Deep brain stimulation of the internal segment of the globus pallidus in delayed runaway dyskinesia

Background: Dyskinesias that occur during a period without medication after embryonic cell transplantation have been commonly reported in double-blind trials; however, to date, they have not been reported in the few patients who participated in open-label pilot studies. Design: Single case observation with preoperative and postoperative data, and intraoperative single-cell physiology. Patient: A patient who underwent embryonic cell transplantation in 1993 as part of the University of South Florida open-label study was referred for evaluation of intractable dyskinesia of the right arm. The dyskinesia was present during evaluation of the patient after a 12-hour period without medication and was clinically disabling. It was manifested as a severe groping movement of the hand. Intraoperative physiologic evaluation revealed decreased firing rates in the internal segment of the globus pallidus. Results: Deep brain stimulation of the internal segment of the globus pallidus resulted in resolution of the dyskinesia. Conclusion: This case highlights the delayed development of runaway dyskinesia after a period without medication as an important potential long-term adverse effect of embryonic cell transplantation in patients with Parkinson disease.