A rare neuroinflammatory disease characterized by the onset of ataxia, dysarthria and cerebral white matter changes that are triggered by viral infection. Episodic progressive neurodegeneration (manifesting with loss of motor and verbal skills, muscle weakness, further cerebral white matter degeneration and eventually, death) is observed in the absence of hematopathology, cytokine overproduction, fever, hypertriglyceridemia, hypofibrinogenemia and hyperferritinemia. [from SNOMEDCT_US]