gms | German Medical Science

Objective: Transitory confusion syndrome is a rare, but well known phenomenon in patients with Parkinson's disease (PD) after deep brain stimulation (DBS) surgery in the subthalamic nucleus (STN). The inferior part of the STN is speculated to be especially sensitive for psychological disturbances. The focus of this present study was the possible influence of intra-operative recording and stimulation of this region.

Method: In a consecutive series of 16 patients with PD undergoing microelectrode recording and test stimulation the mode of application regarding number, micro- and/or semimacro-electrode placement and depths of stimulation were analyzed and correlated to pre-operative evaluation and to the early post-operative course.

Results: All the 16 PD patients were treated bilaterally and received a total of 122 micro/semimacro-electrodes. In 3 patients (19%) a temporary confusion syndrome occurred for a maximum of 2 weeks. Number of electrodes per patient ranged from 4 to 10, on average 7.6 electrodes were applied. Maximum depth of microelectrode insertion was 5 to 6 millimeters below AC-PC-line, performed with 118 electrodes. To these deepest sites, 38 semimacro-electrodes were inserted and tested by stimulation in 14 patients. Neither electrode number nor stimulation intensity could be identified as different in the 3 affected patients compared to those with an uneventful course. All the 3 patients had presented with signs of impulse control disturbance previously. Furthermore, no relation to post-operative stimulation trials could be identified.

Conclusions: Deep insertion of microelectrodes and application of macro-stimulation in the lower part of the STN is well tolerated by most PD patients. At present, a history of impulse control disturbance seems to be the most important warning sign for a risk of transitory confusion syndrome rather than the mode of intra-operative testing.