Ictal signs in tuberous sclerosis complex: Clinical and video-EEG features in a large series of recorded seizures
Epilepsy is the most common neurological symptom in tuberous sclerosis complex (TSC), occurring in 72-85% of affected individuals. Despite the large number of patients reported, their electroclinical phenotype has been rarely described. We analyzed seizure semiology through ictal video-electroencephalography (V-EEG) recordings in a large series of patients. In this multicenter study, we reviewed V-EEGs of 51 patients: ictal recordings were analyzed in correlation with their clinical variables. The median age of epilepsy onset was six months (one day-16 years), with onset in the first year of life in 71% patients (36/51), in 10 of them during the neonatal period. Sixty-five percent of patients (33/51) experienced epileptic spasms in their life, with late-onset (>two years) in five; 42% of the epileptic spasms persisted after age two years, despite the onset in the first year of life. We identified four different electroclinical subsets: focal epilepsy (35%, 18/51), Lennox-Gastaut Syndrome evolution (27%, 14/51), focal seizures with persisting spasms (33%, 17/51), and spasms only (4%, 2/51). We reviewed 45 focal seizures, 13 clusters of epileptic spasms, and seven generalized seizures. In 12 patients, we recorded different seizure types. In 71% of the focal seizures (32/45), the ictal pattern was focal without diffusion. In 38% of the patients (5/13) epileptic spasms were related to typical diffuse slow wave pattern associated with superimposed fast activity, with focal predominance. Focal seizures and focal spasms resulted as the most frequent seizure types in TSC. Seizure onset was variable but showing a predominant involvement of the frontocentral regions (40%). Discrete clinical signs characterized the seizures, and behavioral arrest was the predominant first clinical objective sign. Epileptic spasms were a typical presentation at all ages, frequently asymmetrical and associated with lateralizing features, especially in older patients.