Objective: To assess intellectual outcomes in a clinic-based population of patients with tuberous sclerosis complex (TSC) who also have a history of infantile spasms (IS) and to identify clinical risk factors for mental retardation in these patients.
Methods: This is a retrospective study of 50 patients with TSC and IS seen consecutively at the Massachusetts General Hospital Tuberous Sclerosis Comprehensive Clinic from December 2001 to October 2003. Data were obtained by chart review and by interview with patients' parents.
Results: Thirty-two (64%) of 50 patients with TSC with IS were found to have mental retardation (IQ or developmental quotient < 70). Three clinical variables showed an association with mental retardation: increased duration of IS from clinical onset to cessation (odds ratio [OR] per 1-month interval 1.09, 95% CI: 1.03 to 1.15, p = 0.004), increased time from treatment initiation until IS cessation (OR 1.07, 95% CI: 1.01 to 1.14, p = 0.020), and poor control of other seizures after IS (OR 17.76, 95% CI: 3.47 to 129.1, p = 0.00004). The following variables did not show an association with intellectual outcome: gender, initial seizure type, age at IS onset, or time from IS onset to treatment initiation.
Conclusions: In patients with tuberous sclerosis complex who also have a history of infantile spasms (IS), the rate of mental retardation may be lower than previously reported. The risk of mental retardation increases significantly with prolonged duration of IS, prolonged time from treatment initiation until the cessation of IS, and poor control of subsequent seizures after IS.