Cortical Arousal With Deep Brain Stimulation After General Anesthesia for Laparoscopic Cholecystectomy
Deep brain stimulation (DBS) is a well-established treatment for Parkinson disease (PD) and other movement disorders.1 There are approximately over 100,000 patients with such devices in North America, and it is likely that these patients will require anesthesia care for non-neurological procedures.2 In this report, we present a patient with DBS in situ who showed a clinical and electro-encephalogram evidence of cortical arousal upon turning “on” the DBS device after general anesthesia for laparoscopic cholecystectomy.
A 62-year-old man (height 182 cm, weight 92 kg) was scheduled for an elective laparoscopic cholecystectomy. He was diagnosed PD 18 years ago, and underwent bilateral subthalamic nucleus DBS insertion 4 years ago for refractory bradykinesia and tremors. Patient was recently seen in the movement disorder clinic and his DBS was checked to be functioning well. General anesthesia was induced using standard doses of propofol, fentanyl and rocuronium, and maintained with oxygen nitrous oxide and desflurane mixture. Depth of surgical anesthesia was monitored using entropy (Datex-Ohmeda, GE Healthcare, Helsinki, Finland), titrated to values between 40 and 50. The DBS was switched off following induction of anesthesia, and remained off during the whole procedure. To minimize electrical interference, the surgeons used harmonic scalpel exclusively. Intraoperative course was unremarkable. At the end of the surgery, the neuromuscular blockade was reversed. The inhaled anesthetics were stopped, and the end-tidal desflurane concentration was 0.4 volume% (minimum alveolar concentration 0.1). However, entropy values were (response entropy/state entropy) 14/13 and the patient was not awakening. The DBS was switched on at this time. We noticed an instantaneous increase in entropy values from 14/13 to 98/85 (Fig. 1) along with spontaneous eye opening. The patient was extubated within the next few minutes and his postoperative course was uneventful.
To our knowledge this is the first report of cortical arousal with subthalamic nucleus stimulation. A previous case report has described a similar phenomenon of cortical arousal during globus pallidus internus stimulation during DBS insertion for dystonia.3 In addition to the transthalamic arousal system, cortical arousal is regulated by an interplay of different subcortical arousal-promoting and sleep-promoting systems involving cholinergic and/or orexinergic neurotransmission.4 Emergence from anesthesia in patients with PD can be variable depending upon the disease progression, interaction between PD and anesthetic medications. It is recommend that the DBS device be switched off following induction of general anesthesia to prevent electrical injury to the pulse generator as well neural structures in the brain.1,5 Patients with DBS device in situ are a special subset of population where delayed recovery from anesthesia may result if the DBS device is inadvertently left in the “off” position after surgery. We found that there were no clinical or electrical signs of emergence despite using short acting anesthetic agents (propofol and fentanyl), and ensuring adequate elimination of inhaled anesthetics and reversal of neuromuscular blockade. It is important to be aware of this cortical arousal phenomenon with DBS activation to ensure a timely and complete recovery from general anesthesia.