WHEN CHILDREN WITH EPILEPSY AND MENTAL RETARDATION BECOME SEIZURE-FREE, DISCONTINUATION OF AEDS IS OFTEN SUCCESSFUL: A POPULATION-BASED STUDY

Objectives: Children with epilepsy and mental retardation have a poor prognosis for seizure control. This study addresses the success rate of discontinuing AED treatment when children with mental retardation become seizure-free.

Methods: The Nova Scotia population-based epilepsy cohort has followed 693 children with all types of epilepsy beginning 1977–85. We focused on those with documented mental retardation. Results: Of 693 total epilepsy patients, 131(19%) had mental retardation. 24 died, 1 was untreated, leaving 106 for study with average follow-up 20.6±5.3 years (range 1.5–28). 61/106 (58%) became seizure-free and attempted to discontinue AEDs with the degree of mental retardation related to the chance of attempting to discontinue AEDs: 23/31(74%) with mild retardation, 18/29 (62%) with moderate, 20/46 (43%) with severe/profound. Overall 27/61 (44%) stopped AEDs for a first time successfully and remained seizure-free for 13.2±7 years of further follow-up. For those who failed the first try at stopping AEDs, 11 tried again, 6 successfully. Therefore, a total of 33/61 (54%) discontinuing AEDs at least once were eventually successful. 54 (51%) had symptomatic partial epilepsies (SPE) and 52 (49%) had secondary generalized epilepsies (SGE). Those with SPE were more likely to attempt discontinuation of AEDs (38/54 SPE versus 23/52 SGE p=0.006) but the rate of success with the first AED discontinuation was the same (17/38 SPE versus 11/23 SGE p=0.8). Of the 395 children with normal intelligence and epilepsies characterized by convulsive and partial seizures, 294 (74%) discontinued medication at least once and on the first discontinuation 73% were successful – a higher rate that for those with mental retardation (p<0.0001).

Conclusion: The challenge for children with epilepsy and mental retardation is to become seizure-free. Once they do so, their rate of successfully stopping AED treatment was 44–54%, less than those with normal intelligence but still worth the attempt.