Pretemporal Approach Research Articles

Novel Eyelid Supraorbital Pretemporal Approach to the Anterior Communicating Artery Complex: A Quantitative Cadaveric Comparative Study

Abstract Objectives Access to the anterior communicating artery (ACom) complex may be achieved via the modified orbito-zygomatic (mOZ) or eyelid supraorbital (ES) approaches. Further, the ES approach may improve cosmesis at the cost of decreased exposure and maneuverability. Thus, a novel eyelid supraorbital pretemporal (ESP) approach, a combination of the ES approach with a pretemporal dissection, may optimize the shortcomings of the ES approach. Design This is a cadaveric study. Setting Five ES, ESP, and mOZ approaches were performed on cadaveric heads and compared. Participants Cadaveric specimens were provided under the University of Oklahoma Health Science Center's Willed Body Program. Main Outcome Measures Quantitative measures of exposure, maneuverability, and angles of attack in horizontal and vertical planes were compared between approaches. Results The ESP approach was superior in terms of exposure and deep maneuverability when compared with the ES approach (p < 0.01). In addition, this approach demonstrated superior angles of attack in vertical (p < 0.01) and horizontal (p = 0.045) planes. When compared with the mOZ approach, the ESP approach provided significantly greater exposure to the contralateral A2 (p < 0.01) with a less favorable horizontal angle of attack (p < 0.01). The ESP provides exact exposure to complete the pretemporal osteotomy, offering a unique perspective on the ACom complex. Conclusion When accessing the ACom complex, the ESP approach yields superior exposure and maneuverability compared with the ES approach and is comparable to the mOZ approach, with unique advantages provided by the addition of pretemporal osteotomy and dissection.

Ruptured basilar artery perforator aneurysm mimicking superior cerebellar artery aneurysm

Background and importanceThe diagnosis of basilar artery perforator aneurysm is difficult due to their small size, with high rates of negative angiography. Furthermore, due to the considerable variation of basilar artery perforator (BAP), even if an aneurysm originates from a BAP, it is often difficult to clearly identify its origin on angiography. Clinical presentationA 46-female patient presented with World Federation of Neurological Surgeons Scale 1 subarachnoid hemorrhage. Initial imaging study, including digital subtraction angiography (DSA), revealed no vascular lesions. Two-week after admission, DSA revealed an aneurysm arising from the left superior cerebellar artery (SCA). Endovascular coil embolization was planned first. However, aneurysm selection using microcatheter was failed. Then, surgical approach was done via pre-temporal approach. We identified SCA, but there was no aneurysm. Further dissection revealed an aneurysm arising from basilar artery perforator, which was overlapped by SCA. The parent artery of the aneurysm arose from juxtaproximal to the orifice of left SCA, and crossed SCA at the juxtadistal to the aneurismal sac. Complete clip occlusion was done preserving BAP. After the surgery, the patient developed diplopia without extraoccular movement limitations. Two-month after the surgery, she was fully recovered without any neurologic deficits. ConclusionIt is crucial to adequately consider the possibility of open surgery as a viable option in case that endovascular treatment of aneurysms originated from the distal segment of basilar artery proves unsuccessful.

557 Results of Microsurgical Clipping of Unruptured Anterior Communicating Artery Aneurysms (ACOMa) Using the Pretemporal Minimal Durotomy Approach

INTRODUCTION: Recent reports suggest the superiority of microsurgical clipping of ACOMa compared to endovascular treatments. We present our experience with the pretemporal minimal durotomy (minimal brain exposure) approach in 168 patients. METHODS: Data of 168 patients were prospectively collected and retrospectively reviewed. The pretemporal approach with the removal of the posterior roof of the orbit and the anterior clinoid process with a minimized subfrontal durotomy allowed broad exposure to the ACOMa complex and minimal exposure to the surrounding brain. The technique allowed early proximal control and 360-degree visualization of the aneurysm and its surroundings. RESULTS: The average aneurysm size was 6.4 mm. Total clip occlusion was achieved in 100%, confirmed by intraoperative indocyanine green videography and post-operative computer tomography angiography/cerebral angiography. At discharge, 93.5% were modified Rankin Scale (mRS) 0-2, and 99.0% were mRS 0-2 at 1 year follow up. There was zero mortality, and one patient with a giant aneurysm had a stable residual on follow-up. CONCLUSIONS: Microsurgical clipping of ACOM aneurysms using the pretemporal minimal durotomy approach results in more durable outcomes than endovascular technique with excellent functional outcomes and should be strongly considered as a first treatment option, especially in aneurysms that have anatomic endovascular disadvantages that have a high likelihood of recurrence.

Petrous Carotid to Upper Posterior Circulation Bypass for the Treatment of Basilar Trunk Aneurysm: A Novel High-Flow Intracranial-Intracranial Skull Base Bypass for Posterior Circulation.

Basilar trunk aneurysms are the most surgically challenging, and the spectrum covers small fusiform to dolichoectatic aneurysms and may lead to rupture, brain ischemia, or direct brainstem compression. The current strategy remains cerebral revascularization coupled with aneurysm trapping. Available bypass options for upper posterior circulation (UPC) are based on (1) different flow volumes from diverse blood supplies and (2) distinct modulation purposes for cerebral revascularization; however, the potential compromise of eloquent perforators of the basilar trunk and the occurrence of fatal brainstem infarcts remain unacceptable. To innovate a high-flow intracranial-intracranial skull base bypass for posterior circulation to afford robust retrograde flow and shorten the graft length. We retrospectively reviewed our experience in the treatment of a patient with basilar trunk aneurysm and reported a novel bypass alternative supplied by petrous internal carotid artery to augment blood flow to the UPC by a pretemporal approach. The postoperative course was uneventful, and there was no pons or midbrain ischemia or other complications. Postoperative computed tomography angiogram revealed the patency of bypass. There was no further development or rerupture observed during follow-up. Petrous internal carotid artery as a donor site is a reliable bypass modality for UPC. This approach provides the utmost retrograde flow to alleviate the development of dissecting aneurysms, preserves eloquent perforators of the basilar trunk, maintains bypass patency, and shortens the graft course. Therefore, this novel therapeutic alternative could be beneficial for improving the prognosis of basilar trunk aneurysms.

Cranio-Orbital Pretemporal Approach With Extradural Anterior Clinoidectomy and Optic Nerve Release for Microsurgical Resection of Large Tuberculum Sellae Meningioma-Reversal of Preoperative Bilateral Blindness: 2-Dimensional Operative Video.

Cranio-Orbital Pretemporal Approach With Extradural Anterior Clinoidectomy and Optic Nerve Release for Microsurgical Resection of Large Tuberculum Sellae Meningioma-Reversal of Preoperative Bilateral Blindness: 2-Dimensional Operative Video.

Pretemporal Transcavernous Approach for Resection of Non-meningeal Tumors of the Cavernous Sinus: Single Center Experience.

ObjectivesTo study the outcomes of the pretemporal transcavernous approach in the treatment of non-meningeal tumors involving cavernous sinus and to investigate the surgical strategy for these lesions.MethodsWe conducted a retrospective study of 45 patients with non-meningeal tumors involving cavernous sinus. All 45 patients received microsurgical resection via the pretemporal transcavernous approach from April 2012 to January 2019 by the same neurosurgeon. We analyzed clinical manifestations, image data, perioperative complications, surgical outcomes, functional outcomes, and follow-up data of these patients.ResultsGross total resection was achieved in 38 cases (84.4%) of the 45 patients. Preoperatively, a total of 64 individual cranial nerves were affected. Postoperatively, 92.2% of 64 impaired cranial nerves completely or partially restored function, 7.8% had worsened function compared with their preoperative statuses, and 5 new cranial nerve deficits (CNV) were observed in five patients during the last follow-up. Seven patients presented transient new cranial nerve deficits (5 CNIII and 2 CNVI), three cases suffered transient worsen cranial nerve deficits (3 CNIII and 1 CNVII). There were no cases of intracranial hematoma, intracranial infection, cerebrospinal fluid leaks, and death. The progression of residual tumor was observed in two patients (1 chordoma and 1 pituitary adenoma).ConclusionsNon-meningeal tumors involving cavernous sinus can be safely and radically removed with less morbidity and mortality. Pretemporal transcavernous approach is an ideal approach to the cavernous sinus and can be tailored individually.

Novel System of Simulation Models for Aneurysm Clipping Training: Description of Models and Assessment of Face, Content, and Construct Validity.

Aneurysm clipping simulation models are needed to provide tactile feedback of biological vessels in a nonhazardous but surgically relevant environment. To describe a novel system of simulation models for aneurysm clipping training and assess its validity. Craniotomy models were fabricated to mimic actual tissues and movement restrictions experienced during actual surgery. Turkey wing vessels were used to create aneurysm models with patient-specific geometry. Three simulation models (middle cerebral artery aneurysm clipping via a pterional approach, anterior cerebral artery aneurysm clipping via an interhemispheric approach, and basilar artery aneurysm clipping via an orbitozygomatic pretemporal approach) were subjected to face, content, and construct validity assessments by experienced neurosurgeons (n=8) and neurosurgery trainees (n=8). Most participants scored the model as replicating actual aneurysm clipping well and scored the difficulty of clipping as being comparable to that of real surgery, confirming face validity. Most participants responded that the model could improve clip-applier-handling skills when working with patients, which confirms content validity. Experienced neurosurgeons performed significantly better than trainees on all 3 models based on subjective (P=.003) and objective (P<.01) ratings and on time to complete the task (P=.04), which confirms construct validity. Simulations were used to discuss clip application strategies and compare them to prototype clinical cases. This novel aneurysm clipping model can be used safely outside the wet laboratory; it has high face, content, and construct validity; and it can be an effective training tool for microneurosurgery training during aneurysm surgery courses.

Pure Interventricular Craniopharyngioma

Craniopharyngiomas (CPs) of the third ventricle are rare and can be difficult to treat due to their deep location and relation to neurological structures. A 60-year-old woman presented with a history of memory disturbances with progressive course. On examination, she was conscious but disoriented with time and place, visual field showed bilateral superolateral quadrantanopia, and KPS was 90. Brain images revealed a third ventricular mass that bowed the floor of the third ventricle, expanding into the supraoptic recess, compressing the optic chiasm downward and forward. The mass had solid and cystic components at its inferior and periphery. The patient underwent right pretemporal approach with orbital roof being removed, and a translamina terminalis route was used to reach the third ventricle and the tumor was completely removed. Preoperative localization of the ventricular CPs is essential to choose the optimal surgical approach to avoid undesired injuries and improve the surgical outcome.

Double-Stage Complete Removal of Dumbbell-Shaped Trigeminal Schwannoma: 3-Dimensional Operative Video

Intracranial trigeminal schwannomas are rare tumors.1-4 The aim of this 3-dimensional operative video is to present a double stage complete removal of a dumbbell-shaped trigeminal schwannoma. This is a 25-yr-old male with headaches, diplopia, and facial pain. The MRI shows a big tumor located at the level of the cerebellopontine angle, petroclival region, and middle fossa. Because of the size of the tumor and its growth within the cerebellopontine angle, we decided to operate the patient in two stages. For the first surgery, the patient was in a semi-sitting position, and a retrosigmoid approach was performed. The second surgery was performed 2 mo after the first operation in a supine position for a pretemporal transzygomatic approach. The pathological study was reported as a schwannoma, and the histological findings were spindle cell lesion with a storiform pattern and histiocytes. The patient evolved without neurological deficit after the surgeries, and the postoperative MRI shows a complete resection of the tumor. The patient gave the consent to use the images and surgical video. Preoperative imaging plays an important role in diagnosis and surgical planning.3-6 For these cases of trigeminal schwannomas with a large extension in the posterior fossa and middle fossa, we believe that the most prudent thing is to perform the surgery in 2 stages.3.

Cranio-Orbital Pretemporal Approach for Resection of Right Superior Orbital Fissure/Orbital Renal Cell Metastasis: 2-Dimensional Operative Video.

Orbital metastatic lesions are rare entities1-3 best treated with radical surgical resection with preservation/improvement of neurological and visual function.1-9 Renal cell metastases, in particular, respond less favorably to radiation.9 To our knowledge, an operative video of microsurgical resection of a renal cell carcinoma metastasis to the superior orbital fissure and orbit has not been reported.A patient presented with worsening right eye vision as demonstrated on preoperative visual field testing and found to have a 3 × 1 × 1 cm lesion in the orbit and superior orbital fissure. The patient was placed supine and stealth neuronavigation was used to aid in tumor localization and extension. A cranio-orbital craniotomy and pretemporal exposure2,10,11 were performed to allow extradural dissection of the dura propria off the lateral wall of the cavernous sinus. Right-sided extradural cranial nerves II, III, IV, V1, and V2 were identified, and a high-speed diamond drill was used to perform extradural anterior clinoidectomy and optic nerve decompression. Microsurgical resection of the intraorbital tumor components was performed by the senior author (KIA) to delineate the plane between tumor and periorbita. An oval-shaped dural opening was made to resect the dura involved by tumor, confirmed on histological analysis, followed by closure via dural allograft. The patient's right-sided visual field improved markedly after surgery.Metastatic renal cell carcinoma of the orbit should be resected while preserving and improving preoperative neurological and visual function. The orbitocranial pretemporal approach offers wide visualization to achieve surgical resection.The patient provided written consent and permission to publish her image.

Autologous Temporalis Subfascial Fat Graft for Skull Base Repair: A Novel Technique.

Autologous abdominal fat grafts are occasionally used in the repair of skull base exposures. This surgical procedure typically requires an additional surgical site and may have unexpected postoperative complications. To describe an operative technique for harvesting subfascial fat from the temporal extension of the buccal fat pad for the repair of skull base defects. We review the pertinent anatomy of the temporalis subfascial fat pad and discuss the technique used to harvest the subfascial fat component in a clinical presentation. A pretemporal approach was performed for clip ligation of an anterior circulation aneurysm. A standard frontotemporal incision was made with an interfascial flap to preserve the frontalis branches of the facial nerve. The subfascial fat was inspected and determined to be adequate for harvesting. Monopolar cauterization was carefully utilized to remove the fat. During closure, the graft was used to repair a pneumatized clinoid sinus and for the dural repair of the pretemporal exposure. The patient did not have any postoperative complications. Autologous temporalis subfascial fat graft is a viable and safe technique for skull base dural and sinus repair during frontotemporal approaches in select patients. This technique avoids an additional surgical procedure and potential complications that may be associated with it.

Morphometric Comparison of the Pterional Trans-Sylvian and the Pretemporal Trans-Clinoidal Approaches to the Posterior Communicating Artery.

Posterior communicating (Pcom) aneurysms in the modern era have tended toward increased complexity and technical difficulties. The pretemporal approach is a valuable extension to the pterional approach for basilar apex aneurysms, but its advantages for Pcom aneurysms have not been previously elucidated. To quantify characteristics of the pretemporal approach to the Pcom. We dissected 6 cadaveric heads (12 sides) with a pretemporal transclinoidal approach and measured the following variables: (1) exposed length of internal carotid artery (ICA) proximal to the Pcom artery; (2) exposed circumference of ICA at the origin of Pcom; (3) deep working area between the optic nerve and tentorium/oculomotor nerve; (4) superficial working area; (5) exposure depth; and (6) the frontotemporal (superior posterolateral) and (7) orbito-sphenoidal (inferior anterolateral) angles of exposure. Compared with pterional craniotomy, the pretemporal transclinoidal approach increased the exposed length of the proximal ICA from 3.3 to 11.7 mm (P=.0001) and its circumference from 5.1 to 7.8 mm (P=.0003), allowing a 210° view of the ICA (vs 137.9°). The deep and superficial working areas also significantly widened from 53.7 to 92.4 mm2 (P=.0048) and 252.8 to 418.2 mm2 (P=.0001), respectively; the depth of the exposure was equivalent. The frontotemporal and spheno-Sylvian angles increased by 17° (P=.0006) and 10° (P=.0037), respectively. The pretemporal approach can be useful for complex Pcom aneurysms by providing easier proximal control, wider working space, improved aneurysm visualization, and more versatile clipping angles. Enhanced exposure results in a potentially higher rate of complete aneurysm obliteration and complication avoidance.

Temporary Clipping of the Intracavernous Internal Carotid Artery: A Novel Technique for Proximal Control.

Securing proximal control in complex paraclinoid aneurysm surgery through traditional techniques may be challenging and risky in certain situations. Advancements of anatomical knowledge of the cavernous sinus (CS) and hemostasis have made it more accessible as a surgical option. To describe the technique of temporary clipping of the horizontal segment of the intracavernous internal carotid artery (IC-ICA) in preparation for permanent clipping of complex paraclinoid aneurysms. Through an extradural pretemporal approach, the lateral wall of the CS is exposed. The dura between the trochlear nerve and V1 is opened, and access is made to the horizontal segment of the IC-ICA. After circumferential dissection, the temporary clip can be introduced to the artery, and the extradural clinoidectomy can be continued under secured proximal control. Seven patients with complex paraclinoid aneurysms were treated between May 2013 and May 2016 by the senior author. Temporary clipping of the IC-ICA was performed in all cases. Average time to achieve proximal control was 22.6 min (22.6±13.8). One patient developed transient oculomotor palsy postoperatively. There were no other complications. When the exposed clinoidal segment of the internal carotid artery does not offer sufficient proximal space for temporary clipping, the extradural approach can be extended to the horizontal portion of the IC-ICA. In our experience, this technique is a quick, reliable, and safe alternative to the classical modalities of temporary occlusion.

The extradural minipterional pretemporal approach for the treatment of spheno-petro-clival meningiomas.

Cavernous sinus and petroclival region is an anatomically complex region in close relationship with important neurovascular structures. As such, the surgical treatment of spheno-petro-clival (SPC) meningiomas represents an operative challenge, in which several routes and its combinations might be used. We describe in detail the surgical technique of the extradural minipterional pretemporal approach (eMPT-P) to the SPC region and highlight the main anatomical key elements involved in this approach as well as the technical aspects for avoiding surgical complications. The eMPT-P is a versatile approach that uses the extradural route, and thereby reduces brain retraction, while provides a good angle of exposure of the SPC region.

The pretemporal approach to anterolateral midbrain cavernous malformations.

Operating on the anterolateral midbrain is challenging due to limited surgical freedom provided by classic approaches and restraints imposed by the basilar artery apex and branches, their perforators, and the oculomotor nerve (Abla et al., 2011; Bricolo and Turazzi, 1995; Cavalcanti et al., 2016).This video demonstrates the benefits provided by the pretemporal approach for resection of an anterolateral mesencephalic cavernous malformation (Chaddad-Neto et al., 2014; de Oliveira et al., 1995). Four steps are well demonstrated in the video: 1) section of temporal pole veins to the sphenoparietal sinus; 2) division of arachnoid attaching the oculomotor nerve to the tentorial edge and uncus; 3) releasing the arachnoid between the anterior choroidal artery and uncus; and 4) following the oculomotor nerve to its origin.The video can be found here: https://youtu.be/7ZuK-ewNo6w.

Morphometric Comparison of the Pterional Trans-sylvian and the Pretemporal Transclinoidal Approaches to Posterior Communicating Artery Aneurysms: Anatomical Study

Abstract INTRODUCTION Due to the advent of endovascular techniques, modern series of surgically treated posterior communicating (Pcom) aneurysms have shown a tendency towards higher complexity and more technical difficulties. The pretemporal approach was described as a valuable extension to the pterional approach in treating basilar apex aneurysms. Its use for clipping of ruptured Pcom aneurysms was associated with decreased ischemic complications. However, its anatomical advantages for Pcom aneurysm surgery have not been previously analyzed. METHODS Six cadaveric heads (12 sides) underwent a sequential dissection, starting with a pterional craniotomy, and then extended to a pretemporal transclinoidal approach. In each step, the following variables were measured, taking the origin of Pcom as a focal point: (1) exposed length of the internal carotid artery (ICA) proximal to the Pcom artery, (2) exposed angular circumference of ICA at the origin of Pcom, (3) deep working area between the optic nerve and tentorium/oculomotor nerve, (4) superficial working area, (5) depth of the exposure and the (6) fronto-temporal (superior posterolateral), and (7) orbito-sphenoidal (inferior anterolateral) angles of exposure. Clinical case examples are used to illustrate the advantages of the pretemporal approach. RESULTS Compared to the pterional craniotomy, the pretemporal transclinoidal approach increased the exposed length of the proximal ICA from 3.3 to 11.7 mm (P = .0001), and its circumference from 5.1 to 7.8 mm (P = .0003), allowing a 210-degree view of the ICA (vs 137.9). The deep and superficial working areas also significantly widened from 53.7 to 92.4 mm2 (P = .0048) and 252.8 to 418.2 mm2 (P = .0001), respectively; while the depth of the exposure was equivalent. The frontotemporal and the sphenosylvian angles increased on average by 17 (P = .0006) and 10 (P = .0037) degrees, respectively. The clinical case examples demonstrate the visual, technical and strategic advantages of the pretemporal approach as a consequence of its anatomical exposure. CONCLUSION The pretemporal approach can be useful for complex Pcom aneurysms by providing easier proximal control, wider working space, aneurysm visualization, and more versatile clipping angles. The enhanced exposure potentially results in a higher rate of complete aneurysm obliteration and complication avoidance.

Resection of anterolateral midbrain cavernous malformation via orbitozygomatic transsylvian pretemporal approach with uncal resection.

Brainstem cavernomas are benign, angiographically occult, low-flow lesions and constitute 18%–35% of intracranial cavernomas.4,6 They are known to have an annual rupture risk of 2%–6%,2,5 and once symptomatic, they frequently cause progressive neurological morbidity. A 22-year-old lady presented with progressive profound neurologic deficits from three distinct hemorrhages over 2 months. Surgery was indicated given the aggressive natural history, and the lesion now presented to the surface with displacement of corticospinal tracts noted on diffusion tensor imaging.1,7 We describe a surgical technique via an orbitozygomatic transsylvian pretemporal approach with uncal resection to open the oculomotor-tentorial window and resect the lesion.3The video can be found here: https://youtu.be/j5yYp4OsaRc.

Right Pretemporal-Transsylvian Approach for Resection of a Midbrain Cavernous Malformation: 3-Dimensional Operative Video.

Brainstem cavernous malformations (CMs) account for 15% to 18% of all intracranial CMs1 and 13% of all cerebrovascular pathology in the posterior fossa.1,2 This video demonstrates the resection of a pontomesencephalic CM through a pretemporal approach through the oculomotor-tentorial triangle (OTT).3 A 49-yr-old woman presented with an acute onset of left hemiparesis, diplopia, vertigo, partial oculomotor, and facial palsy. Neuroimaging revealed a 25-mm diameter right pontomesencephalic CM with evidence of prior hemorrhage. Institutional Review Board approval and patient consent were obtained for surgery. A right orbitozygomatic craniotomy was performed, and the lesion was exposed through a pretemporal-transsylvian approach. After a wide Sylvian fissure split, the oculomotor nerve (CN III) was dissected away from the temporal lobe, and the temporal lobe was mobilized posteriorly to access the OTT. The posterior cerebral and superior cerebellar arteries were visualized in this triangle, and the cerebral peduncle and the CM were accessed deep to these arteries. After hematoma evacuation, the CM was resected in a piece-meal fashion using an intracapsular technique. Postoperative imaging confirmed the gross total resection of the lesion. The patient had persistent right CN III palsy and a slight worsening of left hemiparesis, which had resolved completely at the 6-mo follow-up. The OTT provides access to the upper ventrolateral pontomesencephalic area.3 This triangular surgical workspace is entered through a pretemporal-transsylvian corridor and widened with posterior temporal lobe retraction. The OTT is an important working space for accessing midbrain and upper pontine CMs posterolateral to CN III.

The oculomotor-tentorial triangle. Part 1: microsurgical anatomy and techniques to enhance exposure.

Access to the ventrolateral pontomesencephalic area may be required for resecting cavernous malformations, performing revascularization of the upper posterior circulation, and treating vascular lesions such as aneurysms. However, such access is challenging because of nearby eloquent structures. Commonly used corridors to this surgical area include the optico-carotid, supracarotid, and carotid-oculomotor triangles. However, the window lateral to the oculomotor nerve can also be used and has not been studied. The authors describe the anatomical window formed between the oculomotor nerve and the medial tentorial edge (the oculomotor-tentorial triangle [OTT]) to the ventrolateral pontomesencephalic area, and assess techniques to expand it. Four cadaveric heads (8 sides) underwent orbitozygomatic craniotomy. The OTT was exposed via a pretemporal approach. The contents of the OTT were determined and their anatomical features were recorded. Also, dimensions of the brainstem surface exposed lateral and inferior to the oculomotor nerve were measured. Measurements were repeated after completing a transcavernous approach (TcA), and after resection of temporal lobe uncus (UnR). The s1 segment and proximal s2 segment of the superior cerebellar artery (SCA) and P2A segment of the posterior cerebral artery (PCA) were the main contents of the OTT, with average exposed lengths of 6.4 ± 1.3 mm and 5.5 ± 1.6 mm for the SCA and PCA, respectively. The exposed length of the SCA increased to 9.6 ± 2.7 mm after TcA (p = 0.002), and reached 11.6 ± 2.4 mm following UnR (p = 0.004). The exposed PCA length increased to 6.2 ± 1.6 mm after TcA (p = 0.04), and reached 10.4 ± 1.8 mm following UnR (p < 0.001). The brainstem surface was exposed 7.1 ± 0.5 mm inferior and 5.6 ± 0.9 mm lateral to the oculomotor nerve initially. The exposure inferior to the oculomotor nerve increased to 9.3 ± 1.7 mm after TcA (p = 0.003), and to 9.9 ± 2.5 mm after UnR (p = 0.21). The exposure lateral to the oculomotor nerve increased to 8.0 ± 1.7 mm after TcA (p = 0.001), and to 10.4 ± 2.4 mm after UnR (p = 0.002). The OTT is an anatomical window that provides generous access to the upper ventrolateral pontomesencephalic area, s1- and s2-SCA, and P2A-PCA. This window may be efficiently used to address various pathologies in the region and is considerably expandable by TcA and/or UnR.

Pretemporal ("Half-and-Half") Approach for Posterior Circulation Aneurysms in a Patient With Internal Carotid Artery Occlusion.

Pretemporal ("Half-and-Half") Approach for Posterior Circulation Aneurysms in a Patient With Internal Carotid Artery Occlusion.