Encephalitis Lethargica With Isolated Substantia Nigra Lesions Followed by a Second Encephalitis in a Child With Humoral Immunodeficiency

BackgroundEncephalitis lethargica is an encephalitic illness with multiple nervous system symptoms. Lesions only involving substantia nigra on magnetic resonance imaging are uncommon, especially in children. A second encephalitis illness after encephalitis lethargica has never been reported before.Patient DescriptionWe describe a 7-year-old boy with humoral immunity deficiency who developed encephalitis lethargica associated with bilateral substantia nigra lesions on magnetic resonance imaging. After a nearly complete recovery, he developed encephalitis once again. He was diagnosed with encephalitis lethargica with somnolence, akinetic mutism, and ophthalmoplegia after intermittent fever. Cerebrospinal fluid pleocytosis and positive oligoclonal bands were documented. Symmetrical substantia nigra lesions on high-intensity magnetic resonance imaging gradually evolved into a liquid signal. He had almost recovered when he developed fatigue and hypersomnia and was diagnosed with encephalitis again, supported by mild pleocytosis in cerebrospinal fluid and subcortical white matter lesions in the frontal lobes. His symptoms resolved following administration of corticosteroids and immunoglobulins.ConclusionThis is the first report of an immune-deficient child to develop encephalitis lethargica with isolated substantia nigra lesions on magnetic resonance imaging and a second encephalitis illness after recovery from encephalitis lethargica.