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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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Sean M. Lew, Anne E. Matthews, Bruce A. Kaufman and Marike Zwienenberg

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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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Tetsuyoshi Horiuchi, Tetsuya Goto, Yuichiro Tanaka, Kunihiko Kodama, Keiji Tsutsumi, Kiyoshi Ito and Kazuhiro Hongo

OBJECT

Although a number of studies have assessed the surgical treatment of paraclinoid-segment carotid artery aneurysms and resulting visual complications, less attention has been given to the results with respect to the superior hypophyseal artery (SHA). The authors evaluated the relationship between the aneurysm, the SHA itself, and postoperative visual function in patients with ruptured and unruptured SHA aneurysms.

METHODS

From January 1991 through December 2013, 181 patients with 190 paraclinoid carotid artery aneurysms received treatment at Shinshu University Hospital and its affiliated hospitals. The authors retrospectively analyzed charts, operative records, operative videos, and neuroimaging findings for these patients with or without postoperative visual complications.

RESULTS

The authors identified 72 SHA aneurysms in 70 patients (mean age 58 years). Of 69 patients (1 patient died) evaluated, postoperative visual complications occurred in 9 (13.0%). Although the aneurysm size and SHA sacrifice did not lead to postoperative visual impairment, simultaneous treatment of bilateral aneurysms was a risk factor for postoperative visual complications.

CONCLUSIONS

Unilateral SHA impairment may be safe (i.e., it may not induce ischemia of the optic pathway) for many, but not all, patients with SHA aneurysm.

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Kiyoshi Ito, Tetsuyoshi Horiuchi, Kiyomitsu Oyanagi, Tetsuo Nomiyama and Kazuhiro Hongo

Object

Several materials, such as polyethylene glycol (PEG) hydrogel and fibrin glue, have been used to seal dural incisions after brain and spinal surgeries. Although the use of PEG sealant is gaining popularity, it can be associated with postoperative cerebrospinal fluid leakage and infection. However, the reasons for this association are currently unknown. The present study aimed to investigate the effects of PEG sealant and fibrin glue on wound healing and brain damage in vivo.

Methods

Oval-shaped bone defects and dural defects were created bilaterally over the parietal lobes of 22 Japanese white rabbits. The dural defects were covered with 0.5 ml of fibrin glue on one side and 0.5 ml of PEG sealant on the other side. Dural regeneration and brain damage were investigated in each harvested brain and dura mater using light microscopy.

Results

Dural regeneration was more effective in the presence of fibrin glue than it was with PEG sealant (p = 0.014). Of the 22 rabbits, 11 showed thick (Grades ++ and +++) dural regeneration by 28 days postsurgery in the hemisphere where fibrin glue was used, whereas Grade +++ dural regeneration was not observed in the PEG hydrogel hemisphere, and only 4 rabbits showed Grade ++ regeneration. Abscess and granulation formation also tended to be more severe when PEG hydrogel sealant was used. No Grade ++ granulation/abscess formation was observed with fibrin glue, and Grade + was only observed in 13 of 22 rabbits. Conversely, with PEG hydrogel sealant, only 2 rabbits did not show granulation/abscess formation, and Grade +, ++, and +++ granulation/abscess formation was observed in 8, 7, and 5 rabbits, respectively. The extent of cortical damage was significantly greater in rabbits with abscesses and granulations, compared with rabbits without these lesions (p = 0.007).

Conclusions

Dural regeneration tended to occur more rapidly with fibrin glue, whereas granulation was more likely with PEG hydrogel sealant, which led to postoperative complications. Histological analysis indicated that PEG hydrogel sealant inhibited the normal tissue healing process and that outcomes were improved by the use of fibrin glue.

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Hiroshi Nakagawa, Sang-Don Kim, Junichi Mizuno, Yukoh Ohara and Kiyoshi Ito

Object. The authors discuss the safety and efficacy of an ultrasonic bone curette in various spinal surgeries and report its advantages in clinical application.

Methods. Between April 2002 and September 2003, 76 patients with various spinal diseases (29 cervical, five thoracic, 40 lumbosacral, and two foramen magnum regions) were treated microsurgically by using a Sonopet ultrasonic bone curette with longitudinal and torsional tips and lightweight handpieces. The operations were performed successfully and the device was easy to handle. There were no instrument-related complications or -induced damage to any structure even when removing osseous spurs or ossified lesions near the dura mater, nerves, and vessels.

Conclusions. The ultrasonic curette is a useful instrument for procedures performed near the dura mater or other neural tissue without excessive heat production or mechanical injury. This device is recommended for various spinal surgeries in addition to high-speed drills or other tools.

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Yukinari Kakizawa, Hisashi Nagashima, Fusakazu Oya, Kiyoshi Ito, Yuichiro Tanaka, Kazuhiro Hongo and Shigeaki Kobayashi

✓ Although in several histological studies of arteriovenous malformation (AVM) nidi the presence of compartments has been documented, no clinical study has been published. The present study was conducted to determine the presence of nidus compartments in clinical cases by using a new radiographic method.

Two patients with unruptured and one with a ruptured AVM (all Spetzler—Martin Grade III) were studied. A microcatheter was superselectively introduced into each of two or three feeding arteries of the AVMs under three-dimensional (3D) angiographic guidance to obtain 3D images of the nidus by using rotational digital subtraction angiography. On 3D images the different feeding arteries were found to be independent from one another, which allowed the authors to confirm the presence of compartments. On the other hand, separate feeding arteries often had a common draining vessel. Compartments in AVM nidi were demonstrated by a novel rotational 3D angiographic procedure by using superselective microcatheterization, which should be useful for designing treatment strategies for large and complex AVMs.

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Isabel Fernández-Conejero and Vedran Deletis

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Eiji Ito, Masahiro Ichikawa, Takeshi Itakura, Hitoshi Ando, Yuka Matsumoto, Keiko Oda, Taku Sato, Tadashi Watanabe, Jun Sakuma and Kiyoshi Saito

Object

Dysphasia is one of the most serious complications of skull base surgeries and results from damage to the brainstem and/or cranial nerves involved in swallowing. Here, the authors propose a method to monitor the function of the vagus nerve using endotracheal tube surface electrodes and transcranial electrical stimulation during skull base surgeries.

Methods

Fifteen patients with skull base or brainstem tumors were enrolled. The authors used surface electrodes of an endotracheal tube to record compound electromyographic responses from the vocalis muscle. Motor neurons were stimulated using corkscrew electrodes placed subdermally on the scalp at C3 and C4. During surgery, the operator received a warning when the amplitude of the vagal motor evoked potential (MEP) decreased to less than 50% of the control level. After surgery, swallowing function was assessed clinically using grading criteria.

Results

In 5 patients, vagal MEP amplitude permanently deteriorated to less than 50% of the control level on the right side when meningiomas were dissected from the pons or basilar artery, or when a schwannoma was dissected from the vagal rootlets. These 5 patients had postoperative dysphagia. At 4 weeks after surgery, 2 patients still had dysphagia. In 2 patients, vagal MEPs of one side transiently disappeared when the tumors were dissected from the brainstem or the vagal rootlets. After surgery, both patients had dysphagia, which recovered in 4 weeks. In 7 patients, MEP amplitude was consistent, maintaining more than 50% of the control level throughout the operative procedures. After surgery all 7 patients were neurologically intact with normal swallowing function.

Conclusions

Vagal MEP monitoring with transcranial electrical stimulation and endotracheal tube electrode recording was a safe and effective method to provide continuous real-time information on the integrity of both the supranuclear and infranuclear vagal pathway. This method is useful to prevent intraoperative injury of the brainstem corticobulbar tract or the vagal rootlets and to avoid the postoperative dysphagia that is often associated with brainstem or skull base surgeries.

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Yoshinobu Iwasaki, Minoru Akino, Hiroshi Abe, Mitsuo Tsuru, Kunio Tashiro, Kazuo Miyasaka, Kiyoshi Kaneda, Toyohiko Isu and Terufumi Ito

✓ Four cases of calcification of the cervical ligamentum flavum are reported, all in women over 60 years of age. Neurological findings were not significantly different from those of other cervical compressive diseases. Among radiological examinations, computerized tomography was the most valuable diagnostic tool. Calcification might have been induced by the degeneration or abnormal nutritional state of the ligamentum flavum. Endocrine abnormalities and inflammatory processes might also have been contributory factors.