Transverse myelitis is a rare neurological condition characterized by inflammation of the spinal cord. This inflammation can disrupt the normal flow of nerve signals throughout the body. Magnetic Resonance Imaging (MRI) plays a significant role in diagnosing this condition by providing detailed images of the spinal cord, allowing medical professionals to assess for signs of inflammation and rule out other potential causes of symptoms.
What is Transverse Myelitis?
Transverse myelitis involves inflammation affecting both sides of a section of the spinal cord, a cylindrical structure extending from the brainstem down the back. The spinal cord’s primary function is to relay messages between the brain and the rest of the body, controlling movement, sensation, and autonomic functions. When inflammation occurs, it can damage the myelin sheath, the protective covering around nerve fibers, interrupting these signals.
Symptoms of transverse myelitis develop acutely or subacutely, often over hours to days, or sometimes weeks. Common manifestations include muscle weakness, which may progress to partial or total paralysis, and sensory changes such as numbness, tingling, or pain. Bladder and bowel dysfunction may also occur.
Importance of MRI in Diagnosis
Magnetic Resonance Imaging (MRI) is considered the preferred imaging method for diagnosing transverse myelitis due to its ability to visualize soft tissues, including the spinal cord, in high detail. MRI uses a strong magnetic field and radio waves to generate detailed cross-sectional images, allowing physicians to detect subtle changes within the spinal cord.
MRI images enable the identification of inflammation and swelling within the spinal cord, which are hallmarks of transverse myelitis. MRI also helps rule out other conditions that can mimic transverse myelitis, such as spinal cord compression caused by tumors, herniated discs, or vascular abnormalities.
Recognizing Transverse Myelitis on MRI
MRI findings indicative of transverse myelitis include bright signals on T2-weighted sequences, known as T2-hyperintense lesions. These lesions represent inflammation and edema within the spinal cord. They are commonly found centrally and can extend longitudinally over multiple vertebral segments, often three or more, a characteristic sometimes termed longitudinally extensive transverse myelitis.
In the acute phase, spinal cord swelling may be visible on MRI. Gadolinium contrast can further reveal active inflammation, as areas of inflammation may show enhancement after injection.
Causes and Associated Conditions
Transverse myelitis can arise from various underlying factors, broadly categorized into post-infectious and autoimmune conditions. In many cases, the exact cause remains unknown, leading to a classification of idiopathic transverse myelitis.
Post-infectious transverse myelitis can occur following viral or bacterial infections, such as influenza, chickenpox, measles, Mycoplasma pneumonia, herpes viruses, or Lyme disease. The body’s immune response to these infections may mistakenly target the spinal cord. Transverse myelitis can also be associated with systemic autoimmune diseases like multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), lupus, and Sjögren’s syndrome, where the immune system attacks its own tissues.