Mismatch between Augmented Reality Navigation Images and Actual Location of a Cauda Equina Tumor:A Case Report.

BACKGROUND: Augmented reality navigation is the one of the navigation technologies that allows computer-generated virtual images to be projected onto a real-world environment. Augmented reality navigation can be used in spinal tumor surgery. However, it is unknown if there are any pitfalls when using this technique. CASE PRESENTATION: The patient in this report underwent complete resection of a cauda equina tumor at the L2-L3 level using microscope-based augmented reality navigation. Although the registration error of navigation was <1 mm, we found a discrepancy between the augmented reality navigation images and the actual location of the tumor, which we have called "navigation mismatch". This mismatch, which was caused by the mobility of the spinal tumor in the dura mater, seems to be one of the pitfalls of augmented reality navigation for spinal tumors. CONCLUSIONS: Combined use of intraoperative ultrasound and augmented reality navigation seems advisable in such cases. J. Med. Invest. 71 : 174-176, February, 2024.

Cauda equina neuroendocrine tumor: a report of three cases and review of the literature with focus on differential diagnosis and postoperative management.

INTRODUCTION: Cauda equina neuroendocrine tumors (CENETs), previously described as cauda equina paragangliomas (PGLs) are rare and well-vascularized benign entities which can be often misdiagnosed with other intradural tumors more common in this anatomical site, such as ependymomas and neurinomas. We describe three cases of CENETs observed at our institution with particular focus on differential diagnosis and postoperative management. Since the lack of guidelines, we performed a literature review to identify factors that can predict recurrence and influence postoperative decision making. CASE REPORT AND LITERATURE REVIEW: We report on three patients, two of them presenting with a clinical history of lower back pain and sciatica. In all cases magnetic resonance imaging (MRI) of the lumbosacral spine with and without Gd-DTPA revealed an intradural lesion with strong contrast enhancement, first described as atypical ependymoma or schwannoma. A complete tumor resection was achieved in all cases, the histopathological diagnosis classified the tumors as CENETs. In our literature review, a total of 688 articles were screened and 162 patients were included. Patients demographic data, clinical symptoms, resection and recurrence were recorded. DISCUSSION: Differential diagnosis between CENETs and other more common tumors affecting cauda equina region, such as ependymomas or schwannomas (neurinomas), is still very challenging. Due to the lack of specific clinical or radiological characteristics, a correct preoperative diagnosis is almost impossible. With this paper we want to point out that CENETs must be considered in the differential diagnosis, most of all in case of entities with atypical radiological features. According to the literature, tumor recurrence after gross total resection is unlikely, while a long-term follow-up is recommended in case of subtotal resection or local aggressive behavior.

Clinical criteria for filum terminale resection in occult tethered cord syndrome.

OBJECTIVE: Tethered cord syndrome (TCS) comprises three symptom categories: back/leg pain, bowel/bladder, and neurological complaints. MRI typically reveals a low-lying conus medullaris, filum terminale (FT) pathology, or lumbosacral abnormalities. FT resection is established in TCS but not in radiologically occult TCS (OTCS). This study aims to identify patients with OTCS who are likely to benefit from FT resection. METHODS: The authors recruited 149 patients with OTCS (31 pediatric, 118 adult) treated with FT resection-including only cases with progressive TCS, negative spine MRI, and no concurrent neurological/urological conditions. A comprehensive questionnaire collected patient self-reported symptoms and clinical findings at the preoperative and at 3- and 12-month follow-up examinations. Based on questionnaire data, the authors extracted a 15-item symptoms and findings scale to represent the three TCS symptom categories, assigning 1 point for each item present. RESULTS: OTCS presents without radicular/segmental sensorimotor findings, but with leg/back pain and conus dysfunction, in addition to leg fatigue and spasticity; the latter indicating an upper motoneuron pathology. The 15-item scale showed clinical improvement in 89% of patients at the 3-month follow-up and 68% at the 12-month follow-up. Multivariate analysis of the scale revealed that it accurately predicts outcome of FT resection in 82% of cases. Patients with a preoperative score exceeding 6 points are most likely to benefit from surgery. CONCLUSIONS: By applying the study's inclusion criteria and incorporating the novel 15-item scale, surgeons can effectively select candidates for FT resection in patients with OTCS. The observed outcomes in these selected patients are comparable to those achieved in degenerative spine surgery.

The discrepancy in triggered electromyography responses between fatty filum and normal filum terminale.

BACKGROUND: Functional role of filum terminale (FT) was not well studied though it contains structure basis for nerve impulse conduction. We aimed to explore the possible functions of the FT from the perspective of triggered electromyography (EMG) during surgery. METHODS: We retrospectively reviewed intraoperative neurophysiological monitoring data from pediatric patients who underwent intradural surgeries at the lumbar level in Shanghai Children's. Hospital from January 2018 to March 2023. Altogether 168 cases with complete intraoperative neurophysiological recordings of the FT were selected for further analysis. Triggered EMG recordings of the filum originated from two main types of surgeries: selective dorsal rhizotomy (SDR) and fatty filum transection. RESULTS: 96 cases underwent SDR and 72 cases underwent fatty filum transection. Electrical stimulation of the FT with fatty infiltration did not elicit electromyographic activity in the monitored muscles with the maximum stimulus intensity of 4.0 mA, while the average threshold for FT with normal appearance was 0.68 mA, and 89 out of 91 FT could elicit electromyographic responses in monitored channels. The threshold ratio of filum to motor nerve roots at the same surgical segment was significantly higher in patients with fatty filum, and a cut-off point of 21.03 yielded an area under curve of 0.943, with 100% sensitivity and 85.71% specificity. CONCLUSION: Filum with normal appearance can elicit electromyographic activity in the lower limbs/anal sphincter similar to the performance of the cauda equina nerve roots. The threshold of fatty filum is different from that of normal appearing FT. Triggered EMG plays an important role in untethering surgeries.

Hemangioblastomas of the cauda equina: Clinical features and long-term surgical outcomes.

BACKGROUND: Spinal hemangioblastomas (HBs) that involving cauda equina are rare. Data on clinical characteristics and long-term intervention outcomes of patients harboring cauda equina HBs remain lacking due to its scarcity. OBJECTIVE: This study aims to present the clinical-radiological features and treatment results of this rare pathology by using cases from a single center. METHODS: A review of demographic data and intervention outcomes of patients harboring cauda equina HBs in our department between 2009 and 2020 was retrospectively carried out. RESULTS: Ten consecutive adult patients were incorporated, with a slight female predominance (n = 6, 60%). The mean age was 39.9 ± 14.7 (range: 18-58) years. Six patients (60%) had von Hippel‒Lindau (VHL) syndrome and showed multiple symptoms and severe neurological deficits, while 4 (40%) were in the sporadic group and only presented pain symptoms. During follow-up, 3 patients (30%) experienced lesion relapse and underwent repeated surgery. Favorable outcomes were achieved in all patients. CONCLUSION: Cauda equina HBs are rare spinal vascular lesions that should be differentiated from other lumbar canal lesions. Total surgical resection is the main treatment modality and can benefit patients, even recurrent patients. The treatment outcome is usually satisfactory, especially in sporadic cases.

Cauda equina neuroendocrine tumors: A single institutional imaging review of cases over two decades.

Cauda Equina Neuroendocrine Tumors (CE-NET), previously referred to as paragangliomas are a rare subset of spinal tumors, with limited data on imaging. Herein, we present a retrospective review of clinical and imaging findings of CE-NETs in ten patients who were evaluated at our institution over the past two decades. All patients had well-defined intradural lesions in the lumbar spine which demonstrated slow growth. A review of imaging findings revealed the presence of an eccentric vascular pedicle along the dorsal aspect of the tumor in 8 of the 10 patients (eccentric vessel sign), a distinctive finding that has not previously been reported with this tumor and may help improve the accuracy of imaging-based diagnosis. In all cases, a gross-total resection was performed, with resolution of symptoms in most of the cases.

When a dermatopathologist encounters the ultra-rare: A case series of superficial soft tissue/cutaneous myxopapillary ependymomas.

Myxopapillary ependymoma (MPE) is an uncommon variant of ependymoma, almost exclusively seen in conus medullaris or filum terminale. MPE can be diagnostically challenging, especially when arising extra-axially. Here we report 5 cases of superficial soft tissue/cutaneous MPE, identified across three tertiary institutions. All patients were female and three of them (3/5, 60%) were children (median age 11 years, range 6-58 years). The tumors presented as slow-growing masses of the sacrococcygeal subcutaneous soft tissues, occasionally identified after minor trauma and clinically favored to be pilonidal sinuses. Imaging showed no neuraxis connection. Macroscopically, tumors were well-circumscribed, lobulated, and solid and microscopically they exhibited typical histopathology of MPE, at least focally. Two of the tumors (2/5, 40%) showed predominantly solid or trabecular architecture with greater cellular pleomorphism, scattered giant cells, and increased mitotic activity. All tumors (5/5, 100%) showed strong diffuse immunohistochemical expression of GFAP. One tumor clustered at the category "ependymoma, myxopapillary" by methylome analysis. Two patients (2/5, 40%) had local recurrence at 8 and 30 months after the initial surgery. No patients developed metastases during the follow-up period (median 60 months, range 6-116 months). Since a subset of extra-axial MPEs behaves more aggressively, timely and accurate diagnosis is of paramount importance.

Endoscopic spinal cord untethering using a 1 cm skin incision technique in pediatrics: a technical case report.

BACKGROUND: Spinal cord untethering by sectioning the filum terminale is commonly performed in tethered cord syndrome patients with minor abnormalities such as filar lipoma, thickened filum terminale, and low conus medullaris. Our endoscopic surgical technique, using the interlaminar approach, allows for sectioning the filum terminale through a very small skin incision. To our knowledge, this procedure has not been previously reported. This is the first case report involving a 1 cm skin incision. CASE PRESENTATION: A 9-month-old male patient was referred to our neurosurgical department due to a coccygeal dimple. MRI revealed a thickened fatty filum. After considering the treatment options for this patient, the parents agreed to spinal cord untethering. A midline 1 cm skin incision was made at the L4/5 vertebral level. Untethering by sectioning the filum terminale was performed by full endoscopic surgery using the interlaminar approach. The procedure was uneventful and there were no postoperative complications. CONCLUSIONS: In terms of visibility and minimizing invasiveness, our surgical technique of using the interlaminar approach with endoscopy allows for untethering by sectioning the filum terminale through a very small skin incision.

Neurological Analysis Based on the Terminal End of the Spinal Cord and the Narrowest Level of Injured Spine in Thoracolumbar Spinal Injuries.

This study aimed to clarify neurological differences among the epiconus, conus medullaris, and cauda equina syndromes. Eighty-seven patients who underwent surgery for acute thoracolumbar spinal injuries were assessed. We defined the epiconus as the region from the terminal end of the spinal cord to the proximal 1.0 to 2.25 vertebral bodies, the conus medullaris as the region proximal to < 1.0 vertebral bodies, and the cauda equina as the distal part of the nerve roots originating from the spinal cord. On the basis of the distance from the terminal end of the spinal cord to the narrowest level of the spinal canal, the narrowest levels were ordered as follows: the epiconus followed by the conus medullaris and cauda equina. The narrowest levels were the epiconus in 22 patients, conus medullaris in 37 patients, and cauda equina in 25 patients. On admission, significantly more patients had a narrowed epiconus of Frankel grades A-C than a narrowed cauda equina. At the final follow-up, there were no significant differences in neurological recovery among those with epiconus, conus medullaris, or cauda equina syndrome. Anatomically classifying the narrowest lesion is useful for clarifying the differences and similarities among these three syndromes.

Myxopapillary Ependymoma-a Case Report of Rare Multicentric Subtype and Literature Review.

Background: Myxopapillary ependymoma is a rare type of primary spinal tumor, it is distinctly a slow-growing tumor that originates in the conus medullaris, cauda equina, or film terminals and is rarely identified as a multicentric type. Myxopapillary ependymoma has a unique histological characteristic and is associated with a generally better prognosis. Objective: We present a case of a rare multicentric myxopapillary ependymoma. Case presentation: A 28-year-old male with 1-year history of low back pain and 3 months of radiating pain to left lower limb with perianal anesthesia. Magnetic resonance imaging (MRI) exhibited a large intradural intramedullary lesion from the level of the conus medullaris extending to the filum terminals at the level of T12 to L3 with smaller multiple enhancing lesions seen opposite to L4 and L5 level as well as within the exiting nerve roots, at the left side of L1/L2 and L2/L3 and right side of L3/L4 and L5/S1 level. The patient underwent surgical resection with significant improvement in symptoms and no tumor progression on follow up MRI scan. Conclusion: We hereby present a case of multicentric myxopapillary ependymoma with a literature review of the previous reported cases. We believe that our study will make a significant contribution to the literature and will be of interest to the readership regarding of the rarity of multicentric Myxopapillary ependymoma and it will help in decision making for the proper surgical Intervention on these kinds of cases.

Primary Malignant Lymphoma of the Cauda Equina Diagnosed after Decompression for Lumbar Spinal Stenosis: A Case Report.

Primary malignant lymphoma confinement to the cauda equina is rare. Only 14 cases of primary malignant lymphoma in the cauda equina have been reported. In these cases, the clinical features were similar to those of lumbar spinal canal stenosis (LSCS). This report describes a case of diffuse large B-cell lymphoma of the cauda equina that was diagnosed after decompression surgery for LSCS. An 80-year-old man presented with gait disturbance due to progressive muscle weakness in the lower extremities over the previous two months. He was diagnosed with LSCS, and decompression surgery was performed. However, the muscle weakness worsened after surgery; therefore, he was referred to our department. Plain magnetic resonance imaging (MRI) revealed swelling of the cauda equina. It demonstrated marked homogenous enhancement by gadolinium-diethylenetriamine pentaacetic acid. 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) revealed diffuse accumulation of 18F-FDG in the cauda equina. These imaging findings were consistent with those of cauda equina lymphomas. To confirm the diagnosis, we performed an open biopsy of the cauda equina. Histological examination indicated diffuse large B-cell lymphoma. Considering the patient's age and activities of daily living, further treatment was not performed. The patient died four months after the first surgery. Rapid progression of muscle weakness, which cannot be prevented by decompression surgery, and swollen cauda equina on MRI may be signs of this disorder. Gadolinium-enhanced MRI, 18F-FDG PET, and histological investigation of the cauda equina should be performed for diagnosing primary malignant lymphoma of the cauda equina.

Prevention of retethering in untethering surgery of a tight filum terminale.

OBJECTIVE: Untethering surgery for a tight filum terminale is a common treatment with considerable efficacy and safety. On the other hand, retethering has been reported to occur. One of the major mechanisms of retethering is adherence of the cut end of the sectioned filum to the midline dorsal dural surface. To prevent retethering, the authors sectioned a filum terminale at the rostral level to the dural incision to keep the distance between the cut end of the sectioned filum and the dural incision and investigated whether this procedure decreased the occurrence of retethering. METHODS: Among the patients who underwent untethering surgery for a tight filum terminale between 2012 and 2016, patients followed up more than 5 years were included in the study. Symptoms, comorbid malformations, preoperative imaging, surgical details, perioperative complications, and long-term outcomes were reviewed retrospectively. RESULTS: Retrospective data for a total of 342 cases were included. The median age at surgery was 11 months (range 3-156 months). Preoperative MRI revealed 254 patients (74.3%) had a low-set conus. There were 142 patients (41.5%) with filar lipoma and 42 patients (12.3%) with terminal cyst. Syringomyelia was found in 29 patients (8.5%). In total, 246 patients (71.9%) were symptomatic and 96 patients (28.1%) were asymptomatic. There were no perioperative complications that required surgical intervention or prolonged hospitalization. The mean postoperative follow-up was 88 months (range 60-127 months). There were 4 patients (1.2%) with retethering who presented with bladder and bowel dysfunction. The mean time from initial untethering to retethering was 54 months (range 36-80 months). All 4 patients underwent untethering surgery, and preoperative symptoms resolved in 3 patients. CONCLUSIONS: The retethering rate after untethering surgery for a tight filum terminale in our series was lower than those in previously reported studies. Sectioning the filum terminale at the rostral level to the dural incision was considered an effective way to prevent retethering.

Tadpole Sign in Filum Terminale Paragangliomas.

Two normotensive male patients came with complaints of low back pain. Contrast-enhanced magnetic resonance imaging of the lumbosacral spine revealed an enhancing intradural extramedullary lesion (at the L4-L5 vertebral level in the first patient and at the L2-L3 vertebral level in the second patient). The tumor resembled the head and caudal blood vessels the tail of a tadpole, thereby giving the "tadpole sign." This sign is an important radiologic and histopathologic correlate, which is helpful in preoperative diagnosis of spinal paraganglioma.

Microsurgical approach for resection of the filum terminale internum in tethered cord syndrome-a case demonstration of technical nuances and vignettes.

BACKGROUND: In tethered cord syndrome due to filum terminale pathology, the surgical approach to achieve detethering of the spinal cord may vary. Traditionally, sectioning the filum through a laminectomy at the lumbosacral level is performed. METHOD: A microsurgical technique at a higher level to approach the filum below the conus tip is performed. This allows for removal of the entire distal portion of the filum through a limited interlaminar approach and dural opening. CONCLUSION: We propose a technique to transect the filum terminale below the conus tip and extract the distal filum by releasing it from its intradural attachments to minimize any remnants of the filum terminale.

Sporadic hemangioblastoma of cauda equina: A case-report and brief literature review.

Hemangioblastomas are rare lesions accounting for 1-5% of all spinal cord tumors and are mostly associated with von Hippel-Lindau syndrome. Localization in the cauda equina is uncommon. In this manuscript we aim to describe a rare case of sporadic intradural extramedullary hemangioblastoma of the cauda equina and present a literature review. A systematic research was performed on Pubmed, MEDLINE, and Google Scholar, using as keywords "spinal hemangioblastoma" and "cauda equina tumors". The previous literature is integrated by the description of the present case. A 49 year-old female, presented on August 2020 to our institution suffering from claudication neurogena, right sciatica and paraesthesia in right L5 radicular dermatome for more than 3 months. Neurological examination revealed hypoesthesia on right L5 dermatome and weakness of right anterior tibialis muscle. An MRI which showed an intradural mass at L1/2 level and an angiography that showing a nidus of serpiginous vessels inside the lesion. Microsurgical en bloc resection of lesion was performed with adjuvant neurophisological intra operative monitorings. Histological examination provided the diagnosis of hemangioblastoma. After surgery symptoms and neurological impairment gradually improved. A 10 months post-operative MRI showed no residual tumor. Although intradural extramedullary hemangioblastoma of the cauda equina without von Hippel-Lindau syndrome it is a rare pathological entity, this diagnosis must be taken in for cauda equina masses. Preoperative embolization is an option to minimize intraoperative bleeding. Radiosurgery seems to prevent recurrences when the tumor is not completely excised. Complete surgical removal of the lesion is usually possible and lead to a low likelihood of recurrence.

Cauda equina neuroendocrine tumors show biological features distinct from other paragangliomas and visceral neuroendocrine tumors.

Cauda equina neuroendocrine tumors (CENETs) are neoplasms of uncertain histogenesis with overlapping features between those of paragangliomas (PGs) and visceral neuroendocrine tumors (NETs). We have explored their biological relationship to both subsets of neuroendocrine neoplasms. The clinical and radiological features of a cohort of 23 CENETs were analyzed. A total of 21 cases were included in tissue microarrays, along with a control group of 38 PGs and 83 NETs. An extensive panel of antibodies was used to assess epithelial phenotype (cytokeratins, E-cadherin, EpCAM, Claudin-4, EMA, CD138), neuronal and neuroendocrine features (synaptophysin, chromogranin A, INSM1, neurofilaments, NeuN, internexin-α, calretinin), chromaffin differentiation (GATA3, Phox2b, tyrosine hydroxylase), and possible histogenesis (Sox2, T-brachyury, Oct3/4, Sox10). The cohort included 5 women (22%) and 18 men (78%). The average age at the time of surgery was 48.3 years (range from 21 to 80 years). The average diameter of the tumors was 39.27 mm, and invasion of surrounding structures was observed in 6/21 (29%) tumors. Follow-up was available in 16 patients (median 46.5 months). One tumor recurred after 19 months. No metastatic behavior and no endocrine activity were observed. Compared to control groups, CENETs lacked expression of epithelial adhesion molecules (EpCAM, CD138, E-cadherin, Claudin-4), and at the same time, they lacked features of chromaffin differentiation (GATA3, Phox2b, tyrosine hydroxylase). We observed no loss of SDHB. Cytokeratin expression was present in all CENETs. All the CENETs showed variable cytoplasmic expression of T-brachyury and limited nuclear expression of Sox2. These findings support the unique nature of the neoplasm with respect to NETs and PGs.