Clinical imitators of infantile spasms.

We report 53 infants who by clinical history were thought to have infantile spasms but who video-electroencephalograms showed were having other episodes that closely mimicked infantile spasms. Nine patients had other types of seizures. Forty-five patients had episodic symptoms that were not seizures: 11 patients had spasticity, four had gastroesophageal reflux, and the other patients had nonepileptic myoclonus, including 19 patients with benign neonatal sleep myoclonus. Three patients had more than one type of symptom. Infantile spasms imitators occurred in neurologically normal or abnormal infants, in patients with normal or abnormal interictal electroencephalograms, and in patients who also had previous or current infantile spasms. Differentiation of these episodes from infantile spasms prevented the initiation or continuation of anticonvulsant treatment appropriate for infantile spasms but inappropriate for these other behaviors.