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David G. Brachman, Emad Youssef, Christopher J. Dardis, Nader Sanai, Joseph M. Zabramski, Kris A. Smith, Andrew S. Little, Andrew G. Shetter, Theresa Thomas, Heyoung L. McBride, Stephen Sorensen, Robert F. Spetzler and Peter Nakaji

OBJECTIVE

Effective treatments for recurrent, previously irradiated intracranial meningiomas are limited, and resection alone is not usually curative. Thus, the authors studied the combination of maximum safe resection and adjuvant radiation using permanent intracranial brachytherapy (R+BT) in patients with recurrent, previously irradiated aggressive meningiomas.

METHODS

Patients with recurrent, previously irradiated meningiomas were treated between June 2013 and October 2016 in a prospective single-arm trial of R+BT. Cesium-131 (Cs-131) radiation sources were embedded in modular collagen carriers positioned in the operative bed on completion of resection. The Cox proportional hazards model with this treatment as a predictive term was used to model its effect on time to local tumor progression.

RESULTS

Nineteen patients (median age 64.5 years, range 50–78 years) with 20 recurrent, previously irradiated tumors were treated. The WHO grade at R+BT was I in 4 (20%), II in 14 (70%), and III in 2 (10%) cases. The median number of prior same-site radiation courses and same-site surgeries were 1 (range 1–3) and 2 (range 1–4), respectively; the median preoperative tumor volume was 11.3 cm3 (range 0.9–92.0 cm3). The median radiation dose from BT was 63 Gy (range 54–80 Gy). At a median radiographic follow-up of 15.4 months (range 0.03–47.5 months), local failure (within 1.5 cm of the implant bed) occurred in 2 cases (10%). The median treatment-site time to progression after R+BT has not been reached; that after the most recent prior therapy was 18.3 months (range 3.9–321.9 months; HR 0.17, p = 0.02, log-rank test). The median overall survival after R+BT was 26 months, with 9 patient deaths (47% of patients). Treatment was well tolerated; 2 patients required surgery for complications, and 2 experienced radiation necrosis, which was managed medically.

CONCLUSIONS

R+BT utilizing Cs-131 sources in modular carriers represents a potentially safe and effective treatment option for recurrent, previously irradiated aggressive meningiomas.

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M. Yashar S. Kalani, Kaan Yağmurlu and Robert F. Spetzler

The authors describe the interpeduncular fossa safe entry zone as a route for resection of ventromedial midbrain lesions. To illustrate the utility of this novel safe entry zone, the authors provide clinical data from 2 patients who underwent contralateral orbitozygomatic transinterpeduncular fossa approaches to deep cavernous malformations located medial to the oculomotor nerve (cranial nerve [CN] III). These cases are supplemented by anatomical information from 6 formalin-fixed adult human brainstems and 4 silicone-injected adult human cadaveric heads on which the fiber dissection technique was used.

The interpeduncular fossa may be incised to resect anteriorly located lesions that are medial to the oculomotor nerve and can serve as an alternative to the anterior mesencephalic safe entry zone (i.e., perioculomotor safe entry zone) for resection of ventromedial midbrain lesions. The interpeduncular fossa safe entry zone is best approached using a modified orbitozygomatic craniotomy and uses the space between the mammillary bodies and the top of the basilar artery to gain access to ventromedial lesions located in the ventral mesencephalon and medial to the oculomotor nerve.

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Robert F. Spetzler, Joseph M. Zabramski, Cameron G. McDougall, Felipe C. Albuquerque, Nancy K. Hills, Robert C. Wallace and Peter Nakaji

OBJECTIVE

The Barrow Ruptured Aneurysm Trial (BRAT) is a prospective, randomized trial in which treatment with clipping was compared to treatment with coil embolization. Patients were randomized to treatment on presentation with any nontraumatic subarachnoid hemorrhage (SAH). Because all other randomized trials comparing these 2 types of treatments have been limited to saccular aneurysms, the authors analyzed the current BRAT data for this subgroup of lesions.

METHODS

The primary BRAT analysis included all sources of SAH: nonaneurysmal lesions; saccular, blister, fusiform, and dissecting aneurysms; and SAHs from an aneurysm associated with either an arteriovenous malformation or a fistula. In this post hoc review, the outcomes for the subgroup of patients with saccular aneurysms were further analyzed by type of treatment. The extent of aneurysm obliteration was adjudicated by an independent neuroradiologist not involved in treatment.

RESULTS

Of the 471 patients enrolled in the BRAT, 362 (77%) had an SAH from a saccular aneurysm. Patients with saccular aneurysms were assigned equally to the clipping and the coiling cohorts (181 each). In each cohort, 3 patients died before treatment and 178 were treated. Of the 178 clip-assigned patients with saccular aneurysms, 1 (1%) was crossed over to coiling, and 64 (36%) of the 178 coil-assigned patients were crossed over to clipping. There was no statistically significant difference in poor outcome (modified Rankin Scale score > 2) between these 2 treatment arms at any recorded time point during 6 years of follow-up. After the initial hospitalization, 1 of 241 (0.4%) clipped saccular aneurysms and 21 of 115 (18%) coiled saccular aneurysms required retreatment (p < 0.001). At the 6-year follow-up, 95% (95/100) of the clipped aneurysms were completely obliterated, compared with 40% (16/40) of the coiled aneurysms (p < 0.001). There was no difference in morbidity between the 2 treatment groups (p = 0.10).

CONCLUSIONS

In the subgroup of patients with saccular aneurysms enrolled in the BRAT, there was no significant difference between modified Rankin Scale outcomes at any follow-up time in patients with saccular aneurysms assigned to clipping compared with those assigned to coiling (intent-to-treat analysis). At the 6-year follow-up evaluation, rates of retreatment and complete aneurysm obliteration significantly favored patients who underwent clipping compared with those who underwent coiling.

Clinical trial registration no.: NCT01593267 (clinicaltrials.gov)

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Sam Safavi-Abbasi, M. Yashar S. Kalani, Ben Frock, Hai Sun, Kaan Yagmurlu, Felix Moron, Laura A. Snyder, Randy J. Hlubek, Joseph M. Zabramski, Peter Nakaji and Robert F. Spetzler

OBJECTIVE

Fusiform cerebral aneurysms represent a small portion of intracranial aneurysms; differ in natural history, anatomy, and pathology; and can be difficult to treat compared with saccular aneurysms. The purpose of this study was to examine the techniques of treatment of ruptured and unruptured fusiform intracranial aneurysms and patient outcomes.

METHODS

In 45 patients with fusiform aneurysms, the authors retrospectively reviewed the presentation, location, and shape of the aneurysm; the microsurgical technique; the outcome at discharge and last follow-up; and the change in the aneurysm at last angiographic follow-up.

RESULTS

Overall, 48 fusiform aneurysms were treated in 45 patients (18 male, 27 female) with a mean age of 49 years (median 51 years; range 6 months–76 years). Twelve patients (27%) had ruptured aneurysms and 33 (73%) had unruptured aneurysms. The mean aneurysm size was 8.9 mm (range 6–28 mm). The aneurysms were treated by clip reconstruction (n = 22 [46%]), clip-wrapping (n = 18 [38%]), and vascular bypass (n = 8 [17%]). The mean (SD) hospital stay was 19.0 ± 7.4 days for the 12 patients with subarachnoid hemorrhage and 7.0 ± 5.6 days for the 33 patients with unruptured aneurysms. The mean follow-up was 38.7 ± 29.5 months (median 36 months; range 6–96 months). The mean Glasgow Outcome Scale score for the 12 patients with subarachnoid hemorrhage was 3.9; for the 33 patients with unruptured aneurysms, it was 4.8. No rehemorrhages occurred during follow-up. The overall annual risk of recurrence was 2% and that of rehemorrhage was 0%.

CONCLUSIONS

Fusiform and dolichoectatic aneurysms involving the entire vessel wall must be investigated individually. Although some of these aneurysms may be amenable to primary clipping and clip reconstruction, these complex lesions often require alternative microsurgical and endovascular treatment. These techniques can be performed with acceptable morbidity and mortality rates and with low rates of early rebleeding and recurrence.

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Kaan Yagmurlu, M. Yashar S. Kalani, Mark C. Preul and Robert F. Spetzler

The authors describe a safe entry zone, the superior fovea triangle, on the floor of the fourth ventricle for resection of deep dorsal pontine lesions at the level of the facial colliculus. Clinical data from a patient undergoing a suboccipital telovelar transsuperior fovea triangle approach to a deep pontine cavernous malformation were reviewed and supplemented with 6 formalin-fixed adult human brainstem and 2 silicone-injected adult human cadaveric heads using the fiber dissection technique to illustrate the utility of this novel safe entry zone. The superior fovea has a triangular shape that is an important landmark for the motor nucleus of the trigeminal, abducens, and facial nerves. The inferior half of the superior fovea triangle may be incised to remove deep dorsal pontine lesions through the floor of the fourth ventricle. The superior fovea triangle may be used as a safe entry zone for dorsally located lesions at the level of the facial colliculus.

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Kaan Yagmurlu, Sam Safavi-Abbasi, Evgenii Belykh, M. Yashar S. Kalani, Peter Nakaji, Albert L. Rhoton Jr., Robert F. Spetzler and Mark C. Preul

OBJECTIVE

The aim of this investigation was to modify the mini-pterional and mini-orbitozygomatic (mini-OZ) approaches in order to reduce the amount of tissue traumatization caused and to compare the use of the 2 approaches in the removal of circle of Willis aneurysms based on the authors' clinical experience and quantitative analysis.

METHODS

Three formalin-fixed adult cadaveric heads injected with colored silicone were examined. Surgical freedom and angle of attack of the mini-pterional and mini-OZ approaches were measured at 9 anatomical points, and the measurements were compared. The authors also retrospectively reviewed the cases of 396 patients with ruptured and unruptured single aneurysms in the circle of Willis treated by microsurgical techniques at their institution between January 2006 and November 2014.

RESULTS

A significant difference in surgical freedom was found in favor of the mini-pterional approach for access to the ipsilateral internal carotid artery (ICA) and middle cerebral artery (MCA) bifurcations, the most distal point of the ipsilateral posterior cerebral artery (PCA), and the basilar artery (BA) tip. No statistically significant differences were found between the mini-pterional and mini-OZ approaches for access to the posterior clinoid process, the most distal point of the superior cerebellar artery (SCA), the anterior communicating artery (ACoA), the contralateral ICA bifurcation, and the most distal point of the contralateral MCA. A trend toward increasing surgical freedom was found for the mini-OZ approach to the ACoA and the contralateral ICA bifurcation. The lengths exposed through the mini-OZ approach were longer than those exposed by the mini-pterional approach for the ipsilateral PCA segment (11.5 ± 1.9 mm) between the BA and the most distal point of the P2 segment of the PCA, for the ipsilateral SCA (10.5 ± 1.1 mm) between the BA and the most distal point of the SCA, and for the contralateral anterior cerebral artery (ACA) (21 ± 6.1 mm) between the ICA bifurcation and the most distal point of the A2 segment of the ACA. The exposed length of the contralateral MCA (24.2 ± 8.6 mm) between the contralateral ICA bifurcation and the most distal point of the MCA segment was longer through the mini-pterional approach. The vertical angle of attack (anteroposterior direction) was significantly greater with the mini-pterional approach than with the mini-OZ approach, except in the ACoA and contralateral ICA bifurcation. The horizontal angle of attack (mediolateral direction) was similar with both approaches, except in the ACoA, contralateral ICA bifurcation, and contralateral MCA bifurcation, where the angle was significantly increased in the mini-OZ approach.

CONCLUSIONS

The mini-pterional and mini-OZ approaches, as currently performed in select patients, provide less tissue traumatization (i.e., less temporal muscle manipulation, less brain parenchyma retraction) from the skin to the aneurysm than standard approaches. Anatomical quantitative analysis showed that the mini-OZ approach provides better exposure to the contralateral side for controlling the contralateral parent arteries and multiple aneurysms. The mini-pterional approach has greater surgical freedom (maneuverability) for ipsilateral circle of Willis aneurysms.

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João Luiz Vitorino Araujo, José C. E. Veiga, Hung Tzu Wen, Almir F. de Andrade, Manoel J. Teixeira, José P. Otoch, Albert L. Rhoton Jr., Mark C. Preul, Robert F. Spetzler and Eberval G. Figueiredo

OBJECTIVE

Access to the third ventricle is a veritable challenge to neurosurgeons. In this context, anatomical and morphometric studies are useful for establishing the limitations and advantages of a particular surgical approach. The transchoroidal approach is versatile and provides adequate exposure of the middle and posterior regions of the third ventricle. However, the fornix column limits the exposure of the anterior region of the third ventricle. There is evidence that the unilateral section of the fornix column has little effect on cognitive function. This study compared the anatomical exposure afforded by the transforniceal-transchoroidal approach with that of the transchoroidal approach. In addition, a morphometric evaluation of structures that are relevant to and common in the 2 approaches was performed.

METHODS

The anatomical exposure provided by the transcallosal-transchoroidal and transcallosal-transforniceal-transchoroidal approaches was compared in 8 fresh cadavers, using a neuronavigation system. The working area, microsurgical exposure area, and angular exposure on the longitudinal and transversal planes of 2 anatomical targets (tuber cinereum and cerebral aqueduct) were compared. Additionally, the thickness of the right frontal lobe parenchyma, thickness of the corpus callosum trunk, and longitudinal diameter of the interventricular foramen were measured. The values obtained were submitted to statistical analysis using the Wilcoxon test.

RESULTS

In the quantitative evaluation, compared with the transchoroidal approach, the transforniceal-transchoroidal approach provided a greater mean working area (transforniceal-transchoroidal 150 ± 11 mm2; transchoroidal 121 ± 8 mm2; p < 0.05), larger mean microsurgical exposure area (transforniceal-transchoroidal 101 ± 9 mm2; transchoroidal 80 ± 5 mm2; p < 0.05), larger mean angular exposure area on the longitudinal plane for the tuber cinereum (transforniceal-transchoroidal 71° ± 7°; transchoroidal 64° ± 6°; p < 0.05), and larger mean angular exposure area on the longitudinal plane for the cerebral aqueduct (transforniceal-transchoroidal 62° ± 6°; transchoroidal 55° ± 5°; p < 0.05). No differences were observed in angular exposure along the transverse axis for either anatomical target (tuber cinereum and cerebral aqueduct; p > 0.05). The mean thickness of the right frontal lobe parenchyma was 35 ± 3 mm, the mean thickness of the corpus callosum trunk was 10 ± 1 mm, and the mean longitudinal diameter of the interventricular foramen was 4.6 ± 0.4 mm. In the qualitative assessment, it was noted that the transforniceal-transchoroidal approach led to greater exposure of the third ventricle anterior region structures. There was no difference between approaches in the exposure of the structures of the middle and posterior region.

CONCLUSIONS

The transforniceal-transchoroidal approach provides greater surgical exposure of the third ventricle anterior region than that offered by the transchoroidal approach. In the population studied, morphometric analysis established mean values for anatomical structures common to both approaches.

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Alfred P. See, Bruno C. Flores, Karam Moon, Andrew F. Ducruet, Robert F. Spetzler and Felipe C. Albuquerque

Supratentorial arteriovenous malformations in eloquent territories can be difficult to resect. This video presents the treatment of a patient with a symptomatic 3-cm arteriovenous malformation in the left motor strip. At the authors’ institution, per the surgeon’s discretion, preoperative angiography is performed to evaluate the need for preoperative embolization. Multimodality treatment reduced the microsurgical risk by allowing early occlusion of a draining vein, by decreasing overall intraoperative hemorrhage, and by allowing minimal pial dissection in the deep aspect of the arteriovenous malformation that abutted the corticospinal tract. The choice of embolysate was an additional nuance of the embolization.

The video can be found here: https://youtu.be/HWZ0RjgPEXg.

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M. Yashar S. Kalani, John E. Wanebo, Nikolay L. Martirosyan, Peter Nakaji, Joseph M. Zabramski and Robert F. Spetzler