Clinical and Magnetic Resonance Features of Spinal Myxopapillary Ependymoma

Abstract

BACKGROUND AND OBJECTIVES:

Spinal myxopapillary ependymoma (SMPE) is a common primary tumor of the cauda equina region. Despite its benign nature, SMPE is difficult to resect, and early seeding along the neural axis may necessitate further adjuvant therapy. The aim of this study was to analyze the clinical and MRI characteristics of SMPE to enhance pretreatment diagnosis and outcomes.

METHODS:

We retrospectively reviewed patients with SMPE at 2 institutions between 2003 and 2023. Preoperative MRI was reviewed to determine the tumor characteristics. The primary outcomes were progression-free survival and overall recurrence rates, which were analyzed using Kaplan–Meier statistics.

RESULTS:

A total of 20 patients with SMPE were recruited (mean age: 33.1 ± 14.8 years, 70% male). The follow-up period was 103 ± 70.2 months. “Insects in amber” sign and midline position are the most common characteristics indicative of SMPE on MRI and are observed in 90% and 85% of patients, respectively. Seven (35%) patients experienced tumor recurrence. Younger age (P = .008), tumors >50.2 mm in size (P = .019), conus medullaris involvement (P = .043), the presence of tumor seeding before the operation (P < .001), and incomplete resection (P = .002) were associated with a higher rate of tumor recurrence after the operation. The 5- and 10-year progression-free survival rates were estimated to be 70% and 65%, respectively.

CONCLUSION:

SMPE can be diagnosed based on pretreatment MRI findings, such as the “insect in amber” sign and a midline tumor location. We recommend adjuvant therapy and close postoperative follow-up for patients at high risk of tumor recurrence to improve outcomes.

ABBREVIATIONS:

GTR

gross total resection

STR

subtotal resection

T1WI

T1-weighted images

T2WI

T2-weighted images.

Spinal myxopapillary ependymoma (SMPE) is the most common primary tumor in the cauda equina, arising from ependymal glia of the filum terminale.^1-4 According to the 2021 World Health Organization classification, it is a grade 2 tumor.^5,6 Although histologically benign, SMPEs frequently recur and may disseminate along the neuraxis, leading to unfavorable outcomes. Gross total resection (GTR) is the treatment goal, but complete excision with nerve preservation can be challenging. In cases of subtotal resection (STR) or leptomeningeal seeding, adjuvant radiotherapy is often considered.

Clinically, SMPEs are difficult to diagnose because of their slow growth and nonspecific symptoms, similar to other cauda equina tumors.^3,7 MRI findings also overlap with those of schwannomas and meningiomas,^4,8 yet SMPEs generally carry a poorer prognosis due to cerebrospinal fluid dissemination and higher recurrence rates.^9-11 Accurate pretreatment diagnosis is therefore essential for optimizing treatment strategies, including the potential role of adjuvant radiotherapy, and for predicting patient outcomes.

This retrospective study aimed to characterize the clinical and MRI features of SMPE and to evaluate long-term surgical outcomes and prognostic factors associated with tumor recurrence.

METHODS

This retrospective cohort study was approved by the institutional review board. The data were collected from 2 medical centers of the same system. Informed consent for conducting imaging examinations, surgery, and adjuvant cancer treatment was obtained from either the patients or their families.

Patients

Twenty patients with a histological diagnosis of SMPE were identified from the database of 2 institutions between January 2003 and August 2023. The flowchart of patient selection is shown in Supplemental Digital Content 1 (Supplementary Figure 1, http://links.lww.com/NS9/A91). All patients underwent a complete neurological examination. We reviewed their clinical findings, including demographic features, signs and symptoms, and surgical outcomes (Table 1).

TABLE 1.

Patient Characteristics

Variable (n = 20)	Number (%)
Sex (male/female)	14/6 (70%/30%)
Age (y)	33.1 ± 14.8 (13-71)
Symptoms
Pain	18 (90%)
Numbness	11 (55%)
Motor deficit (weakness)	15 (75%)
Autonomic dysfunction	8 (40%)
Duration of symptoms (mo)	22.4 ± 35.1 (0.75-120)
MR features
Tumor location
Thoraco-lumbar	5 (25%)
Lumbar	12 (60%)
Lumbo-sacral	2 (10%)
Sacral	1 (5%)
Tumor seeding	9 (45%)
Tumor size (cm)	5.47 ± 4.85 (0.88-22.5)
Imaging characteristics
T1-weighted signal
Iso to low/iso to low with hyper foci	19 (95%)/1 (5%)
T2-weighted signal
Hyper	20 (100%)
Insects in amber sign	18 (90%)
T1WI/C
Well/poor enhancement	19 (95%)/1 (5%)
Midline location	17 (85%)
Treatment
Surgery
Gross total resection	12 (60%)
Subtotal resection	3 (15%)
Partial resection/biopsy	5 (25%)
Adjuvant radiotherapy	5 (25%)
Surgical outcome
Follow-up period (mo)	103 ± 70.2 (18.3-244)
Recurrence (no.)	7 (35%)
Time to recurrence (mo)	27.3 ± 27.7 (4.7-213)
Death (no.)	0 (0%)

MR, magnetic resonance.

MRI

All patients underwent MRI of the thoracic to lumbar spine and brain for preoperative evaluation. Once the patient exhibited leptomeningeal seeding, we performed whole-spine MRI to determine the degree of tumor seeding along the whole neuraxis. The signals on T1-weighted images (T1WI), T2-weighted images (T2WI), and contrast-enhanced T1WI and the locations of the tumors were recorded. The signal intensity of the tumor was compared with that of the adjacent normal spinal cord. If the tumor was hyperintense on a T2WI with a small central hypointense focus, we named it the “insects in amber” sign (Figure 1). This specific feature is representative of the irregular hypointense focus in the background of a hyperintense tumor resembling an insect inside amber.

FIGURE 1.

The “insects in amber” sign. A 14-year-old boy was diagnosed with spinal myxopapillary ependymoma. Sagittal T1-weighted (A), postcontrast (B), and T2-weighted images (C), along with axial T2-weighted images (D, E), revealed an extramedullary spinal mass located at the L2-L5 level of the spinal cord. The “insects in amber” sign refers to hypointense spots or foci within the hyperintense mass seen on T2-weighted and postcontrast images (indicated by arrowheads). These hypointense lesions resemble an insect trapped inside amber (F, H). A photomicrograph (hematoxylin and eosin staining, ×100) (G) shows multiple areas of intravascular thrombus formation (asterisk) and intratumoral hemorrhage.

The presence of preoperative tumor seeding and tumor invasion into adjacent structures, such as the conus medullaris, was also determined on preoperative MRI. The preoperative tumor seeding was defined as the presence of spatially separate, noncontiguous nodular lesions along the cerebrospinal fluid pathway that demonstrated imaging characteristics similar to the primary tumor on preoperative MRI. The conus medullaris involvement was defined as contact and/or extension of the tumor to the conus medullaris of the spinal cord. The location and length of the tumor were also recorded.

Surgical Techniques

GTR of the tumor was attempted in all patients when technically feasible. GTR was defined as the complete or approximately 100% removal of the primary tumor according to microscopy at the end of surgery and postoperative MRI. For tumors with a well-defined margin or small size, we aim to perform en bloc removal. For large tumors of ill-defined margins or intermingled with the cauda equina, we proceed with a piece-by-piece resection approach to prevent nerve root injury. STR was defined as the removal of 80% to 99% of the primary tumor, and partial resection was defined as the removal of <79% of the primary tumor volume.^12-15 Both STR and partial resection were defined as incomplete resection. All surgical specimens were pathologically evaluated to determine whether there was a correlation with the MRI findings. Adjuvant treatment, such as radiotherapy, was added if the patients had preoperative tumor seeding, recurrent symptoms, and/or incomplete surgical resection.

Follow-up

All patients underwent early postoperative MRI of the spine within the first month after surgery to determine the extent of tumor resection. The patients were then regularly followed up every 3 months in our outpatient department with clinical and MRI examinations for the first 2 years and then every 6 to 12 months thereafter. Any tumor recurrence or neurological symptoms were recorded. Tumor recurrence was defined as the presence of a residual, enhancing, or solid tumor with a volume increase of more than 20% compared with the tumor characteristics on early postoperative MRI.^16-18 This size increase includes either the primary tumor and the initial preoperative seeding lesion or the appearance of a new seeding lesion. Tumor control was defined as the absence of radiologic evidence of tumor progression, including no increase in the size of the primary tumor or any seeding lesion on follow-up MRI.

Statistical Analyses

Statistical analyses were conducted using SPSS V.27 (IBM). Continuous variables are expressed as mean ± SD, and categorical variables are expressed as frequencies or percentages. Groups were compared using the Mann–Whitney U test (nonnormally distributed). χ² tests were used when comparing proportions of a variable between 2 groups. A P value < .05 was considered to indicate statistical significance. We assessed progression-free survival (PFS) using Kaplan‒Meier estimations and defined the timing of recurrence as the time from surgery to the time of recurrence. Continuous variables with significant values were dichotomized around an optimal cutoff identified on receiver operating characteristic curves by applying Youden’s index (the maximum value of sensitivity + specificity).

RESULTS

Patients and Clinical Features

All the demographic features of the 20 patients with SMPEs are presented in Table 1. The mean age was 33.1 ± 14.8 years, and 70% (14/20) were men. The tumors were most frequently located in the lumbar segments (60%, 12/20), followed by the thoraco-lumbar segments (25%, 5/20).

The typical clinical presentation is slow and indolent. Symptoms presented a mean of 22.4 months before diagnosis. The most common symptom was lower back pain (90%, 18/20), with 88.9% (16/18) of patients suffering from lower back pain with radiculalgia. Other symptoms included motor deficits and lower limb weakness (75%, 15/20), numbness of the lower back to the lower limb or foot (55%, 11/20), and autonomic dysfunction (40%, 8/20). The mean pretreatment muscle power of the lower limbs is 4.43 ± 0.9. Among the 8 patients with autonomic dysfunction, 75% complained of urine retention, 25% had urine incontinence, and 75% had dysfunction of the anal sphincter.

MRI Features

The MRI features are presented in Table 1. The tumors presented as well-defined, intradural extramedullary lesions in all 20 patients. The mean tumor size was 5.47 ± 4.85 cm. Eighty-five percent (17 of 20) of the main tumors were symmetrically positioned at the midline of the spinal canal without lateral extension or intervertebral foramen involvement. On MRI, all tumors appeared isointense to hypointense on T1WI and hyperintense on T2WI. Superficial hemosiderosis of the surface of the spinal cord causing decreased signal intensity on T2WI occurred in 3 (15%) patients. “Insects in amber” sign on T2WI was noted in 18 (90%) patients (Figure 1). Ninety-five percent of the tumors (19 of 20) showed intense enhancement on contrast-enhanced T1WI. Conus medullaris involvement was noted in 11 (55%) patients. Tumor seeding as the initial MRI presentation was noted in 9 (45%) patients (Figures 2 and 3).

FIGURE 2.

Large spinal myxopapillary ependymoma with tumor recurrence after surgery. A 14-year-old boy was diagnosed with a spinal myxopapillary ependymoma. Preoperative MRI (A-E) revealed an extramedullary spinal mass measuring approximately 89.6 mm located at the T12-L3 level, with involvement of the conus medullaris (indicated by white arrowheads). The mass appeared isointense on T1-weighted MRI (A), hyperintense with a characteristic “insects in amber” sign on T2-weighted sagittal (C) and axial (E) MRI and demonstrated avid enhancement following contrast media administration (B, D). The tumor was located in the midline axial position (D, E). Preoperative tumor seeding extending approximately 19.5 mm was detected at the S1 level of the spinal cord (indicated by black arrowheads). Subtotal resection of the mass at the T12-L3 level was achieved. However, imaging at 4.5 months after surgery (F) revealed a local recurrent tumor measuring approximately 32.7 mm at the L1 level of the spinal cord (white arrow), along with an increase in the size of the S1 seeding tumor (black arrow).

FIGURE 3.

Small SMPE without tumor recurrence after surgery. This 44-year-old man was diagnosed with a SMPE. Preoperative MRI (A, B, C, E) revealed an extramedullary spinal mass measuring approximately 17 mm at the L2-L3 level (indicated by arrowheads). The tumor appeared isointense on T1-weighted MRI (A), hyperintense on sagittal and axial T2-weighted MRI (C, E), and showed avid enhancement after contrast administration (B). No “insects in amber” sign was observed on T2-weighted images, and the tumor was in an eccentric position on the axial T2-weighted image (E). In addition, the tumor did not involve the conus medullaris, and there was no evidence of preoperative tumor seeding. This patient was initially diagnosed with a schwannoma. Gross total resection was achieved, with the final diagnosis confirming SMPE. A photomicrograph (hematoxylin and eosin staining, ×100) (F) shows blood vessels without thrombi and no intratumoral hemorrhage. Follow-up postcontrast spinal MRI after surgery (D) revealed no tumor recurrence. SMPE, spinal myxopapillary ependymoma.

Treatments

All patients underwent surgery. GTR was achieved in 12 patients (60%), STR was achieved in 3 patients (15%), and partial resection was achieved in 5 patients (25%). Five patients (25%) underwent adjuvant radiotherapy after the operation because of subtotal or partial tumor resection during the operation and preoperative tumor seeding.

Outcomes and Follow-up

The mean follow-up period was 103 ± 70.2 months. The follow-up results are presented in Tables 1 and 2. No patient died during the follow-up period. Motor function improved or remained stable in 10/12 (83.3%) patients but worsened in 2/12 (16.7%) patients. Sensory symptoms and sphincter dysfunction improved or remained stable in all patients. None of them experienced worsening of sensory or autonomic symptoms after the operation.

TABLE 2.

Analyses of the Factors of Spinal Myxopapillary Ependymomas that Were Completely and Incompletely Resected and the Factors of Patients With and Without Tumor Recurrence

	Surgery			Recurrence
	GTR (n = 12)	Incomplete resection (n = 8)	P value	Recurrence (n = 7)	No recurrence (n = 13)	P value
Patient characteristics
Age (y)	40.2 ± 14.4	22.4 ± 7.76	.002	22.4 ± 8.22	38.8 ± 14.7	.008
Sex (M/F)	8/4	6/2	.545	4/3	10/3	.357
Tumor characteristics
Tumor size (mm)	30.5 ± 13.5	91.1 ± 59.8	<.001	83.5 ± 65.3	39.2 ± 29.1	.019
Location (upper/lower)a	10/2	4/4	.137	2/5	4/9	.919
Insects in amber sign	10 (83.3%)	8 (100%)	.347	7 (100%)	11 (84.6%)	.411
Enhancement	12 (100%)	7 (87.5%)	.400	6 (85.7%)	13 (100%)	.350
Midline position	9 (75%)	8 (100%)	.193	7 (100%)	10 (76.9%)	.251
Conus medullaris involvement	6 (50%)	5 (62.5%)	.465	6 (85.7%)	5 (38.5%)	.043
Tumor seeding	2 (16.7%)	7 (87.5%)	<.001	7 (100%)	2 (15.4%)	<.001
Recurrence	1 (8.33%)	6 (75%)	.004
Surgery (GTR/incomplete)				1/6	11/2	.002

F, female; GTR, gross total resection; M, male.

^aLocation within thoracic to lumbar segments above L3 level is upper, location within lumbar segments below L4 level to sacral segments is lower.

Seven patients (35%) experienced tumor recurrence. Of these, 4 had local tumor recurrence, whereas 6 demonstrated an increase in the size of preoperative tumor seeding. The mean time from surgery to recurrence was 27.3 ± 27.7 months. Compared with the patients in the nonrecurrence group, the patients in the tumor recurrence group were significantly younger (P = .008), had larger tumors (P = .019), had conus medullaris involvement (P = .043), and had initial tumor seeding (P < .001) (Table 2). The PFS of patients with the above tumor characteristics is depicted in Figure 4A-4C. Patients with tumors larger than 50.2 mm had a significantly higher risk of recurrence after surgery. Surgical outcomes also affect the tumor recurrence rate. The tumor recurrence rate was significantly lower in the patients who received GTR than that who received incomplete tumor resection (including subtotal and partial resection) (P = .002). The 5-year PFS was 91.7% for the patients who received GTR and 37.5% for the patients who received incomplete resection (Figure 4D).

FIGURE 4.

PFS analysis of patients according to different prognostic factors. A, PFS curve for patients with SMPEs larger than and <50.2 mm. B, PFS curve for SMPEs with or without conus medullaris involvement. C, PFS curve for SMPEs with or without tumor seeding before surgery. D, PFS curves for gross total resection and incomplete resection. PFS, progression-free survival; SMPE, spinal myxopapillary ependymoma.

The 5- and 10-year PFS rates were estimated to be 70% and 65%, respectively. The PFS analysis of all patients is depicted in Figure 5.

FIGURE 5.

Kaplan–Meier curve demonstrating the disease-free progression of all patients. PFS, progression-free survival.

Management of Tumor Recurrence

Among the 7 patients who experienced recurrences, 3 (42.9%) underwent reoperation in addition to radiotherapy and 2 (28.6%) were treated with radiotherapy only. Two of the 7 patients refused treatment, and both remained stable. All the tumors were controlled at the last follow-up.

DISCUSSION

Although typically benign, SMPEs show a propensity for local recurrence and central nervous system dissemination, leading to unfavorable outcomes. Our study demonstrated that SMPE may be characterized by frequently observed pretreatment MRI features, notably the “insects in amber” sign on T2WI (90%) and midline location (85%), with the former representing a potentially novel imaging hallmark. Despite aggressive management, 35% of tumors recurred. Younger age, tumor size >50.2 mm, conus medullaris involvement, preoperative seeding, and incomplete resection were significant predictors of recurrence.

SMPEs present as well-defined encapsulated intradual extramedullary lesions in the thoracolumbar region. We noticed some special characteristics of SMPEs after reviewing our cases. First, the “insects in amber” sign. The “amber” represents the tumor mass itself. The “amber” is isointense to hypointense on T1WI, hyperintense on T2WI, and intensely enhanced on contrast-enhanced T1WI. Histologically, SMPEs are characterized by the radial arrangement of cuboidal to epithelioid elongated glial tumor cells around hyalinized fibrovascular cores in a papillary fashion, with accumulation of myxoid material around blood vessels and in microcysts.¹⁹ Hyperintensity on T2WI (the “amber” part) is possibly due to the mucin component in the SMPE. The “insect” part represents the foci of spiculated or spotty low signal intensity in the center of the SMPE on T2WI. Ninety percent of SMPEs have this special feature. The “insect” on T1WI was hyperintense in only 1 patient (5.6%) but was mostly isointense (94.4%). All the “insects” showed no or poor enhancement after contrast media administration. On correlating the imaging findings with histopathology, the “insects” was found to correspond primarily to intravascular thrombus formation accompanied by minimal intratumoral hemorrhage, whereas hemosiderin accumulation was rarely observed (Figure 1). By contrast, the specimens without this sign did not have intravascular thrombus formation and presented less intratumoral hemorrhage (Figure 3). These signal characteristics of the “insects” differ from those of typical tumor hemorrhage—subacute methemoglobin usually exhibits pronounced T1 hyperintensity, while chronic hemosiderin deposition results in markedly low T2 signal intensity.^20,21 Therefore, the “insects in amber” sign in SMPEs likely reflects intravascular thrombus formation within the myxoid stroma rather than classic hemorrhagic changes, suggesting that this imaging feature may be relatively characteristic of myxopapillary ependymoma.²² On reviewing tumors with similar imaging features, we found that intravascular papillary endothelial hyperplasia (Masson tumor) also exhibited hyperintensity on T2WI with nodular foci of low signal intensity. These hypointense areas on T2WI images corresponded to pathological findings of thrombotic or hemorrhagic material.²³ Song et al²⁴ also reported a significantly higher proportion of SMPEs with the “T2 dark sign” than that of schwannomas. They attributed this sign to hemosiderin deposition resulting from hemorrhage. However, hemosiderin deposition was not very common in SMPEs according to our pathological review. We postulate that intravascular thrombus formation more accurately explain the hypointense areas of SMPEs on T2WI.

Eighty-five percent of SMPEs were located at the midline on both the sagittal and axial scans. We postulated that this is because SMPEs arise from the filum terminalis. This centrally located tumor tends to dorsally and laterally compress and displace the nerve roots of the cauda equina. This intradural location also limits the lateral extension of the SMPE through the intervertebral foramen. By contrast, schwannomas arise from the roots of the cauda equina. The tumor may be located laterally and more commonly displace the roots to the other side. Neurogenic tumors are also likely to extend through the intervertebral foramen. This characteristic could also help us differentiate SMPEs from schwannomas.¹⁰

Spinal MRI is important not only for the correct diagnosis of SMPEs but also for the clarification of the factors related to a high recurrence rate. Younger age was associated with a higher rate of tumor recurrence in our study. Previous reports revealed that SMPEs occurring in pediatric patients are more aggressive and have a propensity for cerebrospinal fluid dissemination.^25-28 Our study included 4 adolescents younger than 18 years. We hypothesize that pediatric spinal nerves are generally more vulnerable to damage during surgical procedures than adult nerves are. In children, the myelin sheath, which insulates and protects nerves, is not fully developed, making nerves more sensitive and prone to injury.²⁹ In addition, children have smaller-diameter nerve fibers and less subcutaneous fat and connective tissue surrounding their nerves, making them more delicate and susceptible to damage during manipulation or retraction.³⁰ These factors make GTR more challenging in pediatric patients than in adults. In addition, the dose for adjuvant radiation therapy must be limited in children.³¹ Radiation can damage the surrounding healthy nervous system, leading to complications such as radiation myelopathy and lower motor neuron syndrome.³² Therefore, the radiation dose for children should be carefully controlled to avoid these adverse effects, which could be associated with a higher tumor recurrence rate.

GTR is the gold standard treatment. Both our study and the systematic review by Feldman et al²⁸ revealed that the recurrence rate was lower with GTR alone than with incomplete resection. However, SMPEs often encase or infiltrate the nerves of the cauda equina and involve the conus medullaris, making complete tumor removal challenging without injuring the nerves. The conus medullaris and cauda equina give rise to the L2-S5 spinal nerves and the coccygeal nerve, providing parasympathetic innervation to the urinary bladder, descending and sigmoid colon, rectum, and both the internal and external reproductive organs. SMPEs with conus medullaris involvement are particularly difficult to completely resect, as surgeons might leave residual tumors in the conus medullaris to avoid adverse neurological outcomes. Al-Habib et al²⁶ confirmed that tumors attached to the conus medullaris were significantly less likely to be completely resected. Our study also revealed an association between conus medullaris involvement and a high tumor recurrence rate.

A large tumor and the presence of tumor seeding before surgery were also associated with postoperative tumor recurrence. Our findings align with those of Montero et al,¹⁴ who analyzed 101 patients with SMPEs, although we defined tumor size more specifically. Slow-growing large tumors might infiltrate and surround more of the cauda equina than small tumors and have a greater chance of conus medullaris involvement, making GTR technically challenging. In addition, removing large tumors without injuring the nerves can lead to capsular violation during surgery. The piecemeal destruction of the tumor may cause iatrogenic tumor seeding, leading to future recurrence. Abdulaziz et al³³ emphasized the strong correlation between capsular violation and recurrence.

The role of adjuvant therapy remains debated. Although some studies (Akyurek et al,³⁴ Agbahiwe et al³⁵) reported reduced tumor progression with radiotherapy, a systematic review (Feldman et al²⁸) found no benefit in patients after STR. In our cohort, only 5 patients received adjuvant radiotherapy, and the analysis did not demonstrate a statistically significant reduction in tumor recurrence. The potential benefit of adjuvant radiotherapy remains inconclusive. Further investigation with larger cohorts is warranted to clarify its therapeutic impact.

The limitations of our study include the small sample size. Owing to the low incidence of SMPE, it is difficult to gather a large cohort of patients. A prospective, multicenter study involving more cases and the application of advanced imaging techniques (such as diffusion-weighted imaging or perfusion imaging) will be helpful for accurate pretreatment diagnosis and outcome improvement. In addition, this study lacked a comparison arm with other common spinal tumors, such as schwannoma or astrocytoma. Therefore, the specificity of the imaging features described here cannot be fully established and should be regarded as preliminary study. Future comparative studies are warranted to further validate these findings. We also lack comprehensive neurological assessments before and after surgery, as well as intraoperative neuromonitoring. We recommend including intraoperative neuromonitoring in future SMPE surgeries.^36,37

CONCLUSION

This study provides educational value by identifying key MRI features—the “insects in amber” sign and midline location—for diagnosing SMPE. Younger age, larger tumors (>50.2 mm), conus medullaris involvement, preoperative seeding, and incomplete resection were associated with recurrence. Adjuvant therapy and close follow-up are advised for high-risk patients.

Funding

This study has received funding from Taipei Veterans General Hospital, Taiwan V115D83-003-MY3-1, V115C-088, V114C-034 (to CHW); V115C-032, V114C-061, V112D67-002-MY3-3 (to FCC), National Science and Technology Council, Taiwan [NSTC 114-2314-B-075-050-MY3 and 111-2314-B-075-025-MY3 (to CHW); 114-2314-B-075-051- and 113-2314-B-075-037- (to FCC)], Vivian W. Yen Neurological Foundation (to CHW and FCC).

Disclosures

The authors have no personal, financial, or institutional interest in any of the drugs, materials, or devices described in this article.

Supplemental Digital Content

Supplemental Digital Content 1: Supplementary Figure 1. Flowcharts of patients diagnosed with spinal myxopapillary ependymomas (SMPEs) between January 2003 and August 2023 at 2 institutions.