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Purpose: Spinal schwannomas often require laminectomy for gross total resection. However, laminectomy may not be necessary due to the unique anatomy of epidural schwannomas at the C1-2 level, even with the intradural part. This study aimed to determine the need for laminectomy by comparing factors between patients who underwent laminectomy and those who did not and to identify the benefits of not performing laminectomy., Methods: Fifty patients with spinal epidural schwannoma confined to C1-C2 level were retrospectively collected and divided into groups based on whether laminectomy was intended and performed. In all cases where laminectomy was conducted, patients underwent laminoplasty using microplate-and-screws, which deviates from the conventional laminectomy approach. Tumor characteristics were compared, and a cut-off value for laminectomy was determined. Outcomes were compared between groups, and factors influencing laminectomy were identified. Postoperative changes in cervical curves were measured., Results: The diameter of the intradural part of the tumor was significantly longer in the laminectomy performed group, with a 14.86 mm cut-off diameter requiring laminectomy. Recurrence rates did not differ significantly between groups. Surgery time was substantially longer for the laminectomy performed group. No significant changes were observed in Cobb's angles of Oc-C2, C1-C2, and Oc-C1 before and after surgery., Conclusion: The study showed that the diameter of the intradural part of the tumor influenced the decision to perform laminectomy for removing epidural schwannomas at C1-C2. The cut-off value of the diameter of the intradural part of the tumor for the laminectomy was 14.86 mm. Not performing laminectomy can be a viable option with no significant differences in removal and complication rates., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Austria, part of Springer Nature.)

Background: The benefits of surgery for symptomatic spinal metastases have been demonstrated, largely based on series of patients undergoing debulking and instrumentation operations. However, as cancer treatments improve and overall survival lengths increase, the incidence of recurrent spinal cord compression after debulking may increase. The aim of the current paper is to document the postoperative evolution of neurological function, pain, and quality of life following debulking and instrumentation in the Global Spine Tumor Study Group (GSTSG) database., Methods: The GSTSG database is a prospective multicenter data repository of consecutive patients that underwent surgery for a symptomatic spinal metastasis. For the present analysis, patients were selected from the database that underwent decompressive debulking surgery with instrumentation. Preoperative tumor type, Tomita and Tokuhashi scores, EQ-5D, Frankel, Karnofsky, and postoperative complications, survival, EQ-5D, Frankel, Karnofsky, and pain numeric rating scores (NRS) at 3, 6, 12, and 24 months were analyzed., Results: A total of 914 patients underwent decompressive debulking surgery with instrumentation and had documented follow-up until death or until 2 years post surgery. Median preoperative Karnofsky performance index was 70. A total of 656 patients (71.8%) had visceral metastases and 490 (53.6%) had extraspinal bone metastases. Tomita scores were evenly distributed above (49.1%) and below or equal to 5 (50.9%), and Tokuhashi scores almost evenly distributed below or equal to 8 (46.3%) and above 8 (53.7%). Overall, 12-month survival after surgery was 56.3%. The surgery resulted in EQ-5D health status improvement and NRS pain reduction that was maintained throughout follow-up. Frankel scores improved at first follow-up in 25.0% of patients, but by 12 months neurological deterioration was observed in 18.8%., Conclusion: We found that palliative debulking and instrumentation surgeries were performed throughout all Tomita and Tokuhashi categories. These surgeries reduced pain scores and improved quality of life up to 2 years after surgery. After initial improvement, a proportion of patients experienced neurological deterioration by 1 year, but the majority of patients remained stable.

Background: For patients with single-level cervical radiculopathy, various types of motion preservation surgeries, such as total disc replacement (TDR), posterior cervical foraminotomy (PCF) and posterior percutaneous endoscopic foraminotomy and discectomy (PECF), are available. In addition to motion preservation, the quality of motion is an important issue. The aim of the present study was to evaluate the influence of these surgeries on cervical motion by comparing the instantaneous axis of rotation (IAR) among PECF, TDR and PCF at the index and superior/inferior adjacent segments., Methods: A retrospective review was performed of patients who underwent index surgery at C5-6 for cervical single-level foraminal disc herniation or foraminal stenosis. Patients with minimal degeneration at the index and other cervical spinal levels and flexion/extension cervical lateral radiographs both preoperatively and 6 months postoperatively were included (PECF, 11 patients; TDR, 11 patients; PCF, 12 patients). The IARs were calculated at the index segment and segments above and below the index segment from the flexion and extension cervical lateral radiographs, which were obtained preoperatively and 6 months postoperatively. A standardized cervical normogram was referenced to qualify shifts in the IAR., Results: Postoperatively, neck pain was significantly decreased, with no difference among the surgical methods. The IARs were not significantly changed after the PECF. Although significant inferior shift occurred at C6-7 after TDR (p = 0.02), the shift occurred within the normal range in the cervical normogram. However, significant inferior shifts in the IARs occurred after PCF at C5-6 (p = 0.02) and C6-7 (p = 0.02), and the IARs moved out of the normal range., Conclusions: The IARs were significantly changed after PCF at either the index segment or the adjacent segment below. The shifts in IAR at the index and adjacent segments were not significant after PECF and TDR. The sample size was too small to allow definitive conclusions, but the present study showed that PECF may be another alternative to motion preservation surgeries.

Background: We aim to provide sagittal and pelvic parameters according to different age groups in an asymptomatic population all over 30 years old and to investigate the possible causes of changes in these parameters., Methods: Whole-spine, standing lateral radiographs were taken in 128 asymptomatic Korean people over 30 years old. The spinal parameters (the total thoracic kyphosis (TTK), maximal lumbar lordosis (MLL), total lumbar lordosis (TLL), lower lumbar lordosis (LLL), thoracolumbar junctional angle (TLJA), and lumbar inclination (LI)), pelvic parameters (pelvic incidence (PI), sacral slope (SS), and pelvic tilt (PT)), and spinal balance parameters (spinal balance, sacropelvic balance, and spinopelvic balance) were measured. The body mass index, body protein mass, waist line, skeletal muscle mass, and body fat mass were also measured for potential causes., Results: TTK and TLJA were significantly increased in the group over 70 years of age compared to the other age groups (p = 0.0002, <0.001). TLL was significantly decreased in the group over 70 years of age (p = 0.002), whereas the PI values were similar to PI even in over 70-year age group. LLL did not differ in the group over 70 years of age (p = 0.29), gradually increasing with an increase in age. SS was significantly decreased and PT was significantly increased in the group over 70 years of age as compared to the other age groups (p = 0.049, 0.049, respectively). PI was similar in all age groups (p = 0.75). Spinal balance was significantly decreased in the group over 70 years of age (p = <0.0001). PT was significantly associated with body protein mass and skeletal muscle mass (p = 0.01, 0.001, respectively). Body protein mass and skeletal muscle mass were significantly lower in the group over 70 years of age (p = 0.02, 0.02) and were possible causes., Conclusions: Several sagittal and pelvic parameters are different in asymptomatic adults over 70 years of age. Decreased body protein mass and skeletal muscle mass are possible causes of these changes.

Background: A conventional iliac bolt and the S2 alar iliac screw fixation technique (S2AI) are commonly used sacropelvic fixation techniques. However, conventional iliac bolt technique requires a lateral connector and commonly has prominent screw head problems. S2AI reportedly has a high instrument failure rate. We aim to introduce a modified iliac screw fixation technique and to investigate its clinical application in adult patients., Methods: The entrance site of the modified iliac screw fixation technique was 1 cm medial and 1 cm caudal from the posterosuperior iliac spine. From 2009 to 2015, ten adult patients underwent sacropelvic fixation with the modified iliac screw fixation technique in our spine clinic. A minimum 12-month clinical and radiographic follow-up was adopted. The mean follow-up period was 30.7 months (12-74 months). Mean number of fixation levels was 7.7 segments (5-10 segments)., Results: Postoperatively, the C7 plumb line (SVA) was significantly decreased (P = 0.04). Upon the last X-ray, SVA did not differ between postoperative and the last X-ray (P = 0.1). There was no breakage during our follow-up period. There was no prominent screw head. There were no cases requiring implant removal., Conclusions: The modified iliac screw fixation technique does not cause prominence in the sacral region, and does not require a lateral connector, both of which are necessary when using the classical iliac bolt technique. This technique also avoids the acute angle between the screw head and the shaft of the screw commonly seen in S2AI. The modified iliac screw fixation technique can be an effective alternative for sacropelvic fixation.

Background: The aim of this work is to evaluate the utility of multimodal intraoperative monitoring (IOM) during intramedullary spinal cord tumor (IMSCT) surgery in our institution, and to investigate which IOM events are likely to be encountered during critical surgical phases., Methods: Twenty-five patients who underwent IMSCT surgery with IOM were included in this study. Our multimodal IOM assessment included SSEP, mMEP, and fEMG monitoring. Positive predictive value (PPV), negative predictive value (NPV), sensitivity, and specificity were assessed 24 h and 1 month after surgery. The IOM events during three main surgical phases were also investigated. For mMEP assessment, two warning criteria (>50 % decrease in mMEP amplitude and all-or-none mMEP amplitude presence) were employed., Results: Long-term outcome prediction was better when the all-or-none criterion was applied than when the >50 % amplitude decrease criterion was applied. Based on the all-or-none criterion, the PPV, NPV, sensitivity, and specificity were 60, 100, 100, and 91 %. Frequent IOM events were observed during the three major main surgical phases. Seven (29 %) patients showed SSEP events during opening of the spinal cord. During tumor removal, 21 of 25 patients (84 %) had IOM events, and 13 of 18 (72 %) of the fEMG events occurred prior to the mMEP events., Conclusions: Based on the association of fEMG events with upcoming mMEP events during tumor removal, we recommend inclusion of fEMG monitoring in IOM. Multimodal IOM provides useful electrophysiological information during IMSCT surgery, especially during the main surgical phases.

Background: Seizure is the most common presentation in patients with cerebral cavernous malformations (CCMs). Although many articles have documented seizure outcomes after resection of CCM, few have conducted long-term follow-ups; thus, the fluctuating seizure outcomes have been neglected. The purpose of this study is to describe long-term postoperative seizure outcomes in patients with CCM and to compare seizure outcomes between patients with sporadic seizures and those with chronic seizures., Methods: Forty-six patients with CCM presenting with seizures underwent surgery. The male-to-female ratio was 1:1, and the average age at initial seizure onset was 27.6 years. The mean preoperative seizure duration was 42.7 months. Patients were divided into two groups: a chronic group (N = 20) and a sporadic group (N = 26) according to seizure frequency and duration. The mean postoperative follow-up duration was 96.3 months, and the postoperative seizure outcomes were checked annually based upon Engel's classification., Results: After the first year of follow-up, 80.8 % of the sporadic group and 75.0 % of the chronic group were evaluated as Engel class I. These rates increased to 100.0 % and 90.0 %, respectively, at the eighth year of follow-up. Overall, 29 (63.0 %) of the 46 patients experienced changes in seizure outcomes over the follow-up period. Despite their delayed improvements, the chronic group showed less favorable outcomes throughout follow-up (p = 0.025)., Conclusions: Long-term follow-up is indispensable for accurately assessing postoperative seizure outcomes because these outcomes change continuously. We recommend earlier surgery to achieve seizure-free status in patients with CCM. However, even in the chronic group, surgery is recommended, considering the overall delayed improvement.

Background: Cervical spondylotic myelopathy (CSM) may be caused by static and dynamic spinal cord compression, particularly during neck extension. Dynamic compression may be better evaluated with dynamic magnetic resonance (MR) images. We performed a retrospective study to determine the clinical indication for dynamic MR imaging, and conducted a survey regarding image interpretation by clinicians., Method: A total of 32 patients (M:F = 20:12, 60.1 ± 10.7 years) who had undergone neutral/extension cervical MR imaging were included. The study population consisted of 22 patients with signs of cervical myelopathy (M group) and 10 patients without signs of myelopathy (NM group). The number of compression levels (complete obliteration of the anterior and posterior subarachnoid space) was assessed at each level in mid-sagittal, T2-weighted, neutral and extension MR images. Reproduced images from 22 patients in the M group were randomly arranged, and four experienced spine surgeons at four different institutes interpreted them to reach a clinicians' agreement. The agreements were then assessed with inter-rater correlation coefficients (ICC)., Results: Analysis with extension MR images found an increased number of compression levels in 23/32 (72 %) of patients; 20/22 in the M group and 3/10 in the NM group (p < 0.01, chi-squared test), as compared to findings of the neutral MR images. Clinical factors for increased compression levels in extension MR images were age (p < 0.01, 63.3 ± 10.0 years vs. 51.9 ± 8.1) and signs of myelopathy (p < 0.01, odds ratio, 23.33). Clinician agreement was improved with extension MR images; ICC was 0.67 with neutral and 0.81 with extension MR images., Conclusions: The evaluation of CSM may be improved with dynamic MR images. Dynamic MR scanning may be considered for elderly patients with signs of myelopathy, but an interpretation for asymptomatic spinal compression based exclusively on extension MR image should be made with caution.

Background: There have been numerous studies on the outcomes of surgery for spinal cord cavernous angiomas. However, the natural history of conservatively treated disease is not well known. The aim of this retrospective study was to investigate the outcomes of conservatively managed patients with spinal cord cavernous angioma to determine the appropriate treatment strategies., Methods: Twenty-four patients who visited a single institution over an 11-year period and who were treated conservatively were enrolled in this study. Their medical records and radiological images were reviewed retrospectively. The neurologic status of the patients was assessed using the Japanese Orthopedic Association scoring system and the clinical presentation of the patients was classified into the following 4 categories: type A, asymptomatic; B, pain only; C, sensory deficits; and D, sensory and motor deficits. The results of types C and D patients were compared with the results of previously reported surgical series from our institution., Results: The mean age of the enrolled patients was 52.0 years (21-73). The mean duration of the clinical follow-up was 60.5 months (11-119) and the follow-up using magnetic resonance imaging was 52.4 months (3-122). Cavernous angiomas presented in the cervical spinal cord in 12 patients, thoracic spinal cord in 10 patients and in multiple levels of the spinal cord in 2 patients. There were 5, 5, 7, and 7 patients, respectively, classified with types A, B, C, and D for clinical presentations. The rate of recurrent hemorrhage was 1.7 %/patient-year and all recurrent hemorrhages only developed in type C or D patients. In types C and D patients, improvement in the JOA score during the follow-up period was 0.77 ± 1.8 in the conservative group and 1.07 ± 1.8 in the surgical group (p = 0.500). However, improvement in the JOA sensory score after surgical treatment was statistically significant (P = 0.007)., Conclusions: Conservative treatment may be a reasonable treatment strategy for patients with types A and B. If patients present with type C or D, surgical treatment is recommended considering the better improvements in sensory deficits and the high rate of recurrent hemorrhage in such patients.

Background: The resection of eloquent areas is challenging due to postoperative neurological deficits. The purpose of this study was to assess the efficacy and risk of awake brain surgery for non-lesional epilepsy involving the eloquent areas or their adjacent areas and to advocate the generation of a resection frequency map., Methods: We enrolled 55 patients who underwent awake surgery between 1994 and 2007 for non-lesional epilepsy involving the primary sensori-motor or language areas. All patients underwent two-staged operations including subdural electrode monitoring and awake resective surgery. For each case, the preoperative and postoperative images were spatially normalized and compared on a standard atlas, and the resection map was then computed by summing up each resected area on the atlas., Results: The postoperative seizure outcome was Engel class I in 27 patients (49.1%), II in nine (16.4%), III in 14 (25.5%) and IV in five (9.1%). Ten patients (18.2%) experienced postoperative neurological deficits including seven transient (12.7%) and three permanent, but mild ones (5.5%). The neurological complication rate of purely eloquent area resection was 36.8% (7/19). The resection frequency map computed in this study showed that the resection of eloquent areas was tolerable, with the exception of the Broca's area., Conclusions: Awake resective surgery with intraoperative brain mapping is an effective and safe treatment option for non-lesional epilepsy involving eloquent areas. The resection frequency map can show the resected area of a group as well as individuals and provide an objective measure of neurological risk.

We report five cases of ganglioglioma in various locations. The tumours were removed with gross total resection in most cases without any further neurological deterioration. Without any additional treatment, no evidence of recurrence or regrowth of tumours was observed in the mean follow-up period of 4.1 years. We suggest that intramedullary spinal cord gangliogliomas be resected totally due to the high risk of recurrence and regrowth rate of the tumours with subtotal resection in the long term considering especially that these tumours affect predominantly young patients.