Unmasking psychiatric symptoms after STN deep brain stimulation in Parkinson's disease

Stereotactic implantation of electrodes for deep brain stimulation (DBS) in the subthalamic nucleus (STN) is a well-established treatment for Parkinson's disease. The treatment gives stable effect over years on the motor symptoms of Parkinson's disease. Psychiatric effects of STN-DBS have attracted increasing attention, with a growing number of reports on psychiatric side effects or exacerbations of known psychiatric disease. However, little is known about the possible unmasking of hidden psychiatric symptoms after surgery.

The aim of this clinical commentary is to illustrate unmasking of psychiatric disease by STN-DBS through the presentation of a case from our clinic.

A patient with Parkinson's disease underwent implantation of STN stimulation electrodes with good results on his motor symptoms. He did not disclose his previous psychiatric history. Soon after the onset of stimulation he developed affective symptoms with manic, aggressive and depressive behaviour, and also an attempted suicide. The stimulation was reduced and his dopaminergic medication increased after the attempted suicide. His previous history of depression and anxiety was now revealed. He received psychiatric attention, and the affective symptoms resolved. The effect of the stimulation on motor symptoms remained stable.

The unmasking of previous psychiatric problems after STN stimulation may be an underestimated problem. It is necessary to fully penetrate the psychiatric anamnesis, especially in patients with a strong wish to be operated and a consequent reluctance to reveal previous problems. Patients with a previous history of a psychiatric disorder are not the best candidates for implantation of STN electrodes.