Spasms in clusters in epilepsies other than typical West syndrome

Although spasms in clusters are one of the major characteristics of West sy ndrome (WS), there are a significant number of patients who show spasms in clusters but do not fit the standard pattern of WS. It is possible to divid e these atypical cases into the following three groups. Group 1: refractory epilepsies beginning in early infancy, associated with atypical electroenc ephalographic (EEG) features Group 2: generalized epilepsies with spasms in clusters at ages of 2-3 years or above; and Group 3: localization-related epilepsies with spasms in clusters. Ictal clinical and EEG findings of spas ms in clusters in these atypical patients and also those in WS are similar. Patients in Group I often suffer from Aicardi syndrome, cortical malformat ions, early myoclonic encephalopathy and Ohtahara syndrome. Most patients i n Group 2 suffer from Lennox-Gastaut syndrome and other generalized epileps ies such as severe epilepsy with multiple independent spike foci. A signifi cant number of them had a history of WS. Small number of patients in Group 2 can be diagnosed as having late-onset WS or long-lasting WS. In Groups I and 3 patients, cortical mechanisms play a critical role in their pathophys iology. The presence of older patients with spasms in clusters might indica te not only developing process of the brain but also some selective dysfunc tion of the brain plays an important role in the occurrence of spasms in cl usters. Investigations on these atypical patients can help the understandin g of pathophysiological mechanisms of WS and its related epileptic syndrome s. (C) 2001 Elsevier Science B.V. All rights reserved.