Reduction in reported nightmares during adjunctive trihexyphenidyl treatment in an adolescent: A case report

Nightmares are a frequent and disabling symptom of posttraumatic stress disorder (PTSD) and may perpetuate fear of sleep, insomnia, and psychiatric deterioration. Evidence for pharmacologic treatment in children and adolescents remains limited. We report a 13-year-old boy with PTSD who reported cessation of persistent nightmares during adjunctive trihexyphenidyl (THP) treatment. Polysomnography showed an apnea-hypopnea index of 9.4/h, with 24.5/h during rapid eye movement (REM) sleep. The patient and his family preferred to prioritize nightmare management and psychiatric care over treatment of obstructive sleep apnea (OSA). THP was started at 1 mg nightly and increased to 2 mg after one week. At one-month follow-up, he reported no nightmares from the first treatment night, and sleep avoidance had resolved despite receiving no OSA treatment. Nightmares recurred within days of abrupt THP discontinuation. Although this course suggests a contribution of THP, we cannot determine whether nightmares ceased or continued without being recalled after awakening. Further studies are needed to clarify its efficacy, safety, dosing, and patient selection.