Endoscopic Keyhole Approach Research Articles

Purely endoscopic subtemporal keyhole anterior transpetrosal approach to access the petrous apex region: surgical techniques and early results.

The anterior transpetrosal approach using a microscope to provide wider access to the petrous apex region has been described for radical resection of lesions of the middle and posterior skull base. The microscopic anterior transpetrosal approach (mATPA) requires a wide craniotomy and meticulous epidural procedures to minimize temporal lobe retraction. Recently, the clinical application of transcranial endoscopic keyhole approaches for minimally invasive surgery has been steadily expanding. In this study, the details of the purely endoscopic subtemporal keyhole ATPA (eATPA) for petrous apex lesions are described and its initial results are reported. Between May 2022 and May 2023, the authors performed eATPA in 10 patients with petrous apex lesions, of which 6 were meningiomas, 3 were trigeminal schwannomas, and 1 was epidermoid cyst. The surgical procedure of the purely eATPA is as follows. After a small temporal craniotomy, the endoscopic procedure is started. The anterior rim of the petrous bone and Meckel's cave are exposed via an intradural subtemporal approach. The lesion is removed with additional drilling of Kawase's triangle, cutting the superior petrosal sinus, opening Meckel's cave, and cutting the tentorium. The authors also compared the outcomes of mATPA versus eATPA for consecutive cases of petrous apex lesions. Gross-total resection was achieved in 8 of the 10 patients. The average operative time was 4 hours 13 minutes. There were 3 cases of transient abducens nerve palsy and 1 case of trochlear nerve palsy in the postoperative period. No new-onset motor deficits or CSF leakage was noted in any of these patients. Only 1 patient exhibited postoperative asymptomatic temporal lobe edema. The Karnofsky Performance Scale (KPS) scores remained unchanged or improved for all patients postoperatively. Compared with mATPA, eATPA achieved a similar extent of resection and comparable postoperative KPS scores with a significantly shorter mean operative time, much smaller temporal craniotomy, and thus less mean blood loss during surgery with lower rates of new-onset temporal lobe edema in the postoperative period. An eATPA allows a direct route to access Meckel's cave and posterior cranial fossa lesions similar to conventional mATPA, with shortening the operative time and reducing the risk of postoperative temporal lobe edema. This eATPA is considered one of the new surgical techniques that can be expected to develop in the future.

Quantitative Anatomical Study of the Supratentorial and Infratentorial “Endoscopic Keyhole” Approach to the Peripineal Region

Background. The pineal region represents significant challenges in terms of neurosurgery. Currently, anatomical research that simulates surgery for the endoscopic keyhole approach to the pineal region is lacking. This study aims to summarize the exposure range and operational characteristics of total endoscopic surgery under the four supratentorial and infratentorial keyhole approaches, through rigorous quantitative anatomical research. We also aim to understand the surgical exposure characteristics and surgical feasibility under each approach. Method. Six wet cadaveric head specimens (a total of 12 sides) were subjected to simulated surgery with a keyhole bone window size of approximately 3 × 4 cm. The median endoscopic supracerebellar infratentorial approach (M‐ESCITA), the paramedian endoscopic supracerebellar infratentorial approach (PM‐ESCITA), the endoscopic occipital transtentorial approach (EOTA), and the endoscopic interhemispheric high occipital transtentorial approach (EHOTA) were used to measure the surgical path depth, maximum distance between the tentorial margins, maximum operable area, operable angle, and relative degree of freedom of each approach. Results. There was no difference in the exposure range of the surgical area. The surgical path of PM‐ESCITA was the longest (p < 0.001), and its horizontal operating angle was the largest (p < 0.001), whereas the anteroposterior operating angle of EHOTA was the largest (p < 0.001). The maximum operational area of M‐ESCITA was the largest in the pineal region (p < 0.01), whereas that of EHOTA was the largest in the tetrapod region (p < 0.001). M‐ESCITA had the highest relative degree of freedom during surgery at the pineal gland level (p < 0.001), PM‐ESCITA at the splenium of the corpus callosum (p < 0.01), and EHOTA at the corpora quadrigemina (p < 0.001). Conclusions. Each of the four endoscopic keyhole approaches has its own advantages. Through anatomical research, doctors can train themselves and master the differences in surgical procedures through different approaches. The choice of approach and surgical challenge are dependent on the microsurgical techniques employed by the surgeon. A balance between minimally invasive and safe endoscopic surgery should be pursued.

Endoscopic Keyhole Approach for Intracranial Epidermoid.

Objective In contemporary neurosurgical practice, keyhole endoscopic approach has established its role in various neurosurgical pathologies. Intracranial epidermoid is an ideal pathology for endoscopic keyhole approach as epidermoid is well encapsulated, extra-axial, avascular, and easily suckable. The objective of this study is to share our experience of endoscopic keyhole approach for intracranial epidermoids at various locations as a new minimally invasive neurosurgical approach to deal with these lesions. Materials and Methods We conducted a retrospective study on 26 patients who underwent keyhole pure endoscopic excision of intracranial epidermoid between July 2015 and December 2019. Patient's demographics, clinical features, radiological imaging, and postoperative complications were noted. Follow-up outcome of preoperative symptoms and postoperative complications were also analyzed. Results The mean age of the study population was 30.5 years with a mean follow-up of 30 months. The common presenting features were headache, hearing loss, and trigeminal neuralgic pain. Gross total resection was achieved in 73.1% cases, while near total resection and subtotal resection were achieved in 19.2 and 7.7% cases, respectively. In the follow-up, maximal improvement was seen in trigeminal neuralgic pain (83%) and headache (66.7%). Major postoperative complications were facial nerve paresis, lower cranial nerve paresis, and transient facial hypoesthesia, most of which improved over time. None of the patients required resurgery till date. Statistical Analysis Patients' data were analyzed using SPSS software version 23 (Statistical Package for Social Sciences, IBM, Chicago, United States). Conclusion This study demonstrates that with careful patient selection, endoscopic keyhole excision of epidermoid is a good alternative to conventional microsurgical excision with comparable surgical and functional outcomes.

Quantitative analysis of exposure and surgical maneuverability of three purely endoscopic keyhole approaches to the floor of the third ventricle.

The quantitative anatomic analysis of comprehensively endoscopic approaches to the third ventricle is scarce at present. The objective of the study is to quantitatively assess and compare the exposure and microsurgical maneuverability of three absolutely endoscopic keyhole approaches, including interhemispheric transcallosal transchoroidal (TCTC), frontal transforminal transchoroidal (TFTC) and supraorbital subfrontal translamina terminalis (SFTL) approaches. Anatomical dissections and exposure of the important structures of the third ventricle were performed using six formalin-fixed cadaveric human heads (twelve sides) under endoscope. Tubular retractor system was used in the TFTC approach. Quantitative anatomical relationship between the important landmarks were obtained. Moreover, the exposure and surgical operability of three approaches were evaluated through applying the rating scale and accomplishing the quantitative anatomic analysis, area of surgical freedom and angle of attack. The mediolateral, anteroposterior (AM: between aqueduct and mammillary body; IM: between infundibular recess and mammillary body) and superoinferior distance of TCTC, TFTC and SFTL approaches were 4.0±1.0, 4.2±0.4, 4.1±1.1 mm; 17.3±1.4, 17.6±0.5, 12.8±3.3 mm (AM); 7.7±0.3, 7.8±0.5 mm, not measured (IM); and 5.6±0.3, 7.8±0.8, 7.8±1.5 mm, respectively. Similar to TFTC, the exposed landmarks of TCTC were almost scored a "4" by three neurosurgeons except the infundibular recess scored a "3" according to the rating scale. During the SFTL approach, apart from the roof, the majority of the landmarks were scored a "4" except for the infundibular recess, which was scored a "3." The mean area of surgical freedom of TCTC (0° endoscope: 220±47; 30°: 247±56 mm2) was not significantly different from that of TFTC approach (0° endoscope: 216±49; 30°: 245±53 mm2) under same endoscope, P>0.05. Mean angle of attack of TCTC (0° endoscope: 21±4°; 30°: 26±4°) was significantly larger than that of TFTC approach (0° endoscope: 16±3°; 30°: 19±3°), P<0.05. Purely endoscopic TCTC and TFTC approaches offer brilliant exposure of the anterior, middle and posterior third ventricle. TCTC approach may have better surgical maneuverability than TFTC approach. Despite the long working distance, the whole third ventricle are exposed well except for the roof in the SFTL approach, and surgical manipulation can be accomplished smoothly.

Minimally Invasive Endoscopic Keyhole Approach for Meningiomas

Abstract INTRODUCTION The advantages of neuroendoscopic surgery are wide viewing angle and freedom of axis of view with minimal surgical trauma. Taking advantage of the features of neuroendoscopy, the authors report the experience of minimally invasive endoscopic keyhole approach (EKA) for various meningiomas. METHODS A total of 28 cases of various type of meningiomas were treated by EKA from 2007 to 2018. A keyhole of about 2.5 cm was created according to the case, and tumor removal was performed using an endoscope and exoscope. The scope was held by a pneumatic holder controlled by the assistant to continue the procedure in a comfortable environment. RESULTS EKAs were performed for anterior skullbase lesions via eyebrow skin incision (n = 12), posterior fossa lesions including tentorial meningiomas, torcular meningiomas (n = 7), falcine lesions (n = 6), subtemporal approach (n = 2), enplaque convexity menigiomas (n = 1). All the tumors were resected as planned with minimum brain retraction and well-illuminated fine vision in deep corner. In the cases of a large tumor in the elderly, maximum internal decompression was performed, and the adhered tumor was left on the surface of the brain to avoid injury. The brain retraction was automatically limited by the small craniotomy, and excellent magnified image in deep corner was obtained by EKA. By eliminating the blind spots, radical resection is achieved. Also, in the aging society, depending on the patient with benign meningioma, it is important to consider what better treatment is, to alleviate symptoms and to coexist with the tumor. The cooperation of the assistant is important for this approach. To avoid the interference between the endoscope and the instrument, it is necessary to have a technique for moving the endoscope as needed in order to keep the fine visual field. CONCLUSION In the treatment of meningioma, the role of endoscopes is important in both the radicality obtained in a wide field of view and the less invasiveness in the aging society.

Cadaveric Study of an Endoscopic Keyhole Middle Fossa Craniotomy Approach to the Superior Semicircular Canal.

Demonstrate that an endoscopic keyhole approach to the middle cranial fossa is technically feasible for repair of semicircular canal dehiscence. Cadaveric technical feasibility/methods development study. Tertiary care military medical center. Three fresh cadaveric heads (six sides). Endoscopic minimally invasive approach to the middle cranial fossa using the Medtronic Fusion Guidance system. Ability to identify the surgical landmarks of the middle cranial fossa and successfully identify and instrument the superior semicircular canal. In every attempt, the arcuate eminence was successfully identified under endoscopic visualization and with the assistance of surgical navigation. The superior semicircular canal was unroofed, and its location confirmed visually and with the navigation system. The opened canal was then plugged with bone wax, bone pate, and covered with fascia. The 15-mm burr hole craniotomy provided ample room for one working instrument and a 4-mm 0-degree endoscope. The endoscopic keyhole approach to superior semicircular canal dehiscence is technically feasible in a human cadaveric model. Further studies will determine 1) if this approach is possible and safe in vivo, 2) is associated with improved surgical outcomes, and 3) if surgical navigation aids in this approach.

Endoscopic controlled clipping of anterior circulation aneurysms via keyhole approach: Our initial experience.

Surgical clipping is the most definite treatment for intracranial aneurysms. Its aim is to achieve complete aneurysmal occlusion without compromising the lumen of a parent vessel or perforators, and with minimal brain tissue trauma. To evaluate the role of endoscopic controlled keyhole approach in clipping of anterior circulation aneurysms. In this retrospective study, all consecutive patients undergoing endoscopic controlled clipping via the keyhole approach by the senior author during the last 1 year were included. The cases in which a microscope was used at any stage of surgery were excluded. Fourteen patients with anterior circulation aneurysms underwent clipping via the endoscopic keyhole approach (supraorbital and mini-pterional). Seven patients had anterior communicating (ACom) artery aneurysms, four had middle cerebral artery (MCA) bifurcation aneurysms, two had internal carotid artery bifurcation aneurysms, and one had a posterior communicating artery aneurysm. Ten patients presented with subarachnoid hemorrhage (Hunt and Hess grade I in 6 and grade II in 4 patients), whereas the remaining four were incidentally detected. The pre-clipping dissection as well as the clipping were successfully performed endoscopically in all patients. The post-clipping inspection revealed inclusion of a perforator within the clip blades in 2 patients (ACom and MCA bifurcation) that required clip readjustment. There was no residual neck/incompletely clipped aneurysm detected on post-clipping inspection. There was no morbidity directly attributable to the use of keyhole approach or the endoscope. Endoscopic keyhole approach for intracranial aneurysms combines the advantages of both keyhole approach and endoscopy. Endoscopic visualization can help to reduce chances of an incompletely clipped aneurysms/residual neck and the risk of parent vessel/perforator occlusion. However, the use of an endoscope in narrow corridors with space constraints has a learning curve that can be overcome by practicing on cadavers and initially performing several simple endoscopic procedures.