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Hirotaka Hasegawa, Tomohiro Inoue, Akira Tamura and Isamu Saito

Acute internal carotid artery (ICA) terminus occlusion is associated with extremely poor functional outcomes or mortality, especially when it is caused by plaque rupture of the cervical ICA with engrafted thrombus that elongates and extends into the ICA terminus. The goal of this study was to evaluate the efficacy and safety of surgical embolectomy in conjunction with carotid endarterectomy (CEA) for acute ICA terminus occlusion associated with cervical plaque rupture resulting in tandem occlusion. A retrospective review of medical records was performed. Clinical and radiographic characteristics were evaluated, including details of surgical technique, recanalization grade, recanalization time, complications, modified Rankin Scale (mRS) score at 3 months, and National Institutes of Health Stroke Scale (NIHSS) score improvement at 1 month. Three patients (mean age 77.3 years; median presenting NIHSS Score 22, range 19–26) presented with abrupt tandem occlusion of the cervical ICA and ICA terminus and were selected for surgery after confirmation of embolic high-density signal at the ICA terminus on CT and diffusion-weighted imaging (DWI)/magnetic resonance angiography (MRA) mismatch. All patients underwent craniotomy for surgical embolectomy of the ICA terminus embolus followed by cervical exposure, aspiration of long residual proximal embolus ranging from the cervical to cavernous ICA, and removal of ruptured unstable plaque by CEA. Postoperative MRA demonstrated Thrombolysis In Myocardial Infarction (TIMI) 3 recanalization in all patients (100%) without evidence of additional infarction according to DWI. Mean recanalization time from hospital arrival was 234 minutes and from start of surgery, 151 minutes. Serial postoperative CT and MRI studies showed no symptomatic hemorrhage, brain edema, or progression of infarction. The patients' mRS scores at 3 months were 3, 3, and 1. All 3 patients demonstrated marked improvements in NIHSS scores (median 17 points; range 13–23 points) at 1 month. Considering the dismal prognosis associated with ICA terminus occlusion, especially when accompanied by cervical plaque rupture, emergent surgical embolectomy in conjunction with CEA might be an effective and decisive treatment option with a high complete recanalization rate and acceptable safety profile.

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Tomohiro Inoue, Akira Tamura and Isamu Saito

The authors show a surgical technique of trapping/resection of ruptured dominant vertebral artery aneurysm in conjunction with reconstruction of vertebral artery by V3–radial artery (RA) graft–V4 bypass through suboccipital craniotomy and far lateral approach. Step by step muscle dissection in posterior fossa enable fine exposure of occipital artery for possible OA-PICA bypass and V3 portion of vertebral artery. Extradural drilling of posterior one-third condyle and condylar fossa facilitate exposure of triangular surgical corridor made by medulla, spinal root of 11th nerve and lower cranial nerves, and thus enabling aneurismal resection and RA–V4 anastomosis.

The video can be found here: http://youtu.be/LxsARGdHSVw.

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Shinya Suematsu, Hideaki Ono, Tomohiro Inoue and Akira Tamura

This video demonstrates a surgical technique of resecting dorsum sellae meningioma using a combined interhemispheric translamina terminalis approach and pterional approach with clinoidectomy. The tumor, 5 cm in maximum diameter, originated from the dorsum sellae, compressed the third ventricle and the midbrain, and displaced the pituitary stalk ventrally. Feeding arteries of the tumor were bilateral meningohypophyseal trunks, mainly from the right side. The authors performed devascularization of the tumor via a right pterional approach following frontotemporal craniotomy, and debulking of the tumor via an interhemispheric translamina terminalis approach following bifrontal craniotomy. These procedures with two separate craniotomies enabled safe and effective resection of the tumor.

The video can be found here: https://youtu.be/DEnKOC5zQ_M.

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Takashi Inoue, Yasutaka Kuzu, Kuniaki Ogasawara and Akira Ogawa

Object

This study investigated the changes in the valve pressure setting of several magnetic pressure-programmable valves after exposure to a 3-tesla magnetic field.

Methods

Five each of four types of pressure-programmable shunt valves were tested: Sophy Polaris, Sophy SM8, Codman-Hakim, and Medtronic Strata. First, the valves were advanced toward the 3-tesla static magnetic field. Second, T1-, T2-, and diffusion-weighted magnetic resonance (MR) images were generated with a radiofrequency magnetic field. Any changes in the pressure setting were observed by visual inspection with a compass or radiography.

The pressure settings were changed after exposure to the static magnetic field in all programmable valves except for the Sophy Polaris. All pressure settings studied were unchanged after exposure to both static and radiofrequency magnetic fields (T1-, T2-, and diffusion-weighted MR imaging) in the Sophy Polaris.

Conclusions

The Sophy Polaris valve allows shunt-dependent patients who need a programmable valve to undergo 3-tesla MR imaging.

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Misao Nishikawa, Hiroaki Sakamoto, Akira Hakuba, Naruhiko Nakanishi and Yuichi Inoue

✓ To investigate overcrowding in the posterior cranial fossa as the pathogenesis of adult-type Chiari malformation, the authors studied the morphology of the brainstem and cerebellum within the posterior cranial fossa (neural structures consisting of the midbrain, pons, cerebellum, and medulla oblongata) as well as the base of the skull while taking into consideration their embryological development. Thirty patients with Chiari malformation and 50 normal control subjects were prospectively studied using neuroimaging. To estimate overcrowding, the authors used a “volume ratio” in which volume of the posterior fossa brain (consisting of the midbrain, pons, cerebellum, and medulla oblongata within the posterior cranial fossa) was placed in a ratio with the volume of the posterior fossa cranium encircled by bony and tentorial structures. Compared to the control group, in the Chiari group there was a significantly larger volume ratio, the two occipital enchondral parts (the exocciput and supraocciput) were significantly smaller, and the tentorium was pronouncedly steeper. There was no significant difference in the posterior fossa brain volume or in the axial lengths of the hindbrain (the brainstem and cerebellum). In six patients with basilar invagination the medulla oblongata was herniated, all three occipital enchondral parts (the basiocciput, exocciput, and supraocciput) were significantly smaller than in the control group, and the volume ratio was significantly larger than that in the Chiari group without basilar invagination.

These results suggest that in adult-type Chiari malformation an underdeveloped occipital bone, possibly due to underdevelopment of the occipital somite originating from the paraxial mesoderm, induces overcrowding in the posterior cranial fossa, which contains the normally developed hindbrain. Basilar invagination is associated with a more severe downward herniation of the hindbrain due to the more severely underdeveloped occipital enchondrium, which further exacerbates overcrowding of the posterior cranial fossa.

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Misao Nishikawa, Hiroaki Sakamoto, Akira Hakuba, Naruhiko Nakanishi and Yuichi Inoue

To investigate overcrowding in the posterior cranial fossa as the pathogenesis of adult-type Chiari malformation, the authors studied the morphology of the brainstem and cerebellum within the posterior cranial fossa (neural structures consisting of the midbrain, pons, cerebellum, and medulla oblongata) as well as the base of the skull while taking into consideration their embryological development. Thirty patients with Chiari malformation and 50 normal control subjects were prospectively studied using neuroimaging. To estimate overcrowding, the authors used a "volume ratio" in which volume of the posterior fossa brain (consisting of the midbrain, pons, cerebellum, and medulla oblongata within the posterior cranial fossa) was placed in a ratio with the volume of the posterior fossa cranium encircled by bony and tentorial structures. Compared to the control group, in the Chiari group there was a significantly larger volume ratio, the two occipital enchondral parts (the exocciput and supraocciput) were significantly smaller, and the tentorium was pronouncedly steeper. There was no significant difference in the posterior fossa brain volume or in the axial lengths of the hindbrain (the brainstem and cerebellum). In six patients with basilar invagination the medulla oblongata was herniated, all three occipital enchondral parts (the basiocciput, exocciput, and supraocciput) were significantly smaller than in the control group, and the volume ratio was significantly larger than that in the Chiari group without basilar invagination.

These results suggest that in adult-type Chiari malformation an underdeveloped occipital bone, possibly due to underdevelopment of the occipital somite originating from the paraxial mesoderm, induces overcrowding in the posterior cranial fossa, which contains the normally developed hindbrain. Basilar invagination is associated with a more severe downward herniation of the hindbrain due to the more severely underdeveloped occipital enchondrium, which further exacerbates overcrowding of the posterior cranial fossa.

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Satoshi Kiyofuji, Tomohiro Inoue, Akira Tamura and Isamu Saito

This video demonstrates combined two separate craniotomies for two difficult unruptured cerebral aneurysms. The anterior communicating artery (ACOM) aneurysm existed at a high position, projected posteriorly, and thus necessitated an interhemispheric approach. Left middle cerebral artery (MCA) aneurysm with complex figure was treated through a separate pterional approach. Meticulous micro-cisternal opening under high magnification enabled safe and effective exposure of both aneurysms with minimal brain retraction, which alleviated brain damage as shown in postoperative images.

The video can be found here: http://youtu.be/mBYsaAVekCA.

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Yuki Ito, Tomohiro Inoue, Akira Tamura and Kazuo Tsutsumi

The authors demonstrate an interhemispheric transchoroidal approach for third ventricular teratoma resection. Interhemispheric dissection exposed the corpus callosum at a length of about 2 cm. A callosotomy was made to enter into the right lateral ventricle. After septal vein ligation, dissection was made of the space between the right fornix and right internal cerebral vein (ICV); thus bilateral fornix and left ICV would be retracted to the left; right choroid plexus, right ICV to the right. By this transchoroidal approach, the foramen of Monro was extended posteriorly, providing enough of a surgical corridor to resect a posteriorly located third ventricular tumor.

The video can be found here: https://youtu.be/gIzPiH3zx_o.

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Tomohiro Inoue, Hiroki Yoshida, Akira Tamura and Isamu Saito

The authors show a surgical technique of clipping in conjunction with superficial temporal artery (STA)–middle cerebral artery (MCA) bypass to treat unruptured anterior communicating artery (AcomA) aneurysm associated with unilateral MCA occlusion. First, through MCA occlusion side, fronto-temporal craniotomy, extra-dural drilling of lesser sphenoid wing, and followed by wide exposure of Sylvian fissure, STA–MCA bypass was performed. Then, through trans-Sylvian, fronto-basal, and lateral trajectory, interhemispheric fissure was dissected from the base, which enabled good exposure and clipping of high positioned AcomA aneurysm.

The video can be found here: http://youtu.be/GWItnRSs3m4.

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Satoshi Kiyofuji, Tomohiro Inoue, Hirotaka Hasegawa, Akira Tamura and Isamu Saito

Embolic intracranial large artery occlusion with severe neurological deficit is associated with an extremely poor prognosis. The safest and most effective treatment strategy has not yet been determined when such emboli are associated with unstable proximal carotid plaque. The authors performed emergent surgical embolectomy for left middle cerebral artery (MCA) occlusion, and the patient experienced marked neurological recovery without focal deficit and regained premorbid activity. Postoperative investigation revealed “vulnerable plaque” of the left internal carotid artery without apparent evidence of cardiac embolism, such as would be seen with atrial fibrillation. Specimens from subsequent elective carotid endarterectomy (CEA) showed ruptured vulnerable plaque that was histologically consistent as a source of the intracranial embolic specimen. Surgical embolectomy for MCA occlusion due to carotid plaque rupture followed by CEA could be a safer and more effective alternative to endovascular treatment from the standpoint of obviating the risk of secondary embolism that could otherwise occur as a result of the manipulation of devices through an extremely unstable portion of plaque. Further, this strategy is associated with a high probability of complete recanalization with direct removal of hard and large, though fragile, emboli.