High Yield Overview

INTRADURAL EXTRAMEDULLARY TUMORS

Schwannoma | Meningioma | Neurofibroma | Myxopapillary Ependymoma

40%Schwannoma (most common)

25%Meningioma

90%Benign histology

80%GTR achievable

COMMON INTRADURAL EXTRAMEDULLARY TUMORS

Schwannoma

PatternMost common IDEM tumor, nerve root origin

TreatmentGTR curative in most cases

Meningioma

PatternSecond most common, dura origin, thoracic

TreatmentGTR with dural resection

Neurofibroma

PatternAssociated with NF1, nerve root infiltration

TreatmentMay require root sacrifice

Myxopapillary Ependymoma

PatternFilum terminale, young adults

TreatmentGTR preferred, radiosensitive

Critical Must-Knows

Schwannoma vs Meningioma: Schwannoma is T2 hyperintense, meningioma is T2 iso/hypointense
Dural tail sign: Suggestive of meningioma (contrast-enhancing dura adjacent to tumor)
Dumbbell tumors: Neural foraminal extension, most commonly schwannoma (69%)
Gross total resection: Curative for most benign IDEM tumors
NF2 association: Multiple schwannomas/meningiomas, consider NF2 screening

Examiner's Pearls

"
T2 bright = schwannoma, T2 iso/dark = meningioma
"
Thoracic location + female = think meningioma
"
Dumbbell shape + cervical = think schwannoma
"
NF1 = neurofibromas, NF2 = schwannomas and meningiomas

Clinical Imaging

Imaging Gallery

(a and b) Axial contrast MRI showing small vestibular schwannomas within bilateral acoustic canal (black arrows) and a posterior parafalcine meningioma (white arrow). (c) Coronal MR cervical spine ima — (a and b) Axial contrast MRI showing small vestibular schwannomas within bilateral acoustic canal (black arrows) and a posterior parafalcine meningiomCredit: Aiyappan SK et al. via J Neurosci Rural Pract via Open-i (NIH) (Open Access (CC BY))

Forty-seven-year-old female with intradural extramedullary menigioma with paraparesis. (A) T1-weighted sagittal MR image shows homogenous high signal intensity mass. The tumor is located at the T10-11 — Forty-seven-year-old female with intradural extramedullary menigioma with paraparesis. (A) T1-weighted sagittal MR image shows homogenous high signal Credit: Song KW et al. via Clin Orthop Surg via Open-i (NIH) (Open Access (CC BY))

Thirty-five-year-old male with intradural extramedullary schwannoma with both upper & lower extremity weakness and tingling sensation below C3 level. (A) T2-weighted sagittal MR image shows a huge — Thirty-five-year-old male with intradural extramedullary schwannoma with both upper & lower extremity weakness and tingling sensation below C3 levCredit: Song KW et al. via Clin Orthop Surg via Open-i (NIH) (Open Access (CC BY))

A man in his late 40s with a schwannoma at C1–C2. A) Post-contrast sagittal T1-weighted MRI showing the enhancing tumor. B) Axial T2-weighted MRI showing the left-sided tumor, which involved the C1–C2 — A man in his late 40s with a schwannoma at C1–C2. A) Post-contrast sagittal T1-weighted MRI showing the enhancing tumor. B) Axial T2-weighted MRI showCredit: Open-i / NIH via Open-i (NIH) (Open Access (CC BY))

Critical IDEM Tumor Exam Points

MRI Differentiation

Schwannoma: T2 hyperintense, may have cystic change, heterogeneous enhancement. Meningioma: T2 iso/hypointense, homogeneous enhancement, dural tail sign. Signal intensity ratio on T2 differentiates reliably.

Location Pattern

Meningioma: 80% thoracic, lateral or posterolateral, 80% female. Schwannoma: Any level, often cervical/lumbar, equal gender. Ependymoma: Lumbar, filum terminale.

Dumbbell Tumors

Neural foraminal extension creates dumbbell shape. Most common cause is schwannoma (69%). Consider stability if large extraforaminal component. May need combined anterior-posterior approach.

NF Association

NF1 (von Recklinghausen): Neurofibromas, plexiform neurofibromas. NF2: Bilateral vestibular schwannomas PLUS spinal schwannomas/meningiomas. Multiple tumors = screen for NF2.

Schwannoma vs Meningioma - Key Differences

Feature	Schwannoma	Meningioma
T2 Signal	HYPERINTENSE (bright)	Iso/HYPOINTENSE (dark)
Enhancement	Heterogeneous, may be cystic	Homogeneous
Dural tail	Absent/rare	Present (64%)
Location	Any level, cervical common	80% thoracic
Gender	M = F	80% female
Foraminal extension	Common (29%)	Rare (3%)
Cystic change	Common (96%)	Rare (24%)
Nerve root origin	Yes (displaced/encased)	No (dural origin)

Mnemonic

IDEM Tumors - By Frequency

Schwannoma

40% - most common, nerve sheath origin, T2 bright

Meningioma

25% - dural origin, thoracic, female, dural tail

Neurofibroma

15% - NF1 associated, infiltrative, root sacrifice may be needed

Ependymoma

10% - filum terminale, myxopapillary type, young adults

Memory Hook:SMNE - Schwannoma Most common, Neurofibromas with NF1, Ependymoma at filum

Mnemonic

Schwannoma vs Meningioma MRI

Signal T2 high

Schwannoma is T2 hyperintense (bright)

Cystic change

Common in schwannoma (96%), rare in meningioma

Heterogeneous enhancement

Schwannoma enhances heterogeneously

Meningioma dark

T2 iso/hypointense, homogeneous

Dural tail

Characteristic of meningioma (64%)

Memory Hook:SCHMD - Schwannoma is bright, Cystic, Heterogeneous; Meningioma is Dark with Dural tail

Mnemonic

NF1 vs NF2 Features

NF1

Neurofibromatosis Type 1

Neurofibromas, cafe-au-lait spots, plexiform, chromosome 17

NF2

Neurofibromatosis Type 2

Bilateral vestibular schwannomas, spinal schwannomas/meningiomas, chromosome 22

Memory Hook:NF1 = Neurofibromas (type 1), NF2 = schwannomas times 2 (bilateral)

Overview and Epidemiology

Intradural extramedullary (IDEM) tumors are located within the dural sac but outside the spinal cord parenchyma. They account for 55-75% of all intradural spinal tumors and are predominantly benign.

Distribution of IDEM Tumors:

Tumor Type	Frequency	Peak Age	Gender
Schwannoma	40%	30-60	M = F
Meningioma	25%	40-70	F more than M (4:1)
Neurofibroma	15%	30-50	M = F
Myxopapillary Ependymoma	10%	20-40	M more than F
Others	10%	Variable	Variable

Key Epidemiological Points:

Meningiomas show strong female predominance (80%) and thoracic predilection. Schwannomas affect males and females equally and occur at any spinal level. Ependymomas of the filum terminale (myxopapillary type) are the most common primary tumor of the conus/cauda equina region.

NF2 Screening

If a patient presents with multiple schwannomas or meningiomas, screen for Neurofibromatosis Type 2. NF2 is characterized by bilateral vestibular schwannomas and multiple spinal tumors. Chromosome 22 mutation.

Pathophysiology

Tumor Origins

Nerve Sheath Origin

Schwannomas arise from Schwann cells of spinal nerve roots. They are encapsulated tumors that displace rather than infiltrate nerve fibers.

Histology:

Antoni A areas: Cellular, organized palisading (Verocay bodies)
Antoni B areas: Loose, myxoid, less cellular
S-100 protein positive

Growth Pattern:

Eccentric growth from nerve root
Nerve fibers displaced around capsule
Usually single nerve root involved
Nerve can often be preserved at surgery

Malignant transformation is extremely rare in sporadic schwannomas but may occur in NF2.

Classification

Spinal Tumor Compartments

Compartment	Location	Common Tumors
Extradural	Outside dura	Metastases, primary bone tumors
Intradural Extramedullary	Inside dura, outside cord	Schwannoma, meningioma, neurofibroma
Intramedullary	Within spinal cord	Ependymoma, astrocytoma, hemangioblastoma

IDEM tumors displace the spinal cord rather than infiltrate it. This generally allows preservation of cord function with surgical resection.

Clinical Presentation

Presenting Symptoms

Pain (Most Common Initial Symptom):

Localized back pain (70%)
Radicular pain following nerve root distribution
May precede neurological deficit by months to years
Night pain common

Neurological Deficit:

Sensory changes (numbness, paresthesias)
Motor weakness (progressive)
Bladder/bowel dysfunction (late)
Gait disturbance

Tumor-Specific Presentations

Schwannoma:

Radicular pain in dermatomal distribution
May have sensory loss in affected root
Motor weakness if motor root involved

Meningioma:

Often presents with progressive myelopathy
Gait disturbance, spasticity
Brown-Sequard syndrome if lateral compression
May have minimal radicular symptoms

Myxopapillary Ependymoma:

Low back pain
Cauda equina symptoms (bowel/bladder, saddle anesthesia)
Often long history before diagnosis

Examination Findings

Upper Motor Neuron Signs (cord compression):

Spasticity, hyperreflexia below lesion
Positive Babinski
Clonus

Lower Motor Neuron Signs (root compression):

Weakness in myotomal distribution
Hyporeflexia at affected level
Muscle atrophy

Cauda Equina Syndrome

Tumors of the lumbar spine may cause cauda equina syndrome with saddle anesthesia, urinary retention, and bilateral leg weakness. This is a surgical emergency requiring urgent decompression.

Investigations

MRI - Gold Standard

Standard Sequences

Essential for IDEM tumor assessment.

T1-Weighted:

Tumors usually isointense to cord
Defines anatomical relationships
Pre-contrast baseline

T2-Weighted/STIR:

Schwannoma: Hyperintense
Meningioma: Iso/hypointense
Key differentiating sequence
Shows cord edema

Post-Gadolinium T1:

All IDEM tumors enhance
Schwannoma: Heterogeneous
Meningioma: Homogeneous + dural tail

Additional: Whole spine MRI to exclude skip lesions or NF2.

Additional Investigations

CT Scan:

Bone erosion (dumbbell tumors)
Calcification (meningioma)
Pre-operative planning

Blood Tests:

Routine pre-operative workup
Consider genetic testing if NF suspected

Management

Surgical Management

Standard Posterior Approach

Most IDEM tumors approached posteriorly.

Laminectomy vs Laminoplasty:

Laminectomy: Standard approach
Laminoplasty: May reduce post-laminectomy kyphosis
Consider instrumented fusion if extensive laminectomy (3+ levels)

Technical Steps:

Posterior midline incision
Laminectomy/laminoplasty
Durotomy (midline or paramedian)
Tumor identification
Microsurgical resection
Watertight dural closure
Bone replacement if laminoplasty

Intraoperative neurophysiological monitoring (SSEP, MEP) recommended.

Non-Surgical Management

Observation:

Small, asymptomatic tumors
Elderly or medically unfit patients
Slow-growing tumors (serial MRI monitoring)

Radiation:

Rarely used for benign IDEM tumors
Consider for recurrent/incompletely resected meningioma
SRS (stereotactic radiosurgery) for small recurrences
Primary treatment if patient not surgical candidate

Nerve Root Sacrifice

For schwannomas, the parent nerve root can often be preserved because the tumor displaces rather than infiltrates nerve fibers. For neurofibromas, nerve fibers pass through the tumor, and root sacrifice is often necessary for complete resection.

Complications

Surgical Complications

Early:

CSF leak (most common, 5-10%)
Wound infection
New neurological deficit (2-5%)
Hematoma

Late:

Post-laminectomy kyphosis
Tumor recurrence
Chronic pain
Arachnoiditis

CSF Leak Prevention

Intraoperative:

Meticulous dural closure
Dural grafting if primary closure not possible
Fibrin sealant augmentation
Watertight closure in layers

If CSF Leak Occurs:

Wound care
Lumbar drain (3-5 days)
Re-exploration if conservative measures fail

Recurrence Rates

Tumor	GTR Recurrence	STR Recurrence
Schwannoma	Less than 5%	30-40%
Meningioma	5-10%	20-30%
Neurofibroma	Variable	Higher with NF1
Myxopapillary Ependymoma	Less than 10%	50-70%

Evidence Base

Schwannoma vs Meningioma MRI Differentiation

III

Maki S et al. • Br J Radiol (2019)

Key Findings:

Signal intensity ratio on T2 differentiates schwannoma from meningioma
Schwannoma: Higher T2/fat signal ratio
Cystic change: 96% schwannoma vs 24% meningioma
Dural tail: 64% meningioma vs 1% schwannoma

Clinical Implication: T2 signal intensity and morphological features on MRI can reliably differentiate schwannoma from meningioma preoperatively

Spinal Schwannoma Surgical Outcomes

Seppala MT et al. • J Neurosurg (1995)

Key Findings:

187 patients with spinal schwannoma
GTR achieved in 93%
Recurrence rate 3% with GTR
Nerve root function preserved in majority

Clinical Implication: Gross total resection of spinal schwannomas provides excellent long-term tumor control with low recurrence rates

Spinal Meningioma Surgery

Gottfried ON et al. • J Neurosurg Spine (2003)

Key Findings:

GTR achievable in 89-100%
Functional improvement in 80%+
Simpson Grade influences recurrence
Long-term recurrence 5-10%

Clinical Implication: Spinal meningiomas have excellent surgical outcomes with low recurrence when gross total resection is achieved

Myxopapillary Ependymoma Outcomes

III

Weber DC et al. • Neuro Oncol (2015)

Key Findings:

En bloc resection associated with better outcomes
Capsule violation increases recurrence risk
GTR alone: 92% 10-year PFS
STR with radiation: 75% 10-year PFS

Clinical Implication: En bloc gross total resection without capsule violation is critical for long-term control of myxopapillary ependymoma

Exam Viva Scenarios

Practice these scenarios to excel in your viva examination

VIVA SCENARIOStandard

Thoracic IDEM Tumor in Female

EXAMINER

"A 55-year-old woman presents with 6 months of progressive gait difficulty and band-like thoracic pain. MRI shows a T6-T7 intradural extramedullary mass that is isointense on T2, enhances homogeneously, and has a dural tail sign."

EXCEPTIONAL ANSWER

**Most Likely Diagnosis:** Spinal meningioma - based on: - T2 isointense (not hyperintense like schwannoma) - Homogeneous enhancement - Dural tail sign (64% specific for meningioma) - Thoracic location (80% of spinal meningiomas) - Female gender (4:1 female predominance) **Pre-operative Assessment:** 1. Full neurological examination (document ASIA score) 2. Medical fitness for surgery 3. MRI whole spine (rule out additional tumors/NF2) 4. CT if concern about calcification or bone involvement **Surgical Management:** 1. Position: Prone 2. Approach: Posterior midline 3. T5-T8 laminectomy or laminoplasty 4. Midline durotomy 5. Microsurgical dissection from cord 6. Identify dural attachment 7. Resect with dural margin (Simpson Grade II) 8. Primary dural closure or graft 9. Neurophysiological monitoring throughout **Post-operative:** - Early mobilization - MRI at 3 months for baseline - Annual MRI surveillance - GTR = 5-10% recurrence at 10 years **Key Point:** T2 isointense with dural tail = meningioma until proven otherwise.

KEY POINTS TO SCORE

T2 iso/hypointense + dural tail = meningioma

80% of spinal meningiomas are thoracic

4:1 female predominance

Simpson Grade II (GTR + dural coagulation) is goal

Excellent prognosis with GTR

COMMON TRAPS

✗Calling it schwannoma (T2 bright, no dural tail)

✗Forgetting to image whole spine for NF2

✗Not achieving dural margin excision/coagulation

VIVA SCENARIOChallenging

Cervical Dumbbell Tumor

EXAMINER

"A 45-year-old man presents with right-sided neck pain and C6 radiculopathy. MRI shows a C5-C6 intradural extramedullary tumor that is T2 hyperintense with heterogeneous enhancement. There is foraminal extension with an extraspinal component."

EXCEPTIONAL ANSWER

**Diagnosis:** Dumbbell schwannoma - based on: - T2 hyperintense (characteristic of schwannoma) - Heterogeneous enhancement - Neural foraminal extension (29% of schwannomas vs 3% meningiomas) - Radicular symptoms - Male patient (meningioma rare in males) **Classification:** Eden Type II or III dumbbell tumor (foraminal and paraspinal extension). **Pre-operative Planning:** 1. CT angiography - relationship to vertebral artery 2. Assess size of extraforaminal component 3. Evaluate for spinal instability 4. Consider embolization if highly vascular **Surgical Approach Options:** **Option 1: Posterior Alone (if small extraforaminal)** - Laminectomy C5-C6 - Extended foraminotomy - Intraspinal tumor resection - Follow tumor into foramen - May need partial facetectomy **Option 2: Combined Anterior-Posterior (if large extraforaminal)** - Stage 1: Posterior laminectomy + intraspinal resection - Stage 2: Anterior approach for extraspinal component - Consider single-stage combined if experienced team **Intraoperative Considerations:** - Neurophysiological monitoring - Identify C6 nerve root - Attempt nerve preservation (stimulate fascicles) - Vertebral artery protection - May need C5-C6 instrumented fusion if extensive facetectomy **Outcomes:** - GTR achievable in 80-90% of dumbbell tumors - Nerve root sacrifice may be necessary - Sensory root sacrifice usually well tolerated

KEY POINTS TO SCORE

T2 hyperintense + foraminal extension = schwannoma

69% of dumbbell tumors are schwannomas

Combined approach may be needed for large extraspinal component

Vertebral artery at risk in cervical region

Nerve preservation often possible (tumor displaces fibers)

COMMON TRAPS

✗Attempting posterior alone for large extraforaminal tumor

✗Forgetting CT angiography for vertebral artery

✗Not considering instability after extended facetectomy

VIVA SCENARIOStandard

Filum Terminale Tumor in Young Adult

EXAMINER

"A 28-year-old man presents with 18 months of low back pain and recent onset of urinary hesitancy. MRI shows a well-circumscribed L3-L4 intradural tumor arising from the filum terminale. It is T2 hyperintense with homogeneous enhancement."

EXCEPTIONAL ANSWER

**Diagnosis:** Myxopapillary ependymoma - based on: - Young adult male (typical demographics) - Filum terminale origin (pathognomonic location) - Well-circumscribed - T2 hyperintense - Homogeneous enhancement **WHO Grade II** - but CSF seeding risk if capsule violated. **Pre-operative Considerations:** 1. MRI whole spine and brain - exclude drop metastases 2. Document baseline neurological function (ASIA, bladder/bowel) 3. Counsel regarding surgical risks (bladder, sexual function) **Critical Surgical Principles:** **1. EN BLOC RESECTION ESSENTIAL** - Do NOT violate tumor capsule - Capsule rupture = CSF seeding risk - Piecemeal resection = 50-70% recurrence - En bloc GTR = less than 10% recurrence **2. Technical Approach:** - L2-L5 laminectomy - Midline durotomy - Identify tumor attachment to filum - Divide filum above and below tumor - Remove en bloc - Examine for any CSF seeding **3. Nerve Root Protection:** - Use stimulation to identify motor roots - Cauda equina roots draped over tumor - Meticulous microsurgical dissection **Post-operative:** - If GTR with intact capsule: Observation - If STR or capsule violated: Adjuvant radiation - MRI surveillance (brain and spine) annually **Prognosis:** - GTR intact capsule: more than 90% 10-year survival - STR: 50% 10-year PFS (better with radiation)

KEY POINTS TO SCORE

Filum terminale origin = myxopapillary ependymoma

EN BLOC resection is CRITICAL

Capsule violation = CSF seeding and recurrence

Piecemeal resection has 50-70% recurrence

Radiation for STR or capsule violation

COMMON TRAPS

✗Performing piecemeal resection

✗Violating tumor capsule

✗Not imaging entire neuraxis

✗Not offering radiation for incomplete resection

VIVA SCENARIOChallenging

Multiple IDEM Tumors

EXAMINER

"A 32-year-old woman presents with progressive gait ataxia. MRI shows three intradural extramedullary tumors at C3, T6, and L2. She also reports hearing loss for 2 years."

EXCEPTIONAL ANSWER

**Suspected Diagnosis:** Neurofibromatosis Type 2 (NF2) - based on: - Multiple spinal intradural tumors - Young female - Hearing loss (suggests vestibular schwannoma) **NF2 Diagnostic Criteria:** 1. Bilateral vestibular schwannomas, OR 2. First-degree relative with NF2 + unilateral VS + 2 of: meningioma, schwannoma, glioma, neurofibroma, cataract **Investigation:** 1. MRI internal auditory meatus - bilateral vestibular schwannomas? 2. MRI whole spine - extent of spinal disease 3. MRI brain - intracranial meningiomas? 4. Audiometry - document hearing 5. Ophthalmology - cataracts, retinal hamartomas 6. Genetic testing - NF2 gene (chromosome 22q12) **If NF2 Confirmed:** 1. Family screening (autosomal dominant) 2. Genetic counseling 3. Multidisciplinary team (neurosurgery, ENT, ophthalmology, genetics) **Surgical Strategy in NF2:** - Prioritize symptomatic tumors - Hearing preservation for VS (when possible) - May need multiple staged surgeries - Conservative approach for slow-growing asymptomatic tumors - Bevacizumab (anti-VEGF) may slow tumor growth **This Patient:** - Gait ataxia suggests T6 tumor may be causing myelopathy - Prioritize symptomatic T6 lesion - C3 and L2 may be observed if asymptomatic - Address hearing loss/VS separately **Prognosis:** - Life expectancy reduced in NF2 - Multiple surgeries typically required - Hearing loss common - Quality of life focus important

KEY POINTS TO SCORE

Multiple spinal tumors + hearing loss = NF2 until proven otherwise

NF2 = chromosome 22 (merlin gene)

Bilateral vestibular schwannomas are hallmark

Screen first-degree relatives

Prioritize symptomatic tumors for surgery

COMMON TRAPS

✗Not recognizing pattern of NF2

✗Operating on all tumors simultaneously

✗Forgetting to image brain and IAMs

✗Not offering genetic testing/family screening

Management Algorithm

INTRADURAL EXTRAMEDULLARY TUMORS

High-Yield Exam Summary

Schwannoma vs Meningioma

•Schwannoma: T2 BRIGHT, heterogeneous, cystic, foraminal extension
•Meningioma: T2 ISO/DARK, homogeneous, dural tail, thoracic
•Signal intensity ratio on T2 reliably differentiates
•Schwannoma = any level, Meningioma = 80% thoracic

Tumor Frequencies

•Schwannoma: 40% (most common)
•Meningioma: 25% (80% female)
•Neurofibroma: 15% (NF1 associated)
•Myxopapillary ependymoma: 10% (filum terminale)

Surgical Goals

•GTR is curative for most IDEM tumors
•Schwannoma: Nerve preservation often possible
•Meningioma: Simpson Grade II (GTR + dural excision)
•Ependymoma: EN BLOC essential (capsule violation = seeding)

Dumbbell Tumors

•69% are schwannomas
•Eden Classification: I-III based on extension
•Combined approach may be needed
•Assess stability if facetectomy required

NF Association

•NF1: Neurofibromas, plexiform, cafe-au-lait, chr 17
•NF2: Schwannomas + meningiomas, bilateral VS, chr 22
•Multiple spinal tumors = screen for NF2
•NF2 requires multidisciplinary approach

Complications

•CSF leak most common (5-10%)
•Post-laminectomy kyphosis (consider fusion if 3+ levels)
•Recurrence: GTR less than 5-10%, STR 30-40%
•Neurological deficit rare with microsurgical technique

Australian Context

Intradural extramedullary spinal tumors are managed by neurosurgeons and spinal surgeons across Australian tertiary centers. Comprehensive neurosurgical units with intraoperative neurophysiological monitoring capability are recommended for optimal outcomes.

For patients with suspected Neurofibromatosis Type 2, referral to specialist NF clinics (available at major children's hospitals and some adult centers) provides coordinated multidisciplinary care including genetic counseling, hearing assessment, and surgical planning.

Access to microsurgical techniques and intraoperative monitoring has significantly improved outcomes for IDEM tumor surgery in Australia, with gross total resection rates comparable to international centers of excellence.

References

Maki S, Yamamoto K, Nakagawa Y, et al. Differentiating spinal intradural-extramedullary schwannoma from meningioma using MRI T2 weighted images. Br J Radiol. 2019;92(1093):20180262.
Seppala MT, Haltia MJ, Sankila RJ, et al. Long-term outcome after removal of spinal schwannoma: a clinicopathological study of 187 cases. J Neurosurg. 1995;83(4):621-6.
Gottfried ON, Gluf W, Quinones-Hinojosa A, et al. Spinal meningiomas: surgical management and outcome. Neurosurg Focus. 2003;14(6):e2.
Weber DC, Wang Y, Miller R, et al. Long-term outcome of patients with spinal myxopapillary ependymoma: treatment results from the MD Anderson Cancer Center and institutions from the Rare Cancer Network. Neuro Oncol. 2015;17(4):588-95.
Jinnai T, Koyama T. Clinical characteristics of spinal nerve sheath tumors: analysis of 149 cases. Neurosurgery. 2005;56(3):510-5.

Feature

Schwannoma

Meningioma

T2 Signal

HYPERINTENSE (bright)

Iso/HYPOINTENSE (dark)

Enhancement

Heterogeneous, may be cystic

Homogeneous

Dural tail

Absent/rare

Present (64%)

Location

Any level, cervical common

80% thoracic

Gender

M = F

80% female

Foraminal extension

Common (29%)

Rare (3%)

Cystic change

Common (96%)

Rare (24%)

Nerve root origin

Yes (displaced/encased)

No (dural origin)

Tumor Type

Frequency

Peak Age

Gender

Schwannoma

40%

30-60

M = F

Meningioma

25%

40-70

F more than M (4:1)

Neurofibroma

15%

30-50

M = F

Myxopapillary Ependymoma

10%

20-40

M more than F

Others

10%

Variable

Compartment

Location

Common Tumors

Extradural

Outside dura

Metastases, primary bone tumors

Intradural Extramedullary

Inside dura, outside cord

Schwannoma, meningioma, neurofibroma

Intramedullary

Within spinal cord

Ependymoma, astrocytoma, hemangioblastoma

Surgical Management

Standard Posterior Approach

Most IDEM tumors approached posteriorly.

Laminectomy vs Laminoplasty:

Laminectomy: Standard approach
Laminoplasty: May reduce post-laminectomy kyphosis
Consider instrumented fusion if extensive laminectomy (3+ levels)

Technical Steps:

Posterior midline incision
Laminectomy/laminoplasty
Durotomy (midline or paramedian)
Tumor identification
Microsurgical resection
Watertight dural closure
Bone replacement if laminoplasty

Intraoperative neurophysiological monitoring (SSEP, MEP) recommended.

Non-Surgical Management

Observation:

Small, asymptomatic tumors
Elderly or medically unfit patients
Slow-growing tumors (serial MRI monitoring)

Radiation:

Rarely used for benign IDEM tumors
Consider for recurrent/incompletely resected meningioma
SRS (stereotactic radiosurgery) for small recurrences
Primary treatment if patient not surgical candidate

Nerve Root Sacrifice

Tumor

GTR Recurrence

STR Recurrence

Schwannoma

Less than 5%

30-40%

Meningioma

5-10%

20-30%

Neurofibroma

Variable

Higher with NF1

Myxopapillary Ependymoma

Less than 10%

50-70%

Type	Location
Type I	Purely intraspinal
Type IIa	Foraminal extension
Type IIb	Paraspinal extension
Type III	Both foraminal and paraspinal

Type	Location
Type I	Purely intraspinal
Type IIa	Foraminal extension
Type IIb	Paraspinal extension
Type III	Both foraminal and paraspinal

Intradural Extramedullary Tumors

Intradural Extramedullary Tumors

INTRADURAL EXTRAMEDULLARY TUMORS

COMMON INTRADURAL EXTRAMEDULLARY TUMORS

Critical Must-Knows

Examiner's Pearls

Clinical Imaging

Imaging Gallery

Critical IDEM Tumor Exam Points

MRI Differentiation

Location Pattern

Dumbbell Tumors

NF Association

Schwannoma vs Meningioma - Key Differences

IDEM Tumors - By Frequency

Schwannoma vs Meningioma MRI

NF1 vs NF2 Features

Overview and Epidemiology

Pathophysiology

Tumor Origins

Classification

Spinal Tumor Compartments

WHO Classification

Eden Classification for Dumbbell Tumors

Neurofibromatosis Classification

Clinical Presentation

Presenting Symptoms

Tumor-Specific Presentations

Examination Findings

Cauda Equina Syndrome

Investigations

MRI - Gold Standard

Additional Investigations

Management

Surgical Management

Non-Surgical Management

Complications

Surgical Complications

CSF Leak Prevention

Recurrence Rates

Evidence Base

Schwannoma vs Meningioma MRI Differentiation

Spinal Schwannoma Surgical Outcomes

Spinal Meningioma Surgery

Myxopapillary Ependymoma Outcomes

Exam Viva Scenarios

Thoracic IDEM Tumor in Female

Cervical Dumbbell Tumor

Filum Terminale Tumor in Young Adult

Multiple IDEM Tumors

Management Algorithm

INTRADURAL EXTRAMEDULLARY TUMORS

Schwannoma vs Meningioma

Tumor Frequencies

Surgical Goals

Dumbbell Tumors

NF Association

Complications

Australian Context

References

Intradural Extramedullary Tumors

Intradural Extramedullary Tumors

INTRADURAL EXTRAMEDULLARY TUMORS

COMMON INTRADURAL EXTRAMEDULLARY TUMORS

Critical Must-Knows

Examiner's Pearls

Clinical Imaging

Imaging Gallery

Critical IDEM Tumor Exam Points

MRI Differentiation

Location Pattern

Dumbbell Tumors

NF Association

Schwannoma vs Meningioma - Key Differences

IDEM Tumors - By Frequency

Schwannoma vs Meningioma MRI

NF1 vs NF2 Features

Overview and Epidemiology

Pathophysiology

Tumor Origins