Purpose: To describe the potentially serious adverse effects of antiepileptic drugs (AEDs) in individuals with severe motor and intellectual disabilities (SMID) and to improve the quality of drug treatment for these patients.

Methods: The data of 99 SMID patients with epilepsy staying at an institute for more than 1 year were retrospectively reviewed. Each patient was taking 3.4 ± 1.6 (range, 1-8) kinds of AEDs, and clinical seizures were still prevalent in 68 patients.

Results: Discontinuation or dose reduction of AEDs ameliorated agitation and/or sleep disturbance, somnolence, vomiting, appetite loss, and stridor in the corresponding patients, and additionally resolved serious gastrointestinal or cardiorespiratory problems in three patients whose clinical courses were detailed. Patient 1 manifested aerophagia-related chronic distension of the abdomen causing mechanical ileus, requiring repeated intestinal resection. The abdominal distension improved significantly after discontinuation of acetazolamide. Patient 2 experienced progressive motor deterioration during young adulthood, with simultaneous sudden elevation in blood phenytoin level. Although motor disability persisted, resolution of hypoventilation was noted after cessation of phenytoin. Patients 3 had long-term use of carbamazepine and exhibited episodic bradycardia (heart rate as low as 25 bpm) that resolved after drug discontinuation.

Conclusions: Patients with SMID sometimes fail to effectively verbalize subjective adverse effects of medications to healthcare providers. The chronic adverse effects of AEDs, including those described in this study, should be broadly evaluated for better patient management.