New endoscopic route to the temporal horn of the lateral ventricle: surgical simulation and morphometric assessment

Ventricular Catheter Insertion on the Occipital and Parietooccipital Bone: A Nonmetric Complementary Technique

Background and Study Aim Hydrocephalus is a common disease of the pediatric population, with cerebrospinal fluid diversion as the management of choice. All current insertion techniques require craniometrics calculation that may not be applicable for pediatric patients, due to significant variation in head circumference. We describe a complementary method of inserting ventricular catheters, devoid of craniometrics.

Materials and Methods The insertion site is based on two imaginary lines on the sagittal plane (superior and inferior limits) and four imaginary lines on the axial plane of a computed tomography/magnetic resonance imaging. The insertion point is chosen based on the shortest location from the outer table of the bone to the ventricle. The length of catheter insertion is calculated based on the distance between the calvarial outer table and the foramen of Monro.

Results Two case examples of ventricular catheter insertions, in pediatric patients with noncommunicating hydrocephalus, are described. External ventricular drain and ventriculoperitoneal shunt were inserted using this technique, with no required craniometrics measurements.

Conclusion This complementary method of inserting ventricular catheters can be easily tailored and implemented by junior neurosurgical residents to senior neurosurgeons as it precludes the measurement of the catheter insertion points.

Three-Dimensional Immersive Photorealistic Layered Dissection of Superficial and Deep Back Muscles: Anatomical Study

Introduction

The distinct anatomy of the superficial and deep back muscles is characterized by complex layered courses, fascial planes, specific vascularization, and innervation. Knowledge of these anatomical parameters is important for some surgical approaches, including lumbar disc herniation, cerebrospinal fluid fistula repair, vascularized muscle pedicle flaps, and posterior fossa extra-intracranial bypass. In the present study, we use modern techniques of three-dimensional (3D) surface scanning to help better illustrate the layered anatomy of the back muscles.

Material and methods

We dissected in layers the back muscles of one cadaver. Every step of the dissection was 3D scanned using a technique called photogrammetry, which allows the extraction of 3D data from 2D photographs. The 3D data were processed using Blender software, and the 3D photorealistic models were uploaded to a dedicated website for 3D visualization. This allows users to see the 3D models from every desktop or mobile device, as well as augmented (AR) and virtual reality (VR) formats.

Results

The photorealistic 3D models present the back muscles' anatomy in a volumetric manner, which can be visualized on any computer device. The web 3D features, including AR and VR, allow users to zoom, pan, and rotate the models, which may facilitate learning.

Conclusion

The technology of photorealistic surface scanning, modern 3D visualization possibilities of web-dedicated formats, as well as advances in AR and VR, have the potential to help with a better understanding of complex anatomy. We believe that this opens the field for further research in the field of medical education.

Endoscopic Intraventricular Atrial Adhesiolysis for the Treatment of Entrapped Temporal Horn after İntraventricular Tumor Surgery

A 21-year-old male patient was operated for third ventricle tumor (central neurocytoma) and showed improvement in the early postoperative period. After 2 weeks of surgery, the patient neurologic status deteriorated with acute decreased level of consciousness. Neuroimaging of the brain revealed entrapped left temporo-occipital horns with adhesion bands at the level of the atrium. Patient was operated with neuronavigation-guided endoscopic approach to the left atrium through the left posterior parietal region. Band adhesiolysis was performed with no complications. The patient showed fast improvement, and follow-up brain magnetic resonance imaging after 2 years showed the release of the ventricular entrapment with significant regression of the left ventricle size.

Craniometrics and Ventricular Access: A Review of Kocher's, Kaufman's, Paine's, Menovksy's, Tubbs’, Keen's, Frazier's, Dandy's, and Sanchez's Points

Intraventricular access is frequently required during neurosurgery, and when neuronavigation is unavailable, the neurosurgeon must rely upon craniometrics to achieve successful ventricular cannulation. In this historical review, we summarize the most well-described ventricular access points: Kocher's, Kaufman's, Paine's, Menovksy's, Tubbs’, Keen's, Frazier's, Dandy's, and Sanchez's. Additionally, we provide multiview, 3-dimensional illustrations that provide the reader with a novel understanding of the craniometrics associated with each point.

Presurgical simulation for neuroendoscopic procedures: Virtual study of the integrity of neurological pathways using diffusion tensor imaging tractography

Background:

White matter (WM) transgression is an unexplored concept in neuroendoscopy. Diffusion tensor image (DTI) tractography could be implemented as a planning and postoperative evaluation tool in functional disconnection procedures (FDPs), which are, currently, the subject of technological innovations. We intend to prove the usefulness of this planning method focused on the assessment of WM injury that is suitable for planning FDPs.

Methods:

Ten cranial magnetic resonance studies (20 sides) without pathological findings were processed. Fascicles were defined by two regions of interest (ROIs) using the fiber assignment method by the continuous tracking approach. Using three-dimensional (3D) simulation and DTI tractography, we created an 8-mm virtual endoscope and an uninjured inferior fronto-occipital fasciculus (IFOF) from two ROIs. The injured tract was generated using a third ROI built from the 3D model of the intersection of the oriented trajectory of the endoscope with the fascicle. Data and images were quantitatively and qualitatively analyzed.

Results:

The average percentage of the injured fibers was 32.0% (range: 12.4%–70%). The average intersected volume was 1.1 cm³ (range: 0.3–2.3 cm³). Qualitative analysis showed the inferior medial quadrant of the inferior fronto-occipital fasciculus (IFOF) as the most frequently injured region. No hemispherical asymmetry was found (P > 0.5).

Conclusion:

DTI tractography is a useful surgical planning tool that could be implemented in several endoscopic procedures. Together with a functional atlas, the presented technique provides a noninvasive method to assess the potential sequelae and thus to optimize the surgical route. The suggested method could be implemented to analyze pathological WM fascicles and to assess the surgical results of FDP such as hemispherotomy or amygdalohippocampectomy. More studies are needed to overcome the limitations of the tractography based information and to develop more anatomically and functionally reliable planning systems.

Morphometric Study of Endoscopic Transoccipital Approach to Lateral Ventricle With Magnetic Resonance Imaging

Endoscopic surgery has been applied in the treatment of lateral cerebral ventricular lesions for years, but few morphometric studies in vivo have been reported with medical imaging. In the current study, the authors aimed to investigate the related morphometric data of endoscopic transoccipital approach to lateral ventricle with the magnetic resonance images of lateral ventricle from healthy adults anonymously. Seven parameters on the axial plane and 3 on the left occipital horn of sagittal plane of T1-weighted image were measured and the results were as follows: The distance from incision to the cranium posterior intersection with midsagittal line (D1) was 29.69 ± 3.09 mm.The distance from incision to the superior border of transverse sinus (D2) was 29.40 ± 4.76 mm; the length between incision and the entry trajectory intersection K of posterior wall of lateral ventricle (D3) was 43.25 ± 4.20 mm; the distance between the midpoint of largest width of occipital horn and the intersection K (D4) was 9.39 ± 2.75 mm; the bilateral occipital horn and left frontal horn (W1, W2, W3) were, respectively: 10.29 ± 2.27, 9.74 ± 2.51, and 7.91 ± 1.19 mm. The angulations between entry trajectory and the projections of longitudinal axis of posterior lateral ventricle body that goes through the midpoint of largest breadths of left occipital horn on the axial and sagittal planes and the longitudinal axis of temporal horn (A1, A2, A3) were separately as follows: (38.10 ± 4.50)°, (30.30 ± 4.47)°, and (31.08 ± 4.54)°. The resultant anatomical data of the distances and angles validate the previous surgical experience and, moreover, facilitate neurosurgery to the lateral ventricle through the endoscopic transoccipital approach.