Seizures and EEG pattern in the 22q13.3 deletion syndrome: clinical report of six Italian cases

Purpose The 22q13.3 deletion syndrome, also known as Phelan–McDermid syndrome, is a rare genetic disorder characterized by hypotonia, severely impaired development of speech and language, autistic-like behaviour, and minor dysmorphic features. Neurologic problems may include seizures of different types, such as febrile, generalized tonic–clonic, focal, and absence seizures. No peculiar EEG features have been associated with 22q13 deletion syndrome to date. In order to verify if a peculiar clinical and EEG pattern is present in 22q13.3 deletion syndrome, we studied six Italian patients with this chromosome abnormality. Method Array CGH analysis was carried out in the six subjects (1 male, 5 females, age range 11–30 years, median 19.5). They underwent a complete general and neurologic examinations. The EEG study consisted of at least one awake and one nap–sleep video-EEG recordings and evaluation of other EEGs performed elsewhere. Results Three subjects suffered from myoclonic or generalized tonic–clonic seizures with a rather benign course; all showed multifocal paroxysmal abnormalities on EEG recording, predominant over the frontal–temporal regions, activated during sleep. Conclusion 22q13.3 deletion syndrome seems to be associated, at least in a subgroup of patients, with a peculiar clinical and EEG pattern, characterized by a childhood epilepsy with a rather benign evolution and with multifocal paroxysmal EEG abnormalities activated by sleep.