Demyelination in a transverse region of the spinal cord due to an inflammatory process that leads to sensory and motor changes below the lesion and autonomic dysfunction. The term “transverse myelitis” (TM) of late refers to any cause of inflammatory myelopathy, irrespective of severity or degree of structural or functional interruption of pathways through a transverse spinal cord section. TM that extends across three or more segments of the cord is referred to as longitudinally extensive TM. The pathologic hallmark of TM is the presence of focal collections of lymphocytes and monocytes with varying degrees of demyelination, axonal injury, and astroglial and microglial activation within the spinal cord.

TM

Idiopathic transverse myelitis (ITM)

• Rapid onset of symmetric or asymmetric paraparesis or paraplegia of the lower extremities over a few days, ascending paresthesia, sensory level at the trunk, back pain, sphincter dysfunction, and positive Babinski, which can be bilateral. The arms may also be involved if the cervical cord is involved, but cervical involvement is less common than thoracic involvement. In the acute phase the weakness is flaccid, with diminished deep tendon reflexes mimicking a peripheral neuropathy such as Guillain-Barré syndrome.
• One third to half of patients present with localizing back pain or a bandlike area of altered sensation, usually at the dermatomal level corresponding to the lesion within the cord.
• There is progression to nadir of clinical deficits between 4 h and 21 days after symptom onset.
• Urinary incontinence or retention, GI disturbances (incontinence or constipation), and sexual dysfunction are common.
• Acute flaccid myelitis is a subtype of myelitis in which patients present with acute limb weakness and have primarily involvement of gray matter on spinal cord imaging.

• The clinical signs are caused by an interruption in ascending and descending sensory, motor, and autonomic pathways in the transverse plane of the spinal cord, resulting in sensory-level weakness and autonomic dysfunction at and below the level of the lesion due to demyelination or inflammation of the spinal cord.
• Can be idiopathic demyelination (15% to 30%) that is a monophasic one-time event or demyelination secondary to neurologic or systemic conditions (Box 1).
• Secondary causes include postinfection, postvaccination, acute demyelinating encephalomyelitis (where TM tends to be monophasic), and others such as MS, NMOSD, connective tissue disorders such as systemic lupus, Sjögren syndrome, antiphospholipid antibody syndrome, sarcoidosis, and paraneoplastic conditions, which can be progressive or relapsing.^1-4
• Infectious causes of myelitis include HIV, syphilis, varicella zoster (associated with shingles), human T-cell leukemia virus type 1, Lyme disease, COVID-19, arboviruses such as West Nile virus (typically causing a poliomyelitis-type acute flaccid paralysis), or enteroviruses (typically causing acute flaccid paralysis mainly in children).⁴
• About 50% of patients have had a recent upper respiratory infection.

• MS (Table 1)
• Neuromyelitis optica spectrum disorder (NMOSD)^4,5
• Metastatic disease
• Spinal cord tumors
• Herniated or slipped disks
• Spinal stenosis
• Spinal epidural abscess
• Vascular malformation
  1. Spinal dural arteriovenous fistula (most common)⁶
  2. Arteriovenous malformation of the spinal cord
• Spinal cord infarction due to either anterior spinal artery or posterior spinal artery occlusion

TM should be suspected in patients with a history of rapid (hours to days) onset of motor weakness and sensory abnormalities with bladder or bowel dysfunction that is referable to the spinal cord. The dysfunction is bilateral (not necessarily symmetric), and there is often a clearly defined sensory (dermatomal) level. It is important to distinguish idiopathic TM from TM due to MS or NMOSD because idiopathic TM does not relapse and does not require long-term immunomodulatory therapy.^1-3 A suggested diagnostic workup for recurrent CNS demyelinating disorders and systemic autoimmune disorders associated with acute TM is summarized in Table 2.

• Lumbar puncture looking for cerebrospinal fluid pleocytosis, oligoclonal bands for MS, or serology and polymerase chain reaction (PCR) looking for infection (Table 3) such as varicella zoster virus and enterovirus PCR.
• Antinuclear antibody, hepatitis B serology, Lyme disease serology, VDRL, SSA, SSB, anticardiolipin antibody, lupus anticoagulant, copper, ceruloplasmin, vitamin B₁₂, RPR.
• Serum NMO-IgG and myelin oligodendrocyte glycoprotein (MOG) antibodies to evaluate for NMOSD.
• If a paraneoplastic etiology is suspected, then appropriate antibodies should be ordered and appropriate cancer screening undertaken.

• Gadolinium-enhanced MRI of brain and MRI of the entire spine (Fig. E1, Fig. E2). This will show demyelinating lesion on T₂ with contrast enhancement. In MS there is usually a short segment lesion (less than three vertebral segments) that is dorsally located. Longitudinally extensive TM that spans more than three or more segments of the cord is more typical of NMOSD, postinfectious, vascular, or other inflammatory causes.^4,5
• Spinal dural arteriovenous (AV) fistulas are often missed initially on MRI and will worsen with steroid treatment. If suspected, may need a computed tomography (CT) spinal angiogram.⁶
• CT of the spine with and without contrast should be obtained if MRI is unavailable, but CT does not allow for visualization of the spinal cord itself.
• CT myelogram may also be obtained if MRI is unavailable to evaluate for compression; however, this does not image the parenchyma of the cord directly.
• Chest CT with and without contrast if sarcoidosis is suspected.

• Physical therapy
• Respiratory and oropharyngeal support

• High-dose IV corticosteroid (e.g., methylprednisolone 1000 mg/day for 3 to 7 days).
• Rescue therapy with plasma exchange may be helpful in patients who do not respond to corticosteroids.
• Combination therapy with plasmapheresis and corticosteroids or other immunosuppressive agents (e.g., rituximab or cyclophosphamide) may also be effective.
• Analgesia for pain.

• Baclofen or tizanidine for muscle spasms and spasticity
• Gabapentin or pregabalin for neuropathic pain
• Low-molecular-weight heparin for deep vein thrombosis prophylaxis in patients with immobility
• Need for chronic immunosuppression will depend on underlying etiology

• One third of patients with TM will have complete recovery, one third will have fair recovery, and one third have permanent disability and do not recover. Recurrence or relapse is possible, especially if the patient has MS, NMOSD, or sarcoidosis.^4,5
• If a patient worsens with steroid treatment, strongly consider spinal dural AV fistula.⁶
• Patients who need further care, including those with urinary retention, may need home nursing assistance. Some patients may benefit from rehabilitation, either inpatient or outpatient.

• Referral to a neurologist to evaluate need for long-term therapy
• Referral for physical and occupational therapy
• Consider psychiatric consultation (high incidence of long-term mood and anxiety disorders)

Multiple Sclerosis (Related Key Topic)

Neuromyelitis Optica Spectrum Disorder (Related Key Topic)