Letter to the Editor. The “wrap” on Tarlov cysts
Rudolph J. Schrot
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.
A novel screw guiding method with a screw guide template system for posterior C-2 fixation
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.
Multistep pedicle screw insertion procedure with patient-specific lamina fit-and-lock templates for the thoracic spine
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.
Angiographically occult spinal dural arteriovenous fistula located using selective computed tomography angiography
Taku Sugawara, Yoshitaka Hirano, Yasunobu Itoh, Hiroyuki Kinouchi, Satoshi Takahashi, and Kazuo Mizoi
✓Spinal dural arteriovenous fistula (DAVF) is the most common type of spinal arteriovenous malformation and may cause progressive myelopathy but is usually treatable in the early stages by direct surgery or intravascular embolization. Selective spinal angiography has been the gold standard for diagnosis, but angiographically occult DAVF is not uncommon. A 67-year-old man presented with a 2-year history of progressive paraparesis. Magnetic resonance (MR) imaging demonstrated segmental atrophy of the spinal cord and dilated coronary veins on the dorsal surface of the spinal cord. A DAVF was suspected, but repeated selective angiography failed to demonstrate the fistula. Findings from spoiled gradient echo MR imaging suggested that the draining vein flowed into the dilated venous plexus at the T-9 level. Selective computed tomography (CT) angiography of the right T-9 intercostal artery confirmed the location of the fistula. The authors successfully occluded the draining vein through surgery, and they observed that the fistula was low flow. The patient exhibited improvement in his symptoms, and postoperative MR imaging confirmed closure of the fistula. Selective CT angiography is useful in locating the draining vein of angiographically occult DAVF and therefore minimizing the extent of the surgical procedure.
Ganglioneuroblastoma of filum terminale
Yoshihiko Okudera, Naohisa Miyakoshi, Taku Sugawara, Michio Hongo, Yuji Kasukawa, Yoshinori Ishikawa, and Yoichi Shimada
Neuroblastic tumors can be classified as neuroblastoma, ganglioneuroblastoma (GNB), or ganglioneuroma. Ganglioneuroblastomas consist of small, round, immature neuroblast cells and matured ganglion cells. They are most commonly found in the mediastinum and retroperitoneum; intraspinal GNBs are extremely rare. There are only 5 cases of intraspinal GNB reported in the English literature. The authors report a case of GNB of the filum terminale. The duration of follow-up after the initial treatment is longer than in any other published reports.
A 36-year-old woman underwent resection of an intradural extramedullary tumor at L1–2 in 1993. Pathological diagnosis was GNB. After surgery, her symptoms resolved and she recovered to a normal condition. In 2009, when she was 53 years old, she presented to the hospital with paralysis of both legs. Magnetic resonance imaging suggested recurrence of spinal tumor. She underwent subtotal resection of the tumors, followed by 4 weeks of radiation therapy.
Neurological symptoms improved, and, after radiation therapy, the patient was able to walk with a crutch. Histological investigation of the excised tumor indicated that it was a nodular type GNB, which was consistent with the diagnosis from the time of the initial surgery in 1993. Follow-up MRI studies showed no growth of residual tumors in the 3 years following the surgery.
The authors present a rare case of spinal GNB. The duration of follow-up after the initial surgery in 1993 represents the longest description of clinical course after treatment for spinal GNB.
Direct repair of a blisterlike aneurysm on the internal carotid artery with vascular closure staple clips
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.
Simultaneous microscopic and endoscopic monitoring during surgery for internal carotid artery aneurysms
Hiroyuki Kinouchi, Toshiharu Yanagisawa, Akira Suzuki, Tohru Ohta, Yoshitaka Hirano, Taku Sugawara, Toshio Sasajima, and Kazuo Mizoi
Object. The authors of this study evaluated the efficacy of simultaneous microscopic and endoscopic monitoring during surgery for internal carotid artery (ICA) aneurysms.
Methods. The endoscopic technique was applied during microsurgery in 11 patients with 13 aneurysms. Nine of these lesions were located on the posterior communicating artery (PCoA), three in the paraclinoid region, and one on the anterior choroidal artery (AChA). Eight patients had unruptured aneurysms and three had ruptured aneurysms. The endoscope was introduced after first exposing the aneurysm through the microscope and was gripped firmly by an air-locked holding arm fitted with a steering system throughout the entire surgery, including dissection of the perforating arteries and application of the aneurysm clips.
Regarding paraclinoid aneurysms, clips were applied through direct visualization of the ophthalmic artery and the proximal neck. In a case involving a superior hypophyseal artery aneurysm in the paraclinoid segment, a ring clip was applied without removing the bone structure around the optic canal. In all aneurysms of the PCoA and the AChA, perforating arteries behind the lesion were identified and dissected using endoscopic control. The aneurysm clip was applied in the best position in a single attempt in 10 of 11 patients. There was no surgical complication related to the endoscopic procedures.
Conclusions. Simultaneous monitoring with the microscope and endoscope is extremely useful in applying clips to ICA aneurysms. This combined method allows for direct dissection of the aneurysm, perforating vessels, and the main trunk in an area not visible through the microscope's eyepiece and promises better surgical results.
Neurosurgical versus endovascular treatment of craniocervical junction arteriovenous fistulas: a multicenter cohort study of 97 patients
Keisuke Takai, Toshiki Endo, Toshitaka Seki, Tomoo Inoue, Izumi Koyanagi, Takafumi Mitsuhara, and the Neurospinal Society of Japan CCJ AVF Study Investigators
Craniocervical junction (CCJ) arteriovenous fistulas (AVFs) are treated using neurosurgical or endovascular options; however, there is still no consensus on the safest and most effective treatment. The present study compared the treatment results of neurosurgical and endovascular procedures for CCJ AVFs, specifically regarding retreatment, complications, and outcomes.
This was a multicenter cohort study authorized by the Neurospinal Society of Japan. Data on consecutive patients with CCJ AVFs who underwent neurosurgical or endovascular treatment between 2009 and 2019 at 29 centers were analyzed. The primary endpoint was the retreatment rate by procedure. Secondary endpoints were the overall complication rate, the ischemic complication rate, the mortality rate, posttreatment changes in the neurological status, independent risk factors for retreatment, and poor outcomes.
Ninety-seven patients underwent neurosurgical (78 patients) or endovascular (19 patients) treatment. Retreatment rates were 2.6% (2/78 patients) in the neurosurgery group and 63% (12/19 patients) in the endovascular group (p < 0.001). Overall complication rates were 22% and 42% in the neurosurgery and endovascular groups, respectively (p = 0.084). Ischemic complication rates were 7.7% and 26% in the neurosurgery and endovascular groups, respectively (p = 0.037). Ischemic complications included 8 spinal infarctions, 2 brainstem infarctions, and 1 cerebellar infarction, which resulted in permanent neurological deficits. Mortality rates were 2.6% and 0% in the neurosurgery and endovascular groups, respectively (p > 0.99). Two patients died of systemic complications. The percentages of patients with improved modified Rankin Scale (mRS) scores were 60% and 37% in the neurosurgery and endovascular groups, respectively, with a median follow-up of 23 months (p = 0.043). Multivariate analysis identified endovascular treatment as an independent risk factor associated with retreatment (OR 54, 95% CI 9.9–300; p < 0.001). Independent risk factors associated with poor outcomes (a postoperative mRS score of 3 or greater) were a pretreatment mRS score of 3 or greater (OR 13, 95% CI 2.7–62; p = 0.001) and complications (OR 5.8; 95% CI 1.3–26; p = 0.020).
Neurosurgical treatment was more effective and safer than endovascular treatment for patients with CCJ AVFs because of lower retreatment and ischemic complication rates and better outcomes.
Ischemic complications in the neurosurgical and endovascular treatments of craniocervical junction arteriovenous fistulas: a multicenter study
Keisuke Takai, Toshiki Endo, Toshitaka Seki, Tomoo Inoue, Izumi Koyanagi, Takafumi Mitsuhara, and and the Neurospinal Society of Japan CCJ AVF Study Investigators
A recent comparative analysis between neurosurgical and endovascular treatments for craniocervical junction (CCJ) arteriovenous fistulas (AVFs) revealed better treatment outcomes in the neurosurgery group than in the endovascular group. This finding was attributed to the higher than expected rate of ischemic complications in the endovascular group than in the neurosurgery group (26% vs 7.7%, p = 0.037). The aim of the present study was to describe ischemic complications associated with treatments for CCJ AVFs.
This descriptive study was authorized by the Neurospinal Society of Japan. Data from 97 consecutive patients with CCJ AVFs who underwent neurosurgical (n = 78) or endovascular (n = 19) treatment between 2009 and 2019 were collected from 29 centers. The primary endpoints were details on ischemic complications and their risk factors. Secondary endpoints were details on other complications.
Among all major complications, ischemic complications were the most common (11% of 97 patients), followed by hemorrhagic complications (7.2%), hydrocephalus (2.1%), and CSF leakage (2.1%). Ischemic complications included 8 spinal, 2 brainstem, and 1 cerebellar infarctions. Iatrogenic occlusion of the anterior or posterior spinal artery from the radiculomedullary or radiculopial arteries caused these complications. Ischemic complications resulted in neurological deficits, including motor paresis, sensory disturbances, and brainstem dysfunction. The modified Rankin Scale score was 3 or higher in 36% of patients with ischemic complications at the final follow-up of 23 months. Risk factors associated with ischemic complications were endovascular treatment (OR 4.3, 95% CI 1.1–16) and spinal feeding arteries (OR 3.8, 95% CI 1.03–14). Most of the other complications were addressed by additional treatment without permanent neurological deficits.
Among ischemic complications associated with treatments for CCJ AVFs, spinal infarctions were the most common and were mostly attributed to endovascular procedures for CCJ AVFs fed by spinal arteries. These results support the use of neurosurgery as the first-line treatment for CCJ AVFs.