Transverse Myelitis MRI

TRANSVERSE MYELITIS

Syn: Idiopathic acute transverse myelitis (IATM)

Inflammatory disorder, demylination involving both halves of spinal cord resulting in bilateral motor, sensory, and autonomic dysfunction.

Best diagnostic clue is a long segment contiguous intra medullary T2 hyper intensity with mild cord swelling.

Thoracic region is more common. Cervical region cord involvement in 10%.
Characteristically involve central cord on axial imaging, more than two-thirds of cross-sectional area of cord.
Variable post-gadolinium enhancement, no to subtle diffuse, patchy or peripheral enhancement and is more frequent in subacute than in acute or chronic stage.

DDs:

Multiple sclerosis
• Eccentric or Peripheral location of lesion.
• Small or short segment lesions, less than two vertebral segments in length.
• Less than half cross-sectional area of cord.
• 90% with associated intracranial lesions.
• Relapsing and remitting clinical course.

Acute Disseminated Encephalomyelitis
• Associated Brain lesions.

Always include brain MRI FSE T2 axial and sagittal images through corpus callosum to exclude associated intracranial lesions of multiple sclerosis or acute disseminated encephalomyelitis.


General Features
• Genetics: No familial predisposition
• Etiology
o Possible association with previous viral infection or vaccination in some cases.
o Autoimmune phenomenon with formation of antigen-antibody complexes
o Small vessel vasculopathy resulting in cord ischemia
o Associated demyelinating process

Epidemiology
o 4.6 new cases of transverse myelitis per million people per year in US
• 1,400 new cases per year
o Majority of cases occurred in late winter through spring in one series
• Life time risk> 50%

Microscopic Features
• Necrosis of gray and white matter
• Destruction of neurons, axons, and myelin
• Astrocytic gliosis
• Perivascular lymphocytic infiltrate

Presentation
• Most common signs/symptom is sensory deficit_ Loss of pain and temperature sensation.
Clearly defined upper level
Ascending paresthesia in bilateral lower extremities
Band-like dysesthesia
Other signs/symptoms are Paraplegia or quadriplegia, back ± radicular pain, bladder and bowl dysfunction, urgency, incontinence, retention; hypotonia and hyporeflexia initially, spasticity and hyperreflexia over time

An associated preceding viral-like illness.
Rapid progression to maximal neurologic deficits within days.

All ages can be affected with two peaks, 10-19 and 30-39 years old.
No gender predilection
No racial predilection

Prognosis
One third of patients experience good to complete recovery. Symptomatic improvement starting 2-12 weeks after onset. Children with slightly better prognosis than adults.
One third fair recovery, residual spasticity and urinary dysfunction.
One third poor recovery, persistent complete deficits requiring assistance in activities of daily living.

Factors portending poor prognosis: 
o Rapid clinical deterioration
o Back pain
o Spinal shock: Loss of motor, sensation, sphincter
control, and areflexia
o MRI signal alteration> 10 spinal segments
o Significant denervation on electromyogram
o Abnormal somatosensory evoked potential

• Typically monophasic. 
If recurrent, must consider Multiple sclerosis (progression to multiple sclerosis in 2-8% of cases of transverse myelitis), SLE, Antiphospholipid syndrome, Vascular malformation.

Treatment
• High dose intravenous steroid pulse therapy
• Physio therapy.