Infantile spasms in tuberous sclerosis complex

The high incidence of infantile spasms (IS) and hypsarrhythmia in tuberous sclerosis complex (TSC) has long been emphasized but it is now, clear that infants with TSC show clinical and EEG differences from those with classica l West syndrome. Seizures at onset are mainly characterized by partial moto r seizures and IS. Subtle partial seizures may be present in the early neon atal period and may precede the onset of IS. Visual recording techniques ha ve led to significant progress in the classification of seizures associated with TSC, demonstrating that they have a focal or multifocal origin in the vast majority of cases. In most cases, an awake interictal EEG shows focal or independent multifocal spike and slow-wave activity at onset and later a pseudo-hypsarrhythmic pattern. Ictal EEG starts with focal spikes origina ting from the posterotemporal, or occipital regions followed by a generaliz ed irregular slow transient and an abrupt diffuse flattening. Although the pathophysiological mechanisms responsible for the coexistence of partial se izures and IS are still unclear, IS associated with TSC may be the result o f a rapid secondary generalization. The presence of IS due to TSC is strong ly predicted by the cortical tuber count, while the age of onset of seizure s and the age of occurrence of EEG foci depend on the localization of corti cal tubers with an earlier expression of the parietooccipital than of the f rontal regions. Early recognition of these distinctive features appears wor thwhile for therapeutic and prognostic implications. Despite the efficacy o f vigabatrin the prognosis of IS is generally poor. Studies using combined topographic mapping of EEG, magnetic resonance imaging and positron emissio n tomography may provide new strategies for selecting candidates suitable f or surgery. (C) 2001 Published by Elsevier Science B.V.