🧠 Non-Compressive Myelopathy – High-Yield Overview
Spinal cord dysfunction without external mechanical compression. Pathology is intrinsic: inflammatory, vascular, metabolic, toxic, infectious, genetic, or infiltrative.
🔥 1. Inflammatory / Immune-Mediated (Most common in neurology)
🧩 Multiple Sclerosis (MS)
- ⚡ Partial myelitis (<3 segments, asymmetric)
- 🧠 Often associated with brain plaques
- 🎯 Patchy short-segment lesions
💧 NMOSD (Aquaporin-4 IgG)
- 📏 Longitudinally extensive lesions (≥3 segments)
- 👁️ Severe myelitis + optic neuritis
- 🚑 Often profound deficits
🟠 MOGAD (MOG-associated disease)
- 🎭 Can mimic NMOSD or short lesions
- 😊 Better recovery compared to AQP4-NMOSD
🎯 Idiopathic Transverse Myelitis
- ⏱️ Acute/subacute
- 🎚️ Sensory level + sphincter involvement
🧬 Paraneoplastic Myelopathy
- 🔗 Anti-Hu, CRMP-5, amphiphysin
- 📉 Progressive course
- 🎗️ Associated malignancy
🌡️ Autoimmune Systemic (SLE, Sjögren, Sarcoidosis)
- 🔥 Granulomatous or vascular myelopathy
- 🪵 Sarcoid: Long lesions, dorsal subpial “Trident sign”
🩸 2. Vascular Causes
❤️🔥 Spinal Cord Infarction
- ⚡ Hyperacute onset with severe back pain
- 🫀 Anterior spinal artery:
- ❌ Motor + pain/temperature loss
- ✔️ Vibration/position preserved
- 🦉 “Owl’s eyes” sign on axial MRI
🌊 Spinal Dural AV Fistula
- 🐌 Slowly progressive
- 💨 Worse with exertion
- 🌀 MRI: T2 hyperintensity + serpiginous flow voids
- 🚨 Treatable cause—don’t miss!
🧪 Venous Infarction / Hypercoagulable States
🦠 3. Infectious Causes
🦠 Viral
- HIV, HTLV-1, HSV-2, EBV, CMV
- ⚖️ HTLV-1 → progressive spastic paraparesis
🧫 Bacterial
- Syphilis (tabes dorsalis / meningomyelitis)
- Lyme
- Tuberculosis
🪱 Parasitic
- Schistosomiasis (Egypt)
- Neurocysticercosis
🧬 4. Metabolic & Deficiency-Related
🟦 Vitamin B12 Deficiency (Subacute Combined Degeneration)
- 🎯 Posterior columns + CST
- 👣 Sensory ataxia + spasticity
🟧 Copper Deficiency
- 🔎 Mimics B12 deficiency
- 🍽️ Often after gastric surgery/zinc excess
🟩 Vitamin E Deficiency
- Rare; posterior column involvement
☣️ 5. Toxic Causes
- 🎈 Nitrous oxide → functional B12 deficiency
- 💉 Chemotherapy (cisplatin, vincristine)
- ☢️ Radiation-induced (months–years delayed)
🧬 6. Genetic / Degenerative
🧵 Hereditary Spastic Paraplegia (HSP)
- 🐌 Slowly progressive spastic paraparesis
- 🧠 MRI often normal or subtle
🌐 Leukodystrophies / Mitochondrial Disorders
- 🌀 Diffuse white-matter + spinal involvement
🦠 7. Neoplastic / Infiltrative (Intrinsic Cord)
(Not compressive but inside the cord)
- 🧫 Astrocytoma
- 🧪 Ependymoma
- 🟣 Lymphoma
- 🩸 Leukemic infiltration
🧲 MRI Hallmarks – Quick Differentiation
📏 Longitudinal (≥3 segments)
- NMOSD
- Sarcoidosis
- Vascular congestion (dAVF)
- B12/copper deficiency
🎯 Posterior column–predominant
- B12
- Copper deficiency
- HIV vacuolar myelopathy
🧩 Patchy short lesions
- MS
🌲 Dorsal subpial enhancement
- Sarcoidosis (“Trident sign”)
🦉 Owl’s eyes
- Spinal cord infarction
🎯 Central gray matter involvement
- Viral (enteroviruses)
- Ischemia
- MOGAD
🔍 Approach to Diagnosis
1️⃣ MRI with contrast
- Enhancement pattern
- Longitudinal extent
- Tract involvement
2️⃣ CSF Analysis
- 🧪 OCBs → MS
- 🔥 Neutrophils → infection
- 📈 High protein / low cells → GBS-variant (rare ascending myelitis)
3️⃣ Serum Studies
- AQP4-IgG, MOG-IgG
- B12, MMA, copper
- ANA, ENA, ACE (sarcoid)
- HIV, HTLV-1, VDRL/TPHA (syphilis)
4️⃣ Spine Angiography
- If dural AV fistula suspected
🚨 Red Flags Requiring Emergent Treatment
- ⏳ Rapidly progressive weakness
- ⚠️ Sphincter dysfunction
- 🔥 Suspected NMOSD flare
- 💉 Severe transverse myelitis → IV methylprednisolone ± plasmapheresis
