Adrenocorticotropic Hormone-Induced Dyskinesia and Probable Sudden Unexpected Death in an Infant with Early Infantile Developmental and Epileptic Encephalopathy—Infantile Epileptic Spasm Syndrome Overlap

A 2.5-month-old infant with global developmental delay, initially had generalized tonic spasms followed by appearance of infantile spasms from 4.5 months of age. Thus, he had evolution from early infantile developmental and epileptic encephalopathy (EIDEE) to infantile epileptic spasm syndrome (IESS). Neuroimaging and screening of inborn errors of metabolism were normal, but sleep electroencephalogram showed suppression-burst pattern. Treatment with intramuscular injections of adrenocorticotropic hormone (ACTH) was associated with significant control of infantile spasms, but was followed by development of right hemichoreiform movements 2 days later. Upon continuing ACTH treatment, the dyskinesia generalized, prompting us to stop it and shift to vigabatrin which resulted in partial control of his spasms. Whole-exome sequencing revealed an autosomal dominant heterozygous variation of uncertain significance in the NPRL3 gene. At 6 months of age, he suffered of a probable sudden unexpected death, without any notable illness. The case is unique because both the phenomena—ACTH-induced dyskinesia and probable sudden unexpected death in infancy—are rarely described in the EIDEE-IESS continuum.