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Nancy McLaughlin and Michel W. Bojanowski

✓ The authors report the case of a 34-year-old woman who presented with increasing headaches. Neuroimaging revealed bilateral anomalous vessels arising at the level of each ophthalmic artery, coursing rostromedially to join the anterior communicating artery (ACA), which harbored an aneurysm. Intraoperatively, the authors identified an abnormal gyral segmentation of the frontoorbital region, with a median gyrus separated from the olfactory tracts on each side by the gyrus rectus. No interhemispheric fissure was observed in the exposed area. This is the first report in the literature of an abnormal gyral segmentation in association with an infraoptic course of an ACA. Recognition of this possible gyral abnormality in association with this vascular anomaly is relevant for surgical exposure and treatment of aneurysms by clip placement.

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Nancy McLaughlin and Michel W. Bojanowski

Elongation of the anterior cerebral artery (ACA) and subsequent compression of the chiasm rarely have been reported as causes of a visual field deficit. Neither has microvascular decompression of the chiasm been described in this circumstance. The authors report on a case of progressive visual deficits caused by compression of the optic apparatus by a right elongated ACA as documented on MR imaging. Microvascular decompression was proposed as treatment. The right A1 segment was larger than usual and tortuous, transmitting its pulsations into the chiasm. A piece of Teflon was inserted between the A1 segment and the chiasm. Following surgery, the visual field deficit progressively improved. At 4 months after surgery, the patient's visual fields were normal. Therefore, an elongated ACA can compress the chiasm and result in a visual field deficit. In such circumstances when facing a progressive visual field deficit, microvascular decompression may improve vision.

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Nancy Mclaughlin and Michel W. Bojanowski

Object. Most reports of series on ruptured intracranial aneurysms contain information on select intraoperative complications. An understanding of all surgical complications, however, may guide us toward improved surgical procedures and enrich discussions concerning alternative management strategies, such as endovascular treatment, which are not exempt from complications and aneurysm recurrence.

Methods. The study consists of a retrospective review of the charts, images, and notes from follow-up visits of 143 consecutive patients with subarachnoid hemorrhage (SAH) who were surgically treated during a 3-year period by one neurosurgeon. A surgical complication was determined based on findings of a clinical and/or radiological study in the absence of confounding factors such as the initial SAH ictus, vasospasm, hydrocephalus, and septic status. Functional outcome was assessed between 2 and 3 months post-SAH by using the Glasgow Outcome Scale (GOS). A procedure-related surgical complication was diagnosed in 29 (20.3%) of 143 patients studied. A brain tissue injury, including cerebral edema and hemorrhagic contusions, was diagnosed in 6.3% of patients, an unpredicted residual aneurysm neck in 5.3% of patients, and a cranial nerve deficit in 2.8% of patients. Functional outcome was good in 22 (75.9%) of the 29 patients with surgical complications. Death due to a surgical complication occurred in one (0.7%) of 143 patients.

Conclusions. Surgical complications are more prevalent than previously thought. They may have been overlooked previously because of the high percentage of good functional outcomes and low mortality rates in this group. The identification of surgical complications may encourage the search for solutions to improve surgical treatment of aneurysmal SAH.

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Felix Scholtes, Francesco Signorelli and Michel W. Bojanowski

Intraventricular hemorrhage is common after the rupture of anterior communicating artery (ACoA) aneurysms, although the anatomical pathway has not been described. Knowledge of the mechanism of hemorrhage may enhance understanding of its prognosis. Using CT angiography, the authors analyzed this pathway in 2 cases of ACoA aneurysm rupture associated with intraventricular hemorrhage. The initial hemorrhages created a hyperdense ventriculographic image on which the subsequent contrast medium ejection could be followed. The contrast medium entered the subarachnoid space of the anterior interhemispheric fissure and broke through the lamina rostralis into the septum pellucidum and into the frontal horns of the lateral ventricles. Thus, the authors provide an explanation for bleeding from ACoA aneurysms into the ventricular system in the presence of an intact lamina terminalis. The septum pellucidum may act as a buffer before extension of the bleeding into the ventricular system.

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Judith Marcoux, Daniel ROY and Michel W. Bojanowski

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Marc Lévêque, Nancy McLaughlin, Mathieu Laroche and Michel W. Bojanowski

Distal choroidal artery aneurysms stemming from the lateral wall of the ventricles are rare and are mostly associated with moyamoya disease. The treatment of these aneurysms is difficult because of their deep location. The authors report the case of a 50-year-old woman followed for moyamoya disease presenting with 2 intraventricular hemorrhages. Cerebral angiography showed an aneurysm located on the left distal choroidal artery. Magnetic resonance imaging also demonstrated that the lesion protruded from the lateral wall of the trigone of the left lateral ventricle. Using MR imaging–guided stereotactic localization, the aneurysm was accurately reached endoscopically and successfully resected from the parent artery. The patient was discharged neurologically intact. To the best of the authors' knowledge, this is the first report of a successfully endoscopically treated distal anterior choroidal artery aneurysm. Endoscopic surgery may be added to the armamentarium of procedures used to treat intraventricular aneurysms.

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W. Michel Bojanowski, Robert F. Spetzler and L. Philip Carter

✓ A patient with a giant aneurysm of the left middle cerebral artery (MCA) presented with a history of subarachnoid hemorrhage and ischemic symptoms. When the aneurysm was explored, its base was found to be very firm and atherosclerotic. Temporary clips were applied to the MCA, the aneurysm was excised, and the MCA bifurcation was reconstructed using microsurgical techniques. Good flow in the reconstructed MCA trunk was demonstrated by intracranial Doppler ultrasonography. A description of the operative procedure is presented.

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Pierre-Olivier Champagne, Emile Lemoine and Michel W. Bojanowski


Sphenoid wing meningiomas are a heterogeneous group of tumors with variable surgical risks and prognosis. Those that have grown to a very large size, encasing the major cerebral arteries, are associated with a high risk of stroke. In reviewing the authors’ series of giant sphenoid wing meningiomas, the goal was to evaluate how the extent of the tumor’s invasion of surrounding structures affected the ability to safely remove the tumor and restore function.


The authors conducted a retrospective study of a series of giant sphenoid wing meningiomas operated on between 1996 and 2016. Inclusion criteria were meningiomas with a globoid component ≥ 6 cm, encasing at least 1 major intradural cerebral artery. Extent of resection was measured according to Simpson grade.


This series included 12 patients, with a mean age of 59 years. Visual symptoms were the most common clinical presentation. There was complete or partial encasement of all 3 major cerebral arteries except for 3 cases in which only the anterior cerebral artery was not involved. The lateral wall of the cavernous sinus was invaded in 8 cases (67%) and the optic canal in 6 (50%). Complete resection was achieved in 2 cases (Simpson grades 2 and 3). In the remaining 10 cases of partial resection (Simpson grade 4), radical removal (> 90%) was achieved in 7 cases (70%). In the immediate postoperative period, there were no deaths. Four of 9 patients with visual deficits improved, while the 5 others remained unchanged. Two patients experienced transient neurological deficits. Other than an asymptomatic lacuna of the internal capsule, there were no ischemic lesions following surgery. Tumor recurrence occurred in 5 patients, between 24 and 168 months (mean 61 months) following surgery.


Although these giant lesions encasing major cerebral arteries are particularly treacherous for surgery, this series demonstrates that it is possible to safely achieve radical removal and at times even gross-total resection. However, the risk of recurrence remains high and larger studies are needed to see if and how improvement can be achieved, whether in surgical technique or technological advances, and by determining the timing and modality of adjuvant radiation therapy.

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Josée Bérubé, Nancy Mclaughlin, Pierre Bourgouin, Gilles Beaudoin and Michel W. Bojanowski


Conventional imaging demonstrates intertwined fibers of the cerebral white matter as a homogeneous substrate. Recently, diffusion tensor imaging has allowed 3D reconstruction of these fiber bundles. The goal of this study was to analyze the modifications of the association fibers induced by an arteriovenous malformation (AVM) in the parietotemporooccipital (PTO) associative area and their clinical significance.


The authors analyzed the long association fibers in seven patients harboring an AVM in or near the PTO region in relation with the fibers' clinical manifestation. The fibers include the arcuate fasciculus (AF), the occipitofrontal fasciculus (OFF), and the inferior longitudinal fasciculus (ILF). These structures were compared with the contra-lateral bundles.


The modification of the tracts could establish a pattern signature depending on the specific location of the vascular malformation. There was a positive correlation between the degree of modifications of OFF and ILF fiber tracts and visual deficits. Alteration of the AF correlated with a speech disorder and the risk of postoperative deficits.


Diffusion tensor imaging enables in vivo dissection of fiber tracts coursing through the PTO area. Depending on the location of the AVMs, long association fibers are variously modified. These findings correlate with clinical manifestations and may predict outcome after surgery.

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Michel W. Bojanowski, Alexander G. Weil, Nancy McLaughlin, Chiraz Chaalala, Elsa Magro and Jean-Yves Fournier


Blister aneurysms of the supraclinoid part of the internal carotid artery (ICA) are known for their high morbidity and mortality rates related to treatment, regardless of whether the treatment is surgical or endovascular. However, this grim prognosis is based on results that indiscriminately group all blister aneurysms together without taking into account the heterogeneous appearance of these lesions. The goal of this study was 2-fold: to determine whether different blister aneurysm morphologies present different pitfalls, which would then require different surgical strategies, as well as to determine whether there are identifiable subgroups of these types of aneurysms based on morphology.


The authors reviewed the charts, cerebral catheter angiograms, surgical reports, and intraoperative videos of all ICA blister aneurysms treated surgically at the Centre Hospitalier de l'Université de Montréal from 2005 to 2012 to investigate whether there was a relationship between morphology and pitfalls, and whether different surgical strategies had been used according to these pitfalls. During this review process the authors noted 4 distinct morphological aspects. These 4 aspects led to a review of the English and French literature on blister aneurysms in which imaging was available, to determine whether other cases could also be classified into the same 4 subgroups based on these morphological aspects.


The retrospective review of the authors’ series of 10 patients allowed a division into 4 distinct subtypes: Type I (classic), Type II (berry-like), Type III (longitudinal), and Type IV (circumferential). These subtypes may at times be progressive stages in the arterial anomaly, and could represent a continuum. Each subtype described in this paper presented its own pitfalls and required specific surgical adaptations. Upon reviewing the literature the authors retained 35 studies involving a total of 61 cases of blister aneurysms, and all cases were able to be classified into 1 of these 4 distinct subtypes.


Although they share some common characteristics, blister aneurysms may be divided into distinct subtypes, suggestive of a continuum. Such a classification with a detailed description of each type of blister aneurysm would allow for better recognition to anticipate complications during intervention and better assess the different treatment strategies according to the subtypes.