Transverse Myelitis - Comprehensive Overview

Definition

• Goldman-Cecil Medicine, p. 3995
• Rosen's Emergency Medicine, p. 1508

Causes / Etiology

1. Idiopathic

• No identifiable cause in ~30% of cases

2. Post-infectious / Para-infectious (most common trigger)

• Follows viral infection in ~30% of patients
• Viruses: Herpes simplex virus (HSV), Varicella zoster virus (VZV), Cytomegalovirus (CMV), Epstein-Barr virus (EBV), enteroviruses, rabies
• Post-exanthematous: measles, rubella
• Post-vaccinal: rabies, polio vaccines

3. Demyelinating / Autoimmune Disease

• Multiple sclerosis (MS) - typically incomplete/asymmetric TM
• Neuromyelitis optica spectrum disorder (NMOSD) - associated with anti-AQP4 (aquaporin-4) antibodies; causes longitudinally extensive TM (LETM) spanning 3+ vertebral segments
• MOG-antibody disease (MOGAD) - myelin oligodendrocyte glycoprotein antibody-associated

4. Systemic Connective Tissue / Autoimmune Diseases

• Systemic lupus erythematosus (SLE)
• Sjogren syndrome
• Antiphospholipid antibody syndrome
• Mixed connective tissue disease
• Vasculitis

5. Vascular / Structural

• Spinal cord infarction
• Dural arteriovenous fistula
• Antiphospholipid antibody syndrome

6. Neoplastic

• Paraneoplastic myelopathy
• Primary or metastatic spinal cord tumors

7. Compressive / Traumatic

• Herniated intervertebral disc
• Trauma, metastases, extradural extension of mediastinal/thoracic lesions
• Localization in Clinical Neurology, 8e, p. 255
• Rosen's Emergency Medicine, p. 1508

Clinical Features

Onset

• Typically rapid: 66% reach maximal deficit within 24 hours; may progress over days to weeks
• The thoracic cord is affected in 60-70% of cases (cervical cord rarely involved)
• Prodrome: ~one-third report a preceding infectious illness weeks before onset; low-grade fever, back pain possible

The Classic Triad

Additional Features

• Back or neck pain at the level of the lesion
• Lhermitte's sign may be present (electrical sensation down the spine on neck flexion) in cervical TM
• Sensory level - the most diagnostically important sign; all sensory modalities impaired below the lesion level
• Sphincter dysfunction (anal and bladder) - anal sphincter tone reduced
• Spinal shock phase: flaccid paralysis + absent reflexes early
• Chronic phase: spastic paralysis + brisk reflexes + Babinski sign

Pattern Based on Extent

• Longitudinally extensive TM (LETM): spans 3+ vertebral segments - hallmark of NMOSD
• Incomplete/partial TM: more associated with MS
• Cervical involvement: autonomic instability more prominent, risk of respiratory compromise
• Adams and Victor's Principles of Neurology, 12th Ed., p. 926
• Rosen's Emergency Medicine, p. 1508

Gold Standard - Diagnosis

Primary Gold Standard: MRI Spine with Gadolinium

• T2 hyperintensity in the spinal cord at the affected level (most sensitive finding)
• Cord swelling/enlargement in acute phase
• Gadolinium enhancement of the lesion (indicates active inflammation/breakdown of blood-spinal cord barrier)
• In LETM: lesion extending across 3 or more vertebral body lengths
• Absence of compressive lesion (important to rule out)
• Note: MRI findings may lag behind clinical presentation, especially early in the disease

Supporting Investigations

Diagnostic Criteria (Transverse Myelitis Consortium Working Group)

1. Bilateral sensorimotor/autonomic dysfunction attributable to the spinal cord
2. Defined sensory level
3. Inflammation confirmed by CSF pleocytosis/elevated IgG index, OR gadolinium enhancement on MRI
4. Progression to nadir within 4 hours to 21 days
5. No compressive etiology on MRI

• Bradley and Daroff's Neurology in Clinical Practice, p. 472 - "Transverse myelitis is a clinical diagnosis"
• Goldman-Cecil Medicine, p. 3995
• Rosen's Emergency Medicine, p. 1508

Differential Diagnosis

• Multiple sclerosis (partial TM, brain lesions present)
• Spinal epidural abscess (fever, localized spine tenderness)
• Spinal epidural hematoma
• Spinal cord infarction
• NMOSD
• Primary/metastatic spinal neoplasm
• Surfer's myelopathy
• Vitamin B12 deficiency (subacute combined degeneration)

Treatment

Prognosis

• Good recovery: ~30%
• Fair recovery: ~25%
• Poor outcome: ~30%
• Mortality: ~15%
• Recovery usually begins within 1-3 months; maximal improvement by 3-6 months
• Prognosis is worse than MS - significant recovery in fewer than 50%
• Patients with rapid onset to nadir (<4 hours) and spinal shock have poorer prognosis
• Goldman-Cecil Medicine, p. 3995
• Rosen's Emergency Medicine, p. 1509

• MRI spine with gadolinium = gold standard investigation
• TM is a clinical diagnosis - based on clinical syndrome + MRI confirmation of intramedullary lesion + exclusion of compression
• LETM (3+ vertebral segments) = think NMOSD until proven otherwise
• Always check AQP4-IgG and MOG-IgG as they guide long-term immunotherapy
• Thoracic cord is most commonly involved (60-70%)