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Teiji Tominaga, Toshiyuki Takahashi, Hiroaki Shimizu, and Takashi Yoshimoto

✓ Vertebral artery (VA) occlusion by rotation of the head is uncommon, but can result from mechanical compression of the artery, trauma, or atlantoaxial instability. Occipital bone anomalies rarely cause rotational VA occlusion, and patients with nontraumatic intermittent occlusion of the VA usually present with compromised vertebrobasilar flow.

A 34-year-old man suffered three embolic strokes in the vertebrobasilar system within 2 months. Magnetic resonance imaging demonstrated multiple infarcts in the vertebrobasilar territory. Angiography performed immediately after the third attack displayed an embolus in the right posterior cerebral artery. Radiographic and three-dimensional computerized tomography bone images exhibited an anomalous osseous process of the occipital bone projecting to the posterior arch of the atlas. Dynamic angiography indicated complete occlusion of the left VA between the osseous process and the posterior arch while the patient's head was turned to the right. Surgical decompression of the VA resulted in complete resolution of rotational occlusion of the artery.

An occipital bone anomaly can cause rotational VA occlusion at the craniovertebral junction in patients who present with repeated embolic strokes resulting from injury to the arterial wall.

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Teiji Tominaga, Hiroshi Shamoto, Hiroaki Shimizu, Mika Watanabe, and Takashi Yoshimoto

✓ The histological changes that occur in brain tissue have rarely been documented in patients with dural arteriovenous fistulas (AVFs). In this study the authors report on two patients with dural AVFs in the transverse—sigmoid sinus who presented with subarachnoid hemorrhage or progressive dementia. Histological studies of the cerebellar cortices showed a selective loss of Purkinje cells, indicating an ischemic insult caused by venous hypertension. Admission N-isopropyl-p-123I-iodoamphetamine single-photon emission computerized tomography scans demonstrated a decrease in cerebral blood flow, including flow through the cerebellum. Venous hypertension caused by transverse—sigmoid sinus dural AVFs provokes an ischemic condition severe enough to cause selective neuronal damage in the cerebellum.

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Tomoo Inoue, Hiroaki Shimizu, Hitoshi Okabe, and Teiji Tominga

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Taku Sugawara, Naoki Higashiyama, Shinya Tamura, Takuro Endo, and Hiroaki Shimizu

OBJECTIVE

Perineural cysts, also called Tarlov cysts, are dilatations of the nerve root sleeves commonly found in the sacrum. The majority of the cysts are asymptomatic and found incidentally on routine spine imaging. Symptomatic sacral perineural cysts (SPCs) that induce intractable low-back pain, radicular symptoms, and bladder/bowel dysfunction require surgery. However, the surgical strategy for symptomatic SPCs remains controversial. The authors hypothesized that the symptoms were caused by an irritation of the adjacent nerve roots caused by SPCs, and developed a wrapping surgery to treat these cysts.

METHODS

Seven patients with severe unilateral medial thigh pain and ipsilateral SPCs were included. Preoperative MRI showed that the cysts were severely compressing the adjacent nerve roots in all patients. After a partial laminectomy of the sacrum, the SPCs were punctured and CSF was aspirated to reduce their size, followed by dissection of the adjacent nerve roots from the SPCs. The SPCs were then wrapped with a Gore-Tex membrane to avoid reexpansion.

RESULTS

All 7 patients experienced substantial relief of their symptoms. The average numeric rating scale pain score was reduced from an average preoperative value of 7.9 to 0.6 postoperatively. Postoperative MRI showed that all cysts were reduced in size and the adjacent nerve roots were decompressed. Regrowth of the treated cysts or recurrence of the symptoms did not occur during the entire follow-up period, which ranged from 39 to 90 months. No complications were noted.

CONCLUSIONS

The authors’ new wrapping technique was effective in relieving radicular symptoms for patients with symptomatic SPCs. The results suggested that the symptoms stemmed from compression of the adjacent nerve roots caused by the SPCs, and not from the nerve roots in the cysts.

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Hiroshi Karibe, Hiroaki Shimizu, Teiji Tominaga, Keiji Koshu, and Takashi Yoshimoto

Object. Diffusion-weighted (DW) magnetic resonance imaging was used to visualize corticospinal tract injury in patients with deep intracerebral hemorrhage (ICH), and the results were used to predict motor impairment of the extremities.

Methods. Twenty-eight patients with deep ICH (17 men and 11 women, mean age 58 ± 14 years) were examined. The volume of the ICH was assessed on initial computerized tomography scans. Twelve patients had ICH volumes of 40 ml or more and were treated surgically, and 16 patients who had an ICH volume of less than 40 ml were treated medically. Initial corticospinal tract injury was classified into four grades according to the anatomical relationship between the corticospinal tract and the ICH on DW images. Motor impairment of both the upper and lower extremities was assessed at admission and 1 month poststroke by using the National Institutes of Health Stroke Scale. The extent of correlation was determined between motor impairment and corticospinal tract injury.

Initial corticospinal tract injury was not correlated with the impairment of extremities at admission but was closely correlated with motor impairment of the upper (r = 0.843, p < 0.001) and lower (r = 0.868, p < 0.001) extremities at 1 month poststroke. Impairment of the upper extremities correlated better with anterior than with posterior corticospinal tract injury (r = 0.911 compared with r = 0.600), and impairment of the lower extremities correlated better with posterior than with anterior injury (r = 0.890 compared with r = 0.787).

Conclusions. Early evaluation of corticospinal tract injury based on DW imaging can provide predictive value for motor functional outcome in patients with deep ICH.

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Yosuke Akamatsu, Hiroaki Shimizu, Atsushi Saito, Miki Fujimura, and Teiji Tominaga

Object

In the intraluminal suture model of middle cerebral artery occlusion (MCAO) in the mouse, disturbance of blood flow from the internal carotid artery to the posterior cerebral artery (PCA) may affect the size of the infarction. In this study, PCA involvement in the model was investigated and modified for consistent MCAO without involving the PCA territory.

Methods

Thirty-seven C57Bl/6 mice were randomly divided into 4 groups according to the length of coating over the tip of the suture (1, 2, 3, or 4 mm) and subjected to transient MCAO for 2 hours. Real-time topographical cerebral blood flow was monitored over both hemispheres by laser speckle flowmetry. After 24 hours of reperfusion, the infarct territories and volumes were evaluated.

Results

The 1- and 2-mm coating groups showed all lesions in the MCA territory. In the 3- and 4-mm coating groups, 62.5% and 75% of mice, respectively, showed lesions in both the MCA and the PCA territories and other lesions in the MCA territory. Mice in the 1- and 2-mm coating groups had significantly smaller infarct volumes than the 3- and 4-mm groups. Laser speckle flowmetry was useful to distinguish whether the PCA territory would undergo infarction.

Conclusions

Small changes in the coating length of the intraluminal suture may be critical, and 1–2 mm of coating appeared to be optimal to produce consistent MCAO without involving the PCA territory. Laser speckle flowmetry could predict the territory of infarction and improve the consistency of the infarct size.

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Yasuo Nishijima, Kuniyasu Niizuma, Miki Fujimura, Yosuke Akamatsu, Hiroaki Shimizu, and Teiji Tominaga

OBJECT

Numerous studies have attempted to reveal the pathophysiology of ischemic neuronal injury using a representative transient global cerebral ischemia (tGCI) model in rodents; however, most of them have used gerbil or rat models. Recent advances in transgene and gene-knockout technology have enabled the precise molecular mechanisms of ischemic brain injury to be investigated. Because the predominant species for the study of genetic mutations is the mouse, a representative mouse model of tGCI is of particular importance. However, simple mouse models of tGCI are less reproducible; therefore, a more complex process or longer duration of ischemia, which causes a high mortality rate, has been used in previous tGCI models in mice. In this study, the authors aimed to overcome these problems and attempted to produce consistent unilateral delayed hippocampal CA1 neuronal death in mice.

METHODS

C57BL/6 mice were subjected to short-term unilateral cerebral ischemia using a 4-mm silicone-coated intraluminal suture to obstruct the origin of the posterior cerebral artery (PCA), and regional cerebral blood flow (rCBF) of the PCA territory was measured using laser speckle flowmetry. The mice were randomly assigned to groups of different ischemic durations and histologically evaluated at different time points after ischemia. The survival rate and neurological score of the group that experienced 15 minutes of ischemia were also evaluated.

RESULTS

Consistent neuronal death was observed in the medial CA1 subregion 4 days after 15 minutes of ischemia in the group of mice with a reduction in rCBF of < 65% in the PCA territory during ischemia. Morphologically degenerated cells were mostly positive for terminal deoxynucleotidyl transferase–mediated deoxyuridine triphosphate nick-end labeling and cleaved caspase 3 staining 4 days after ischemia. The survival rates of the mice 24 hours (n = 24), 4 days (n = 15), and 7 days (n = 7) after being subjected to 15 minutes of ischemia were 95.8%, 100%, and 100%, respectively, and the mice had slight motor deficits.

CONCLUSIONS

The authors established a model of delayed unilateral hippocampal neuronal death in C57BL/6 mice by inducing ischemia in the PCA territory using an intraluminal suture method and established inclusion criteria for PCAterritory rCBF monitored by laser speckle flowmetry. This model may be useful for investigating the precise molecular mechanisms of ischemic brain injury.

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Hidenori Endo, Shin-ichiro Sugiyama, Toshiki Endo, Miki Fujimura, Hiroaki Shimizu, and Teiji Tominaga

The most frequently used option to reconstruct the anterior cerebral artery (ACA) is an ACA-ACA side-to-side anastomosis. The long-term outcome and complications of this technique are unclear. The authors report a case of a de novo aneurysm arising at the site of A3-A3 anastomosis. A 53-year-old woman underwent A3-A3 side-to-side anastomosis for the treatment of a ruptured right A2 dissecting aneurysm. At 44 months after surgery, a de novo aneurysm developed at the site of anastomosis. The aneurysm developed in the front wall of the anastomosis site, and projected to the anterosuperior direction. A computational fluid dynamics (CFD) study showed the localized region with high wall shear stress coincident with the pulsation in the front wall of the anastomosis site, where the aneurysm developed. A Y-shaped superficial temporal artery (STA) interposition graft was used successfully to reconstruct both ACAs, and then the aneurysm was trapped. To the authors’ knowledge, this is the first case of a de novo aneurysm that developed at the site of an ACA-ACA side-to-side anastomosis. A CFD study showed that hemodynamic stress might be an underlying cause of the aneurysm formation. A Y-shaped STA interposition graft is a useful option to treat this aneurysm. Long-term follow-up is necessary to detect this rare complication after ACA-ACA anastomosis.

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Takashi Inoue, Hiroaki Shimizu, Miki Fujimura, Atsushi Saito, and Teiji Tominaga

Object

In this paper, the authors' goals were to clarify the characteristics of growing unruptured cerebral aneurysms detected by serial MR angiography and to establish the recommended follow-up interval.

Methods

A total of 1002 patients with 1325 unruptured cerebral aneurysms were retrospectively identified. These patients had undergone follow-up evaluation at least twice. Aneurysm growth was defined as an increase in maximum aneurysm diameter by 1.5 times or the appearance of a bleb.

Results

Aneurysm growth was observed in 18 patients during the period of this study (1.8%/person-year). The annual rupture risk after growth was 18.5%/person-year. The proportion of females among patients with growing aneurysms was significantly larger than those without growing aneurysms (p = 0.0281). The aneurysm wall was reddish, thin, and fragile on intraoperative findings. Frequent follow-up examination is recommended to detect aneurysm growth before rupture.

Conclusions

Despite the relatively short period, the annual rupture risk of growing unruptured cerebral aneurysms detected by MR angiography was not as low as previously reported. Surgical or endovascular treatment can be considered if aneurysm growth is detected during the follow-up period.

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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.