Diagnosis and differential diagnosis of acute transverse myelopathy. The role of neuroradiological investigations and review of the literature.

Acute transverse myelopathy (ATM) is a clinical definition of an acute neurologic condition that reflects impairment of spinal cord function. The term "myelopathy" has a different meaning from "myelitis", even if the words are often confused. Both terms indicate spinal cord involvement by some pathological event; but while myelopathy does not imply any etiological factor, myelitis refers to inflammatory diseases of the spinal cord. Acute spinal pathology can be associated with intra-axial or extra-axial lesions; extra-axial spinal pathology, however, has more often a chronic and progressive presentation. In this paper, we discuss primarily intra-axial lesions with attention on the role of neuroradiological investigations in diagnosis and differential diagnosis. Magnetic resonance imaging is the modality of choice for diagnosis; it shows signal abnormalities, usually T2 hyperintensity, focal or extensive, gadolinium enhancement and sometimes cord swelling. Despite its high sensitivity, about 40% of acute transverse myelopathies remain undemonstrated. Concerning etiology (multiple sclerosis (MS), vasculitis, infection, autoimmune disorders) no clearly different and specific patterns have been found; however small multiple enhancing lesions are more suggestive of MS (or lupus) while extensive, multilevel abnormalities reflect vasculitis as in antiphospholipid antibody syndrome.