Objective To investigate the relationship between C1 screw trajectory and occipital bone erosion in C1–2 posterior fixation.
Methods This retrospective cohort study analyzed 27 patients (54 screws) who underwent C1–2 posterior fixation between March 2018 and March 2023 at a single institution by multiple surgeons. Screws were classified by trajectory: Tan technique (n=39) or Harms-Goel (HG) technique (n=15). Primary outcome was occipital bone erosion; the secondary outcome was breach of inner cortical layer. Per-screw analysis was performed using generalized estimating equations to account for bilateral screw clustering.
Results Mean follow-up was 48.3 (range, 24–84) months. Occipital bone erosion occurred in 51.3% (20 of 39) of Tan screws versus 6.7% (1 of 15) of HG screws (p<0.001). Breach of inner cortical layer occurred exclusively with the Tan technique (10.3% vs. 0%, p=0.302). In mixed Tan+HG cases (n=3), erosion occurred only on the Tan side (2 of 3 screws) with no erosion on HG side (0 of 3 screws). C1 upper line transgression was a critical risk factor; no erosion occurred in screws that did not exceed this anatomical landmark (adjusted relative risk [RR], 6.82; 95% confidence interval [CI], 2.41–19.31). Additional risk factors included height O–C1 ≤4.5 mm (RR, 3.81; 95% CI, 1.51–6.28) and height O–C1 extension ≤1 mm (RR, 4.86; 95% CI, 2.05–11.53). No patients required reoperation for erosion-related symptoms during follow-up.
Conclusion Screw trajectory is the primary determinant of occipital bone erosion following C1–2 fixation. The HG technique demonstrated significantly lower erosion rates (6.7% vs. 51.3%). When anatomically feasible, HG technique may be considered to reduce erosion risk.
Objective To assess the current management of primary spinal cord tumors (PSCTs) and determine whether and to what extent there are differences in surgical strategies for PSCTs.
Methods The Neurospinal Society of Japan conducted a survey between April 1 and 30, 2021. Certified spine surgeons were requested for information on the frequency of surgeries in 2020 and the surgical strategies adopted for each PSCTs. The following tumor histologies were focused: schwannoma, meningioma, and cauda equina tumor as extramedullary tumors; and ependymoma, hemangioblastoma, astrocytoma, and cavernoma as intramedullary tumors. The participants were divided according to their response as follows: experts, who had experienced ≥ 100 surgeries for PSCTs, and nonexperts.
Results Among 308 participants (63%), 35 (11%) were experts. The total number of PSCTs in 2020 was 802 of which 564 tumors were extramedullary and 223 were intramedullary. Schwannoma accounted for 53% of the extramedullary tumors, and ependymoma accounted for 39% of the intramedullary tumors. Surgical strategies significantly differed among both the experts and nonexperts groups. Some discrepancies in the adopted surgical strategies were observed between groups. Some of the nonexperts, and none of the experts, ruled out surgery for schwannomas (Eden type 4), astrocytomas, or cavernomas. Five nonexperts (2.2%), and none of the experts, resected the entire dura for meningiomas.
Conclusion A nationwide survey revealed that a sufficient consensus did not exist regarding surgical strategies for PSCTs. A disease-specific registry for PSCTs is necessary in academic societies.
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Neurospine 2022;19(2):441-452. Published online June 30, 2022
Objective We performed a retrospective observational study to demonstrate the surgical risks and long-term prognoses of intramedullary tumors in Japan using a multicenter registry authorized by the Neurospinal Society of Japan.
Methods Data from 1,033 consecutive patients with intramedullary tumors, treated between 2009 and 2020, were collected from 58 centers. Patients with spinal lipomas or myxopapillary ependymomas were excluded. Patient characteristics, clinical presentations, imaging characteristics, treatments, and outcomes were analyzed. The modified McCormick scale was used to classify functional status. Survival was described using Kaplan-Meier curves, and multivariable logistic regression analyses were performed.
Results The mean age of the patients was 48.4 years. Data of 361 ependymomas, 196 hemangioblastomas, 168 astrocytic tumors, 160 cavernous malformations, and the remaining 126 cases including subependymomas, metastases, schwannomas, capillary hemangiomas, and intravascular B-cell lymphomas were analyzed. Twenty-two patients were undiagnosed. The mean follow-up duration was 46.1 ± 38.5 months. Gross total tumor removal was achieved in 672 tumors (65.1%). On the modified McCormick scale, 234 patients (22.7%) had worse postoperative grades at the time of discharge. However, neurological status gradually improved. At 6 months postoperatively, 251 (27.5%), 500 (54.9%), and 160 patients (17.6%) had improved, unchanged, and worsened grades, respectively. Preoperative functional status, gross total tumor removal, and histopathological type were significantly associated with mortality and functional outcomes.
Conclusion Our findings demonstrate better postoperative functional outcomes in patients with fewer preoperative neurological deficits. Degree of resection, postoperative treatments, and prognoses are closely related to the histology of intramedullary tumors.
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