|Year : 2022 | Volume
| Issue : 3 | Page : 149-158
Management of intramedullary spinal cord tumors: An updated review
Sanjeev Pattankar, Kuntal Kanti Das, Jayesh Sardhara, Awadhesh Kumar Jaiswal
Department of Neurosurgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
|Date of Submission||16-May-2022|
|Date of Acceptance||04-Jun-2022|
|Date of Web Publication||13-Sep-2022|
Kuntal Kanti Das
Department of Neurosurgery, Sanjay Gandhi Postgraduate Institute of Medical Sciences, Lucknow - 226 014, Uttar Pradesh
Source of Support: None, Conflict of Interest: None
Intramedullary spinal cord tumors are one of the most challenging neurosurgical conditions. The compact spinal cord fiber bundles (ascending and descending tracts) and spinal cord vascularity are at a huge risk during tumor resection. Hence, the resection of such tumors always has an inherent risk of inducing neurological deficits. Thus, the determination of tumor–cord interface assumes the greatest importance. The refinement in surgical technique and intraoperative neuromonitoring has increased the safety level of modern-day results with such tumors. Management of tumor recurrence and the exact role of adjuvant therapy, however, remains to be defined. In this review, we highlight surgically relevant aspects of these tumors, the current state of adjuvant treatment choices, and a literature review.
Keywords: Astrocytomas, ependymomas, hemangioblastomas, intramedullary tumors, spinal cord tumors
|How to cite this article:|
Pattankar S, Das KK, Sardhara J, Jaiswal AK. Management of intramedullary spinal cord tumors: An updated review. J Spinal Surg 2022;9:149-58
|How to cite this URL:|
Pattankar S, Das KK, Sardhara J, Jaiswal AK. Management of intramedullary spinal cord tumors: An updated review. J Spinal Surg [serial online] 2022 [cited 2022 Dec 1];9:149-58. Available from: http://www.jossworld.org/text.asp?2022/9/3/149/356021
| Overview|| |
The term “intramedullary spinal cord tumors (IMSCTs)” denotes a neoplastic lesion that arises within the spinal cord substance. Being relatively rare, these IMSCTs account for only one-third of the total intradural spinal pathologies (the remaining two-thirds by intradural extramedullary lesions).,, From a pathological perspective, 90% of all IMSCTs are either astrocytomas or ependymomas. The remaining 10% is constituted by other tumors such as gangliogliomas and hemangioblastomas. Patients usually end up developing functionally debilitating sensorimotor and autonomic symptoms. Surgery remains the mainstay of treatment. Although technical advances in spinal surgery made it a distinct subspecialty of neurosurgery three decades ago, the surgical management of spinal cord tumors remains a challenging task for neurosurgeons worldwide. It is possibly because of the delicate and peculiar surgical anatomy of the spinal cord and spinal cord tumors, combined with the requirement of mastery over microsurgical skills and the availability of scientifically demanding intraoperative neurophysiological monitoring (IONM) systems.,, Many controversies also exist regarding the desired extent of resection in these tumors and the role of adjuvant therapies in achieving long-term tumor control and quality of life. The recent advancements in molecular profiling of spinal cord tumors have enabled a better understanding of their biological behaviors and appropriate prognostication, along with the impetus for the development of targeted therapies. The current article focuses on the surgical aspects of this challenging neurosurgical condition.
| Epidemiology and Pathology|| |
Among the intradural spinal cord tumors, extramedullary variants are more common, with rarer IMSCT pathologies comprising only about 20%–35% of these intradural tumors in adults. However, these IMSCTs are more frequent in children, making up as much as 55% of all intradural neoplasms. The most common childhood intramedullary tumors are astrocytomas, with a predominantly low-grade (pilocytic 75% and fibrillary 7%) histology. High-grade glial tumors are a rarity in the pediatric population. Accounting for another 15% of pediatric IM tumors are gangliogliomas, seen commonly under 5 years of age. Ependymomas, the most frequently encountered IMSCT in adults, are sparsely seen in children (12%). The remaining tumor varieties such as hemangioblastomas, lipomas, dermoids, and epidermoids are very limited in their occurrence. [Table 1] depicts the epidemiological features of pediatric IMSCTs.
|Table 1: Epidemiological characteristics of pediatric and adult intramedullary spinal cord tumors|
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Among adults, ependymomas are the most frequent intramedullary tumors. Arising from the ependymal cells of the central canal, 75% of ependymomas are located intramedullary, with 10% situated intradural extramedullary (commonly around filum terminale). Unlike the cranial ependymomas predominantly being the cellular type, the myxopapillary variant (grade 1) is prevalent in spinal cases. Occasionally, tanycytic (grade 2) and anaplastic (grade 3) variants are reported from spinal locations. Astrocytomas are uncommon in the adult population. Another routinely seen spinal IMSCT is hemangioblastoma, with at least 40% being diagnosed with Von Hippel–Lindau (VHL) syndrome. The key epidemiological characteristics of adult IMSCTs are tabulated in [Table 1].
The recent 2021 WHO central nervous system classification has brought about some changes in spinal ependymoma classification. As the clinical outcome of myxopapillary and classical spinal cord ependymomas is found comparable, unlike the 2016 WHO classification, the current classification recommends grading myxopapillary variant as grade 2 instead of grade 1. The classification additionally recognized a recently described spinal cord ependymoma variant characterized by MYCN amplification, early dissemination, and a poor prognosis as a distinct new tumor type.
| Radiological Characteristics|| |
The investigation of choice for IMSCTs is magnetic resonance imaging (MRI). The standard imaging protocol comprises axial and sagittal cuts of T1- and T2-weighted sequences, along with the sagittal, axial, and coronal cuts of gadolinium-enhanced T1-weighted sequences. Lately, short time inversion recovery sequences are also being used, especially to rule out bony vertebral abnormalities. Advanced sequences such as diffusion tensor imaging (DTI) and fiber tractography can delineate white matter tracts in relation to spinal cord tumors, and thus, help in deciding surgical corridors., Cysts, either intratumoral or peritumoral (syrinx), are far more common in ependymomas than astrocytomas. Studies, such as the one by Seaman et al. (2021), have shown that the presence of such cysts/syrinxes are associated with better resectability. In addition, Xu et al. reported a high incidence of syrinx even in spinal hemangioblastomas (55.2%), with no direct correlation found between the presence of syrinx and clinical prognosis. However, among the patients who were symptomatic for syrinx, a better clinical prognosis was seen with a shorter duration of involvement (0–6 months).
Other radiological interventions such as myelography, angiography, and positron emission tomography (PET) have limited and specific roles in spinal cord tumor management. Angiography can be used to demonstrate the vascularity in tumors such as hemangioblastomas, and rarely, for preoperative embolization. PET can help pick up high-grade intradural lesions. Occasionally, the age-old cerebrospinal fluid (CSF) analysis can be employed to identify either malignant cells or inflammatory markers in select cases. [Table 2] compares the key radiological features of IMSCTs.
|Table 2: Radiological characteristics of common intramedullary spinal cord tumors|
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| Surgical Management|| |
Maximum safe surgical resection is the mainstay of treatment for IMSCTs. The goals that can be achieved are as follows: (1) histopathological confirmation of the pathology, (2) safe possible reduction of tumor burden, (3) effective implementation of adjuvant oncologic treatment, and (4) hopeful prevention of long-term neurological dysfunction. Optimized microsurgical techniques using bipolar suction cautery, and other specialized instruments such as intraoperative ultrasound/Cavitron ultrasonic aspirator/Nd-YAG laser, along with a continuous IONM, are used in achieving safe surgical resection, minimizing inadvertent injury to the surrounding normal cord tissue.,,,, Depending on the specific tumor at hand, the surgical technique needs to be tailored.
| Key Steps in Surgery|| |
Key steps in the surgical management of IMSCTs are as follows:s
- Positioning: The most commonly used position is prone in all instances. Some may prefer lateral oblique positioning, as it eliminates the respiratory cycle-induced movements under high magnification of the microscope and simultaneously drains out the operative field via gravity., The head is fixed to a rigid holder like Sugita or Mayfield frame in cervical and cervicothoracic tumors, to achieve a neutral spine position. Pressure points need to be appropriately padded
- Bony access: Either a laminectomy or an osteoplastic laminotomy/laminoplasty is performed with a high-power drill and rongeurs. The bony access must expose the solid tumor, but not necessarily the rostral/caudal peritumoral cysts, unless they appear as intratumoral cysts. Peritumoral cysts resolve once the tumor is excised. Intraoperative ultrasound can be used to confirm the adequacy of the bony excess
- Tumor access: The basic concept for selecting the appropriate approach is using the shortest and most direct approach to the tumor, as there are no noneloquent areas in the spinal cord. The preoperative imaging, along with the intraoperative visual inspection, helps in deciding the safest tumor access. The three possible accesses are (1) posterior median sulcus approach, (2) posterolateral sulcus approach, and (3) lateral direct subpial approach.,,,,, The posterior median sulcus approach is preferred for tumors such as ependymomas and astrocytomas. In eccentrically located tumors, the posterolateral sulcus approach/dorsal root entry zone (DREZ) myelotomy can be used. Whereas, the lateral direct subpial approach may be suitable for vascular lesions such as hemangioblastomas. [Figure 1] shows the illustrative representation of the possible myelotomy approaches
- Establishing tumor–cord interface: The importance of this step cannot be overstated. An atraumatic myelotomy and properly placed pial stay sutures are prerequisite for tumor–cord interface establishment. In cases of infiltrative tumors without a good peritumoral plane, maximum safe excision should be attempted. In all other cases, gross total excision is the ultimate goal
- Closure: Complete tumor removal usually needs no further hemostasis. After removing the pial stay sutures, pial edges are sutured to restore normal cord shape. A zip closure technique has also been described and preferred by the lead author (KKD). The dura mater along with the arachnoid membrane is closed primarily or with dural supplements, to prevent CSF leak or chances of cord tethering at the level of surgery.
|Figure 1: Illustrative representation of the spinal cord cross-section (a), along with the various possible intramedullary tumor locations, and the appropriate myelotomy approaches, i.e., posterior median (b), posterolateral (c), and the subpial approach (d)|
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| Factors Influencing Surgical Outcomes|| |
Ependymomas appear red or dark gray with a clear margin from the surrounding spinal cord. Hence, this tumor can be meticulously separated in craniocaudal extent, before in toto excision. Ventral adherence to the small vessels coming through the anterior median raphe is a common feature of ependymomas. Special care to not injure the anterior spinal artery is necessary.,,, While on contrary to ependymomas, astrocytomas almost never have a defined tumor–cord plane. These tumors are usually removed in a piecemeal fashion, starting with internal decompression, and continuing outward until the cord–tumor interface is reached. Hemangioblastomas are subpial, highly vascular lesions, with small arterial feeders that terminate within the lesions. These need to be removed en masse by coagulating feeder vessels close to the tumor surface. The postsurgical functional outcome depends on multiple factors such as tumor location, size, preoperative neurological deficits, tumor characteristics (histopathological/molecular profiling), surgical technique, and postoperative complications., The shorter and lesser the preoperative neurological deficits, the better the chances of postoperative recovery. Studies have also found that functional outcomes were better in high-volume centers compared to low-volume centers.
| How Tumor Histology Affects Resectability and Outcomes?|| |
Garcés-Ambrossi et al., analyzing 101 consecutive cases of IMSCTs, reported a gross total resection (GTR) rate of 59%, which was independent of the histological tumor type, but dependent on identifiable intraoperative tumor plane and decreasing tumor size. However, the histological tumor type and an identifiable intraoperative tumor plane correlated with better progression-free survival. On the contrary, Karikari et al. (2011), analyzing 102 consecutive cases of IMSCTs, reported tumor histology as the most important predictor of both resectability (GTR rates: ependymomas 90.9%, astrocytomas 14.3%, hemangioblastomas 91.7%, and others 85.7%) and recurrence (at 41.3-month follow-up: ependymoma 7.3%, astrocytoma 47.6%, hemangioblastomas 0%, and others 7.1%), thus favoring a better functional outcome.
| Is Frozen Section-Based Resection Appropriate?|| |
Hongo et al. (2018) tried to find out the accuracy of frozen sections in IMSCTs and the outcomes associated with the frozen section-based resections. Frozen sections in IMSCTs were accurate to the degree of 71%–72%, which is much lower compared to the reported accuracies of brain lesions (83%–97%). Among the 9 cases of ependymoma with the frozen section (astrocytoma 4 and nonspecific 5) disagreeing with the histological diagnosis, GTR was achievable in 6 cases due to the presence of a dissection plane. Similarly, of the 5 cases of astrocytoma with the frozen section (ependymoma 1 and nonspecific 4) disagreement, GTR was achieved in 1 case. Therefore, the study concluded that the surgical strategies cannot be based on frozen section alone, but should incorporate inputs from multiple factors (clinical characteristics, preoperative imaging, frozen-section diagnosis, and intraoperative tumor plane, etc.).
| Outcomes in Multisegmental Versus Monosegmental IMSCTS?|| |
Yang et al. (2022), analyzing outcomes in 62 (<3 segments in 19, ≥3 segments in 43) cases of surgically treated spinal ependymomas, reported that though the multisegmental (≥3 segments) lesions had poorer preoperative neurological status, contrary to the expectations, the postoperative short-term neurological functions, as well as long-term functional outcomes, were similar to that of the monosegmental (<3 segments) lesions.
| Posterior Midline Myelotomy Versus Posterolateral Myelotomy?|| |
Posterior midline myelotomy (PMM) remains the most common surgical approach for tumor access, as it is considered to provide the greatest extent of tumor resection. Posterolateral myelotomy's (PLM's) usage is restricted to eccentrically located tumors alone. PLM, also known as DREZ myelotomy, theoretically has advantages which include reduced dorsal column morbidity and better pain relief secondary to the lesioning of Rexed laminae I to V and the Lissauer's tract. Especially in cases of distorted regional anatomy, the nerve rootlets act as an excellent anatomical landmark in identification of the posterior lateral sulcus, aiding successful PLM approach. On the other hand, because the proximity to corticospinal/spinocerebellar/spinothalamic tracts, there is an increased risk of neurological deficits in PLM approach. Another possible disadvantage is the suboptimal tumor exposure, especially for tumors that lie deep and medially, such as ependymomas. Katsigiannis et al. (2020) evaluated PLM's alternative role in IMSCTs in 27 patients. They reported a satisfactory extent of resection (GTR rates: ependymomas – 86%, astrocytomas – 0%, and hemangioblastomas – 100%) with reduced risk of tissue damage and excellent pain relief. Further studies are needed which directly compare PLM with PMM, to further confirm these findings.
| Special Considerations|| |
Role of intraoperative neurophysiological monitoring
The iatrogenic morbidity of spinal cord tumor surgeries can be minimized with regular use of intraoperative spinal eloquence monitoring. These techniques were introduced by orthopedic deformity surgeons in the late 1980s., Their excellent ability to predict functional outcomes has made them a necessary adjunct in all cases of spinal cord tumors. Most regularly used modalities for IONM in spinal cord tumors are somatosensory evoked potentials (SSEP) and motor evoked potentials (MEP). [Table 3] gives an overview of the IONM modalities and their effectiveness in detecting intraoperative spinal cord damage.
|Table 3: Intraoperative neuromonitoring in intramedullary spinal cord tumors|
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Sala et al. found a better improvement in McCormick grade at 3 months postoperatively in patients with IONM. Similarly, Quiñones-Hinojosa et al. reported that a loss of MEP waveform in 12 patients correlated with worse motor deficits, compared with those otherwise. Mehta et al. showed dorsal column dysfunction in only 9% of patients with SSEP monitoring (vs. 50% without SSEP).
Newer surgical adjuncts
DTI tractography can be used as an additional tool for predicting the resectability of an IMSCT. Setzer et al. used DTI tractography to divide IMSCTs into three groups: (1) fiber tracts splayed around solid lesions, (2) fiber tracts partially mixed but mostly splayed around solid lesions, and (3) >50% of fiber tracts indistinguishable from the solid lesion. The authors showed a substantial agreement between preoperative tractography and intraoperative findings. The utility of DTI in IMSCT treatment may also prove valuable in the preoperative counseling of patients on the likely outcomes of surgery.
5-Aminolevulinic acid (5-ALA) is a fluorescent dye which can penetrate the blood–brain barrier, most notably in areas with a high density of malignant cells. Its efficacy in glioma surgeries is established, but the same is not the case in IMSCTs. Small case series have reported that most ependymomas show 5-ALA fluorescence, as do drop metastases and hemangiopericytomas. This adjunct may be especially useful in determining the amount of residual tumor in intramedullary anaplastic astrocytomas and glioblastoma but may have limited benefit in low-grade astrocytomas.
Indocyanine green videoangiography can be used to provide real-time angiographic images during surgeries of vascular IMSCTs such as hemangioblastomas, identifying the normal circulation of the spinal cord, as well as the feeding arteries and draining veins.
Expected complications and their avoidance
The upper thoracic lesions are accompanied by higher chances of surgical complications and worse postoperative functional status (secondary to watershed vascular areas and narrow spinal canal). The 30-day readmission, resurgery, and major complication rates in spinal cord tumor patients were found to be 10.2%, 5.3%, and 14.4%, respectively, by an analysis published by the United States' National Surgical Quality Improvement Program.
Position-related complications such as pressure sores or decubitus ulcers occur due to improper padding of pressure points during surgical positioning, leading to tissue ischemia and necrosis. Older age obese patients with diabetes/long-term steroid therapy are prone to such complications. Although the biggest risk factor remains the duration of the surgery, proper padding of bony prominences is of utmost importance. Free the external genitalia from pressure or catheter traction. To ensure an unhindered cardiac venous return in prone positioning, the abdomen is kept free of compression. Not doing so can limit the inferior vena cava flow, engorging the epidural veins and leading to bleeding. Appropriately sized frames (e.g., Wilson's frame) can help achieve this.
Although the risk of perioperative visual impairment is 0.02%–0.2% in prone spinal surgeries, every precaution has to be taken to avoid such a disastrous occurrence. Causes for such visual deterioration include (1) ischemic optic neuropathy, (2) central retinal artery occlusion, and (3) amaurosis. Risk factors for ischemic optic neuropathy include diabetes, intraoperative hypotension, anemia, and prolonged Trendelenburg position (elevated orbital venous pressure). Central retinal artery occlusion, also known as headrest syndrome, occurs either due to thromboembolism or increased intraocular pressure from ocular bulb compression, disrupting the retinal perfusion. Such patients have unilateral periorbital swelling and visual loss. Inadequate positioning can also lead to certain neurological complications such as brachial plexus injury or acute cervical myelopathy or spinal cord infarction.
Wound-related complications are the most common and lead to increased postoperative morbidity. These include seroma/hematoma, wound infection, dehiscence, and abscess. Steps to prevent wound-related complications are as follows: (1) identify and treat, any and all, distant infections to the surgical site prior to surgery; (2) preoperative blood glucose level optimization; (3) antiseptic shower/bathing a night before surgery; (4) proper surgical site preparation and maintaining asepsis during surgery; (5) antibiotic prophylaxis; (6) careful and minimal tissue handling, with proper wound closure; and (7) drain placement.
CSF leak-related complications after spinal tumor surgery have been reported in 5%–18% of patients.,,, This is a potential complication after any dural opening, either accidental or intentional, leading to significant morbidity and mortality. In every circumstance, primary dural closure should be attempted, whenever possible. Dural supplements should be used for secondary watertight dural closure. Additional augmentation of dural closure with fat graft might help in such instances.
Meningitis is the gravest by-product of CSF leak/wound-related complications, with its incidence ranging between 0.4% and 7%. Other possible risk factors for meningitis include immunosuppression like diabetes/steroids/drug induced. In cases of suspected meningitis, a lumbar puncture CSF sample should be collected for microscopy and culture/sensitivity, followed by empirical antibiotics at meningitic doses should be administered. Later, antibiotics are altered as per the sensitivity reports.
Other complications such as nosocomial urinary tract infections and pneumonia are commonly acquired preventable complications during the postoperative phase. Spinal surgeries are classified in the moderate risk category for deep vein thrombosis and pulmonary embolism, which can be prevented with thromboprophylaxis and early mobilization of the patients. The development of contractures, because of immobilization due to muscle paralysis, can be prevented by early and appropriate neurorehabilitation. Always keep a watchful eye on possible complications, trying to implement proactive preventive measures.
Laminectomy, laminoplasty, or fusion
Another complication that requires special mention is postlaminectomy kyphosis. Surgeries for spinal cord tumors often require extensive laminectomies, spanning over several spinal segments, leading to spinal instability and immediate or delayed spinal deformities. The risk is higher in patients with a preexisting spinal degenerative process. The anterior horn cell injury leading to paraspinal muscle paralysis also adds to the spinal deformities. Secondary to its more relative mobility, the cervical spine is at higher risk of postlaminectomy kyphosis. The pediatric population, due to its inherent characteristics (horizontal facets/poor viscoelasticity of posterior ligament complex/nonossified status of vertebral bodies) of spinal anatomy, are more prone to postlaminectomy kyphosis. This leads us to the dilemma – laminectomy, laminoplasty, or fusion?
Careful preoperative planning using radiological scans in various planes (sagittal/coronal/axial/dynamic) is essential to decide for/against simultaneous instrumented fusion. Based on the available literature, the general indications for instrumented fusion in spinal cord tumor surgeries are as follows: (1) ≥3 level laminectomy or a junctional level laminectomy, (2) >50% unilateral or bilateral facetectomy, (3) C2 laminectomy, and (4) preexisting deformity in the spinal segments undergoing laminectomies. The threshold for advising instrumented fusion is relatively less in the young adult population. Classically, the thoracic spine is considered the most stable spinal region due to the additional support provided by the ribs, and hence, greater restraint is shown in adopting an instrumented fixation. It is also imperative to discuss the possible complications that accompany instrumented fusion in patients with spinal cord tumors. Hardware misplacement and bony malunion are the two potential complications of instrumentation, along with the MRI artifactual impediment caused in assessing residual/recurrence of tumor.
The role of laminoplasty in preventing postlaminectomy kyphosis remains controversial in the adult population, even though literature supports its role in the pediatric population. Other surgical modifications that have been proposed to avoid these cases of spinal deformities are (1) muscle and facet joint-preserving laminectomies; (2) minimally invasive hemilaminectomies for eccentric tumors; (3) endoscopic techniques, either dynamic (Destandau's procedure) or fixed (tubular retractors); and (4) mini-open interlaminar and/or transspinous approaches.,, With the growing popularity of minimally invasive spinal techniques for tumor resections, the onus falls on the surgeon, not to compromise on the oncological and functional outcome in due process.
In patients who have developed postlaminectomy kyphosis, symptoms and radiological flexibility of the kyphosis generally guides the treatment strategy. The presence of a symptomatic rigid deformity may require osteoligamentous release posteriorly, anteriorly, or both based on the extent of correction desired. On the other hand, a symptomatic flexible kyphotic deformity may benefit from posterior fixation alone. These revision surgeries in the previous laminectomy-performed segments are more prone to complications, and hence, a preplanned single setting tumor excision with instrumented fusion is preferable.
Adjuvant therapy and targeted therapies
There is clearly a lack of consensus as far as the postoperative adjuvant therapy in IMSCTs is concerned. It is generally reserved for the management strategy for patients with malignant IMSCTs, either with substantial residual tumor or an inoperable recurrence.
Radiotherapy in IMSCTs can be delivered via modalities such as conventional external-beam radiotherapy (EBRT), intensity-modulated radiotherapy (IMRT), and stereotactic radiosurgery (SRS). The benefits of radiotherapy in low-grade tumors are outweighed by their deleterious effects, hence not indicated. No studies evaluating the role of primary radiotherapy in IMSCTs are available. Its adjuvant role in spinal metastases, following initial surgical intervention, has been established by a randomized study by Patchell et al. A meta-analysis by Isaacson reported only a modest tumor control and betterment in overall survival in patients with spinal ependymomas and astrocytomas, receiving conventional EBRT. Dose-limiting complications of radiotherapy were found to be radiation myelopathy, gastrointestinal inflammation, and infertility. This points to the fact that EBRT has a limited utility in spinal IMSCTs. Spinal SRS and IMRT, on the contrary, are emerging modalities for radiation delivery. These strategies have improved their safety profile of the radiotherapy, by delivering image-guided highly conformal biologically effective dosages. A substantial case series on SRS outcomes for spinal metastases found excellent long-term pain improvement (96%) and imaging control (100%). SRS is also increasingly being used to treat multiple syndromic spinal hemangioblastomas with good outcomes.,
Chemotherapy's role in IMSCTs is uncertain, with at least the current body of evidence. Chemotherapeutic agents have very poor penetration through the blood–spinal cord barrier. Few case reports on chemotherapy outcomes in low-grade tumors are available, with no substantial inferences. Even in high-grade spinal cord tumors, chemotherapy has not been found to provide a big survival benefit.
Targeted therapies in IMSCTs have recently made noteworthy advancements, as neuro-oncology is moving more and more toward molecular and genomic profiling of tumors. In sporadic pediatric low-grade spinal gliomas, the genomic alterations that occur in MAPK pathways are the most frequent molecular attributes. The tumors with BRAF fusion KIAA1549:BRAF can potentially benefit from the use of target therapies such as MEK inhibitors and BRAF inhibitors., In pilocytic astrocytomas, the most common point mutation is the BRAFV600E mutation, which has shown a response (44%) to first-generation BRAF inhibitor dabrafenib. Another routinely seen mutation that benefits from everolimus is the phosphoinositide 3-kinase/protein kinase B/mTOR (PI3K/Akt/mTOR) pathway mutations. Surprisingly, IDH1 mutations are quite rare in IMSCTs. Some of the target drugs that are being studied in VHL syndrome are monoclonal antibodies (bevacizumab and pegaptanib), tyrosine kinase inhibitors (semaxanib, pazopanib, erlotinib, dovitinib, and sorafenib), and biological response modifiers.
Evidence-based management strategies
Taking into account the currently available body of scientific literature on IMSCTs management, Tobin et al. have summarized the levels of evidence available for various treatment strategies for individual disease entities, which are tabulated in [Table 4]. Based on our own institutional experience, some proposals have been made.
|Table 4: Evidence-based recommendations and proposed management strategies for intramedullary spinal cord tumors|
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| Conclusion|| |
Although surgical management remains the mainstay of treatment, patients with IMSCTs require a multidisciplinary management involving, but not limited to, neurosurgeons, neurologists, medical oncologists, radiation oncologists, physiatrists, and physical therapists. Preoperative neurological status and maximally safe resection predict better outcomes. Modifications in the microsurgical technique and acceptable rates of resection are dictated by the tumor pathology. The benefits of adjuvant therapies such as chemotherapy and targeted therapies remain questionable, whereas there is increasing evidence that radiotherapy is beneficial, particularly the SRS and IMRT modalities. Further understanding of the molecular characteristics of IMSCTs, along with the development of newer technical adjuncts aiding safer surgeries, will pave the way for better functional outcomes in these patients.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4]