Fear and Depression as Side Effect of Deep Brain Stimulation of the Subthalmic Nucleus in Parkinson's Disease

For the treatment of advanced Parkinson's disease deep brain stimulation in the Nc. subthalamicus has gained more and more importance in recent years. Usually this technique is considered as safe and short of psychiatric side effects, except for sometimes seen changes in frontal executive functions and transient postoperative depression. We report a 58-year-old patient with a 14 year history of Idiopathic Parkinson's disease. Due to severe L-Dopa-Induced dyskinesias and motor fluctuations the patient was deep brain stimulated in the Nc. subthalamicus. During intraoperative macrostimulation the patient developed sudden severe existential anxiety together with vegetative dysregulation for no obvious reason. After ending the test stimulation the anxiety vanished within a few seconds. This phenomenon was reproducible in another test stimulation. Using the next apical lead resulted in good symptom control considering IPD with no obvious side effects at first sight. During the next half-year the patient developed a fixed passiveness, loss of interest, apathy and loss of humor very unusual for him considering the preoperative state. The symptoms extended the sometimes seen mild transient postoperative dysthymia considering severity as well as duration of symptoms. Treatment with SSRI's led to no improvement of mental situation. A reprogramming of the neurostimulator, now using an even further apical lead resulted in a sudden and complete vanishing of the depressive symptoms within a few minutes. The now used lead still provides good symptom control, but without side effects with regard to mood.