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Ali Tayebi Meybodi, Michael T. Lawton, Leandro Borba Moreira, Xiaochun Zhao, Michael J. Lang, Peter Nakaji, and Mark C. Preul

OBJECTIVE

Harvesting the occipital artery (OA) is challenging. The subcutaneous OA is usually found near the superior nuchal line and followed proximally, requiring a large incision and risking damage to the superficially located OA. The authors assessed the anatomical feasibility and safety of exposing the OA through a retromastoid-transmuscular approach.

METHODS

Using 10 cadaveric heads, 20 OAs were harvested though a 5-cm retroauricular incision placed 5 cm posterior to the external auditory meatus. The underlying muscle layers were sequentially cut and recorded before exposing the OA. Changes in the orientation of muscle fibers were used as a roadmap to expose the OA without damaging it.

RESULTS

The suboccipital segment of the OA was exposed without damage after incising two consecutive layers of muscles and their investing fasciae. These muscles displayed different fiber directions: the superficially located sternocleidomastoid muscle with vertically oriented fibers, and the underlying splenius capitis with anteroposteriorly (and mediolaterally) oriented fibers. The OA could be harvested along the entire length of the skin incision in all specimens. If needed, the incision can be extended proximally and/or distally to follow the OA and harvest greater lengths.

CONCLUSIONS

This transmuscular technique for identification of the OA is a reliable method and may facilitate exposure and protection of the OA during a retrosigmoid approach. This technique may obviate the need for larger incisions when planning a bypass to nearby arteries in the posterior circulation via a retrosigmoid craniotomy. Additionally, the small skin incision can be enlarged when a different craniotomy and/or bypass is planned or when a greater length of the OA is needed to be harvested.

Free access

Robert T. Wicks, Xiaochun Zhao, Douglas A. Hardesty, Brandon D. Liebelt, and Peter Nakaji

Ethmoidal dural arteriovenous fistulas (DAVFs) have a near-universal association with cortical venous drainage and a malignant clinical course. Endovascular treatment options are often limited due to the high frequency of ophthalmic artery ethmoidal supply. A 64-year-old gentleman presented with syncope and was found to have a right ethmoidal DAVF. Rather than the traditional bicoronal craniotomy, an endoscope-assisted mini-pterional approach for clip ligation is demonstrated. The mini-pterional craniotomy allows a minimally invasive approach to ethmoidal DAVF via a lateral trajectory. The endoscope can help achieve full visualization in the narrow corridor.

The video can be found here: https://youtu.be/ZroXp-T35DI.

Open access

Peyton L. Nisson, Robert T. Wicks, Xiaochun Zhao, Whitney S. James, David Xu, and Peter Nakaji

Cavernous malformations of the brain are low-flow vascular lesions that have a propensity to hemorrhage. Extensive surgical approaches are often required for operative cure of deep-seated lesions. A 23-year-old female presented with a cavernous malformation of the left posterior insula with surrounding hematoma measuring up to 3 cm. A minimally invasive (mini-)pterional craniotomy with a transsylvian approach was selected. Endoscopic assistance was utilized to confirm complete resection of the lesion. The minipterional craniotomy is a minimally invasive approach that provides optimal exposure for sylvian fissure dissection and resection of many temporal and insular lesions.

The video can be found here: https://youtu.be/9z6_EhU6lxs.

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Lena Mary Houlihan, Evgenii Belykh, Xiaochun Zhao, Michael G. J. O’Sullivan, and Mark C. Preul

Transorbital surgery has gained recent notoriety because of its incorporation into endoscopic skull base surgery. The use of this surgical corridor has been pervasive throughout the 20th century. It has been utilized by multiple disciplines for both clinical and experimental purposes, although its historical origin is medically and ethically controversial. Hermann Knapp first introduced the orbital surgical technique in 1874, and Rudolf Krönlein introduced his procedure in 1889. Rivalry between Walter Dandy in neurosurgery and Raynold Berke in ophthalmology further influenced methods of tackling intracranial and intraorbital pathologies. In 1946, Walter Freeman revolutionized psychosurgery by completing seemingly successful transorbital leucotomies and promoting their minimally invasive and benign surgical characteristics. However, as Freeman’s legacy came into disrepute, so did the transorbital brain access corridor, again resulting in its stunted evolution. Microsurgery and endoscopy further influenced the use, or lack thereof, of the transorbital corridor in neurosurgical approaches. Historical analysis of present goals in modern skull base surgery echoes the principles established through an approach described almost 150 years ago: minimal invasion, minimal morbidity, and priority of patient satisfaction. The progression of the transorbital approach not only reflects psychosocial influences on medical therapy, as well as the competition of surgical pioneers for supremacy, but also describes the diversification of skull base techniques, the impact of microsurgical mastery on circumferential neurosurgical corridors, the influence of technology on modernizing skull base surgery, and the advancing trend of multidisciplinary surgical excellence.

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Colin J. Przybylowski, Benjamin K. Hendricks, Fabio A. Frisoli, Xiaochun Zhao, Claudio Cavallo, Leandro Borba Moreira, Sirin Gandhi, Nader Sanai, Kaith K. Almefty, Michael T. Lawton, and Andrew S. Little

OBJECTIVE

Recently, the prognostic value of the Simpson resection grading scale has been called into question for modern meningioma surgery. In this study, the authors analyzed the relationship between Simpson resection grade and meningioma recurrence in their institutional experience.

METHODS

This study is a retrospective review of all patients who underwent resection of a WHO grade I intracranial meningioma at the authors’ institution from 2007 to 2017. Binary logistic regression analysis was used to assess for predictors of Simpson grade IV resection and postoperative neurological morbidity. Cox multivariate analysis was used to assess for predictors of tumor recurrence. Kaplan-Meier analysis and log-rank tests were used to assess and compare recurrence-free survival (RFS) of Simpson resection grades, respectively.

RESULTS

A total of 492 patients with evaluable data were included for analysis, including 394 women (80.1%) and 98 men (19.9%) with a mean (SD) age of 58.7 (12.8) years. The tumors were most commonly located at the skull base (n = 302; 61.4%) or the convexity/parasagittal region (n = 139; 28.3%). The median (IQR) tumor volume was 6.8 (14.3) cm3. Simpson grade I, II, III, or IV resection was achieved in 105 (21.3%), 155 (31.5%), 52 (10.6%), and 180 (36.6%) patients, respectively. Sixty-three of 180 patients (35.0%) with Simpson grade IV resection were treated with adjuvant radiosurgery. In the multivariate analysis, increasing largest tumor dimension (p < 0.01) and sinus invasion (p < 0.01) predicted Simpson grade IV resection, whereas skull base location predicted neurological morbidity (p = 0.02). Tumor recurrence occurred in 63 patients (12.8%) at a median (IQR) of 36 (40.3) months from surgery. Simpson grade I resection resulted in superior RFS compared with Simpson grade II resection (p = 0.02), Simpson grade III resection (p = 0.01), and Simpson grade IV resection with adjuvant radiosurgery (p = 0.01) or without adjuvant radiosurgery (p < 0.01). In the multivariate analysis, Simpson grade I resection was independently associated with no tumor recurrence (p = 0.04). Simpson grade II and III resections resulted in superior RFS compared with Simpson grade IV resection without adjuvant radiosurgery (p < 0.01) but similar RFS compared with Simpson grade IV resection with adjuvant radiosurgery (p = 0.82). Simpson grade IV resection with adjuvant radiosurgery resulted in superior RFS compared with Simpson grade IV resection without adjuvant radiosurgery (p < 0.01).

CONCLUSIONS

The Simpson resection grading scale continues to hold substantial prognostic value in the modern neurosurgical era. When feasible, Simpson grade I resection should remain the goal of intracranial meningioma surgery. Simpson grade IV resection with adjuvant radiosurgery resulted in similar RFS compared with Simpson grade II and III resections.

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Xiaochun Zhao, Ali Tayebi Meybodi, Mohamed A. Labib, Sirin Gandhi, Evgenii Belykh, Komal Naeem, Mark C. Preul, Peter Nakaji, and Michael T. Lawton

OBJECTIVE

Aneurysms that arise on the medial surface of the paraclinoid segment of the internal carotid artery (ICA) are surgically challenging. The contralateral interoptic trajectory, which uses the space between the optic nerves, can partially expose the medial surface of the paraclinoid ICA. In this study, the authors quantitatively measure the area of the medial ICA accessible through the interoptic triangle and propose a potential patient-selection algorithm that is based on preoperative measurements on angiographic imaging.

METHODS

The contralateral interoptic trajectory was studied on 10 sides of 5 cadaveric heads, through which the medial paraclinoid ICA was identified. The falciform ligament medial to the contralateral optic canal was incised, the contralateral optic nerve was gently elevated, and the medial surface of the paraclinoid ICA was inspected via different viewing angles to obtain maximal exposure. The accessible area on the carotid artery was outlined. The distance from the distal dural ring (DDR) to the proximal and distal borders of this accessible area was measured. The superior and inferior borders were measured using the clockface method relative to a vertical line on the coronal plane. To validate these parameters, preoperative measurements and intraoperative findings were reviewed in 8 clinical cases.

RESULTS

In the sagittal plane, the mean (SD) distances from the DDR to the proximal and distal ends of the accessible area on the paraclinoid ICA were 2.5 (1.52) mm and 8.4 (2.32) mm, respectively. In the coronal plane, the mean (SD) angles of the superior and inferior ends of the accessible area relative to a vertical line were 21.7° (14.84°) and 130.9° (12.75°), respectively. Six (75%) of 8 clinical cases were consistent with the proposed patient-selection algorithm.

CONCLUSIONS

The contralateral interoptic approach is a feasible route to access aneurysms that arise from the medial paraclinoid ICA. An aneurysm can be safely clipped via the contralateral interoptic trajectory if 1) both proximal and distal borders of the aneurysm neck are 2.5–8.4 mm distal to the DDR, and 2) at least one border of the aneurysm neck on the coronal clockface is 21.7°–130.9° medial to the vertical line.

Open access

Xiaochun Zhao, Robert T. Wicks, Evgenii Belykh, Colin J. Przybylowski, Mohamed A. Labib, and Peter Nakaji

Neurocysticercosis is primarily managed with anthelminthic, antiepileptic, and corticosteroid therapies. Surgical removal of the larval cyst is indicated when associated mass effect causes neurological symptoms, as demonstrated in two cases. Cyst resection was achieved via the far lateral approach for a cervicomedullary cyst in one patient and via the subtemporal approach for a mesencephalic cyst in another. The cyst wall should be kept intact, when possible, to avoid dissemination of the inflammation-evoking contents. As the contents are usually semisolid and can be removed via suction, it is not necessary to remove the gliotic capsule or adherent portions of the cyst wall in highly eloquent locations.

The video can be found here: https://youtu.be/GqbaJu5sy1o.

Open access

Jianping Song, Peiliang Li, Yanlong Tian, Xiaochun Zhao, Xiaowen Wang, and Wei Zhu

The large intracranial hemangioblastoma is a top surgical challenge due to its nature of invading brain parenchyma, tight adherence to the pia, and rich blood supply from numerous pial vasculatures and arteries in the proximity. If the brainstem is involved in the lesion, the surgery will be more dangerous because of potential brainstem impingement. In this illustrative video, we present a case of a 54-year-old male with a large hemangioblastoma at the mesencephalic-cerebellar region, which was successfully treated by hybrid endovascular embolization and microsurgery via an occipital interhemispheric transtentorial approach with minimal intraoperative blood loss and a favorable outcome.

The video can be found here: https://youtu.be/pJqFhY_Zhv0.

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Qing Sun, Xiaochun Zhao, Sirin Gandhi, Ali Tayebi Meybodi, Evgenii Belykh, Daniel Valli, Claudio Cavallo, Leandro Borba Moreira, Peter Nakaji, Michael T. Lawton, and Mark C. Preul

OBJECTIVE

The cisternal pulvinar is a challenging location for neurosurgery. Four approaches for reaching the pulvinar without cortical transgression are the ipsilateral supracerebellar infratentorial (iSCIT), contralateral supracerebellar infratentorial (cSCIT), ipsilateral occipital transtentorial (iOCTT), and contralateral occipital transtentorial/falcine (cOCTF) approaches. This study quantitatively compared these approaches in terms of surgical exposure and maneuverability.

METHODS

Each of the 4 approaches was performed in 4 cadaveric heads (8 specimens in total). A 6-sided anatomical polygonal region was configured over the cisternal pulvinar, defined by 6 reachable anatomical points in different vectors. Multiple polygons were subsequently formed to calculate the areas of exposure. The surgical freedom of each approach was calculated as the maximum allowable working area at the proximal end of a probe, with the distal end fixed at the posterior pole of the pulvinar. Areas of exposure, surgical freedom, and the working distance (surgical depth) of all approaches were compared.

RESULTS

No significant difference was found among the 4 different approaches with regard to the surgical depth, surgical freedom, or medial exposure area of the pulvinar. In the pairwise comparison, the cSCIT approach provided a significantly larger lateral exposure (39 ± 9.8 mm2) than iSCIT (19 ± 10.3 mm2, p < 0.01), iOCTT (19 ± 8.2 mm2, p < 0.01), and cOCTF (28 ± 7.3 mm2, p = 0.02) approaches. The total exposure area with a cSCIT approach (75 ± 23.1 mm2) was significantly larger than with iOCTT (43 ± 16.4 mm2, p < 0.01) and iSCIT (40 ± 20.2 mm2, p = 0.01) approaches (pairwise, p ≤ 0.01).

CONCLUSIONS

The cSCIT approach is preferable among the 4 compared approaches, demonstrating better exposure to the cisternal pulvinar than ipsilateral approaches and a larger lateral exposure than the cOCTF approach. Both contralateral approaches described (cSCIT and cOCTF) provided enhanced lateral exposure to the pulvinar, while the cOCTF provided a larger exposure to the lateral portion of the pulvinar than the iOCTT. Medial exposure and maneuverability did not differ among the approaches. A short tentorium may negatively impact an ipsilateral approach because the cingulate isthmus and parahippocampal gyrus tend to protrude, in which case they can obstruct access to the cisternal pulvinar ipsilaterally.

Free access

Xiaochun Zhao, Evgenii Belykh, Colin J. Przybylowski, Leandro Borba Moreira, Sirin Gandhi, Ali Tayebi Meybodi, Claudio Cavallo, Daniel Valli, Robert T. Wicks, and Peter Nakaji

OBJECTIVE

Meningiomas at the falcotentorial junction represent a rare subgroup of complex meningiomas. Debate remains regarding the appropriate treatment strategy for and optimal surgical approach to these tumors, and surgical outcomes have not been well described in the literature. The authors reviewed their single-institution experience in the management, approach selection, and outcomes for patients with falcotentorial meningiomas.

METHODS

From the medical records, the authors identified all patients with falcotentorial meningiomas treated with resection at the Barrow Neurological Institute between January 2007 and October 2017. Perioperative clinical, surgical, and radiographic data were retrospectively collected. For patients who underwent the supracerebellar infratentorial approach, the tentorial angle was defined as the angle between the line joining the nasion with the tuberculum sellae and the tentorium in the midsagittal plane.

RESULTS

Falcotentorial meningiomas occurred in 0.97% (14/1441) of the patients with meningiomas. Most of the patients (13/14) were female, and the mean patient age was 59.8 ± 11.3 years. Of 17 total surgeries (20 procedures), 11 were single-stage primary surgeries, 3 were two-stage primary surgeries (6 procedures), 2 were reoperations for recurrence, and 1 was a reoperation after surgery had been aborted because of brain edema. Hydrocephalus was present in 5 of 17 cases, 4 of which required additional treatment. Various approaches were used, including the supracerebellar infratentorial (4/17), occipital transtentorial/transfalcine (4/17), anterior interhemispheric transsplenial (3/17), parietal transventricular (1/17), torcular (2/17), and staged supracerebellar infratentorial and occipital transtentorial/transfalcine (3/17) approaches. Of the 17 surgeries, 9 resulted in Simpson grade IV resection, and 3, 1, and 4 surgeries resulted in Simpson grades III, II, and I resection, respectively. The tentorial angle in cases with Simpson grade I resection was significantly smaller than in those with an unfavorable resection grade (43.3° ± 4.67° vs 54.0° ± 3.67°, p = 0.04). Complications occurred in 10 of 22 approaches (17 surgeries) and included visual field defects (6 cases, 2 permanent and 4 transient), hemiparesis (2 cases), hemidysesthesia (1 case), and cerebellar hematoma (1 case).

CONCLUSIONS

Falcotentorial meningiomas are challenging lesions. A steep tentorial angle is an unfavorable preoperative radiographic factor for achieving maximal resection with the supracerebellar infratentorial approach. Collectively, the study findings show that versatility is required to treat patients with falcotentorial meningiomas and that treatment goals and surgical approach must be individualized to obtain optimal surgical results.