Imaging Gallery

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 > 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

Extramedullary Intradural Tumors:

• Meningioma, nerve sheath tumor (schwannoma, neurofibroma)
• Clinical: early radicular pain, late myelopathy
• MRI: dural tail sign, CSF cap around tumor, cord displacement not expansion

Demyelinating Disease (Multiple Sclerosis):

• Relapsing-remitting pattern
• Multiple CNS lesions on MRI brain
• CSF oligoclonal bands
• Optic neuritis and internuclear ophthalmoplegia

Arteriovenous Malformation:

• Sudden onset symptoms or stepwise progression
• Flow voids on MRI (serpentine vessels)
• Spinal angiography definitive
• Subarachnoid hemorrhage risk

Transverse Myelitis:

• Acute onset over hours to days
• Preceding viral illness or vaccination
• Diffuse cord edema on MRI
• CSF pleocytosis

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

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This comprehensive topic provides Gold Standard coverage of intramedullary spinal cord tumors for FRACS examination preparation, emphasizing surgical technique, decision-making, and evidence-based outcomes.