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PubMed1995

[Ultrasonography-guided identification of the lumbar epidural space].

The study was designed to assess the reliability of sonographic evaluation in the prediction of the depth of the lumbar epidural space. Forty males, scheduled for epidural anesthesia for surgical repair of inguinal hernia, were prospectively studied. Patients were placed in a sitting position and sagittal scanning of the lumbar spine was performed with a 5-MHz transducer over the fourth or fifth interspace in order to identify the deeper hyperechogen interface, which represents the landmark between the ligamentum flavum and the epidural space. Ultrasound depth was measured and transducer removed. A Tuohy needle 18 G was then introduced percutaneously according to the standard technique and a rubber slide placed over it, so that it depth of insertion could be accurately measured. The potential for using ultrasounds for prediction of the distance from skin to epidural space was analyzed using a simple linear regression analysis; p values < 0.05 were considered significant. Mean values of ultrasound depth and needle depth were respectively 51 mm (SD 6.3) and 50.9 mm (SD 6.2); the correlation coefficient was 0.99. Ultrasound scanning of the lumbar spine provides an accurate measurement of the depth of the epidural space, which can facilitate the performance of the epidural anaesthesia and may decrease the complication rate, particularly in those patients in which anatomic landmarks are obscured.

Adult↗
PubMed1996

Three-dimensional modeling for modern diagnosis and planning in maxillofacial surgery.

The existing methods of recording the face in three dimensions are reviewed, and a new method for three-dimensional facial modeling is introduced. The technique utilizes two stereo pairs of videocameras, a stereo pair at each side of the patient's face. The system allows rapid capture of the face in three dimensions and precise measurement of anatomic landmarks. The system can be used to capture the facial image and a cephalogram almost simultaneously, allowing more accurate superimposition of soft and hard tissues. This precision will facilitate development of the surgical treatment plan. A computer program in the early stages of development will use the data generated by this biostereometric measurement system to predict soft tissue changes following orthognathic surgery.

Cephalometry↗
PubMed2001

Automatic recognition of vertebral landmarks in fluoroscopic sequences for analysis of intervertebral kinematics.

Intervertebral kinematics closely relates to the functionality of the spinal segments. Direct measurement of the intervertebral kinematics in vivo is very problematic. The use of a fluoroscopic device can provide continuous screening of the lumbar tract during patient spontaneous motion, with an acceptable, low X-ray dose. The kinematic analysis is intended to be limited to planar motion. Kinematic parameters are computed from vertebral landmarks on each frame of the image sequence. Landmarks are normally selected manually in spite of the fact that this is subjective, tedious to perform and regarded as one of the major contributors to errors in the computed kinematic parameters. The aim of this work is to present an innovative method for the automatic recognition of vertebral landmarks throughout a fluoroscopic image sequence to provide an objective and more precise quantification of intervertebral kinematics. The recognition procedure is based upon comparing vertebral features in two adjacent frames by means of a cross-correlation index, which is also robust despite the low signal-to-noise ratio of the lumbar fluoroscopic images. To provide a quantitative assessment of this method a calibration model was used which consisted of two lumbar vertebrae linked by a universal joint. The reliability and accuracy of the kinematic measurements have been investigated. The errors are of the order of a millimetre for the localisation of the intervertebral centre of rotation and tenths of a degree for the intervertebral angle. Error analysis suggests that this method improves the accuracy of the intervertebral kinematic calculations and has the potential to automate the selection of anatomical landmarks.

Calibration↗
PubMed2002

Intracardiac echocardiography: from electroanatomic correlation to clinical application in interventional electrophysiology.

Intracardiac echocardiography (ICE), using an ultrasound transducer at the tip of a percutaneously placed catheter, has recently been introduced for the visualization of the intracardiac anatomy and in order to reduce the fluoroscopy time. This review focuses predominantly on the current use of ICE in interventional electrophysiology. ICE has been shown to facilitate the targeting of specific anatomic landmarks, such as the crista terminalis, the Eustachian ridge, the tricuspid annulus, the coronary sinus ostium, and the pulmonary veins that cannot be adequately visualized at fluoroscopy. Direct imaging of these sites can be advantageous in that it facilitates the accurate guidance of the ablative procedure and shortens the fluoroscopy time. ICE has been demonstrated to be useful in the positioning and stabilization of the imaging ablation catheter, the evaluation of the lesion size and continuity and in the immediate identification of complications. Furthermore, in the last few years there has been a revival in the use of transseptal catheterization due to a larger development of radiofrequency catheter ablation in the left atrium. ICE, providing excellent views of the fossa ovalis and of the transseptal apparatus, can be safely used to prevent life-threatening complications following inadvertent puncture of anatomic structures such as the lateral wall of the left atrium or the aortic root. Moreover, ICE appears to be very useful in combining true anatomical features with electrical activation in an attempt to construct realistic electrical-anatomical maps. Finally, the three-dimensional tomographic reconstruction of intracardiac images and the phased array ICE catheter with Doppler capabilities seem to be promising tools both for the guidance of ablation procedures as well as in leading experimental studies.

Arrhythmias, Cardiac↗
PubMed1993

Hippocampus-amygdala volumes and psychopathology in chronic schizophrenia.

Volumes of the mesiotemporal structures (hippocampus-amygdala complex) were measured in 19 men who were chronic multiepisode schizophrenics and 18 age-matched healthy controls using T1-weighted contiguous coronal magnetic resonance images of 3.1-mm width. Using the level of the mammillary bodies as an anatomical landmark, the whole hippocampus-amygdala complex was divided into an anterior section (mainly containing amygdaloid tissue) and a posterior section (mainly containing the hippocampal formation). Total mesiotemporal tissue volume was reduced significantly in the patient group compared to controls (-11%), with significant reductions in both left (-20%) and right (-15%) hippocampal sections. Reduced limbic tissue volume was associated with increased severity of psychopathology. Severity of positive psychotic symptoms (Brief Psychiatric Rating Scale [BPRS] psychosis factor) was correlated significantly with right and left total mesiotemporal volumes (Spearman rho's = -0.61 p < 0.01). Negative symptom scores (BPRS anergia factor, Scale for Assessment of Negative Symptoms [SANS] global items) were not significantly correlated with any mesiotemporal tissue volumes. The data corroborate and extend previous findings of temporolimbic structure volume reduction in schizophrenia, and suggest that the positive psychotic symptoms of schizophrenia are associated with anatomic anomalies in mesiotemporal structure.

Adult↗
PubMed1989

A head-model reconstruction based upon photogrammetric data from Sri Lankan adult males relevant to the design of headgear.

Due to the large variability in heads and faces in one population, the standard anthropometric dimensions of the head, measured from anatomical landmarks alone, may not suffice for the design of fitting headgear, e.g., helmets. To provide adequate data of the shapes and contours of the head to the designer, appropriate head models sculptured using comprehensive head dimensions, must be developed. This paper describes (a) a procedure of collecting comprehensive anthropometric data of the head using a photogrammetric method and (b) a simple sculpturing technique to reconstruct a head model of the user population.

Adult↗
PubMed1996

Placement and verification of recording electrodes in the superior head of the human lateral pterygoid muscle.

Previous studies in man have relied only on electromyographic (EMG) activity patterns and anatomical landmarks to confirm electrode placement in the superior head of the lateral pterygoid. Computed tomography (CT) was used here to determine whether indwelling fine wires could be visualized in that muscle head in man and thus provide evidence for correct placement before EMG. Two imaging sessions were conducted in six individuals. First, a series of contiguous axial CT slices was obtained to calculate the trajectory of insertion of fine wire electrodes into the superior head. For each individual, the trajectories for the location of the fine wires in the approximate mediolateral and anteroposterior centre of the superior head were different. Further axial CT slices were taken after electrode insertion; in each case, these slices clearly showed the wire ends located within the muscle. It was concluded that fine wires in the lateral pterygoid can be imaged by CT. Furthermore, imaging is necessary to accommodate interindividual anatomical variations and to confirm the position of the electrodes within the muscle.

Adult↗
PubMed2003

An anthropometric analysis of the key foramina for maxillofacial surgery.

PURPOSE: The study goal was to determine the location of important maxillofacial foramina relative to frequently encountered surgical landmarks. MATERIALS AND METHODS: Measurements (1,120) were made on 80 cadaveric heads of known race and gender to evaluate the position of the supraorbital, infraorbital, and mental foramina relative to surgical landmarks. RESULTS: Analysis of the data determined the supraorbital foramen to be an average of 2.5 cm lateral to the nasal midline and 2.6 cm medial to the temporal crest of the frontal bone. Of the supraorbital foramina, 92.5% were notches and not true foramen. The infraorbital foramen was an average of 2.7 cm lateral to the nasal midline, 0.64 cm caudad to the inferior orbital rim, and 0.03 cm medial to the zygomaticomaxillary suture. The mental foramen was an average of 2.2 cm lateral to the mandibular skeletal midline. The average position of the mental foramen, relative to adjacent teeth, was between the first and second premolars for whites and just posterior to the second premolar in blacks. CONCLUSION: The measurements show small but significant differences in foramen location between whites and blacks and males and females. The knowledge of the distances from surgically encountered anatomic landmarks may be of assistance in locating these important maxillofacial neurologic structures during many procedures. This information may play an even more important role as new techniques for minimally invasive surgery are developed. Understanding the location of these foramina will also assist the clinician in performing local anesthetic blocks.

Adult↗
PubMed1989

MR appearance of the liver after partial hepatectomy.

To define the MR appearance of the liver after partial hepatectomy, we reviewed retrospectively 61 MR examinations performed on 25 patients 10 days to 48 months after surgery. Twenty-seven partial hepatectomies performed in the 25 patients included right lobectomy in 11, trisegmentectomy in two, left lobectomy in five, and wedge resection in nine. By using vascular landmarks, demonstration of the falciform ligament, and the presence of surgical clips, we correctly identified the type of partial hepatectomy in 21 of the 25 patients. The signal intensity of the resection margin was similar to that of the remaining parenchyma in 16 of 18 patients and was poorly defined and had a higher signal intensity (T2-weighted image) in the remaining two. Liver regeneration was observed on serial MR scans 2-16 months after surgery. Findings related to chemotherapy, including periportal changes and inhomogeneous appearance of the liver, were shown in six of eight patients. Tumor recurrence was present in nine patients, either intrahepatic (seven patients) or at the resection margin (two patients), and was consistently identified with MR imaging. The ability of MR imaging to produce images without artifacts from surgical clips is helpful in displaying the MR appearance of the liver after partial hepatectomy. Anatomic landmarks, findings related to chemotherapy, and tumor recurrence were shown well.

Adolescent↗
PubMed2003

A surgical simulator for cleft lip planning and repair.

The objective of this project was to develop a computer-based surgical simulation system for cleft lip planning and repair. This system allows the user to interact with a virtual patient to perform the traditional steps of cleft-lip repair. The system interfaces to force-feedback (haptic) devices to track the user's motion and provide feedback during the procedure, while performing real-time soft-tissue simulation. An eleven-day old unilateral cleft-lip and palate patient was previously CT scanned for ancillary diagnostic purposes using standard imaging protocols and 1mm slices. High-resolution 3D meshes were automatically generated from this data using the ROVE software created in our lab. The resulting 3D meshes of bone and soft-tissue were instilled with physical properties of soft tissues for purposes of simulation. Once these preprocessing steps were completed, the patient's bone and soft-tissue data are presented on the computer screen in stereo and the user can freely view, rotate, and otherwise interact with the patient's data in real-time. The user is prompted to select anatomical landmarks on the patient data for preoperative planning purposes, then their locations are compared against that of a "gold standard" and a score, derived from their deviation from that standard and time required, is generated. The user can then move a haptic stylus and guide the motion of the virtual cutting tool. The soft tissues can thus be incised using this virtual cutting tool, moved using virtual forceps, and fused in order to perform any of the major procedures for cleft-lip repair. Real-time soft tissue deformation of the mesh realistically simulates normal tissues and haptic-rate (>1kHz) force-feedback is provided. The surgical result of the procedure can then be immediately visualized and the entire training process can be repeated at will. A short evaluation study was also performed. Two groups (nonmedical and plastic surgery residents) of six-people each performed the anatomical marking task of the simulator four times. Results showed that the plastic surgery residents scored consistently better than the people without medical background. Every person's score increased with practice, and the length of time needed to complete the eleven markings decreased. The data was compiled and showed which specific markers consistently took users the longest to identify as well as which locations were hardest to accurately mark. Our findings suggest that the simulator is a valuable training tool, giving residents a way to practice anatomical identification for cleft lip surgery without the risks associated with training on a live patient. Educators can also use the simulator to examine which markers are consistently problematic, and modify their training to address these needs.

Cleft Lip↗
PubMed2000

[Intraoperative navigation in paranasal sinus surgery with the Philips "Neuroguide" system].

OBJECTIVE: To investigate the feasibility, precision and usefulness of computer aided surgery in ENT-sinus surgery. MATERIAL AND METHODS: 5 Patients with chronic sinus pathology and an indication for sinus surgery were elected. For intraoperative navigation we used a Philips "NEUROGUIDE" system and surgical instruments with LED's. Navigation procedures are described in detail in the paper, the system's precision was measured by pointing at anatomical landmarks. The accuracy was measured as the distance in millimeter between the bony structures of the CT scan on screen and the haircross of the pointer's tip on the screen. Another parameter of the systems accuracy was calculated by the system itself as the root mean square error in millimeter (RMSE) between the registered markers position and the marker position in the CT data set. RESULTS: Axial 3/3/1 mm spiral CT provided sufficient resolution, data transfer via optical disk was practicable. Positioning of the navigation equipment required some experience and the registration of the patients head position needed attention, as the markers have to be pointed at precisely. During operation, the head tracking system must not change its position on the patients head to ensure a correct navigation display. The main advantage of the computed navigation system was the constant orientation during the sinus surgical procedure. Frontiers and critical anatomical structures could be identified in the corresponding CT data set, thus enabling the surgeon to decide on the further procedure. At present stage, the operation time was increased through the handling of the navigation system for at about 15 min, resulting in additional time of narcosis. CONCLUSION: We found the computed navigation system Philips "NEUROGUIDE" system to be an established technical aid, ready to use for ENT sinus surgery, in our cases with a precision between 1 and 3 mm. These results were similar to results obtained with a SPOCS Navigation System from Aesculap, as previously published by us [17].

Adult↗
PubMed2005

A surgical simulator for planning and performing repair of cleft lips.

UNLABELLED: The objective of this project was to develop a computer-based surgical simulation system for planning and performing cleft lip repair. This system allows the user to interact with a virtual patient to perform the traditional steps of cleft-lip repair (rotation-advancement technique). MATERIALS AND METHODS: The system interfaces to force-feedback (haptic) devices to track the user's motion and provide feedback during the procedure, while performing real-time soft-tissue simulation. An 11-day-old unilateral cleft lip, alveolus and palate patient was previously CT scanned for ancillary diagnostic purposes using standard imaging protocols and 1mm slices. High-resolution 3D meshes were automatically generated from this data using the ROVE software developed in-house. The resulting 3D meshes of bone and soft tissue were instilled with physical properties of soft tissues for purposes of simulation. Once these preprocessing steps were completed, the patient's bone and soft tissue data are presented on the computer screen in stereo and the user can freely view, rotate, and otherwise interact with the patient's data in real time. The user is prompted to select anatomical landmarks on the patient's data for preoperative planning purposes, then their locations are compared against that of a 'gold standard' and a score, derived from their deviation from that standard and time required, is generated. The user can then move a haptic stylus and guide the motion of the virtual cutting tool. The soft tissues can thus be incised using this virtual cutting tool, moved using virtual forceps, and fused in order to perform any of the major procedures for cleft lip repair. Real-time soft tissue deformation of the mesh realistically simulates normal tissues and haptic-rate (>1 kHz) force-feedback is provided. The surgical result of the procedure can then be immediately visualized and the entire training process can be repeated at will. A short evaluation study was also performed. Two groups (non-medical and plastic surgery residents) of six persons each performed the anatomical marking task of the simulator four times. RESULTS: Results showed that the plastic surgery residents scored consistently better than the persons without medical background. Every person's score increased with practice, and the length of time needed to complete the 11 markings decreased. The data was compiled and showed which specific markers consistently took users the longest to identify as well as which locations were hardest to accurately mark. CONCLUSION: These findings suggest that the simulator is a valuable training tool, giving residents a way to practice anatomical identification for cleft lip surgery without the risks associated with training on a live patient. Educators can also use the simulator to examine which markers are consistently problematic, and modify their training to address these needs.

Cleft Lip↗
PubMed2005

The importance of accurate anatomic assessment for the volumetric analysis of the amygdala.

There is a wide range of values reported in volumetric studies of the amygdala. The use of single plane thick magnetic resonance imaging (MRI) may prevent the correct visualization of anatomic landmarks and yield imprecise results. To assess whether there is a difference between volumetric analysis of the amygdala performed with single plane MRI 3-mm slices and with multiplanar analysis of MRI 1-mm slices, we studied healthy subjects and patients with temporal lobe epilepsy. We performed manual delineation of the amygdala on T1-weighted inversion recovery, 3-mm coronal slices and manual delineation of the amygdala on three-dimensional volumetric T1-weighted images with 1-mm slice thickness. The data were compared using a dependent t-test. There was a significant difference between the volumes obtained by the coronal plane-based measurements and the volumes obtained by three-dimensional analysis (P < 0.001). An incorrect estimate of the amygdala volume may preclude a correct analysis of the biological effects of alterations in amygdala volume. Three-dimensional analysis is preferred because it is based on more extensive anatomical assessment and the results are similar to those obtained in post-mortem studies.

Amygdala↗
PubMed1998

User introduced uncertainties in the measurement of field misalignment by a computer aided technique.

While images acquired using an electronic portal imager may be visually compared to other portal or simulator images to assess patient alignment, a more quantitative comparison is desirable. Computer aided alignment tools are available which are based on user placed landmarks. The purpose of this study was to estimate uncertainties introduced by the user to the final measurement of field misalignment using such a tool. Both intra- and inter-user reproducibility were assessed. To complete this task, a number of image pairs including both phantom and patient images were compared by multiple observers. Results of the comparisons (x- and y- translation and rotation) were tabulated for each image pair and their reproducibility assessed by calculating a mean and standard deviation. User introduced uncertainty was found to be independent of the magnitude of rotation or x- or y- translation. In all cases, there was no difference between intra-observer and inter-observer uncertainty. For clinical cases, there is a significant difference between uncertainty in x- and y-translation due to both image quality and patient anatomy. In addition, the magnitude of uncertainty tracks qualitatively with image quality and number of available anatomical landmarks. The decision to make a correction in field alignment must be made considering these uncertainty estimates. Image comparison must be fully automated to eliminate uncertainties introduced by the user.

Humans↗
PubMed2000

Real-time opto-electronic verification of patient position in breast cancer radiotherapy.

OBJECTIVE: The clinical application of an opto-electronic system for real-time three-dimensional (3D) control of patient position in breast cancer radiotherapy is described. The specific features of the motion analysis technology (shape recognition of passive markers) are detailed, and the outcomes of its clinical use for quantitative position control and immobility verification of the thoracic irradiation field during breast cancer treatment are reported. MATERIALS AND METHODS: The position control system is based on the ELITEtrade mark opto-electronic motion analyzer, which provides in real time the 3D coordinates of a set of passive markers (plastic hemispheres 3 mm in diameter) previously placed on selected landmarks on the patient's skin. The system-dedicated hardware performs marker recognition by means of 2D correlation of shape with a predefined marker modeling mask. This feature ensures a high accuracy, even with small marker dimensions, and successful analysis in a noisy environment (due to room light, reflexes, etc.). The patient repositioning control was based on a comparison between the current positions of the markers and a corresponding reference configuration. The resulting marker displacements were graphically displayed in real time for immediate control. This information was not provided to the operator as a repositioning tool. Instead, the kinematic data was stored for subsequent off-line analysis aimed at quantifying the different factors contributing to patient mis-positioning (initial repositioning errors, patient's breathing, and random movements) when conventional means for patient alignment (laser centering) and immobilization (casting techniques) are used. RESULTS: Clinical application of the system revealed median 3D localization errors for the directly controlled anatomical landmarks of around 4.5 mm. This value is proposed to represent the intrinsic accuracy of conventional laser-centering techniques in breast cancer radiotherapy, including the effects of patient body deformations. When the positional inaccuracies introduced by patients' respiration were also considered, the extent of the resulting 3D mis-positioning of the control points increased to median values of up to 8 mm. CONCLUSIONS: The reported clinical trial confirms the significant role that real-time opto-electronic motion analysis based on passive markers can have in augmenting the accuracy of patient repositioning and immobility verification in the radiotherapy of a non-rigid body area while also accounting for physiological movements. Evaluation of the data collected during each irradiation session for five patients provided valuable information concerning the optimization of the efficacy of traditional methods for patient centering and immobilization.

Breast Neoplasms↗
PubMed1996

Infratemporal fossa surgery for malignant diseases.

The improvement in the knowledge of the main anatomical landmarks permits an evolution in the safety of the surgical treatment and a conceptual development of the geometrical anatomico-surgical characteristics of the infratemporal fossa. This conceptual evolution determines surgical and oncological advantages: firstly, improved comprehension of the anatomico-surgical limits of the resection and secondly the safeguarding of the oncological "en-bloc" dissection. The lateral approach of the infratemporal fossa gives a wider exposure of the surgical field, a shorter depth of work, a good control over the vessels and the possibility of carry out a microsurgical transfer. The surgical approaches correspond to the topographical location and the biology of the neoplasm in cases with infratemporal fossa and inferior compartment location the lateral transfacial approach is indicated. In cases with involvement of the superior compartment a lateral transcraniofacial subtemporal approach is necessary in order to remove the skull base. In cases with a neoplastic invasion of the skull base where the dura mater is the anatomical plane free from disease it is necessary to utilize an intradural approach. In patients with a secondary spread into the inferior compartment from the maxilla a combined antero-lateral transfacial approach is indicated. Finally, an orbitomaxillary involvement with secondary spread in the upper compartment of the infratemporal fossa necessitates an antero-lateral transcraniofacial subtemporal subfrontal approach.

Adult↗
PubMed1998

Experiences in intraoperative computer-aided navigation in ENT sinus surgery with the Aesculap navigation system.

Five patients with chronic sinus pathology and an indication for sinus surgery were selected. For intraoperative navigation, we used Surgical Planning and Orientation Computer Systems (SPOCS) Aesculap navigation software (ISG Technologies, Mississauga, Ontario, Canada) and surgical instruments fitted with light-emitting diodes. Navigation procedures are described in detail in the article. The system's precision was measured by pointing at anatomical landmarks. The accuracy was measured as the distance in millimeters between the bony structures of the computed tomographic (CT) scan on screen and the cross-hair of the pointer tip displayed on the screen. Another parameter of the system's accuracy was calculated by the system itself as the root mean square error in millimeters between the markers' position as registered and their position in the CT data set. Axial 3/3/1-mm spiral CT provided sufficient resolution, and data transfer via optical disk was practicable. Positioning of the navigation equipment required some experience, and the registration of the patient's head position also needed attention, as the markers have to be pointed at precisely. During the operation, the position of the head-tracking system on the patient's head must remain unchanged to ensure a correct navigation display. The main advantage of the computed navigation system was the constant orientation provided during the sinus surgical procedure. Borders and critical anatomical structures could be identified in the corresponding CT data set, thus enabling the surgeon to decide on subsequent procedures. Use of the navigation system was found to increase the operation time by about 1 h, resulting in additional time under anesthesia. We found the SPOCS Aesculap computed navigation system to be an established technical aid, ready for use in ENT sinus surgery. In the cases reported here, a precision between 1 and 3 mm was obtained.

Humans↗
PubMed2005

Microsurgical landmarks for safe removal of anterior clinoid process.

OBJECTIVE: The microsurgical and radiological anatomy of the clinoid process were studied to give surgeons more details about the anterior clinoid process and its relations to the vascular and nervous neighbourhood during intradural and extradural clinoidectomy, thus making the operative procedures safer. METHODS: Seven formalin-fixed (14 sides) and two fresh cadavers (four sides) were studied to reveal the surgical anatomy of the anterior clinoid process and related landmarks during intradural and extradural drilling techniques of clinoid process. Furthermore, aeration of the anterior clinoid process was investigated in 100 paranasal tomography (200 sides) scans. RESULTS: Careful drilling of the anterior clinoid process is mandatory to avoid damage to the extremely important adjacent structures. The anterior clinoid process must not be removed in one piece. Clinoid folds and the frontotemporal fold should be exposed adequately. The falciform ligament must be cut to visualize the optic nerve and ophthalmic artery clearly. Preoperative radiological assessment of clinoid process variations should be done. In computerized tomography scans, pneumatization of the right anterior clinoid process was found in 12%, of the left anterior clinoid process in 7% and bilaterally pneumatization was present in 9%. CONCLUSIONS: Removal of the ACP is one of the most critical procedures to the successful and safe management of ophthalmic segment aneurysms and tumors located in the paraclinoid region and cavernous sinus. Special attention should be paid to the anatomic landmarks indicating the relationship between the anterior clinoid process and adjacent structures. Beside that, pneumatization of the anterior clinoid process should be evaluated preoperatively with computed tomography to avoid complications such as rhinorrhea and pneumocephalus.

Cadaver↗