Transverse Myelitis

Transverse myelitis is an acute or subacute inflammatory disorder of the spinal cord that causes motor, sensory and autonomic dysfunction caudal to a defined level, with a nadir between 4 hours and 21 days. It may be idiopathic or associated with multiple sclerosis, neuromyelitis optica spectrum disorder, MOG antibody disease, infection or systemic autoimmune disease.

The incidence is about 1 to 8 in every million people each year. It affects all ages with peaks at 10 to 19 and 30 to 39 years, and both sexes.

Causes. Idiopathic, multiple sclerosis, aquaporin-4 and MOG antibody diseases, systemic lupus erythematosus, Sjögren syndrome, sarcoidosis, post-infectious and post-vaccine illness, and infections (herpesviruses, HIV, syphilis, Lyme disease, tuberculosis).

Course. Recovery begins in 1 to 3 months. About one third recover well, one third have moderate disability and one third are left severely disabled; longitudinally extensive lesions and spinal shock predict a worse outcome.

Pathophysiology.

Immune mediated or infectious inflammation causes demyelination, axonal injury and, in severe cases, necrosis of the spinal cord.

Antibody mediated disease targets astrocytes (aquaporin-4) or myelin (MOG).

• Back or radicular pain, followed by weakness (paraparesis or quadriparesis), sensory loss with a sensory level, and sphincter dysfunction.
• Early spinal shock with flaccid weakness and areflexia, followed by spasticity and hyperreflexia.
• Autonomic features: urinary retention, constipation, sexual dysfunction and blood pressure instability in cervical or high thoracic lesions.
• Lhermitte sign, band like sensation and tonic spasms.

Red flags.

• Rapid ascent, respiratory involvement or cervical lesion.
• Signs of cord compression: abrupt weakness, local spinal pain or trauma (surgical emergency).
• Fever, immunosuppression or rash (infection).
• Optic neuritis, area postrema syndrome (aquaporin-4 disease).

• Urgent MRI of the whole spine with contrast and of the brain; exclude compression, then look for T2 hyperintensity and enhancement; a lesion over 3 vertebral segments suggests neuromyelitis optica spectrum disorder or MOG antibody disease.
• Lumbar puncture: cells, protein, oligoclonal bands, infection studies and cytology.
• Serum aquaporin-4 and MOG antibodies (cell based assay); antinuclear antibodies, extractable nuclear antigens, ESR, B12, copper, HIV, syphilis serology, Lyme serology and chest imaging.
• Visual evoked potentials or optical coherence tomography when optic involvement is possible.

Differential diagnosis. Compressive myelopathy, spinal cord infarction, Guillain-Barré syndrome, acute flaccid myelitis, subacute combined degeneration, vascular malformation, tumour, multiple sclerosis and neuromyelitis optica spectrum disorder.

• Methylprednisolone 1000 mg intravenously once daily for 3 to 5 days, started as soon as compression and infection are excluded. Maximum 5 g in a course. Monitor blood pressure, glucose, mood, infection and gastric protection. Avoid with active untreated infection; use caution in diabetes, peptic ulcer and psychosis.
• Plasma exchange for severe or non-responding disease: 5 to 7 exchanges of 1 to 1.5 plasma volumes on alternate days, started within 2 weeks. Monitor calcium, blood pressure, coagulation and line infection. Avoid in unstable cardiovascular disease and sepsis.
• Intravenous immunoglobulin 2 g/kg in total over 2 to 5 days as an alternative where exchange is unavailable.
• Specific treatment of cause: antimicrobials for infection (for example aciclovir 10 mg/kg intravenously every 8 hours for 14 to 21 days for herpes viruses, with renal dose adjustment), and long term immunosuppression for aquaporin-4 and MOG antibody disease through a specialist.
• Baclofen for spasticity: 5 mg orally three times daily, increased by 5 mg every 3 days to a usual 30 to 75 mg daily in 3 to 4 divided doses. Maximum 100 mg daily. Monitor sedation, weakness and seizures; withdraw slowly. Reduce dose in renal impairment (creatinine clearance under 50 mL/min); avoid in peptic ulcer and use caution in epilepsy.
• Thromboprophylaxis while immobile: enoxaparin 40 mg subcutaneously once daily. Maximum 40 mg daily (20 mg daily when creatinine clearance is under 30 mL/min). Monitor platelets, renal function and bleeding. Avoid in active bleeding.
• Bladder care: intermittent catheterisation; bowel programme; pressure area care; neuropathic pain treatment.
• Early multidisciplinary rehabilitation, and psychological support.

Monitoring. Neurological examination and bladder scans daily during the acute phase; review at 4 to 6 weeks, 3 months and 6 months; repeat MRI as needed.

Referral and escalation. Neurology urgently, neurosurgery for compression, intensive care for respiratory involvement, rehabilitation and urology.

Special groups. Children: weight based dosing and paediatric neurology. Pregnancy: plasma exchange and immunoglobulin are preferred to long term immunosuppressants that harm the foetus.