Alberto Di Somma, Cristobal Langdon, Matteo de Notaris, Luis Reyes, Santiago Ortiz-Perez, Isam Alobid and Joaquim Enseñat
Over the years, Meckel’s cave pathologies have been judged off-limits because of high rates of morbidity. Even though several studies have defined various surgical routes with tolerable morbidity and mortality rates, controversies related to the optimal avenue to treat different categories of Meckel’s cave and cavernous sinus neoplasms persist.
With unceasing energy to cultivate minimally invasive neurosurgical approaches, the endoscopic endonasal route has been tested, and the approach effectively performed, to provide a valid surgical window to these areas. In this dynamic and challenging scenario, another ventral endoscopic minimally invasive route—that is, the superior eyelid endoscopic transorbital approach—has been very recently proposed, and used in selected cases, to access the cavernous sinus and Meckel’s cave regions.
The authors report the technical nuances of a combined and simultaneous endoscopic endonasal and transorbital surgical treatment of a patient with a Meckel’s cave schwannoma. The operation involved collaboration among neurosurgery, otorhinolaryngology, and ophthalmology (oculoplastic surgery). The patient recovered well, had no neurological deficits, and was discharged to home 3 days after surgery.
The multiportal combined route was proposed for the following reasons. The endonasal approach, considered to be more familiar to our skull base team, could allow control of possible damage of the internal carotid artery. From the endonasal perspective, the most inferior and medial portion of the tumor could be properly managed. Finally, the transorbital route, by means of opening the lateral wall of the cavernous sinus via the meningoorbital band, could allow control of the superolateral part of the tumor and, most importantly, could permit removal of the portion entering the posterior cranial fossa via the trigeminal pore. Simultaneous surgery with two surgical teams working together was planned in order to reduce operative time, hospital stay, and patient stress and discomfort, and to ensure “one-shot” complete tumor removal, with minimal or no complications.
This study represents the translation into the real surgical setting of recent anatomical contributions related to the novel endoscopic transorbital approach and its simultaneous integration with the endoscopic endonasal pathway. Accordingly, it may pave the way for future applications related to minimally invasive, multiportal endoscopic surgery for skull base tumors.
Andrea Ruggeri, Joaquim Enseñat, Alberto Prats-Galino, Antonio Lopez-Rueda, Joan Berenguer, Martina Cappelletti, Matteo De Notaris and Elena d'Avella
Neurosurgical management of many vascular and neoplastic lesions necessitates control of the internal carotid artery (ICA). The aim of this study was to investigate the feasibility of achieving control of the ICA through the endoscopic endonasal approach by temporary occlusion with a Fogarty balloon catheter.
Ten endoscopic endonasal paraseptal approaches were performed on cadaveric specimens. A Fogarty balloon catheter was inserted through a sellar bony opening and pushed laterally and posteriorly extraarterially along the paraclival carotid artery. The balloon was then inflated, thus achieving temporary occlusion of the vessel. The position of the catheter was confirmed with CT scans, and occlusion of the ICA was demonstrated with angiography. The technique was performed in 2 surgical cases of pituitary macroadenoma with cavernous sinus invasion.
Positioning the Fogarty balloon catheter at the level of the paraclival ICA was achieved in all cadaveric dissections and surgical cases through a minimally invasive, quick, and safe approach. Inflation of the Fogarty balloon caused interruption of blood flow in 100% of cases.
Temporary occlusion of the paraclival ICA performed through the endoscopic endonasal route with the aid of a Fogarty balloon catheter may be another maneuver for dealing with intraoperative ICA control. Further clinical studies are required to prove the efficacy of this method.
Alberto Di Somma, Norberto Andaluz, Luigi Maria Cavallo, Matteo de Notaris, Iacopo Dallan, Domenico Solari, Lee A. Zimmer, Jeffrey T. Keller, Mario Zuccarello, Alberto Prats-Galino and Paolo Cappabianca
Recent studies have proposed the superior eyelid endoscopic transorbital approach as a new minimally invasive route to access orbital lesions, mostly in otolaryngology and maxillofacial surgeries. The authors undertook this anatomical study in order to contribute a neurosurgical perspective, exploring the anterior and middle cranial fossa areas through this purely endoscopic transorbital trajectory.
Anatomical dissections were performed in 10 human cadaveric heads (20 sides) using 0° and 30° endoscopes. A step-by-step description of the superior eyelid transorbital endoscopic route and surgically oriented classification are provided.
The authors’ cadaveric prosection of this approach defined 3 modular routes that could be combined. Two corridors using bone removal lateral to the superior and inferior orbital fissures exposed the middle and anterior cranial fossa (lateral orbital corridors to the anterior and middle cranial base) to unveil the temporal pole region, lateral wall of the cavernous sinus, middle cranial fossa floor, and frontobasal area (i.e., orbital and recti gyri of the frontal lobe). Combined, these 2 corridors exposed the lateral aspect of the lesser sphenoid wing with the Sylvian region (combined lateral orbital corridor to the anterior and middle cranial fossa, with lesser sphenoid wing removal). The medial corridor, with extension of bone removal medially to the superior and inferior orbital fissure, afforded exposure of the opticocarotid area (medial orbital corridor to the opticocarotid area).
Along with its minimally invasive nature, the superior eyelid transorbital approach allows good visualization and manipulation of anatomical structures mainly located in the anterior and middle cranial fossae (i.e., lateral to the superior and inferior orbital fissures). The visualization and management of the opticocarotid region medial to the superior orbital fissure are more complex. Further studies are needed to prove clinical applications of this relatively novel surgical pathway.
Jose Juan González Sánchez, Jordina Rincon-Torroella, Alberto Prats-Galino, Matteo de Notaris, Joan Berenguer, Enrique Ferrer Rodríguez and Arnau Benet
The temporal horn of the lateral ventricle is a complex structure affected by specific pathological conditions. Current approaches to the temporal horn involve a certain amount of corticotomy and white matter disruption. Surgeons therefore set aside anterior temporal lobectomy as a last resource and avoid it in the dominant hemisphere. The authors propose a minimally invasive endoscopic intraventricular approach to the temporal horn and describe a standardized analysis and technical assessment of the feasibility of this approach.
To determine the best trajectory, angulation, and entry point to the temporal horn of the lateral ventricle, the authors evaluated 50 cranial MRI studies (100 temporal lobes) from healthy patients. They studied and systematized the neurosurgical endoscopic anatomy. They also simulated the proposed approach in 9 cadaveric specimens (18 approaches).
Mean scalp entry point coordinates (± SD) were 2.7 ± 0.28 cm lateral to the inion and 5.6 ± 0.41 cm superior to the inion. The mean total distance from the uncal recess to the scalp (± SD) was 10.64 ± 0.6 cm. The mean total intraparenchymal distance crossed by the endoscope was 3.76 ± 0.36 cm. The approach was successfully completed in all studied specimens.
In this study, the endoscopic intraventricular approach to the temporal horn is standardized. The morphometric analysis makes this approach anatomically feasible and replicable. This approach provides minimally invasive endoscopic access to the uncal recess, amygdala, hippocampus, fornix, and paraventricular temporal lobe structures. The following essential strategies enabled access to and maneuverability inside the temporal horn: tailored preoperative planning of the trajectory and use of anatomical and radiological references, constant irrigation, and an angled endoscopic lens. Safety assessment and novel instruments and techniques may be proposed to advance this very promising route to pathological changes in the temporal lobe.
Alberto Di Somma, Luigi Maria Cavallo, Matteo de Notaris, Domenico Solari, Thomaz E. Topczewski, Manuel Bernal-Sprekelsen, Joaquim Enseñat, Alberto Prats-Galino and Paolo Cappabianca
Different surgical routes have been used over the years to achieve adequate decompression of the optic nerve in its canal including, more recently, endoscopic approaches performed either through the endonasal corridor or the transorbital one. The present study aimed to detail and quantify the amount of bone removal around the optic canal, achievable via medial-to-lateral endonasal and lateral-to-medial transorbital endoscopic trajectories.
Five human cadaveric heads (10 sides) were dissected at the Laboratory of Surgical Neuroanatomy of the University of Barcelona (Spain). The laboratory rehearsals were run as follows: 1) preliminary preoperative CT scans of each specimen, 2) anatomical endoscopic endonasal and transorbital dissections and Dextroscope-based morphometric analysis, and 3) quantitative analysis of optic canal bone removal for both endonasal and transorbital endoscopic approaches.
The endoscopic endonasal route permitted exposure and removal of the most inferomedial portion of the optic canal (an average of 168°), whereas the transorbital pathway allowed good control of its superolateral part (an average of 192°). Considering the total circumference of the optic canal (360°), the transorbital route enabled removal of a mean of 53.3% of bone, mainly the superolateral portion. The endonasal approach provided bone removal of a mean of 46.7% of the inferomedial aspect. This result was found to be statistically significant (p < 0.05). The morphometric analysis performed with the aid of the Dextroscope (a virtual reality environment) showed that the simulation of the transorbital trajectory may provide a shorter surgical corridor with a wider angle of approach (39.6 mm; 46.8°) compared with the simulation of the endonasal pathway (52.9 mm; 23.8°).
Used together, these 2 endoscopic surgical paths (endonasal and transorbital) may allow a 360° decompression of the optic nerve. To the best of the authors' knowledge, this is the first anatomical study on transorbital optic nerve decompression to show its feasibility. Further studies and, eventually, surgical case series are mandatory to confirm the effectiveness of these approaches, thereby refining the proper indications for each of them.
Iacopo Dallan, Alberto Di Somma, Alberto Prats-Galino, Domenico Solari, Isam Alobid, Mario Turri-Zanoni, Giacomo Fiacchini, Paolo Castelnuovo, Giuseppe Catapano and Matteo de Notaris
Exposure of the cavernous sinus is technically challenging. The most common surgical approaches use well-known variations of the standard frontotemporal craniotomy. In this paper the authors describe a novel ventral route that enters the lateral wall of the cavernous sinus through an interdural corridor that includes the removal of the greater sphenoid wing via a purely endoscopic transorbital pathway.
Five human cadaveric heads (10 sides) were dissected at the Laboratory of Surgical NeuroAnatomy of the University of Barcelona. To expose the lateral wall of the cavernous sinus, a superior eyelid endoscopic transorbital approach was performed and the anterior portion of the greater sphenoid wing was removed. The meningo-orbital band was exposed as the key starting point for revealing the cavernous sinus and its contents in a minimally invasive interdural fashion.
This endoscopic transorbital approach, with partial removal of the greater sphenoid wing followed by a “natural” ventral interdural dissection of the meningo-orbital band, allowed exposure of the entire lateral wall of the cavernous sinus up to the plexiform portion of the trigeminal root and the petrous bone posteriorly and the foramen spinosum, with the middle meningeal artery, laterally.
The purely endoscopic transorbital approach through the meningo-orbital band provides a direct view of the cavernous sinus through a simple and rapid means of access. Indeed, this interdural pathway lies in the same sagittal plane as the lateral wall of the cavernous sinus. Advantages include a favorable angle of attack, minimal brain retraction, and the possibility for dissection through the interdural space without entering the neurovascular compartment of the cavernous sinus. Surgical series are needed to demonstrate any clinical advantages and disadvantages of this novel route.
Matteo de Notaris, Domenico Solari, Luigi M. Cavallo, Alfonso Iodice D'Enza, Joaquim Enseñat, Joan Berenguer, Enrique Ferrer, Alberto Prats-Galino and Paolo Cappabianca
The tuberculum sellae is a bony elevation ridge that lines up the anterior aspect of the sella, dividing it from the chiasmatic groove. The recent use of the endoscopic endonasal transtuberculum approach has provided surgeons with a method to reach the suprasellar area, offering a new surgical point of view somehow “opposite” of this area. The authors of this study aimed to define the tuberculum sellae as seen from the endoscopic endonasal view while also providing CT-based systematic measurements to objectively detail the anatomical features of such a structure, which was renamed the “suprasellar notch.”
The authors analyzed routine skull CT scans from 24 patients with no brain pathology or fractures and measured the interoptic distance at the level of the limbus sphenoidale, the chiasmatic groove sulcal length and width, and the angle of the suprasellar notch.
Indeed, the suprasellar notch was defined as the angle between 2 lines, the first passing through the tuberculum sellae midpoint and perpendicular to the cribriform plate, and a second line passing between 2 points, the midpoints of the limbus sphenoidale and the tuberculum sellae. Moreover, the authors performed on 15 cadaveric heads an endoscopic endonasal transplanum transtuberculum approach with the aid of a neuronavigator to achieve a step-by-step comparison with the radiological data. The whole CT scanning set was statistically analyzed to determine the statistical interdependency of the suprasellar notch angle with the other 3 measurements, that is, the sulcal length at the midline, the interoptic distance at the optic canal entrance, and the interoptic distance at the limbus.
Based on the endoscopic endonasal view and CT imaging analysis, the authors identified a certain anatomical variability and thus introduced a new classification of the suprasellar notch: Type I, angle < 118°; Type II, angle of 118°–138°; and Type III, angle > 138°. They then analyzed the surgical implications of the endoscopic endonasal approach to the suprasellar area, which could be affected by each of these structural types.
The new classification identifies 3 different types of suprasellar notch and, accordingly, their surgical relevance. Above all, the authors found that the different types of suprasellar notch can affect the osteodural defect reconstruction technique, namely the positioning/wedging of the buttress in the extradural space. A precise endoscopic anatomical knowledge of the neurovascular and bony relationships—especially in cases of a less pneumatized sphenoid sinus—is crucial when approaching the anterior skull base via a transtuberculum transplanum route.