Late-onset epileptic spasms in children with Pallister-Killian syndrome: a report of two new cases and review of the electroclinical aspects.

Pallister-Killian syndrome is a rare syndrome of multiple congenital anomalies attributable to the presence of a mosaic supernumerary isochromosome (12p). Although the clinical manifestations of Pallister-Killian syndrome are variable, the most common anomalies include craniofacial dysmorphisms, limb deformities, progressive psychomotor development delay, severe hypotonia, and epilepsy. Standard karyotype is nearly always normal, but the isochromosome (12p) is present in a high percentage of skin fibroblasts. In this article, we report the case of 2 boys with Pallister-Killian syndrome having late-onset, drug-resistant epileptic spasms. Seizures have been reported in 40% of patients with Pallister-Killian syndrome but are poorly described. Epileptic spasms are not unusual in patients with brain malformations, chromosomal aberrations, and genetic syndromes, but epileptic spasms could be easily mistaken for behavioral manifestations. A better electroclinical characterization of epileptic seizures in Pallister-Killian syndrome using appropriate polygraphic tests (video-electroencephalography, electromyography) may lead to an early diagnosis and specific treatment for this form of epileptic spasms caused by this rare syndrome.