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Despite technological advances in endovascular therapy, surgical clipping of paraclinoid aneurysms remains an indispensable treatment option and has an acceptable profile risk. Intraoperative monitoring of motor and somatosensory evoked potentials has proven to be an effective tool in predicting and preventing postoperative motor deficits during aneurysm clipping.1,2 We describe the case of a 61-yr-old Japanese woman with a history of hypertension and smoking. During follow-up for bilateral aneurysms of ophthalmic segment of the internal carotid artery (ICA), left-sided aneurysm growth was detected. A standard pterional approach with extradural clinoidectomy was used to approach the aneurysm. After clipping, a significant intraprocedural change in motor evoked potential (MEP) amplitude was observed despite native vessel patency was confirmed through micro-Doppler and indocyanine green video angiography.3-5 After extensive dissection of the sylvian fissure and exposure of the communicating segment of ICA, the anterior choroidal artery was found to be compressed and occluded by the posterior clinoid because of an inadvertent shift of the ICA after clip application and removal of brain retractors. Posterior clinoidectomy was performed intradurally with microrongeur and MEP amplitude returned readily to baseline values. Computed tomography (CT) angiogram demonstrated complete exclusion of the aneurysm, and magnetic resonance imaging (MRI) was negative for postoperative ischemic lesions on diffusion weighted images. The patient tolerated the procedure well and was discharged home on postoperative day 3 with modified Rankin Scale (mRS) 0. The patient signed the Institutional Consent Form to undergo the surgical procedure and to allow the use of her images and videos for any type of medical publications.

Abstract BACKGROUND: Magnetic resonance angiography (MRA) is helpful for preoperatively evaluating the degree of carotid stenosis, although it is not always useful for assessing surgical accessibility to the distal internal carotid artery (ICA) due to the lack of osteological information. OBJECTIVE: To demonstrate a method for evaluating the accessible distal portion of the ICA for carotid endarterectomy (CEA) using MRA. METHODS: As an indicator of the upper limit of the operating field, a line drawn from the C1 transverse process to the hyoid bone (C1-H line) was defined. The cross-point between the C1-H line and distal ICA was delineated on 3-dimensional (3-D) MRA and 3-D tomography angiography (CTA). The distance between the carotid bifurcation and C1-H line was measured in 11 patients. The exposed distal ICA was compared with the extent of intraoperative ICA exposure. RESULTS: The mean vertical distance (27.5 mm) from the carotid bifurcation to the C1-H line measured using 3-D MRA was almost the same as the distance (28 mm) evaluated on 3-D CTA. The discrepancy in distance between the 2 modalities was 1.9 ± 1.7 mm. Furthermore, the point of the ICA across the C1-H line created on 3-D MRA was in accordance with the intraoperative measurement (28.7 mm) of the exposed ICA. CONCLUSION: The C1-H line measured on 3-D MRA is a simple and useful indicator of the distal point of the accessible ICA during CEA, especially in patients with renal dysfunction and allergies to contrast medium.

Abstract BACKGROUND Microsurgical clipping with extradural anterior clinoidectomy (EDAC) for paraclinoid aneurysm is an established technique with good angiographic outcomes, although postoperative worsening of visual acuity remains a concern. Multiple reports show visual acuity deteriorating after clipping, yet the cause remains unclear. OBJECTIVE To analyze results of asymptomatic paraclinoid aneurysm surgeries treated with EDACs, specifically focusing on the microanatomy of paraclinoid structure dissection. This determined the causes of delayed visual impairment and microsurgical indications. METHODS Results of the treatment with EDAC of 94 patients with cerebral aneurysm and normal preoperative visual acuity but also full visual fields were retrospectively analyzed. RESULTS The mean aneurysm size was 6.2 (±3.3) mm. Clipping was performed in 87 cases and trapping in 7 cases. Complete angiographic occlusion was observed in 91 patients. In 26 cases, a postoperative visual deficit occurred. A total of 20 cases exhibited partial visual field deficits, including 5 who were asymptomatic. Visual deficits were only detectable by postoperative ophthalmologic testing. Six showed light perception impairment or blinding. Of the 15 patients with symptomatic partial visual field deficits, 5 showed improvement at follow-up. Visual deficits persisted in 22 patients at the last follow-up. Multivariate logistic regression analysis revealed that medial projecting aneurysm (adjusted odds ratio [OR]: 10.43) and the opening of the carotidoculomotor membrane (adjusted OR: 5.19) were significantly related to visual impairment. CONCLUSION Excess dissection of carotidoculomotor membranes causes postoperative delayed visual worsening. For treating small, asymptomatic paraclinoid aneurysms, carotidoculomotor membranes should not be opened, and microsurgical clipping should not be performed for preoperative asymptomatic medial projecting aneurysms.

BACKGROUND:In a short window of time, intravenous and intra-arterial thrombolysis is the first treatment option for patients with an acute ischemic stroke caused by the occlusion of one of the major brain vessels. Endovascular treatment techniques provide additional treatment options. In selected cases, high revascularization rates following microsurgical thromboembolectomy in the anterior circulation were reported. A technical note on successful thromboembolectomy of the proximal posterior cerebral artery has not yet been published. OBJECTIVE:To describe the technique of microsurgical thromboembolectomy of an acute proximal posterior cerebral artery occlusion and the brainstem perforators via the anterior temporal approach. METHODS:The authors present a technical report of a successful thromboembolectomy in the proximal posterior cerebral artery. The 64-year-old male patient had an acute partial P1 thromboembolic occlusion, with contraindications for intravenous recombinant tissue plasminogen activator. The patient underwent an urgent microsurgical thromboembolectomy after a frontotemporal craniotomy. RESULTS:The postoperative computerized tomography angiography showed complete recanalization of the P1 segment and its perforators, which were previously occluded. The early outcome after 1 month and 1 year follow-ups showed improvement from modified Rankin scale 4 to modified Rankin scale 1. CONCLUSION:Microsurgical thromboembolectomy can be an effective treatment option for proximal occlusion of the posterior cerebral artery in selected cases and experienced hands. Compared with endovascular treatment, direct visual control of brainstem perforators is possible. ABBREVIATIONS:ICG, indocyanine greenmRS, modified Rankin scaleP1, precommunicating segment of posterior cerebral arteryPCA, posterior cerebral arteryr-tPA, recombinant tissue plasminogen activator

Background The preoperative imaging diagnosis of the distal portion of the internal carotid artery (ICA) is extremely important for carotid endarterectomy (CEA). Herein the authors defined a line from the C1 transverse process to the hyoid bone (C1-H line) and evaluated whether the line can be used to predict an accessible ICA in CEA. Methods A cross point between the C1-H line and distal ICA was analyzed using three-dimensional computerized tomographic angiography (3D-CTA) in 20 patients. The C1-H line was compared to the line drawn from the mastoid process to the mandible (M-M line). Intraoperative exposure of the distal ICA was evaluated using both lines. Furthermore, the distance of each line from the C2 vertebra was measured to identify the distance difference of each line in relation to the cervical posture. Results A distal ICA exposed at a cross point of the C1-H line corresponded well with the intraoperative findings. The cross point between the C1-H line and distal ICA was positioned at an average of 7.0 ± 0.7 mm cranially in comparison to the M-M line. The C1-H line showed smaller distance differences at different cervical positions than the M-M line. The C1-H line moved an average of 2.8 ± 2.5 mm from a cervical neutral position to an extensional one in the perpendicular direction. Conclusion The C1-H line measured by 3D-CTA is a simple and useful indicator of the distal ICA exposure in the preoperative diagnosis for CEA.

Abstract BACKGROUND: It is essential to identify and be aware of the anatomy of the posterior condylar emissary vein (PCEV) for achieving an adequate operative field for the transcondylar fossa approach (TCFA). OBJECTIVE: To describe the variations in the drainage patterns of PCEVs and the technical issues encountered in such cases. METHODS: This was a retrospective analysis of the anatomy of PCEVs in 104 sides in 52 cases treated by the TCFA. Preoperative findings of multidetector-row computed tomography (CT) and CT venography (CTV) were compared with the intraoperative findings. The drainage patterns were classified as 5 types: the sigmoid sinus (SS), jugular bulb (JB), occipital sinus (OS), anterior condylar emissary vein (ACEV), and marginal sinus (MS). RESULTS: The SS, JB, ACEV, and OS types were observed in 33 (31.7%), 42 (40.3%), 8 (7.7%), and 1 (1.0%) side(s), respectively. One side (1.0%) each had combined drainage from MS and JB, and ACEV and JB, respectively. In 17 sides (16.3%), the PCEVs and posterior condylar canals could not be identified on CT and CTV. CONCLUSIONS: Preoperative CT and CTV findings correlated well with the intraoperative findings. To make a sufficient operative field for TCFA, PCEVs should be appropriately dealt with based on the preoperative knowledge of their running course, pattern, and origin.

Intracranial osteomas completely unrelated to osseous tissues are extremely rare. In the present study, the case of a 40-year-old female who presented with persistent headache is reported. Computed tomography (CT) and bone window CT revealed an ossified lesion in the frontal area. Fast imaging employing steady-state acquisition (FIESTA)/CT venography fusion imaging demonstrated that the mass was located just below the superior sagittal sinus and cortical veins, and had adhered partially to these veins. Surgery achieved complete tumor removal with preservation of the cortical veins and superior sagittal sinus. The histological examination findings were compatible with osteoma. The present postoperative course was uneventful. The present rare case of intracranial osteoma originating from the falx was successfully treated surgically. Preoperative FIESTA/CT venography fusion imaging was very useful to demonstrate adhesion between the tumor mass and the superior sagittal sinus and cortical veins.

Object Coil extraction during microsurgery for recanalized intracranial aneurysms can be associated with high morbidity. We evaluated our preliminary experience using the clip-coil ratio to predict the need for coil extraction. Methods A multi-institutional retrospective review of previously coiled aneurysms that were clipped for recurrence between 2005 and 2009 was performed. The maximal height and the widths of the recanalization were measured. The largest of these dimensions was divided by the other. We defined this as the clip-coil ratio, which is a modification of the aspect ratio. Results Thirteen patients were included in this study. The mean age of the patients was 53 years (range 41–68 years). The aneurysm locations were anterior communicating artery ( n  = 5), pericallosal artery ( n  = 2), ophthalmic artery ( n  = 1), and posterior communicating artery ( n  = 5). A clip-coil ratio ≥1.3 allowed for microsurgical clipping without coil extraction. The mean ratio in these patients was 1.6. Coil extraction was necessary in two patients with a clip-coil ratio <1.3. Conclusion In reviewing our preliminary experience, we observed that coil extraction during microsurgery was not necessary when the clip coil ratio was ≥1.3. The ratio may serve as an indirect indicator of the amount of aneurysm tissue that can be incorporated within a clip; however, given the small patient population, further studies are needed to validate this concept.