This document provides an overview of common spinal cord diseases characterized by high signal within the cord on T2-weighted MRI. It discusses the differential diagnosis and key features of demyelinating diseases like multiple sclerosis and neuromyelitis optica, acute disseminated encephalomyelitis, transverse myelitis, spinal cord tumors, vascular conditions like infarction and vasculitis. Multiple sclerosis is the most common demyelinating disease and can present with short segment focal lesions in the posterior spinal cord with associated periventricular brain lesions. Neuromyelitis optica preferentially involves the optic nerve and spinal cord.