Known risk factors for developing of first-time psychosis in patients with deep brain stimulator (DBS) include older age, short time after implant placement and cerebral target for stimulation. In particular, stimulation of subtalamic nucleus and globus pallidus internus has been shown to elicit psychotic symptoms in various case reports. To date, there are no cases describing onset of psychosis due to DBS in the ventralis intermediate nucleus (Vim) of the thalamus.

Case describtion of psychotic episode provoked by DBS in Vim region

Case report of 70 y.o. female with unilateral DBS from 2012 in Vim for essential tremor, who developed therapy resistant psychotic symptoms right after adjusted settings of the DBS.

Psychotic onset of otherwise healthy 70 y.o. patient occurred and gradually worsened after adjustment of DBS settings in absence of other iatrogenic factors, including medication and comorbidity, and required involuntary hospitalization one week after beginning of psychosis. Treatment after hospitalization comprised olanzapine 10 mg. 1dd1 did not cause resolvent of psychosis. Because of therapy resistance to psychofarmaca and worsening of psychotic symptoms, by way of exception neurologists had to change the settings back to basic leading to complete and sustained remission of psychosis within two days.

Among side effects of DBS in Vim, psychotic symptoms have never been reported. However, as in our patient, psychosis occurred after changes of settings in DBS and presented acutely, was severe, resulted in involuntary hospitalization and was therapy resistant. Pathophysiology of DBS-induced psychosis in Vim region is not known and requires further investigation.

No significant relationships.

Impulsivity and impaired decision-making have been proposed as obsessive-compulsive disorder (OCD) endophenotypes, running in OCD and their healthy relatives independently of symptom severity and medication status. Deep brain stimulation (DBS) targeting the ventral limb of the internal capsule (vALIC) and the nucleus accumbens (Nacc) is an effective treatment strategy for treatment-refractory OCD. The effectiveness of vALIC-DBS for OCD has been linked to its effects on a frontostriatal network that is also implicated in reward, impulse control, and decision-making. While vALIC-DBS has been shown to restore reward dysfunction in OCD patients, little is known about the effects of vALIC-DBS on impulsivity and decision-making. The aim of the study was to compare cognitive impulsivity and decision-making between OCD patients undergoing effective vALIC-DBS or treatment as usual (TAU), and healthy controls.

We used decision-making performances under ambiguity on the Iowa Gambling Task and reflection impulsivity on the Beads Task to compare 20 OCD patients effectively treated with vALIC-DBS, 40 matched OCD patients undergoing effective TAU (medication and/or cognitive behavioural therapy), and 40 healthy subjects. Effective treatment was defined as at least 35% improvement of OCD symptoms.

OCD patients, irrespective of treatment modality (DBS or TAU), showed increased reflection impulsivity and impaired decision-making compared to healthy controls. No differences were observed between OCD patients treated with DBS or TAU.

OCD patients effectively treated with vALIC-DBS or TAU display increased reflection impulsivity and impaired decision-making independent of the type of treatment.