The main neuroimmune diseases in childhood: Multiple sclerosis and acute disseminated encephalomyelitis - Neuroradiological features

Demyelination is the hallmark of neuroimmune disease. It is caused by a breakdown of myelin already formed, relative sparing of myelin producing oligodendrocytes, neurons and astrocytes, and venous inflammation with perivenous infiltration. The neuroradiological investigation of choice in this setting is magnetic resonance (MR) due to its ability to monitor the neuropathological process. Acute disseminated encephalomyelitis (ADEM), also known as postinfectious or hyperergic encephalomyelitis, disseminated vasculoencephalomyelitis and perivenous encephalitis, is the commonest neuroimmune disorder of childhood. Neuroradiological investigation is highly sensitive for a diagnosis of demyelinating disease. MR is highly sensitive but not specific. Spectroscopy is useful for diagnosis: the reduction in axonal density leads to a decrease in N-acetylaspartate with a concomitant increase in choline and myoinositol due to glial proliferation. Spectroscopic findings positive for a decrease of NAA and an increase in choline during the first episode of demyelinating disease in adolescence are suggestive of an evolution to MS.