Changes in self-perception in patients treated with neurostimulating devices.

Background: In recent years, qualitative changes in self-perception have been reported in individual patients undergoing brain stimulation to treat their neurological disease. We here report a first systematic study addressing these unwanted treatment effects in a semiquantitative way.

Hypotheses: Hypothesis 1 (H1): Changes in self-perception can be detected and documented in patients following interventions with various neurostimulating devices using standardized assessment tools. Hypothesis 2 (H2): Central nervous-implanted neurostimulating devices (deep brain stimulation [DBS]) will have a greater impact on the patient's self-perception than "peripheral" implanted devices (implanted vagus nerve stimulation [iVNS]) and external devices (transcutaneous vagus nerve stimulation [tVNS] or transcutaneous electrical trigeminal nerve stimulation [eTNS]).

Methods: Application of a newly developed semiquantitative questionnaire (FST-questionnaire [Fragebogen zur Veränderung der Selbstwahrnehmung unter tiefer Hirnstimulation]: Questionnaire regarding changes in self-perception while treated with DBS) to systematically assess changes in self-perception in a single-center, cross-sectional pilot-study at the University Hospital Freiburg, Germany on 50 patients (44% male; age 50 years [range: 27-73 years]), undergoing neurostimulation (DBS, iVNS, tVNS, or eTNS) to treat Parkinson's disease or epilepsy.

Results: Standardized assessment detected alterations in self-perception in all treatment groups (H1 approved). This included rare self-alienating changes in self-perception. Unexpectedly, peripheral neurostimulation had similar effects as central stimulation techniques.

Conclusions: Properly designed questionnaires - like the FST-questionnaire as standardized assessment tool - can detect changes in self-perception in patients during neurostimulatory treatment in a wide spectrum of brain stimulation techniques. This may provide a strategy to systematically identify the subgroup of patients liable to experience such problems during treatment already prior to treatment decisions.