Exploratory study of the caloric vestibular stimulation short term therapeutic effect upon delusions and insight of illness

Objective : Introduction Caloric vestibular nerve stimulation (CVS) utilizing ice water (4 xC) irrigation to the left auditory canal is a simple procedure inducing contra-lateral right hemispheric brain activation of the anterior cingulate cortex and the insula, both reported to be involved in schizophrenia and bipolar illness. Preliminary data suggest that it induces short-lived immediate beneficial effect on denial of illness (anosognosia). Aim Exploring the short term effect of CVS on
delusions and insight-judgment of illness in patients suffering from
schizoaffective disorder and schizophrenia.
Methods : Recently, we studied 3 patients with left versus right ear ice water (4 xC) CVS. One patient had a schizoaffective disorder with manic and depressive episodes. The other two patients had chronic schizophrenia with prominent delusions. All patients were evaluated with the Delusions item of the PANSS (Item P1), the total PANSS positive symptoms subscale (t-P-PANSS) and the lack of insightjudgment item of the PANSS (item G12) at baseline, prior to the CVS stimulation of one ear, immediately after and 20, 60 minutes and 24 hours later. The same procedure was repeated on the other ear 4 days later.
Results : All patients showed a clear beneficial difference, favoring left versus right ear CVS. This improvement was maintained for at least 20 minutes and then diminished over 60 minutes. In one patient the stimulation of both right and left vestibular nerves was validated by videonystagmography, and a more robust effect on the brain was reflected by quantitative electroencephalography (QEEG) with left versus right CVS.
Conclusion : The activation of key structures in the right hemisphere may carry short term improvement on delusions and insightjudgment of illness in patients suffering from schizoaffective disorder and schizophrenia.