CON: Deep Brain Stimulator Insertion for Functional Neurosurgery Under General Anesthesia.

S ince the introduction of surgically implanted deep brain stimulator (DBS) in the 1980s, there is interest in expanding its use for variety of neurological and psychiatric disorders. The lack of making a destructive lesion, allows a more reversible nature with the technique, and offers its use for treating medically refractory conditions as an attractive option. DBS has an established role in treatment of many patients with intractable Parkinson disease and essential tremor. Other less common role includes patients with other conditions such as dystonia, chronic pain, and some psychiatric problems. The subthalamic nucleus or the globus pallidus internus are often preferred targets for treatment of Parkinson disease and the ventral intermediate nucleus in patients with essential tremor. Globus pallidus internus is the preferred target in patients with dystonia undergoing DBS. The postoperative outcome of the patient’s symptoms depends on the accuracy of placement of the electrodes in the target structure. This is aided by neuroimaging techniques, microelectrode recording (MER) in the patients with Parkinson disease and dystonia, and the macrostimulation of the patient intraoperatively for observation of potential side effects. The procedure consists of multiple steps including (1) placement of the head stereotactic frame followed by imaging; (2) stereotactic insertion of electrodes through a burr hole into the target brain nuclei; and (3) tunneling of the DBS wires and placement of pulse generators subcutaneously under the chest. Usually the procedure is performed in 2 stages. Regarding the first stage with the implantation of the intracranial electrodes, the anesthesiologist is confronted to a difficult choice in providing anesthesia to these patients. The anesthetic techniques for the intracranial electrode implantation varies widely with the patient fully awake and local anesthesia (LA), LA with some degree of sedation with no airway manipulation and general anesthesia (GA) with endotracheal intubation. Placement of DBS for Parkinson disease has historically been done under LA with the patient awake and fully responsive. This technique allows the surgeons to have a better “on time” monitoring of the patient’s neurological status while they are simultaneously getting MER recording on the patient. Obtaining reliable MER for the precise placement of the electrodes into the target nuclei. Visualize the motor and vocal responses to the intraoperative stimulation of the patients to see the improvements of the symptoms. Avoid the unnecessary adverse effects that could result from the passage of the current into the adjacent structures. The goals of the anesthesiologists in providing anesthesia for awake patients are as follows. To provide patient comfort while properly attending to the positioning in the bed. Keeping the patient responsive and cooperative for a long period of time often while they are off their medication. To control the blood pressure within the normal range due to their anxiety to avoid the intracerebral bleeding. Continuous monitoring of the patient’s neurosurgical status ready to resuscitate the patient in case of adverse acute event such as intracerebral hemorrhage or stroke. Some centers provide conscious sedation to the patients to provide comfort and alleviate their anxiety and stop the sedation a few minutes before the MER so that it does not interfere with the recordings and also to allow some neuro monitoring (motor and verbal) of the patients. However, providing sedation to the patients with the stereotactic frame covering their face and part of the airway can be sometimes challenging. Obstruction of the airway under sedation will lead to a challenging situation as the airway cannot be accessed through the stereotactic frame. However some frames are designed with a removable front part which allows a better airway access. Furthermore, patients with these types of neurological disorders are usually extremely sensitive to sedation and may not be as responsive as needed for a precise neurological examination. GA is an option for the patients with dystonia and may pull out of their frame if they exhibit strong dystonic contractures, claustrophobic or suffer an “off medication” side effects to be safely controlled during the surgical part or could hurt themselves on the table. The same has always been the rule for the pediatric population. However, in some POINTS OF VIEW