FV 15 Influencing factors for the occurrence of intraoperative drowsiness, which hamper the reliability of intraoperative clinical testing in deep brain stimulation

Abstract

Question: Several meta-analyses comparing the outcome of awake versus asleep deep brain stimulation procedures did not reveal significant differences concerning the improvement of motor symptoms. Only rarely informations are given how the awake operations were performed and how often somnolence and disorientation occurred, which might hamper the reliability of intraoperative clinical testing. The aim of our study was to investigate possible influencing factors on the occurrence of somnolence and disorientation in awake procedures. Methods: We retrospectively analyzed 122 patients with Parkinson's disease having received implantation of a DBS system at our centre. Patient age ranged from 42 -75 years (mean 61,8 years). The occurrence of intraoperative somnolence and postoperative disorientation was correlated with the duration of disease prior to surgery, number of microelectrode trajectories, AC-PC-coordinates of the planned target, UPDRS-scores, intraoperative application of sedative drugs, duration of the surgical procedure, perioperative application of Apomorphin and the preoperative L-DOPA, equivalence dosage. Results: Patients in whom intraoperative somnolence occurred were significantly older than patients without this effect (p=0,039). Patients with intraoperative somnolence had a longer duration of the disease prior to surgery (p=0,080) and their preoperative off-medication- UPDRS was higher (p=0,071). If the planned target was more medial (p=0,060) and more inferior (p=0,051) intraoperative somnolence occurred more often. Sedative drugs, applied to cover skin incision and burr hole trepanation, again, led to more pronounced somnolence (p=0,019). The same was true for longer durations of the surgical procedure (p=0,020). Higher numbers of microelectrode trajectories were more likely associated with postoperative disorientation. Perioperatively applied Apomorphin could reduce the occurrence of somnolent phases during the operation (p=0,026). Conclusion: Several influencing factors were found to seemingly increase the risk of intraoperative somnolence and postoperative disorientation. These factors should be taken into account and adjusted, if possible, to permit reliable interpretations of intraoperative clinical testing.