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Ayumi Narisawa, Toshiki Endo, Kenichi Sato, Mika Watanabe, Akira Takahashi and Teiji Tominaga

The authors report on a 49-year-old man with a thoracic spinal dural arteriovenous shunt (dAVS) in which rupture of a varix caused intramedullary hemorrhage. In the literature, patients with a thoracic dAVS predominantly present with congestive myelopathy; however, the patient featured in this report presented without increased deep tendon reflexes or muscle weakness, but instead with intermittent stabbing chest pain and paresthesia. Magnetic resonance images and angiograms demonstrated tortuous enlargement and the formation of a varix-like structure of the draining veins, features compatible with those of high-flow angiopathy. Recognition of this phenomenon is important in thoracic dAVS because intramedullary hemorrhage dramatically degrades outcome. A high index of clinical suspicion can prevent a similar case of thoracic dAVS from progressing to intramedullary hemorrhage.

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Sherif Rashad, Shin-ichiro Sugiyama, Kuniyasu Niizuma, Kenichi Sato, Hidenori Endo, Shunsuke Omodaka, Yasushi Matsumoto, Miki Fujimura and Teiji Tominaga

OBJECTIVE

Risk factors for aneurysm rupture have been extensively studied, with several factors showing significant correlations with rupture status. Several studies have shown that aneurysm shape and hemodynamics change after rupture. In the present study the authors investigated a static factor, the bifurcation angle, which does not change after rupture, to understand its effect on aneurysm rupture risk and hemodynamics.

METHODS

A hospital database was retrospectively reviewed to identify patients with cerebral aneurysms treated surgically or endovascularly in the period between 2008 and 2015. After acquiring 3D rotational angiographic data, 3D stereolithography models were created and computational fluid dynamic analysis was performed using commercially available software. Patient data (age and sex), morphometric factors (aneurysm volume and maximum height, aspect ratio, bifurcation angle, bottleneck ratio, and neck/parent artery ratio), and hemodynamic factors (inflow coefficient and wall shear stress) were statistically compared between ruptured and unruptured groups.

RESULTS

Seventy-one basilar tip aneurysms were included in this study, 22 ruptured and 49 unruptured. Univariate analysis showed aspect ratio, bifurcation angle, bottleneck ratio, and inflow coefficient were significantly correlated with a ruptured status. Logistic regression analysis showed that aspect ratio and bifurcation angle were significant predictors of a ruptured status. Bifurcation angle was inversely correlated with inflow coefficient (p < 0.0005), which in turn correlated directly with mean (p = 0.028) and maximum (p = 0.014) wall shear stress (WSS) using Pearson's correlation coefficient, whereas aspect ratio was inversely correlated with mean (0.012) and minimum (p = 0.018) WSS.

CONCLUSIONS

Bifurcation angle and aspect ratio are independent predictors for aneurysm rupture. Bifurcation angle, which does not change after rupture, is correlated with hemodynamic factors including inflow coefficient and WSS, as well as rupture status. Aneurysms with the hands-up bifurcation configuration are more prone to rupture than aneurysms with other bifurcation configurations.

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Alaa Elkordy, Hidenori Endo, Kenichi Sato, Yasushi Matsumoto, Ryushi Kondo, Kuniyasu Niizuma, Toshiki Endo, Miki Fujimura and Teiji Tominaga

OBJECTIVE

The anterior and posterior choroidal arteries are often recruited to supply arteriovenous malformations (AVMs) involving important paraventricular structures, such as the basal ganglia, internal capsule, optic radiation, lateral geniculate body, and medial temporal lobe. Endovascular embolization through these arteries is theoretically dangerous because they supply eloquent territories, are of small caliber, and lack collaterals. This study aimed to investigate the safety and efficacy of embolization through these arteries.

METHODS

This study retrospectively reviewed 13 patients with cerebral AVMs who underwent endovascular embolization through the choroidal arteries between 2006 and 2014. Embolization was performed as a palliative procedure before open surgery or Gamma Knife radiosurgery. Computed tomography and MRI were performed the day after embolization to assess any surgical complications. The incidence and type of complications and their association with clinical outcomes were analyzed.

RESULTS

Decreased blood flow was achieved in all patients after embolization. Postoperative CT detected no hemorrhagic complications. In contrast, postoperative MRI detected that 4 of the 13 patients (30.7%) developed infarctions: 3 patients after embolization through the anterior choroidal artery, and 1 patient after embolization through the lateral posterior choroidal artery. Two of the 4 patients in whom embolization was from the cisternal segment of the anterior choroidal artery (proximal to the plexal point) developed symptomatic infarction of the posterior limb of the internal capsule, 1 of whom developed morbidity (7.7%). The treatment-related mortality rate was 0%. Additional treatment was performed in 12 patients: open surgery in 9 and Gamma Knife radiosurgery in 3 patients. Complete obliteration was confirmed by angiography at the last follow-up in 10 patients. Recurrent bleeding from the AVMs did not occur in any of the cases during the follow-up period.

CONCLUSIONS

Ischemic complications are possible following the embolization of cerebral AVMs through the choroidal artery, even with modern neurointerventional devices and techniques. Although further study is needed, embolization through the choroidal artery may be an appropriate treatment option when the risk of surgery or radiosurgery is considered to outweigh the risk of embolization.

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Kenichi Sato, Toshiki Endo, Kuniyasu Niizuma, Miki Fujimura, Takashi Inoue, Hiroaki Shimizu and Teiji Tominaga

Object

Dural arteriovenous fistulas (DAVFs) and perimedullary arteriovenous fistulas (PAVFs) are uncommonly associated in the craniocervical junction. The purpose of this study was to describe the clinical and angiographic characteristics of such concurrent lesions.

Methods

Authors reviewed 9 cases with a coexistent DAVF and PAVF at the craniocervical junction. Clinical presentation, angiographic characteristics, intraoperative findings, and treatment outcomes were assessed.

Results

All patients (male/female ratio 5:4; mean age 66.3 years) presented with subarachnoid hemorrhage. Angiography revealed that 8 patients had both a DAVF and PAVF on the same side, whereas 1 patient had 3 arteriovenous fistulas, 1 DAVF, and 1 PAVF on the right side and 1 DAVF on the left side. All of the fistulas shared dilated perimedullary veins (anterior spinal vein, 7 cases; anterolateral spinal vein, 2 cases) as a main drainage route. The shared drainage route was rostrally directed in 8 of 9 cases. Eight patients exhibited an arterial aneurysm on the distal side of the feeding arteries to the PAVF, and the aneurysm in each case was intraoperatively confirmed as a bleeding point. One patient had ruptured venous ectasia at the perimedullary fistulous point. All patients underwent direct surgery via a posterolateral approach. No recurrence was observed in the 4 patients who underwent postoperative angiography, and no rebleeding event was recorded among any of the 9 patients during the follow-up period (mean 38.4 months).

Conclusions

The similarity of the angioarchitecture and the close anatomical relationship between DAVF and PAVF at the craniocervical junction suggested that these lesions are pathogenetically linked. The pathophysiological mechanism and anatomical features of these lesions represent a unique vascular anomaly that should be recognized angiographically to plan a therapeutic strategy.

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Hidenori Endo, Yasushi Matsumoto, Ryushi Kondo, Kenichi Sato, Miki Fujimura, Takashi Inoue, Hiroaki Shimizu, Akira Takahashi and Teiji Tominaga

Object

Internal coil trapping is a treatment method used to prevent rebleeding from a ruptured intracranial vertebral artery dissection (VAD). Postoperative medullary infarctions have been reported as a complication of this treatment strategy. The aim of this study was to determine the relationship between a postoperative medullary infarction and the clinical outcomes for patients with ruptured VADs treated with internal coil trapping during the acute stage of a subarachnoid hemorrhage (SAH).

Methods

A retrospective study identified 38 patients who presented between 2006 and 2011 with ruptured VADs and underwent internal coil trapping during the acute stage of SAH. The SAH was identified on CT scanning, and the diagnosis for VAD was rendered by cerebral angiography. Under general anesthesia, the dissection was packed with coils, beginning at the distal end and proceeding proximally. When VAD involved the origin of the posterior inferior cerebellar artery (PICA) with a large cerebellar territory, an occipital artery (OA)–PICA anastomosis was created prior to internal coil trapping. The pre- and postoperative radiological findings, clinical course, and outcomes were analyzed.

Results

The internal coil trapping was completed within 24 hours after admission. An OA-PICA anastomosis followed by internal coil trapping was performed in 5 patients. Postoperative rebleeding did not occur in any patient during a mean follow-up period of 16 months. The postoperative MRI studies showed medullary infarctions in 18 patients (47%). The mean length of the trapped VAD for the infarction group (15.7 ± 6.0 mm) was significantly longer than that of the noninfarction group (11.5 ± 4.3 mm) (p = 0.019). Three of the 5 patients treated with OA-PICA anastomosis had postoperative medullary infarction. The clinical outcomes at 6 months were favorable (modified Rankin Scale Scores 0–2) for 23 patients (60.5%) and unfavorable (modified Rankin Scale Scores 3–6) for 15 patients (39.5%). Of the 18 patients with postoperative medullary infarctions, the outcomes were favorable for 6 patients (33.3%) and unfavorable for 12 patients (66.7%). A logistic regression analysis predicted the following independent risk factors for unfavorable outcomes: postoperative medullary infarctions (OR 21.287 [95% CI 2.622–498.242], p = 0.003); preoperative rebleeding episodes (OR 7.450 [95% CI 1.140–71.138], p = 0.036); and a history of diabetes mellitus (OR 45.456 [95% CI 1.993–5287.595], p = 0.013).

Conclusions

A postoperative medullary infarction was associated with unfavorable outcomes after internal coil trapping for ruptured VADs. Coil occlusion of the long segment of the VA led to medullary infarction, and an OA-PICA bypass did not prevent medullary infarction. A VA-sparing procedure, such as flow diversion by stenting, is an alternative treatment in the future, if this approach is demonstrated to effectively prevent rebleeding.

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Ahmed Mansour, Kuniyasu Niizuma, Sherif Rashad, Akira Sumiyoshi, Rie Ryoke, Hidenori Endo, Toshiki Endo, Kenichi Sato, Ryuta Kawashima and Teiji Tominaga

OBJECTIVE

The cognitive deficits of vascular dementia and the vasoocclusive state of moyamoya disease have often been mimicked with bilateral stenosis/occlusion of the common carotid artery (CCA) or internal carotid artery. However, the cerebral blood flow (CBF) declines abruptly in these models after ligation of the CCA, which differs from “chronic” cerebral hypoperfusion. While some modified but time-consuming techniques have used staged occlusion of both CCAs, others used microcoils for CCA stenosis, producing an adverse effect on the arterial endothelium. Thus, the authors developed a new chronic cerebral hypoperfusion (CCH) model with cognitive impairment and a low mortality rate in rats.

METHODS

Male Sprague-Dawley rats were subjected to unilateral CCA occlusion and contralateral induction of CCA stenosis (modified CCA occlusion [mCCAO]) or a sham operation. Cortical regional CBF (rCBF) was measured using laser speckle flowmetry. Cognitive function was assessed using a Barnes circular maze (BCM). MRI studies were performed 4 weeks after the operation to evaluate cervical and intracranial arteries and parenchymal injury. Behavioral and histological studies were performed at 4 and 8 weeks after surgery.

RESULTS

The mCCAO group revealed a gradual CBF reduction with a low mortality rate (2.3%). White matter degeneration was evident in the corpus callosum and corpus striatum. Although the cellular density declined in the hippocampus, MRI revealed no cerebral infarctions after mCCAO. Immunohistochemistry revealed upregulated inflammatory cells and angiogenesis in the hippocampus and cerebral cortex. Results of the BCM assessment indicated significant impairment in spatial learning and memory in the mCCAO group. Although some resolution of white matter injury was observed at 8 weeks, the animals still had cognitive impairment.

CONCLUSIONS

The mCCAO is a straightforward method of producing a CCH model in rats. It is associated with a low mortality rate and could potentially be used to investigate vascular disease, moyamoya disease, and CCH. This model was verified for an extended time point of 8 weeks after surgery.

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Shunsuke Omodaka, Hidenori Endo, Kuniyasu Niizuma, Miki Fujimura, Takashi Inoue, Toshiki Endo, Kenichi Sato, Shin-ichiro Sugiyama and Teiji Tominaga

OBJECTIVE

Recent MR vessel wall imaging studies have indicated intracranial aneurysms in the active state could show circumferential enhancement along the aneurysm wall (CEAW). While ruptured aneurysms frequently show CEAW, CEAW in unruptured aneurysms at the evolving state (i.e., growing or symptomatic) has not been studied in detail. The authors quantitatively assessed the degree of CEAW in evolving unruptured aneurysms by comparing it separately to that in stable unruptured and ruptured aneurysms.

METHODS

A quantitative analysis of CEAW was performed in 26 consecutive evolving aneurysms using MR vessel wall imaging. Three-dimensional T1-weighted fast spin echo sequences were obtained before and after contrast media injection, and the contrast ratio of the aneurysm wall against the pituitary stalk (CRstalk) was calculated as the indicator of CEAW. Aneurysm characteristics of evolving aneurysms were compared with those of 69 stable unruptured and 67 ruptured aneurysms.

RESULTS

The CRstalk values in evolving aneurysms were significantly higher than those in stable aneurysms (0.54 vs 0.34, p < 0.0001), and lower than those in ruptured aneurysms (0.54 vs 0.83, p < 0.0002). In multivariable analysis, CRstalk remained significant when comparing evolving with stable aneurysms (odds ratio [OR] 12.23, 95% confidence interval [CI] 3.53–42.41), and with ruptured aneurysms (OR 0.083, 95% CI 0.022–0.310).

CONCLUSIONS

The CEAW in evolving aneurysms was higher than those in stable aneurysms, and lower than those in ruptured aneurysms. The degree of CEAW may indicate the process leading to rupture of intracranial aneurysms, which can be useful additional information to determine an indication for surgical treatment of unruptured aneurysms.

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Shiro Imagama, Yukihiro Matsuyama, Yoshihito Sakai, Hiroshi Nakamura, Yoshito Katayama, Zenya Ito, Norimitsu Wakao, Koji Sato, Mitsuhiro Kamiya, Fumihiko Kato, Yasutsugu Yukawa, Yasushi Miura, Hisatake Yoshihara, Kazuhiro Suzuki, Kei Ando, Kenichi Hirano, Ryoji Tauchi, Akio Muramoto and Naoki Ishiguro

Object

The purpose of this study was to provide the first evidence for image classification of idiopathic spinal cord herniation (ISCH) in a multicenter study.

Methods

Twelve patients who underwent surgery for ISCH were identified, and preoperative symptoms, severity of paralysis and myelopathy, disease duration, plain radiographs, MR imaging and CT myelography findings, surgical procedure, intraoperative findings, data from spinal cord monitoring, and postoperative recovery were investigated in these patients. Findings on sagittal MR imaging and CT myelography were classified into 3 types: a kink type (Type K), a discontinuous type (Type D), and a protrusion type (Type P). Using axial images, the location of the hiatus was classified as either central (Type C) or lateral (Type L), and the laterality of the herniated spinal cord was classified based on correspondence (same; Type S) or noncorrespondence (opposite; Type O) with the hiatus location. A bone defect at the ISCH site and the laterality of the defect were also noted.

Results

Patients with Type P herniation had a good postoperative recovery, and those with a Type C location had significant severe preoperative lower-extremity paralysis and a significantly poor postoperative recovery. Patients with a bone defect had a significantly severe preoperative myelopathy, but showed no difference in postoperative recovery.

Conclusions

The authors' results showed that a Type C classification and a bone defect have strong relationships with severity of symptoms and surgical outcome and are important imaging and clinical features for ISCH. These findings may allow surgeons to determine the severity of preoperative symptoms and the probable surgical outcome from imaging.