative individualized prediction of seizure outcomes in patients who have been judged eligible for epilepsy surgery could be conveniently facilitated. This may aid epileptologists in presurgical evaluation by providing a tool to explore various surgical options, offering complementary information to existing clinical techniques.

Grinding trajectory generator in robot-assisted laminectomy surgery.

Grinding trajectory planning for robot-assisted laminectomy is a complicated and cumbersome task. The purpose of this research is to automatically obtain the surgical target area from the CT image, and based on this, formulate a reasonable robotic grinding trajectory. We propose a deep neural network for laminae positioning, a trajectory generation strategy, and a grinding speed adjusting strategy. These algorithms can obtain surgical information from CT images and automatically complete grinding trajectory planning. The proposed laminae positioning network can reach a recognition accuracy of 95.7%, and the positioning error is only 1.12mm in the desired direction. The simulated surgical planning on the public dataset has achieved the expected results. In a set of comparative robotic grinding experiments, those using the speed adjustment algorithm obtained a smoother grinding force. Our work can automatically extract laminar centers from the CT image precisely to formulate a reasonable surgical trajectory plan. It simplifies the surgical planning process and reduces the time needed for surgeons to perform such a cumbersome operation manually.

Analyzing the Risk of Injury for Pathways of Instrument Insertion into a Surgical Target Area While Preparing for Laparoscopic Surgery

A procedure is developed for automatically classifying tissues with regard to the risk of injury when analyzing the pathways of instrument insertion into a surgical target area. Two quantitative parameters, coefficients of the severity of injury and displaceability, are proposed for estimating the risk of injury. An algorithm is developed for filling in objects of arbitrary shape in three-dimensional computer tomography images from the patients.

Endoscopic endonasal approach for pituitary adenomas

Pituitary surgery is a continuous evolving specialty of neurosurgery, requiring precise anatomical knowledge, technical skills and integrated appreciation of the pathophysiology. We herein detail the features of the endoscopic endonasal approach for the management of pituitary adenomas, as experienced at the Division of Neurosurgery of the Universita' degli Studi di Napoli "Federico II". The endoscopic endonasal technique brings advantages to the patient (less nasal traumatism, less post-op pain), to the surgeon (wider and closer view of the surgical target area, increase of the scientific activity, smoothing of interdisciplinary cooperation), and to the institution (shorter post-op hospital stay, and increase of the case load).

Endoscopic pituitary surgery

Pituitary surgery is a continuous evolving speciality of the neurosurgeons' armamentarium, which requires precise anatomical knowledge, technical skills and integrated appreciation of the pituitary pathophysiology. What we consider "pure" endoscopic transsphenoidal surgery is a procedure performed through the nose and the sphenoid bone, with the endoscope alone throughout the whole approach to visualize the surgical target area and without the use of any transsphenoidal retractor. It offers some advantages due to the endoscope itself: a superior close-up view of the relevant anatomy and an enlarged working angle are provided with an increased panoramic vision inside the surgical area. Concerning results in terms of mass removal, relief of clinical symptoms, cure of the underlying disease and complication rate, they are, at least, similar to those reported in the major microsurgical series, but patient compliance is by far better. Furthermore transsphenoidal endoscopy brings advantages to the patient (less nasal traumatism, no nasal packing, less post-op pain and usually quick recovery), to the surgeon (wider and closer view of the surgical target area, increase of the scientific activity as from the peer-reviewed literature on the topic in the last 10 years, smoothing of interdisciplinary cooperation), to the institution (shorter post-op hospital stay, increase of the case load). Besides, further progress and technological advance are expected from the close cooperation between different technologies and industries. Continuing works in such field of "minimalism" will offer further possibilities to provide the surgeon with even more effectiveness and safety, and, on the other hand, the patient with improvement of results.

A single bicaval venous cannula used for optimization of endoscopic robotically assisted procedures of the heart.

Robotically assisted heart operation is one of the minimally invasive approaches that have revolutionized many surgical procedures. Robotic procedures on the heart, however, are by no means routine, and their optimization requires development of new instruments and techniques. Described here is the robotically assisted use in a sheep model of a new peripherally inserted bicaval venous cannula in the totally endoscopic closure of atrial septal defect. The exposure of the surgical target area was successful with no obstructions in the surgical view. The cannula shows sufficient flow characteristics for cardiopulmonary bypass. Subsequent suturing of the atrial septum defect was achieved without complications in the 4 experimental animals.

Three-dimensional image registration of phantom vertebrae for image-guided surgery: a preliminary study.

Applications of three-dimensional ultrasound (3D US) are emerging throughout the field of medicine. In this study, tracked, free-hand 3D phantom US images were mapped to computed tomograms (CT) as a development for image-guided surgery (IGS) of the spine. In the operating room, the registration of tracked 3D US images to other imaging modalities, such as CT, could allow the surgeon to identify more precisely the surgical target area prior to the incision. An independent quantitative measure of registration accuracy using a fiducial marker system was provided. Three-dimensional free-hand US images of a phantom spine were created by tracking the transducer with an optical sensing system. Two sets of images were acquired from three lumbar vertebrae using 4.5- and 7.5-MHz transducers. These images were then segmented for the extraction of the posterior vertebral surface. Next, a surface-based registration of US to the corresponding segmented CT images was performed. Registration errors were computed as the distance between a set of target points transformed using the experimental transformation and the same set of target points transformed using fiducial markers as a gold standard. Results indicated that alignment of these image sets is feasible using only part of the vertebral surface. In particular, the regions of the spinous process and laminae were used for registration. Target registration errors (TREs) were found to be lowest using the highest resolution CT images. Using the CT scans with 2-mm slice thickness, the TRE was calculated to be 1.33 +/- 0.30 mm for the 7.5-MHz US data set and 2.81 +/- 0.10 mm for the 4.5-MHz US data set. Moreover, residual errors in these surface alignments were 0.69 +/- 0.18 mm and 0.61 +/- 0.20 mm for the 4.5- and 7.5-MHz sets, respectively. A rigid, surface-based registration of CT images to phantom spinal US images, acquired with a free-hand, tracked transducer, is achievable with a limited, easily obtainable portion of the vertebral surface.

Three-Dimensional Image Registration of Phantom Vertebrae for Image-Guided Surgery: A Preliminary Study

Objective: Applications of three-dimensional ultrasound (3D US) are emerging throughout the field of medicine. In this study, tracked, free-hand 3D phantom US images were mapped to computed tomograms (CT) as a development for image-guided surgery (IGS) of the spine. In the operating room, the registration of tracked 3D US images to other imaging modalities, such as CT, could allow the surgeon to identify more precisely the surgical target area prior to the incision. An independent quantitative measure of registration accuracy using a fiducial marker system was provided.Methods: Three-dimensional free-hand US images of a phantom spine were created by tracking the transducer with an optical sensing system. Two sets of images were acquired from three lumbar vertebrae using 4.5-and 7.5-MHz transducers. These images were then segmented for the extraction of the posterior vertebral surface. Next, a surface-based registration of US to the corresponding segmented CT images was performed. Registration errors were computed as the distance between a set of target points transformed using the experimental transformation and the same set of target points transformed using fiducial markers as a gold standard.Results: Results indicated that alignment of these image sets is feasible using only part of the vertebral surface. In particular, the regions of the spinous process and laminae were used for registration. Target registration errors (TREs) were found to be lowest using the highest resolution CT images. Using the CT scans with 2-mm slice thickness, the TRE was calculated to be 1.33 ± 0.30 mm for the 7.5-MHz US data set and 2.81 ± 0.10 mm for the 4.5-MHz US data set. Moreover, residual errors in these surface alignments were 0.69 ± 0.18 mm and 0.61 ± 0.20 mm for the 4.5-and 7.5-MHz sets, respectively.Conclusion: A rigid, surface-based registration of CT images to phantom spinal US images, acquired with a free-hand, tracked transducer, is achievable with a limited, easily obtainable portion of the vertebral surface.

Emotional responses to subcortical electrical stimulation in psychiatric patients

Subcortical electrical stimulation was applied to the prospective surgical target area during 158 stereotactic operations in 135 psychiatric patients. The following target areas were studied: rostral cingulum below and in front of the genu of the corpus callosum (52 cases) genu (46) cingululum just above the genu (11) middle cingulum (6) anterior internal capsule (33) subcaudate region, ‘substantia innominata’ (10 cases). Forty-seven per cent of the cases reacted to stimulation with subjective emotional or sensory responses. Stimulation of different targets had significantly different results. Responses were obtained most frequently from the cingulum and genu, and least frequently from the anterior capsule and subcaudate regions. Stimulation of the rostral cingulum often caused ‘negative’ responses, i.e. an increase in or the appearance of anxiety and tension (11/15 cases). The opposite was true of the adjacent genu of the corpus callosum; on stimulation of this structure anxiety and tension disappeared or diminished (18/19 cases). Schizophrenic patients experienced such ‘positive’ responses significantly more often than non-schizophrenics. In non-anesthetized patients autonomic reactions were very rare.