Intramedullary spinal cord tumors (IMSCTs) arise from within the substance of the spinal cord parenchyma, representing 4-10% of all central nervous system tumors. The most common types are ependymomas (60%), astrocytomas (30%), and hemangioblastomas (3-5%). These tumors present a unique surgical challenge requiring microsurgical techniques to maximize resection while preserving neurological function.

Key Recognition Features:

• Progressive myelopathy with sensory and motor deficits
• Central cord syndrome pattern (dissociated sensory loss, upper limb weakness)
• MRI showing intramedullary enhancement with cord expansion
• Typically solitary lesion (except hemangioblastoma in von Hippel-Lindau)

Critical Diagnostic Pathway:

1. MRI whole spine with gadolinium contrast (gold standard)
2. Assessment of syrinx formation (present in 40-60%)
3. Exclude extramedullary differential diagnoses
4. Consider von Hippel-Lindau screening if hemangioblastoma
5. Pre-operative neurophysiological assessment

High-Yield Exam Points:

• Ependymomas are most common, well-circumscribed, WHO Grade II, excellent surgical plane
• Astrocytomas infiltrative, less distinct plane, poorer prognosis
• Hemangioblastomas highly vascular, pial-based, associated with VHL syndrome
• Intraoperative neuromonitoring (SSEP, MEP) mandatory during resection
• Gross total resection (GTR) is goal for ependymoma and hemangioblastoma; subtotal for infiltrative astrocytoma

Spinal Cord Microanatomy

Understanding the internal architecture of the spinal cord is essential for surgical planning:

Transverse Organization:

• Gray matter (butterfly-shaped): central location, motor neurons ventral, sensory neurons dorsal
• White matter: surrounding tracts organized in columns
• Central canal: remnant of neural tube, potential syrinx formation site
• Anterior median fissure and posterior median sulcus: anatomical landmarks

White Matter Tracts:

• Dorsal columns (posterior): proprioception and fine touch
• Lateral corticospinal tracts: motor function (crossed)
• Spinothalamic tracts (anterolateral): pain and temperature (crossed)
• Preservation critical during myelotomy

Vascular Supply:

• Anterior spinal artery (single): supplies anterior two-thirds of cord
• Posterior spinal arteries (paired): supply posterior one-third
• Radicular arteries: segmental supply, variable anatomy
• Artery of Adamkiewicz: major anterior radicular artery (T9-L2), critical to preserve

Surgical Corridor Implications:

• Posterior median sulcus: avascular midline entry point for myelotomy
• Dorsal columns: least morbid route to access intramedullary lesions
• Avoid lateral myelotomy: risks corticospinal and spinothalamic tracts

Tumor Histopathology

Ependymoma Characteristics:

• Origin: Ependymal cells of central canal
• WHO Grade: II (most common), III (anaplastic, rare)
• Macroscopic: Well-encapsulated, "pushes" rather than infiltrates
• Microscopic: Perivascular pseudorosettes, true ependymal rosettes
• Location: Cervical and cervicothoracic most common (60%)
• Syrinx: Associated rostral/caudal syrinx in 60% of cases
• Resectability: Excellent surgical plane allows GTR in 80-90%

Astrocytoma Characteristics:

• Origin: Neoplastic astrocytes
• WHO Grade: II (low-grade) or III-IV (high-grade glioblastoma)
• Macroscopic: Infiltrative, indistinct margins, cord enlargement
• Microscopic: Fibrillary background, nuclear atypia, mitoses (high-grade)
• Location: Thoracic most common in adults, cervical in children
• Syrinx: Less commonly associated
• Resectability: GTR rarely achievable due to infiltration

Hemangioblastoma Characteristics:

• Origin: Pial vessels and subpial region
• WHO Grade: I (benign)
• Macroscopic: Highly vascular nodule with feeding vessels, pial-based
• Microscopic: Stromal cells and abundant capillaries
• Location: Cervical and thoracic, often dorsal cord
• Association: Von Hippel-Lindau syndrome in 25% (autosomal dominant)
• Resectability: GTR achievable if vascular control obtained

Pathophysiological Mechanisms of Cord Dysfunction

Mechanical Compression:

• Direct pressure on neural tracts from tumor expansion
• Interruption of axonal transport and nerve conduction
• Venous congestion and edema around tumor
• Progressive weakness and sensory loss

Vascular Compromise:

• Compression of radicular arteries
• Tumor neovascularization "stealing" blood supply
• Venous hypertension from tumor mass effect
• Risk of cord infarction during manipulation

Syrinx Formation (40-60% of cases):

• Obstruction of CSF flow around tumor
• Dissection of fluid into central canal
• Progressive cavity formation rostral and caudal to tumor
• Syringomyelia symptoms: dissociated sensory loss, weakness
• Syrinx often resolves after tumor resection

Presenting Symptoms

Motor Dysfunction (85% of patients):

• Progressive weakness in limbs
• Upper motor neuron pattern: spasticity, hyperreflexia, clonus
• Lower motor neuron signs if anterior horn cell involvement
• Gait disturbance and ataxia
• Progression over months to years (indolent tumors)

Sensory Disturbances (75% of patients):

• Dissociated sensory loss: impaired pain/temperature, preserved proprioception
• Indicates central cord involvement (spinothalamic tract)
• Paresthesias and dysesthesias
• Sensory level indicating tumor location
• Posterior column signs: impaired vibration and proprioception

Pain Syndromes (65% of patients):

• Local back or neck pain at tumor level
• Radicular pain in dermatomal distribution
• Central neuropathic pain (burning, dysesthetic)
• Nocturnal pain common
• Exacerbated by Valsalva maneuvers

Autonomic Dysfunction (30% of patients):

• Bladder dysfunction: urgency, frequency, retention
• Bowel dysfunction: constipation
• Sexual dysfunction
• Indicates advanced cord involvement
• Associated with poorer outcomes

Syringomyelia Features:

• Cape-like distribution of sensory loss (shoulders and arms)
• Dissociated sensory loss (pain/temperature affected, proprioception spared)
• Charcot joints (neuropathic arthropathy)
• Horner syndrome if cervical syrinx

Clinical Examination Findings

Cervical Level Tumors:

• Upper limb weakness (proximal greater than distal initially)
• Hand intrinsic muscle atrophy if C8-T1
• Inverted radial reflex (C5-C6 tumor)
• Horner syndrome (T1 involvement)
• Respiratory compromise if high cervical (C3-C5)

Thoracic Level Tumors:

• Truncal ataxia and gait disturbance
• Abdominal wall reflex abnormalities
• Sensory level on trunk
• Lower limb spasticity and weakness
• Bladder dysfunction common

Conus/Cauda Tumors:

• Lower limb weakness (mixed UMN/LMN pattern)
• Saddle anesthesia
• Early bladder and bowel dysfunction
• Erectile dysfunction
• Absent ankle reflexes

Differential Diagnosis

The cardinal task is separating a true intramedullary neoplasm from extramedullary compression and from non-neoplastic intramedullary signal change (the "VITAMIN" myelopathy mimics: vascular, inflammatory/demyelinating, infective, transverse myelitis, metabolic). The distinguishing features below are the high-yield discriminators.

MRI Imaging (Gold Standard)

Protocol Requirements:

• Whole spine sagittal and axial sequences
• T1-weighted pre- and post-gadolinium
• T2-weighted for cord signal and syrinx
• STIR or fat-suppressed sequences
• Thin slices (3 mm) through tumor

Characteristic MRI Findings by Tumor Type:

Additional MRI Assessment:

• Cord expansion: typically 2-3 vertebral levels
• Pial enhancement: suggests pial-based tumor or leptomeningeal spread
• Hemosiderin staining: previous hemorrhage (hemangioblastoma)
• Extent of syrinx: may require drainage in addition to tumor resection

Ancillary Investigations

Pre-Operative Workup:

• MRI brain: exclude intracranial lesions (especially if hemangioblastoma)
• Spine X-rays: assess spinal alignment and bony anatomy
• CT chest/abdomen/pelvis: staging if high-grade or metastatic potential
• Cardiac and respiratory assessment: anesthesia fitness
• Urodynamic studies: if bladder dysfunction present

Von Hippel-Lindau Screening (if Hemangioblastoma):

• Genetic testing for VHL gene mutation
• Retinal examination: retinal angiomas
• MRI brain: cerebellar hemangioblastomas
• Ultrasound/CT abdomen: renal cell carcinoma, pancreatic tumors
• Family history assessment
• Annual surveillance imaging if VHL confirmed

Neurophysiology:

• Pre-operative SSEP and MEP: baseline motor and sensory function
• Intraoperative monitoring: real-time assessment during resection
• Post-operative studies: document neurological changes

Tissue Diagnosis

Intraoperative Frozen Section:

• Confirms tumor pathology during surgery
• Guides extent of resection
• Differentiates tumor from gliosis or demyelination
• Limited accuracy compared to permanent sections

Permanent Histopathology:

• Hematoxylin and eosin staining
• Immunohistochemistry: GFAP (astrocytoma), EMA (ependymoma)
• Ki-67 proliferation index: predicts tumor behavior
• WHO grading determines adjuvant therapy need

Molecular Markers (Emerging):

• IDH1/2 mutations: prognostic in astrocytomas
• MGMT methylation: predicts chemotherapy response
• Chromosome 1p/19q codeletion: oligodendroglioma differentiation
• BRAF mutations: targeted therapy potential

Pre-Operative Planning

Surgical Indications:

• Symptomatic tumor with progressive neurological deficit
• Radiological progression on serial imaging
• Diagnostic uncertainty requiring tissue diagnosis
• Symptomatic syrinx associated with tumor

Contraindications to Surgery:

• Medically unfit for general anesthesia
• Extensive tumor spanning greater than 8 vertebral levels (relative)
• Severe pre-existing neurological deficit (Frankel A) - relative
• Disseminated disease with limited life expectancy

Risk-Benefit Discussion:

• Risk of neurological deterioration: 10-30% depending on tumor and cord function
• Expected degree of resection based on imaging characteristics
• Natural history without surgery: progressive neurological decline
• Role of adjuvant radiotherapy or chemotherapy
• Realistic functional outcomes and rehabilitation needs

Microsurgical Resection Technique

Extent of Resection Definitions

Gross Total Resection (GTR):

• No visible tumor on post-operative MRI at 3 months
• Gold standard for ependymoma and hemangioblastoma
• Associated with best long-term outcomes
• Lower recurrence rates (ependymoma 10-year recurrence less than 20%)

Subtotal Resection (STR):

• Residual tumor less than 10% of original volume
• Often appropriate for infiltrative astrocytoma
• May require adjuvant radiotherapy
• Higher recurrence risk

Partial Resection:

• Greater than 10% residual tumor
• Reserved for highly infiltrative or eloquent location tumors
• Adjuvant therapy usually indicated
• May provide symptomatic relief and tissue diagnosis

Adjuvant Therapy

Radiation Therapy Indications:

• High-grade astrocytoma (WHO Grade III-IV): definitive radiotherapy
• Residual ependymoma after STR
• Recurrent ependymoma
• Anaplastic ependymoma (WHO Grade III)
• Typical dose: 45-54 Gy in 25-30 fractions

Chemotherapy:

• Limited role in spinal cord gliomas
• Temozolomide for high-grade astrocytoma
• Combination with radiotherapy (Stupp protocol)
• Clinical trial enrollment when appropriate

Surveillance Imaging:

• MRI at 3 months post-operative (baseline)
• Every 6 months for 2 years
• Annually thereafter
• Lifelong surveillance due to late recurrence risk

Early Complications (less than 30 days):

Neurological Deterioration:

• Incidence: 15-30% of patients
• Mechanisms: cord edema, manipulation injury, vascular compromise
• Presentation: worsening weakness, ascending sensory level
• Management: high-dose dexamethasone, maintain MAP greater than 85 mmHg, urgent MRI if concern for hematoma
• Prognosis: 60-70% recover to baseline or better by 6 months

Epidural Hematoma:

• Incidence: 2-5%
• Presentation: acute neurological deterioration within 24 hours
• Diagnosis: urgent MRI showing epidural collection with cord compression
• Management: emergency surgical evacuation
• Prevention: meticulous hemostasis, avoid epidural drain

CSF Leak:

• Incidence: 5-10%
• Presentation: wound drainage, CSF otorrhea (if high cervical), positional headache
• Diagnosis: fluid analysis (glucose, beta-2 transferrin)
• Management: bed rest, acetazolamide, wound re-exploration if persistent
• Complications: meningitis risk, pseudomeningocele

Infection:

• Meningitis: 1-2% incidence, presents with fever, headache, neck stiffness
• Wound infection: 3-5%, erythema, drainage, fever
• Diagnosis: CSF analysis (pleocytosis, low glucose), wound cultures
• Management: broad-spectrum antibiotics (vancomycin plus ceftriaxone), surgical washout if deep infection

Late Complications (greater than 30 days):

Spinal Instability and Deformity:

• Risk factors: greater than 50% facet resection, pediatric age, multilevel laminectomy
• Presentation: progressive kyphosis, mechanical back pain
• Prevention: preserve facets, laminoplasty in children, prophylactic fusion if high risk
• Management: posterior instrumented fusion if symptomatic

Tumor Recurrence:

• Ependymoma: 10-year recurrence 15-20% after GTR, 40-50% after STR
• Astrocytoma: 10-year recurrence 60-80% (infiltrative nature)
• Hemangioblastoma: 5-10% if GTR, higher if VHL syndrome (new tumors)
• Management: re-resection if feasible, radiotherapy, chemotherapy for high-grade

Persistent Syrinx:

• Incidence: 10-20% after tumor resection
• Usually asymptomatic if stable size
• Symptomatic syrinx may require syringosubarachnoid shunt
• Investigate for tumor recurrence or arachnoiditis

Several management questions in intramedullary tumour surgery remain unresolved and are favourite examiner territory because they expose understanding of evidence rather than recall.

• Timing of surgery for the minimally symptomatic tumour. Pre-operative neurological status is the most consistent predictor of outcome, arguing for early resection before deficits become fixed. Against this is the real operative risk of converting a mildly symptomatic patient to a worse state. There is no randomised evidence; practice is individualised to tumour type, growth and patient preference.

• MEP versus D-wave thresholds. A transient MEP drop with a preserved D-wave usually predicts only transient weakness, whereas a D-wave fall over 50% predicts permanent loss. The exact alarm criteria and how aggressively to continue after a transient MEP change are not standardised, and D-wave recording is not feasible in every cord segment or in young children.

• Role of adjuvant radiotherapy for subtotally resected ependymoma. Some series support radiotherapy for residual or anaplastic disease while others, including the original McCormick experience, achieved durable control with surgery alone. There is no level I evidence, and radiotherapy carries risks of myelopathy and second malignancy.

• Radiotherapy for low-grade astrocytoma. Because degree of resection does not change survival within grade and benefit of adjuvant radiotherapy is unproven for grade II tumours, many centres observe after maximal safe resection and reserve radiotherapy for progression - but practice varies widely.

• Surgery versus observation in VHL hemangioblastoma. Asymptomatic lesions can be observed given their indolent, multifocal nature, yet some advocate earlier resection of accessible dorsal lesions before they enlarge. The decision balances cumulative operative morbidity against the risk of symptomatic progression.

• Prophylactic fusion / laminoplasty. Whether to fuse or perform laminoplasty to prevent post-laminectomy kyphosis - particularly in children and after multilevel exposure - is not settled by trial evidence and is guided by age, sagittal alignment and extent of facet preservation.

• Molecular reclassification. WHO CNS5 (2021) increasingly defines spinal ependymoma and glioma by molecular markers (e.g. MYCN amplification in spinal ependymoma, which carries a poor prognosis). How molecular subtype should modify the surgical aggressiveness and adjuvant strategy is still evolving.

Global Epidemiology

• Intramedullary spinal cord tumours are rare, comprising roughly 4-10% of all CNS tumours and 20-30% of all intraspinal tumours in adults; they are proportionally more common in children, in whom astrocytoma predominates over ependymoma.
• In adults the order of frequency is ependymoma (around 60%), astrocytoma (around 30%) and hemangioblastoma (3-5%); in the paediatric population astrocytoma is the most common intramedullary tumour.
• Hemangioblastoma is associated with von Hippel-Lindau disease in roughly a quarter of cases; VHL is autosomal dominant (chromosome 3p25, VHL gene) with a 50% risk to offspring.
• Spinal ependymoma shows a slight male predominance and peaks in the third-to-fifth decades; myxopapillary ependymoma characteristically arises at the conus/filum.

Side-by-Side Guidance

There is no single dedicated international guideline for intramedullary tumours; practice is informed by neuro-oncology bodies and surgical society consensus. The table summarises where authoritative sources converge and where emphasis differs.

Registry & Outcome Notes

• Because these tumours are rare, robust data come from population cancer registries (e.g. CBTRUS in the US) and large single-/multi-centre surgical series rather than implant-style joint registries. CBTRUS-type data confirm the rarity and the histological distribution above.
• Reported gross total resection rates from high-volume centres are around 70-90% for ependymoma and over 90% for hemangioblastoma, but under 20-45% for infiltrative astrocytoma - figures that should temper consent discussions.

High- vs Limited-Resource Practice Variation

• High-resource settings: routine whole-spine 1.5-3T MRI with contrast, intraoperative neuromonitoring including D-wave, ultrasonic aspiration, neuro-anaesthesia and ICU support, molecular pathology, and access to conformal radiotherapy and genetic services for VHL.
• Limited-resource settings: MRI access and intraoperative monitoring may be restricted, shifting practice toward later presentation, more conservative (often subtotal) resection to avoid deficit without monitoring, and limited molecular/genetic testing. Outcomes are correspondingly more dependent on pre-operative neurological status, reinforcing the universal principle of operating before deficits become fixed.

1. McCormick PC, Torres R, Post KD, Stein BM. Intramedullary ependymoma of the spinal cord. J Neurosurg. 1990;72(4):523-532. doi:10.3171/jns.1990.72.4.0523. PMID 2319309.

2. Halvorsen CM, Kolstad F, Hald J, et al. Long-term outcome after resection of intraspinal ependymomas: report of 86 consecutive cases. Neurosurgery. 2010;67(6):1622-1631. doi:10.1227/NEU.0b013e3181f96d41. PMID 21107192.

3. Lonser RR, Weil RJ, Wanebo JE, DeVroom HL, Oldfield EH. Surgical management of spinal cord hemangioblastomas in patients with von Hippel-Lindau disease. J Neurosurg. 2003;98(1):106-116. doi:10.3171/jns.2003.98.1.0106. PMID 12546358.

4. Cannizzaro D, Mancarella C, Nasi D, et al. Intramedullary spinal cord tumors: the value of intraoperative neurophysiological monitoring in a series of 57 cases. J Neurosurg Sci. 2022;66(5):447-455. doi:10.23736/S0390-5616.19.04758-1. PMID 31565906.

5. Siller S, Szelenyi A, Herlitz L, Tonn JC, Zausinger S. Spinal cord hemangioblastomas: significance of intraoperative neurophysiological monitoring for resection and long-term outcome. J Neurosurg Spine. 2017;26(4):483-493. doi:10.3171/2016.8.SPINE16595. PMID 27982764.

6. McGirt MJ, Goldstein IM, Chaichana KL, et al. Extent of surgical resection of malignant astrocytomas of the spinal cord: outcome analysis of 35 patients. Neurosurgery. 2008;63(1):55-60. doi:10.1227/01.NEU.0000335070.37943.09. PMID 18728568.

7. Innocenzi G, Salvati M, Cervoni L, Delfini R, Cantore G. Prognostic factors in intramedullary astrocytomas. Clin Neurol Neurosurg. 1997;99(1):1-5. doi:10.1016/s0303-8467(96)00555-0. PMID 9107459.

8. Samartzis D, Gillis CC, Shih P, O'Toole JE, Fessler RG. Intramedullary spinal cord tumors: part I--epidemiology, pathophysiology, and diagnosis. Global Spine J. 2015;5(5):425-435. doi:10.1055/s-0035-1549029. PMID 26430598.

9. Samartzis D, Gillis CC, Shih P, O'Toole JE, Fessler RG. Intramedullary spinal cord tumors: part II--management options and outcomes. Global Spine J. 2016;6(2):176-185. PMID 26933620.

Evidence was verified against PubMed; every EvidenceCard carries a confirmed PMID and DOI.