[Case of respiratory arrest during intraoperative magnetic resonance imaging (iMRI) for awake craniotomy]

We had a neurosurgical patient who developed apnea during iMRI. She was suspected of obstructive sleep apnea. The tumor had a risk of motor aphasia, and therefore awake craniotomy with iMRI was planned. First, the patient was anesthetized and her airway was secured. After 11 minutes of termination of anesthetics, the patient regained consciousness. The level of consciousness was sufficient. Her respiration was stable with oxygen supply. Anesthetics were not given any more. She gradually became drowsy when the tasks were finished and tumor was removed, although she responded to verbal commands. During the second iMRI, capnogram showed flat line and peripheral oxygen saturation level dropped to 90%. Scanning was urgently stopped and the patient was intubated. The patient recovered without any neurological deficits the day after the surgery although the reason of respiratory arrest is still unknown. Awake craniotomy could be challenging because of unsecured airway with risks of vomitting, epileptic attacks or unstable level of consciousness. It is considered that the patient monitoring becomes more difficult when iMRI is performed because the patient's face cannot be obsereved directly. We should remember that conscious level as well as respiration pattern may change during operation.