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Tetsuyoshi Horiuchi, Yuichiro Tanaka, Kazuhiro Hongo and Shigeaki Kobayashi

Object. Aneurysmal subarachnoid hemorrhage rarely occurs in young adults. The aim of this work was to clarify the clinical characteristics of ruptured aneurysms in young adults in the third and fourth decades of life and to compare these two age groups.

Methods. The authors retrospectively investigated 2493 patients who underwent surgical repair for ruptured cerebral aneurysms during a 14-year period (1988–2001). There were 25 patients (1%) in the third decade of life and 106 patients (4.3%) in the fourth decade. In general, favorable outcome was achieved in both groups. There were significant differences in the sizes and locations of aneurysms between the two age groups. Among patients in the fourth decade of life, the aneurysm was large and was located more often on the anterior cerebral artery.

Conclusions. In this study the authors summarize the clinical characteristics of a large series of 131 young adult patients with ruptured cerebral aneurysms. Congenital factors as well as hemodynamic stress may contribute to differences in aneurysm size and location between the two age groups.

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Kiyoshi Ito, Tatsuro Aoyama, Tetsuyoshi Horiuchi and Kazuhiro Hongo

OBJECT

The nonpenetrating titanium clip has been successfully used in peripheral arterial bypass surgery. The purpose of this study was to evaluate the leakage pressures and patterns of nonpenetrating titanium clips using a simple model that mimicked spinal surgery. In addition, the authors describe their surgical experience with these clips and the follow-up results in 31 consecutive patients.

METHODS

The authors compared nonpenetrating titanium clips and expanded polytetrafluoroethylene (ePTFE) sutures in relation to the water pressure that could be tolerated by sutured ePTFE sheets, and the leakage pressure patterns were determined. The changes in leakage pressures at 5 minutes, 30 minutes, and 12 hours were examined when the clips and sutures were used in combination with the mesh-and-glue technique in an in vitro study. Thirty-one patients underwent spinal intradural procedures using nonpenetrating titanium clips to suture the dura maters using the meshand-glue technique, involving fibrin glue and polyglycolic acid-fibrin sheets.

RESULTS

A significant difference was apparent between the ePTFE suture group and the nonpenetrating titanium clip group, with the latter showing a leakage pressure that could be sustained and was 1508% higher than that of the former (p = 0.001). In relation to leakage patterns, the nonpenetrating titanium clips did not make any suture holes in the ePTFE sheet and fluid leakage occurred between the clips, whereas fluid leakage was associated with the pressure elevation that occurred at the suture holes made by the ePTFE sutures. Of the 31 patients who underwent spinal intradural procedures using nonpenetrating titanium clips, 1 (3.2%) experienced cerebrospinal fluid (CSF) leakage postoperatively. No other complications—for example, allergic reactions, adhesions, or infections—were encountered.

CONCLUSIONS

The interrupted placement of nonpenetrating titanium clips enables dural closure without creating any holes. These clips facilitate improvements in the initial leakage pressure and reduce postoperative CSF leakage following spinal surgery. The authors conclude that it is very beneficial to suture the spinal dura mater using nonpenetrating titanium clips given the anatomical characteristics of the spinal dura mater and the fact that the clips do not create suture holes.

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Tetsuyoshi Horiuchi, Junpei Nitta, Keiichi Sakai, Yuichiro Tanaka and Kazuhiro Hongo

Object

The authors evaluated the efficacy of emergency embolectomy in patients with acute middle cerebral artery occlusion (MCAO).

Methods

A retrospective review of the charts for patients undergoing embolectomy at the authors’ institution was performed. Between October 1997 and May 2004, 12 patients (mean age 70 years) with acute MCAO were treated using embolectomy. Local intraarterial fibrinolysis with urokinase was initially undertaken in eight of 12 patients. Sufficient recanalization was not achieved with fibrinolysis in any patient, and thus embolectomy was performed immediately thereafter. Recanalization by embolectomy was achieved in all patients (mean occlusion time 6 hours, 11 minutes). Each patient’s condition was evaluated on discharge. Outcomes in the 12 patients according to the Glasgow Outcome Scale were good recovery in five, moderate disability in two, severe disability in three, vegetative state in one, and death due to a cardiac complication in one. None of the 12 patients had symptomatic hemorrhagic infarction.

Conclusions

Emergency embolectomy can be performed in patients with MCAO with minimal morbidity and death. The procedure can be used to achieve good recovery even in patients in whom fibrinolysis is insufficient after acute MCAO and should be a part of the algorithm for the treatment of MCAO.

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Kiyoshi Ito, Tatsuro Aoyama, Takuya Nakamura, Yoshiki Hanaoka, Tetsuyoshi Horiuchi and Kazuhiro Hongo

The authors report on a new method for removing dumbbell-shaped spinal tumors that avoids the risk of postoperative cerebrospinal fluid (CSF) leakage. Adequate visualization of the intra- and extradural components of the tumor is achieved with the use of separate dural incisions. First, the dura mater is opened along the dural theca to provide adequate visualization of the intradural portion of the mass; then, a second incision is made along the nerve root to remove the extradural component. Meticulous suturing is essential in intradural lesion cases; however, the dura mater is usually thin and fragile in such cases. During suturing with a needle and thread, the dura mater can become lacerated proximal to the needle holes and result in CSF leakage. In the authors' technique, instead of using a needle and thread, nonpenetrating vascular clips were used to close the dural incisions. When operating on dumbbell-shaped spinal tumors, the authors found that the “separate-dural-incision method” was preferable to the conventional T-shaped dural incision method because no dural defects occurred after the intradural procedure and meticulous dural closure with vascular clips was achieved. The authors conclude that the novel separate-dural-incision method for removing dumbbell-shaped tumors and the use of nonpenetrating vascular clips permits reliable dural closure, prevents postoperative CSF leakage, and promises good postoperative clinical results.

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Prajak Saesue, Tetsuyoshi Horiuchi, Tetsuya Goto, Yuichiro Tanaka and Kazuhiro Hongo

Object. In vascular smooth-muscle cells, the Na+/H+ exchanger (NHE) is involved in the regulation of [Na+]i, pHi through [H+], and cell volume. Recently, investigations have determined that this exchanger contributes to ischemia and reperfusion injury in coronary circulation. Nonetheless, there is limited information on this glycoprotein in cerebral circulation, especially microcirculation. Thus, the authors in the present study examined the role of NHE in the regulation of cerebral arteriolar tone and its related mechanisms in vitro.

Methods. The internal diameter of isolated pressurized intracerebral arterioles in rats was monitored with the aid of a microscope. To examine the basal activity of NHE two kinds of Na+/H+ exchange inhibitors (FR183998 and 5-[N,N-hexamethylene] amiloride) were administered in the arterioles. Furthermore the authors studied the effects of nitric oxide (NO) synthase inhibitor (NG methyl-l-arginine), Na+/K+—adenosine triphosphatase (NKA) inhibitor (ouabain), and the Na+/Ca++ exchange inhibitor (SEA0400) on the vascular response induced by either of the Na+/H+ exchange inhibitors.

Both of the Na+/H+ exchange inhibitors constricted the arteriole. Subsequent application of NO synthase inhibitor further decreased the diameter of the arterioles. The Na+/H+ exchange inhibitor—induced constriction was completely abolished in the presence of ouabain and SEA0400.

Conclusions. The NHE is active in the basal condition and regulates cerebral arteriolar tone through NKA and the Na+/Ca++ exchanger. Endogenous NO is not related to the activity of NHE in basal conditions.

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Kiyoshi Ito, Mitsunori Yamada, Tetsuyoshi Horiuchi and Kazuhiro Hongo

OBJECTIVE

Few reports have been published regarding the detailed microsurgical anatomy of the dura mater at the craniovertebral junction (CVJ), although many neurosurgeons have had the opportunity to conduct surgeries in this region, such as in cases of Chiari malformation. The authors aimed to evaluate the detailed and precise microsurgical anatomy of the dura mater at the CVJ for safe and effective surgical treatment at this area.

METHODS

This study consisted of dissection of 4 formalin-fixed, continuous, human cadaveric dura maters, extending from the posterior fossa to the C2 level. After removing the occipital bone and C1 laminae, a dural incision was made to harvest the specimen. The following structural and topographical aspects of the dura mater in each region were studied: 1) thickness, 2) morphological characteristics, and 3) vascular structures.

RESULTS

The average thicknesses of the dura mater were 313.4 ± 137.0 μm, 3051.5 ± 798.8 μm, and 866.5 ± 359.0 μm in the posterior cranial fossa, CVJ, and spinal region, respectively. The outer layer of the posterior cranial dura mater and the tendon of the rectus capitis posterior minor muscle were connected, forming the “myodural bridge.” The dura mater at the CVJ had a well-developed vascular network. These vascular structures were determined to be veins or the venous sinus, and were mainly located around the interface between the inner layer of the cranial dura mater and the rectus capitis posterior minor muscle layer. Regarding the morphological features, the bulging located in the inner layer of the dura mater at the CVJ was determined to be the marginal sinus, and contained a pacchionian granulation that allowed for CSF circulation. In the spinal region, the dura mater was characterized by a single, thick layer enclosing the collagen fibers with almost the same orientation.

CONCLUSIONS

The dura mater at the CVJ displayed dynamic morphological changes within an extremely short segment. Its characteristic anatomical features were not similar to those in the cranial regions. The dural bulging at the CVJ was determined to be the venous sinus. During surgery in the posterior fossa, CVJ, and spinal cord, different procedures should be used because of the specific microsurgical anatomy of each region.

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Yukinari Kakizawa, Tatsuya Seguchi, Tetsuyoshi Horiuchi and Kazuhiro Hongo

Object

The aim of this study was to evaluate cerebral aneurysm clips, and to know in more detail the characteristics of currently available clips in the 3-T magnetic field.

Methods

According to the protocol recommended by the American Society for Testing and Materials (ASTM), the authors conducted quantitative evaluation for displacement force and qualitative evaluation for torque in 52 aneurysm clips and 48 samples of raw materials in the 3-T environment.

Results

The largest displacement force occurred near the bore opening, and the force was directed to the isocenter. Deflection angles of all objects in this study were within 45°. The translational force in the peripheral position in the bore was larger than that in the center, and the translational force in the magnetic field was proportional to the weight of the objects. The proportion coefficients varied depending on the metallic materials. In the titanium alloy, the deflection angle was also detected to be approximately 2°, although no response was observed in titanium in a previous report. This behavior was similar to that of the Elgiloy and Phynox materials in the 1.5-T environment. No difference was observed among the groups of shapes (straight, bent, and fenestrated). The amount of torque that occurred was dependent on the clip's or material's loop and bent shape. The torque on the titanium was perpendicular to the torque on the other materials (which was perpendicular to the magnetic field).

Conclusions

Care must be taken with patients near the bore opening while moving them to the center of the magnet's bore on the MR imaging table. Although all the clips examined in this study met the ASTM requirements, the titanium alloy clips are preferable in the 3-T environment for safety's sake. Suitably sized clips should be selected for the aneurysm size, because the translational force increases proportionally to the object's weight.