A very rare multisystem neurodegenerative disorder characterized by the presence of eosinophilic intranuclear inclusions in neuronal and glial cells, and neuronal loss. Infantile, juvenile, and adult-onset cases have been described. As any part of the nervous system can be affected (central, peripheral, and autonomic nervous systems), the clinical manifestations depend on the sites involved, and widely vary. The most common neurological signs include ataxia, extra-pyramidal signs (tremor and oculogyral crises), lower motor neuron findings (absent deep tendon reflexes, weakness, muscle wasting, foot deformities), and less apparent behavioral or cognitive difficulties. Most cases are sporadic.