Although numerous studies have discussed the predictors of surgical outcomes in patients with spinal ependymomas, the majority of existing evidence focuses on tumor recurrence and overall survival [18,15,22-24], and investigations concerning neurological functions remain limited [5,19,24]. In 2011, Boström and colleagues retrospectively analyzed functional outcomes in 57 cases of spinal ependymoma, in which complete resection was gained in 83% of cases. Additionally, 86% of the participants had stable or improved McCormick grades immediately after the operation, and 7% of the patients experienced permanent functional deterioration. Noteworthily, in their study, various histopathological variants were included, including subependymomas (WHO Grade I), myxopapillary ependymomas (WHO Grade I), ependymomas (WHO Grade II), and anaplastic ependymomas (WHO Grade III); therefore, the histopathology may be an intrinsic confounding factor [5]. In 2018, Domazet et al. conducted a retrospective study on 43 patients over a 10-year span, and they found early postoperative neurological functions were either better or equivalent to the baseline level in 80% of cases [7]. In our study, only ependymomas (WHO Grade II) were enrolled. We found neurological deficiencies were exacerbated in 44 (81.5%) patients postoperatively, and long-term functional deterioration was noted in 5 (9.3%) patients during the follow-up, which is highly consistent with Boström’s and Domazet’s reports. Furthermore, in Domazet’s study, approximately 76.5% of patients suffered from an ependymoma affecting only one spinal segment, while the tumor expanded over two or more spinal segments in 23.5% of cases [7]. There is a considerable discrepancy with our findings (25.9% in the monosegmental group).
Till now, the correlation between segments of the spinal cord affected by ependymomas and postoperative functional outcomes has not yet been clarified. Ardeshiri et al. proposed that patients with ependymomas involving more than three spinal segments may have a significantly higher risk of postoperative neurological deterioration compared to patients with short-segmental lesions [1]. In our study, the preoperative neurological functions in the patients with monosegmental ependymomas were remarkably better than those in patients with multisegmental lesions. However, we found no significant difference in the postoperative short-term or follow-up long-term neurological functions between the monosegmental ependymomas and their multisegmental counterparts. We speculate that multisegmental ependymomas may cause more damage to the spinal cord; nevertheless, this damage is not necessarily related to permanent neurological deficits. Unlike Ardeshiri’s findings, our results indicate that long-segmental involvement of the spinal cord is not a risk factor of postoperative neurological deterioration.
It has become researchers’ concerns whether the tumor morphology affects neurological outcomes. A German team led by Behmanesh proposed that regional spinal cord atrophy was associated with poor long-term outcome after surgical removal of intramedullary spinal cord ependymoma [4]. Fei et al. postulated the tumor-to-cord ratio might be a predictor for the surgical outcome of upper cervical ependymomas, while the logistic regression analysis yielded a negative result [8]. Arima and coworkers found that quantitative analysis of near-infrared indocyanine green angiography could predict functional outcomes after spinal ependymoma removal [2].
Ge et al. found that the neurological deterioration rate was significantly higher in patients undergoing subtotal resection than that in the patient receiving gross total resection (P = 0.011) [10]. Recently, Salari et al. performed a systematic review involving 407 cases in 23 studies; the authors concluded that complete surgical resection of intramedullary spinal cord ependymoma could prolong the progression-free survival (P = 0.004) and improve follow-up neurological functions (P = 0.019) in comparison with incomplete resection [19]. In the current study, 51 (94.4%) patients achieved gross total resection, and incomplete resection was only performed in 3 (5.6%) patients. Due to the small sample size in the incomplete resection cohort, we failed to analyze the correlation between the extent of surgical resection and functional outcomes.
Some scholars found permanent deficits after the spinal ependymoma resection was independently predicted by older age [3,8,27]. Bansal et al. followed up 146 patients with spinal intramedullary tumors; they found that the surgical outcome at the last follow-up was correlated with age, sex, the preoperative functional status, tumor size, location, pathology, the extent of surgical resection, and the presence of syringomyelia [3]. Gavin et al. investigated the clinical outcomes of spinal ependymomas, which revealed that the longer symptom duration prior to treatment was associated with worse functional outcomes (P = 0.006). Further multivariate analysis revealed that a shorter duration of symptoms prior to surgery predicted favorable postoperative ambulatory status [9]. In another study, Moquin and coworkers found that the long-term functional outcome was related to the preoperative neurological status, tumor location, the presence of myelomalacia, and the presence of arachnoid scarring. Remarkably, little improvement was seen in patients with preoperative long-standing neurological deficits, and patients with short duration of preoperative neurological deficits experienced the most remarkable symptomatic improvement [17]. In the present study, we did not note the correlation between long-term functional outcomes and demographic or radiological characteristics, and only preoperative neurological status was identified as a predictor of long-term neurological improvement.