Poor mental development in patients with tuberous sclerosis complex: clinical risk factors.

OBJECTIVE: To identify clinical risk factors for poor mental development among patients with tuberous sclerosis complex (TSC).
DESIGN: Case-control analysis of a clinic population.
SETTING: Specialty clinic in a hospital. PATIENTS: One hundred six patients with TSC consecutively seen between January 1984 and December 1995 at the Child Neurology Clinic of the Children's Memorial Health Institute in Warsaw, Poland. STUDY VARIABLES: Seizure type, age at seizure onset, sex, and history of diphtheria, tetanus, and pertussis immunization. MAIN OUTCOME MEASURE: Moderate to profound developmental delays.
RESULTS: Seizure type (ie, infantile spasms) was the only analyzed risk factor that showed a consistent and independent association with poor mental development (adjusted odds ratio, 3.0; 95% confidence interval, 1.1-8.4; P =.03). Age at seizure onset, which initially showed a significant association with poor mental development, was no longer significantly associated after adjustment for seizure type (adjusted odds ratio, 1.6; P = .43). Neither sex (odds ratio, 1.1; P = .96) nor history of diphtheria, tetanus, and pertussis immunization (odds ratio, 1.0; P = .80) showed evidence of being a risk factor for poor mental development among patients with TSC.
CONCLUSIONS: Infantile spasms, as the type of seizure on initial examination, is a significant risk factor for poor mental development in patients with TSC. Age at time of first seizure is not an independent risk factor but reflects the early ages at which these patients are seen with infantile spasms. Neither sex nor history of diphtheria, tetanus, and pertussis immunization is a risk factor for the subsequent development of poor mental development among patients with TSC.