[Demyelinating disorders]

Demyelinating diseases are a group of conditions of autoimmune etiology directed against the myelin of the central nervous system. In many cases, the onset of the illness is preceded by a nonspecific viral infection. Multiple sclerosis is a disease that evolves with relapses and remissions with polyfocal neurological deficits, being the most frequent optic neuritis, transverse myelitis and encephalic trunk involvement. Typically, magnetic resonance image (MRI) shows peri-ventricular, peri-callosal, cerebellum, brain stem and spinal cord hyperintensive lesions in T2 and FLAIR weighted images. Optic neuromyelitis is characterized by the presence of optic neuritis and transverse myelitis associated with the postrema and diencephalic area syndrome. MRI lesions are distributed in sectors rich with aquaporine-4 channels (AQP-4): hypothalamus, third and fourth ventricle, optic nerves and spinal cord. Finding anti AQP4 antibodies is useful for the diagnosis although they are not essential for it. Acute disseminated encephalomyelitis is typically a monophasic condition characterized by acute encephalopathy associated with hyperintense MRI large, bilateral and irregular asymmetric lesion in T2 and FLAIR weighted images. In all three cases, cerebral spine fluid (CSF) can show pleocytosis and hyperproteinorrachia. The presence of oligoclonal bands in CSF is characteristic of multiple sclerosis. In all cases, acute treatment includes high dose intravenous corticosteroids and plasmapheresis in non-responsive cases. Both multiple sclerosis and optic neuromyelitis require long-term treatment to prevent relapse and recurrent diseases.