Intraoperative Cone-Beam Computed Tomography Assessment of Spinal Pedicle Screws Placement Precision Is in Full Agreement with Postoperative Computed Tomography Assessment.

OBJECTIVE: To assess agreement between pedicle screw placement evaluated on postoperative computed tomography (CT) and on intraoperative cone-beam CT (CBCT) and compare procedure characteristics when using first-generation and second-generation robotic C-arm systems in the hybrid operating room. METHODS: All patients who received pedicle screws for spinal fusion at our institution between June 2009 and September 2019 and underwent intraoperative CBCT and postoperative CT were included. The CBCT and CT images were reviewed by 2 surgeons to assess the screw placement using the Gertzbein-Robbins and the Heary classifications. Intermethod agreement of screw placement classifications as well as interrater agreement were assessed using Brennan-Prediger and Gwet agreement coefficients. Procedure characteristics using first-generation and second-generation generation robotic C-arm systems were compared. RESULTS: Fifty-seven patients were treated with 315 pedicle screws at thoracic, lumbar, and sacral levels. No screw had to be repositioned. On CBCT, accurate placement was found for 309 screws (98.1%) using the Gertzbein-Robbins classification and 289 (91.7%) using the Heary classification and on CT, these were 307 (97.4%) and 293 (93.0%), respectively. Intermethod between CBCT and CT and interrater agreements between the 2 raters were almost perfect (>0.90) for all assessment. There were no significant differences in mean radiation dose (P = 0.83) and fluoroscopy time (P = 0.82), but length of surgery using the second-generation system was estimated at 107.7 minutes (95% confidence interval, 31.9-183.5 minutes; P = 0.006) shorter. CONCLUSIONS: Intraoperative CBCT provides accurate assessment of pedicle screw placement and enables intraoperative repositioning of misplaced screws.

Preoperative assessment of dominant occipital sinus in patients with Chiari malformation type I: anatomical variations and implications for preventing potentially life-threatening surgical complications.

OBJECTIVE: The surgical treatment of Chiari malformation type I (CM-I) frequently involves dural incision at the posterior cranial fossa. In cases of persistent patent occipital sinus (OS), the sinus is usually obliterated and divided. However, there are some patients whose OS is prominent and requires crucial modification of the operative planning to avoid potentially life-threatening massive hemorrhage and disturbance of cerebral venous circulation. In the present study, the anatomical variations of the dominant OS in patients with CM-I were analyzed and the authors attempted to develop treatment recommendations for patients with CM-I with dominant OS. METHODS: The study included 213 patients with CM-I who underwent MR venography (MRV) prior to surgical treatment. OS dominance was assessed using 2D time-of-flight MRV or 3D phase-contrast MRV. Particular attention was paid to the pattern of venous outflow channels. The characteristics of the patients with dominant OS and the surgical outcomes were retrospectively reviewed. RESULTS: Dominant OS was identified in 7 patients (3.3%). The age in those with dominant OS was significantly younger than in those without (p = 0.0202). The incidence of concurrent scoliosis in the patients with dominant OS was significantly higher than in those without (p = 0.0366). All the dominant OSs were found to be of the oblique type. Unilateral oblique OS (OOS) with normal ipsilateral transverse sinus (TS) and hypoplastic contralateral TS was found in 2 patients (0.9%). The authors found 1 patient each (0.5%) who had unilateral OOS with hypoplastic ipsilateral TS and normal contralateral TS, unilateral OOS with bilateral hypoplastic TSs, and bilateral OOSs with bilateral normal TSs. Bilateral OOSs with bilateral hypoplastic TSs were found in 2 patients (0.9%). All these patients had syringomyelia. Instead of performing Y-shaped dural incision and duraplasty, surgical procedures were modified depending on the types of the OOSs to preserve their venous drainage routes. Although massive bleeding from the dominant OS during dural incision occurred in 1 patient, none suffered neurological deterioration. The syrinx volume decreased in all but 1 of the patients postoperatively. CONCLUSIONS: Assessment of the venous drainage pattern using MRV is indispensable for safe surgical treatment in patients with CM-I. The surgical procedure should be modified based on the type of dominant OS to minimize the surgical risks.

MRI characteristics of syringomyelia associated with foramen magnum arachnoiditis: differentiation from Chiari malformation.

BACKGROUND: It is important to distinguish foramen magnum arachnoiditis (FMA) from Chiari malformation (CM) before surgery because the operative strategies for these diseases differ. In the current study, we compared pretreatment magnetic resonance imaging (MRI) of FMA with CM and investigated the MRI findings useful to differentiate between these diseases. METHODS: We retrospectively reviewed patients with FMA or CM aged ≥ 18 years who underwent surgeries at our institution between 2007 and 2019. The morphologies of the syrinx, neural elements, and posterior cranial fossa were preoperatively evaluated with MRI. We used the receiver operating characteristic (ROC) curve for the fourth ventricle-to-syrinx distance (FVSD). RESULTS: Ten patients with FMAs and 179 with CMs were included. FVSD in the FMA group was significantly shorter than that in the CM group (7.5 mm [IQR, 2.8-10 mm] in FMA vs. 29.9 mm [IQR, 16.3-52.9 mm] in CM, p < 0.0001). The other MRI findings that showed the height, size, and length of the syrinx; size of the foramen magnum; degree of cerebellar tonsillar descent; shape of the cerebellar tonsil; and dorsal subarachnoid space at the foramen magnum differed significantly between the two groups. The ROC curve analysis showed that patients whose FVSD was less than 11 mm could be diagnosed with FMA with a specificity of 90% and sensitivity of 96%. CONCLUSIONS: A more cranial syrinx development (FVSD < 11 mm) appears to be the characteristic MRI finding in FMA.

Severity by National Institute of Health Stroke Scale Score and Clinical Features of Stroke Patients with Patent Foramen Ovale Stroke and Atrial Fibrillation.

The comparative severity of patent foramen ovale (PFO)-related stroke in patients without atrial fibrillation (AF) and AF-related stroke in patients without PFO is unknown. Therefore, we compared the severity of PFO-related stroke and AF-related stroke. Twenty-six patients who underwent transesophageal echocardiography (TEE) were diagnosed with cardioembolic stroke from July 2018 to March 2020. Cases with AF detected by electrocardiograms or thrombus in the left atrium or left atrial appendage on TEE were included in the AF-related stroke group. Cases with a positive microbubble test on the Valsalva maneuver during TEE, and with no other factors that could cause stroke, were included in the PFO-related stroke group. This study was designed as a single-center, small population pilot study. The stroke severity of the two groups by the National Institute of Health Stroke Scale (NIHSS) score was compared by statistical analysis. Of the 26 cases, five PFO-related stroke patients and 21 AF-related stroke patients were analyzed. The NIHSS score was 2.2 ± 2.8 and 11.5 ± 9.2 (p-value < 0.01), the rate of hypertension was 20.0% and 85.7% (p-value = 0.01), and the HbA1c value was 5.5 ± 0.2% and 6.3 ± 1.3% (p-value = 0.02) in the PFO-related and AF-related stroke groups, respectively. Compared with AF-related stroke patients, stroke severity was low in PFO-related stroke patients.

[A Case of Foix-Alajouanine Syndrome due to Perimedullary AVF: Remission and Aggravation Mechanism Considered by an Open Surgical Biopsy and Intraoperative ICG Angiography].

Foix-Alajouanine syndrome (FAS), also known as congestive myelopathy due to spinal vascular malformations, presents with paraplegia, sensory disturbance of lower limbs, and dysfunction of the bladder and rectum. Although FAS is characterized by a subacute onset of neurological symptoms that may wax and wane over a few years, the progression mechanism remains unclear. We report a case of FAS due to an angiographically occult arteriovenous fistula (AVF) that was diagnosed by an open surgical biopsy and intraoperative indocyanine green (ICG) angiography. The patient was a 74-year-old female who presented with a one-year history of gradually progressive gait disturbance, weakness, and decreased sensation in her legs associated with bladder and rectum dysfunction. MRI showed intramedullary T1 hypointensity, T2 hyperintensity at level Th4-12, and intramedullary enhancing with a Gd-DTPA lesion at level Th8-12. A true-FISP image of the MRI revealed an abnormal tortuous vessel in the dorsal spinal subarachnoid space, but digital subtraction angiography of the spine at the C1-L5 level showed no abnormality. The patient also underwent Th8-12 laminectomy for open biopsy. ICG angiography revealed blood flow stagnation in an abnormally enlarged posterior spinal vein. Histological findings indicated necrotizing myelopathy and stenosis with wall thickening of the posterior spinal vein. We hypothesized that the progression mechanism in the present case may have resulted from histological changes in the draining veins of an AVF. Intraoperative ICG angiography may be a valuable method, not only for diagnosing AVFs but also for determining the existence and pathological characteristics of FAS.

Prevalence of spinal meningeal cyst in the sacrum.

Spinal meningeal cysts in the sacrum (SMC) are known to be occasionally symptomatic with low back pain as well as leg pain, but no distinct prevalence of this pathological entity including asymptomatic lesions has been described. This prospective study investigated the prevalence of SMCs based on magnetic resonance (MR) myelography in 102 consecutive Japanese women with gynecological problems, who underwent pelvic conventional MR imaging. Ten of 102 patients were suspected of being positive for SMC (9.8%), but pseudo-positive findings were possible. A high probability of positive SMC was found in 7/102 (6.9%). MR myelography was better to detect SMCs than conventional MR imaging. Multiplicity and female preponderance may be other features of SMC. The speculated prevalence of SMCs in Japanese females ranged from 6.9% to 9.8%.

Robotic digital subtraction angiography systems within the hybrid operating room.

BACKGROUND: Fully equipped high-end digital subtraction angiography (DSA) within the operating room (OR) environment has emerged as a new trend in the fields of neurosurgery and vascular surgery. OBJECTIVE: To describe initial clinical experience with a robotic DSA system in the hybrid OR. METHODS: A newly designed robotic DSA system (Artis zeego; Siemens AG, Forchheim, Germany) was installed in the hybrid OR. The system consists of a multiaxis robotic C arm and surgical OR table. In addition to conventional neuroendovascular procedures, the system was used as an intraoperative imaging tool for various neurosurgical procedures such as aneurysm clipping and spine instrumentation. RESULTS: Five hundred one neurosurgical procedures were successfully conducted in the hybrid OR with the robotic DSA. During surgical procedures such as aneurysm clipping and arteriovenous fistula treatment, intraoperative 2-/3-dimensional angiography and C-arm-based computed tomographic images (DynaCT) were easily performed without moving the OR table. Newly developed virtual navigation software (syngo iGuide; Siemens AG) can be used in frameless navigation and in access to deep-seated intracranial lesions or needle placement. CONCLUSION: This newly developed robotic DSA system provides safe and precise treatment in the fields of endovascular treatment and neurosurgery.

A unique device, the disc space-fitted distraction device, for anterior cervical discectomy and fusion: early clinical and radiological evaluation.

OBJECT: To perform interbody distraction and to obtain spinal curvature correction during anterior cervical discectomy and fusion (ACDF), the authors recently adopted a new stand-alone device, a disc space-fitted distraction device (DFDD). In this preliminary report the authors introduce this unique device and discuss some advantages in terms of short-term clinical and radiological evaluations. METHODS: The most unique aspect of the DFDD is the function of gentle distraction at anterior disc space with maximum lordotic correction of up to 8 degrees while rotating a screw at the front of the device. Additional advantages are related to its configuration such as disc space-matched shape in all dimensions, tapering contour for easy insertion into the disc space, multiple spikes to avoid dislodgment, wider contact area to the vertebral endplate for diminishing sinking process, and sufficient space for accommodation of bone-conductive materials. Twenty-four patients who have been observed more than 12 months after ACDF were involved in this evaluation. RESULTS: The objective clinical outcome, measured by the Neurological Cervical Spine Scale, was significantly improved. In radiological evaluation, statistically significant improvement compared with preoperative values was noted on the curvature index, C2-7 curvature, and disc angle (p < 0.01) throughout the entire postoperative period, up to 12 months. A high fusion rate and remodeling process around the implants were also observed. CONCLUSIONS: The DFDD may have some advantages over other devices-its distraction action, diminished sinking, and early solid bone union resulted in maintaining sufficient correction of the spinal curvature. This corrected spinal curvature may play an important role in preventing progressive adjacent-disc degeneration subsequent to ACDF in the long term.

New surgical technique to secure the bone strut during anterior cervical corpectomy and fusion: kusabi fixation technique--technical note.

Fixation using an anterior cervical plate is frequently used in anterior cervical discectomy or corpectomy and fusion procedures because of the higher fusion rate than without instrumentation. The surgical outcomes with the anterior plate technique are acceptable, but various hardware-related complications have been reported. The authors describe a new surgical technique, called the kusabi fixation technique, for securing the bone strut during anterior cervical corpectomy using cylindrical cages. Following corpectomy, the trimmed bone strut was placed into the space drilled-out. Two small holes of 5-6-mm diameter and 5-mm depth were drilled out at the interface of two bones at the top and bottom of the bone strut in a diagonal orientation. Two cylindrical cages filled with autologous bone tips were tapped into the interface. Eight patients with myelopathy were treated by this method. All procedures were uneventfully performed as a single level surgery (two vertebral bodies and one disk level). Solid bone union was obtained in all patients at 6 months after the operation. Apparent alignment change in the cervical spine was observed in only one patient, who developed asymptomatic kyphosis. No instrumentation failure or significant complications related to the surgery occurred. Precise biomechanical aspects and long-term radiographic analysis compared with the plate fixation technique should be established, but this new method provides another way to secure the bone strut in anterior cervical corpectomy and fusion.

New titanium spacer for cervical laminoplasty: initial clinical experience. Technical note.

Many commercially available hydroxyapatite (HA) spacers for cervical laminoplasty have been introduced but have disadvantages such as lack of plasticity, easy cracking, and occasional difficulty in fixation by sutures. Here we present the short-term results of a newly designed titanium spacer (Laminoplasty Basket) in open-door cervical laminoplasty, and evaluated clinically and radiologically. The titanium box-shaped spacer with two arms for fixation was easily inserted and fixed into the laminoplasty space with 4-mm or 5-mm length screws after the posterior cervical arch was repositioned for the canal expansion. Twenty-one patients with cervical myelopathy due to spondylosis or ossification of the longitudinal ligament or developmental narrow canal observed for more than 6 months postoperatively were enrolled in this study. The neurological condition of these patients improved from 9.4 points on the Japanese Orthopaedic Association scale preoperatively to 13.5 points at 6 months after surgery. Postoperative radiological evaluation showed no laminar closure or implant failure and cervical spine curvature was maintained. These results seemed to have no significant difference compared with those using HA spacers. This titanium spacer is a potential substitute for conventional HA or other similar devices in cervical laminoplasty.

[Intraoperative photodynamic diagnosis for spinal ependymoma using 5-aminolevulinic acid: technical note].

OBJECTIVE: The fluorescence-guided resection using 5-aminolevulinic acid (5-ALA) is a well established method for the treatment of brain tumor, especially malignant glioma. However, there is no report on photodynamic diagnosis (PDD) for spinal tumor. In the present study, we evaluated the usefulness of PDD for spinal ependymoma using 5-ALA. METHODS: Three patients with spinal ependymoma received oral doses of 5-ALA (20 mg/kg body weight) 2 hours before anesthesia induction. Intraoperatively, fluorescence was observed with a 420 nm sharp cut filter after excitation with a violet semiconductor laser (405 nm) and was verified by analysis of fluorescent spectra. Residual fluorescent samples taken from the tumor cavity were examined histologically RESULTS: Fluorescence peaked at 636nm in the removed tumors in all cases. Fluorescent tissue tended to exist at the cranial and caudal portion in the tumor cavity or around the anterior median fissure. The residual fluorescent tissue was not detected after removal of the tumor in case 1. The residual fluorescent tissue was composed of tumor cells and ependymal lining in case 2 or the infiltrated inflammatory cells and vascular endothelial cells in case 3. Postoperative magnetic resonance (MR) imaging showed no residual tumor in any of the cases. CONCLUSION: The results of this study indicate the usefulness of 5-ALA-induced tumor fluorescence in guiding resection of spinal ependymoma. 5-ALA-induced porphyrin fluorescence may label spinal ependymomas easily and clearly enough to enhance the completeness of tumor removal.

Laminoplasty with preservation of posterior cervical elements: surgical technique.

OBJECTIVE: We have developed a modified laminoplasty procedure that preserves the posterior cervical elements, and we have used it to treat multilevel cervical canal stenosis, with or without spondylotic changes, in 30 patients. METHODS: In this procedure, the posterior bony elements, such as the spinous processes, are not completely detached from the ligaments and musculature and are repositioned in the midline, to maintain normal cervical anatomic relationships. Thirty patients (mean age, 55.2 yr) were registered and evaluated in this study, with a mean follow-up period of 18.1 months, between November 1995 and October 2000. The rates of bony union of the reconstructed laminae and alignment of the cervical spine were assessed by using computed tomographic scans and lateral radiographs. RESULTS: All patients except one noted some improvement in sensation, motor function, or both. Changes in spinal curvature were noted for two patients for whom a kyphotic deformity had developed before surgery (because of S-shaped or straight curvature). The average decrease in the range of motion was 7.26 degrees. Estimated rates of bony fusion at the sites of the gutters, spacers, and spinous processes were 94.6, 62.3, and 86.6%, respectively. A stable bony arch was assumed to be achieved with bony fusion at the gutters on the hinge side, as well as the spinous processes, approximately 6 months after surgery. CONCLUSION: Our new technique of cervical laminoplasty preserves the posterior musculature and bony elements. This new procedure also helps maintain correct spinal alignment.