Background and Goal of Study:
Dexmedetomidine (DEX) provides sedation without respiratory depression and it seems not to interfere with electrophysiological records (EPRs) and neurocognitive tests (NTs) during deep brain stimulation procedures (DBS). The goal of the study was to confirm the usefulness of DEX for DBS in patients with movement disorders in our setting.
Materials and Methods:
Seventeen consecutive patients scheduled for DBS during 2015-2016 were included (14 Parkinson, 2 essential tremors, 1 dystonia). The stereotaxic frame was placed under local anaesthesia. Monitoring included electrocardiogram, pulse oximeter, BIS®, capnography and invasive blood pressure. Oxygen was provided through nasal prongs. A total of 1 µg.kg-1 of DEX was administered along 10 minutes at the beginning of the procedure, followed by perfusion (0.1-1 μg.kg-1.h-1) adjusted as needed. Sedation was assessed with Richmond Scale (RASS).  If necessary, propofol and/or opioids (fentanyl or remifentanil) were added in bolus or "target controlled infusion" system. Ropivacaine 0.75% 10 ml + Lidocaine 2% 10 ml was used for bilateral ‘scalp block’ prior to cranial incision. The variables analysed were sedation level, patient comfort by Visual Analogue Scale (VAS), hemodynamic changes and respiratory depression. The correct placement of the stimulators, guided by EPRs, and possible incidences during NTs were also recorded.
Results and Discussion:
All patients reached an adequate level of sedation. The RASS ranged from -1 to -3, without respiratory depression. One patient presented oversedation (-4) after the bolus of DEX. Mean perfusion DEX doses were 0.5 ± 0.2 μg.kg-1.h-1. VAS remained <3 except in a patient with VAS 5, who required higher doses of fentanyl.  Hemodynamic complications were episodes of mild bradycardia and hypotension in two different patients, both solved with atropine and phenylephrine respectively. Arterial hypertension was needed to treat in six  patients with urapidil, another one required clevidipine. One patient presented postoperative agitation, and a surgery was stopped for pneumocephalus. Both, the location of the implantation site of the stimulators through EPRs  and NTs were carried out without evidence of drug interferences.
Conclusion(s):
DEX provided conscious sedation and comfort without respiratory depression and with an appropriate hemodynamic profile. In addition, we did not detect interferences with NTs or EPRs during DBS location in our patient population. 


01 / Clinical experience in the use of dexmedetomidine for deep brain stimulation.