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Novel wrapping surgery for symptomatic sacral perineural cysts

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


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.


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.


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.


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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A novel screw guiding method with a screw guide template system for posterior C-2 fixation

Clinical article

Shuichi Kaneyama, Taku Sugawara, Masatoshi Sumi, Naoki Higashiyama, Masato Takabatake, and Kazuo Mizoi


Accurate insertion of C-2 cervical screws is imperative; however, the procedures for C-2 screw insertion are technically demanding and challenging, especially in cases of C-2 vertebral abnormality. The purpose of this study is to report the effectiveness of the tailor-made screw guide template (SGT) system for placement of C-2 screws, including in cases with abnormalities.


Twenty-three patients who underwent posterior spinal fusion surgery with C-2 cervical screw insertion using the SGT system were included. The preoperative bone image on CT was analyzed using multiplanar imaging software. The trajectory and depth of the screws were designed based on these images, and transparent templates with screw guiding cylinders were created for each lamina. During the operation, after templates were engaged directly to the laminae, drilling, tapping, and screwing were performed through the templates. The authors placed 26 pedicle screws, 12 pars screws, 6 laminar screws, and 4 C1–2 transarticular screws using the SGT system. To assess the accuracy of the screw track under this system, the deviation of the screw axis from the preplanned trajectory was evaluated on postoperative CT and was classified as follows: Class 1 (accurate), a screw axis deviation less than 2 mm from the planned trajectory; Class 2 (inaccurate), 2 mm or more but less than 4 mm; and Class 3 (deviated), 4 mm or more. In addition, to assess the safety of the screw insertion, malpositioning of the screws was also evaluated using the following grading system: Grade 0 (containing), a screw is completely within the wall of the bone structure; Grade 1 (exposure), a screw perforates the wall of the bone structure but more than 50% of the screw diameter remains within the bone; Grade 2 (perforation), a screw perforates the bone structures and more than 50% of the screw diameter is outside the pedicle; and Grade 3 (penetration), a screw perforates completely outside the bone structure.


In total, 47 (97.9%) of 48 screws were classified into Class 1 and Grade 0, whereas 1 laminar screw was classified as Class 3 and Grade 2. Mean screw deviations were 0.36 mm in the axial plane (range 0.0–3.8 mm) and 0.30 mm in the sagittal plane (range 0.0–0.8 mm).


This study demonstrates that the SGT system provided extremely accurate C-2 cervical screw insertion without configuration of reference points, high-dose radiation from intraoperative 3D navigation, or any registration or probing error evoked by changes in spinal alignment during surgery. A multistep screw placement technique and reliable screw guide cylinders were the key to accurate screw placement using the SGT system.

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Multistep pedicle screw insertion procedure with patient-specific lamina fit-and-lock templates for the thoracic spine

Clinical article

Taku Sugawara, Naoki Higashiyama, Shuichi Kaneyama, Masato Takabatake, Naoko Watanabe, Fujio Uchida, Masatoshi Sumi, and Kazuo Mizoi


Pedicle screw fixation is a standard procedure of spinal instrumentation, but accurate screw placement is essential to avoid injury to the adjacent structures, such as the vessels, nerves, and viscera. The authors recently developed an intraoperative screw guiding method in which patient-specific laminar templates were used, and verified the accuracy of the multistep procedure in the thoracic spine.


Preoperative bone images of the CT scans were analyzed using 3D/multiplanar imaging software and the trajectories of the screws were planned. Plastic templates with screw guiding structures were created for each lamina by using 3D design and printing technology. Three types of templates were made for precise multistep guidance, and all templates were specially designed to fit and lock on the lamina during the procedure. Plastic vertebra models were also generated and preoperative screw insertion simulation was performed. Surgery was performed using this patient-specific screw guide template system, and the placement of screws was postoperatively evaluated using CT scanning.


Ten patients with thoracic or cervicothoracic pathological entities were selected to verify this novel procedure. Fifty-eight pedicle screws were placed using the screw guide template system. Preoperatively, each template was found to fit exactly and to lock on the lamina of the vertebra models, and screw insertion simulation was successfully performed. Intraoperatively the templates also fit and locked on the patient lamina, and screw insertion was completed successfully. Postoperative CT scans confirmed that no screws violated the cortex of the pedicles, and the mean deviation of the screws from the planned trajectories was 0.87 ± 0.34 mm at the coronal midpoint section of the pedicles.


The multistep, patient-specific screw guide template system is useful for intraoperative pedicle screw navigation in the thoracic spine. This simple and economical method can improve the accuracy of pedicle screw insertion and reduce the operating time and radiation exposure of spinal fixation surgery.

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Endoscope-assisted clipping of a superior hypophyseal artery aneurysm without removal of the anterior clinoid process

Case report

Hiroyuki Kinouchi, Katsuya Futawatari, Kazuo Mizoi, Naoki Higashiyama, Hisashi Kojima, and Tetsuya Sakamoto

✓ A 47-year-old man presented with a superior hypophyseal artery aneurysm and an ipsilateral posterior communicating artery aneurysm. Both lesions were successfully clipped without removal of the anterior clinoid process or retraction of the optic nerve by using endoscopic guidance. The endoscope was introduced into the prechiasmatic cistern and provided a clear visual field around the aneurysm that could not be seen via the operating microscope. The endoscope was useful in the identification of the medially projecting lesion and the small perforating branches of the ophthalmic segment of the internal carotid artery. A fenestrated clip could be introduced around the neck of the aneurysm and placed in the best position under endoscopic guidance. Endoscopy-assisted clipping is potentially a very useful procedure for aneurysm surgery.

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Direct repair of a blisterlike aneurysm on the internal carotid artery with vascular closure staple clips

Technical note

Toshiharu Yanagisawa, Kazuo Mizoi, Taku Sugawara, Akira Suzuki, Tohru Ohta, Naoki Higashiyama, Masataka Takahashi, Toshio Sasajima, and Hiroyuki Kinouchi

✓ Vascular closure staple clips made of titanium were originally developed for microvascular anastomosis. Clinical applications for these clips include arteriotomy closure for carotid endarterectomy, extracranial—intracranial bypass, and dural closure. This is the first report in which vascular closure staple clips have been used successfully for direct repair of a tear on the internal carotid artery (ICA). This report involves a 65-year-old man who presented with sudden onset of headache. Admission computerized tomography scans demonstrated a diffuse and thick subarachnoid hemorrhage in the basal cisterns. Cerebral angiograms demonstrated a broad-based, small bulge on the superomedial wall of the left ICA. Intraoperatively, an extremely thin-walled aneurysm was seen on the segment of the ICA at the C-2 vertebral level. The aneurysm ruptured abruptly, although no surgical manipulation was being performed on the aneurysm itself. After temporary clips were applied on the vessel, a large tear of the ICA was repaired with vascular closure staple clips. Reconstruction with the vascular closure staple clips required only a short period of temporary occlusion of the ICA. Postoperative angiograms revealed reduction of the aneurysm bulge and good patency of the ICA. The postoperative course was uneventful, and the patient has been free of symptoms. The vascular closure staple clipping procedure is useful for urgent repair of an aneurysm tear. This method is a new treatment option for these fragile aneurysms in cases in which other options, such as encircling clips or bypass procedures, may have drawbacks or be impossible.