JOURNAL OF CHILD AND ADOLESCENT PSYCHOPHARMACOLOGY Volume 6, Number 4, 1996 Mary Ann Liebert, Inc. Pp. 273-279 Open Trial of Lamotrigine in the Treatment of Self-Injurious Behavior in an Adolescent with Profound Mental Retardation PABLO A. DAVANZO, M.D. and BRYAN H. KING, M.D. ABSTRACT This single case reports an open trial of lamotrigine in the treatment of self-injurious behavior (SIB) and epilepsy in an 18-year-old female diagnosed with generalized seizure dis- order, Stereotypie movement disorder, and compulsive SIB in the context of profound men- tal retardation. Animal models of SIB suggest that the glutamate neurotransmitter systems, involved in the generation of epileptic seizures, may also have a role in the pathophysiology of SIB. Data suggesting that lamotrigine may decrease glutamate release encouraged an empirical trial of lamotrigine for treatment of SIB. After 4 weeks of treatment of lamotrig- ine 200 mg daily, decreases in agitation and fearfulness were clinically observed, along with a 50% reduction in the frequency of SIB as measured by standardized scales. Good seizure control was maintained throughout the trial. No significant adverse effects were observed. Positive effects persisted at 1-year follow-up. Symptoms of Stereotypie movement disorder appeared unchanged. Because these findings are preliminary, no clinical recommendations for the treatment of SIB with lamotrigine can be made until controlled studies have been completed. Compulsive self-injurious behavior (SIB) involving chronic repetitious actions resulting in physical harm (e.g., head banging, biting, head hitting) constitutes a significant problem among people with mental retardation (Hyman et al. 1990). Prevalence studies of SIB suggest a rate of 8%-30% among insti- tutionalized populations in the United States (Griffin et al. 1984) and 7%-22% elsewhere (Singh 1977). Cost estimates for the care of a person with SIB approach $100,000 annually (Rojahn 1984). SIB is not pathognomonic for a particular disease but occurs in a heterogeneous group of patients and disorders (Cataldo et al. 1982, King et al. 1994). Lesch-Nyhan, Cornelia de Lange, and Rett syndrome are among conditions frequently associated with SIB (Hyman et al. 1990). Extensive research (Bréese et al. 1990a, Wong et al. 1996, Criswell et al. 1993) has not resulted in the identification of pathophysiologic mechanisms responsible for SIB. Dopaminergic (Bréese et al. 1990b, Wong et al. 1992, Criswell et al. 1993), opioidergic (Sandman 1991), and serotonergic (Nyhan et al. 1980, King 1993, Pies 1995) mecha- nisms have been postulated as contributors to this phenomenon. Studies evaluating susceptibility for SIB in 6-hydroxydopamine (6-OHDA) lesioned rats after microinjection with muscimol (a GABA agonist) into Division of Child and Adolescent Psychiatry, UCLA School of Medicine. 273