A healthy 4-month-old girl presented to the emergency department with symptoms of vomiting and diarrhea. During physical evaluation, patient’s mother shared that she recently started having chaotic eye movements. She also had been having jerking movements of her arms and legs periodically. A video was uploaded and reviewed by the neurology team, who was concerned that the movements appeared to be consistent with opsoclonus. She was admitted for further evaluation. 

Upon evaluation by both neurology and ophthalmology, there was agreement that movements were consistent with opsoclonus and myoclonus. Patient also was thought to have a distended abdomen. An ultrasound of the abdomen found no abdominal mass. MRI of brain, spine, chest and abdomen were also unrevealing.  

Meanwhile, the initial urine drug screen was positive for phencyclidine (PCP). Toxicology was consulted and initially suggested that this could be a false positive result. Ultimately, the comprehensive urine drug profile confirmed PCP in two separate samples of urine. As these results returned, patient’s opsoclonus and myoclonus gradually improved until they resolved by day 4 of hospitalization. Family later admitted to presence of PCP in the home. 

Our patient followed up with neurology six months after discharge, with normal development and no noticeable sequelae.