P060: ANESTHETIC MANAGEMENT OF A PATIENT WITH MYOTONIA CONGENITA UNDERGOING ENDOSCOPIC ENDONASAL PITUITARY RESECTION FOR CUSHING'S DISEASE
Elizabeth C Lleonart, MD; Michael Mahla, MD
University of Miami Hospital, Jackson Health System
Introduction: Myotonia congenita is a rare inherited neuromuscular disease caused by a mutation in the CLCN1 gene for the skeletal muscle voltage gated chloride channel leading to muscular hyperexcitability. Typical symptoms include difficulty relaxing muscles after contraction, muscle stiffness, muscle cramps, and potentially muscle weakness as well. Patients with myotonia congenita and other neuromuscular diseases present specific challenges at all stages of anesthetic administration.
Methods/Case Description: The patient is a 33 year-old female with history of myotonia congenita and newly diagnosed pituitary adenoma resulting in Cushing’s disease who presented for an endoscopic endonasal pituitary adenoma resection under general anesthesia. During preoperative evaluation for anesthesia, it was elicited from the patient that her myotonia symptoms were generally mild however she did experience intermittent cramping of the hands but not severe enough to impair her daily activities. The patient was induced with propofol, lidocaine, and fentanyl followed by rocuronium for paralysis. Succinylcholine was not used to avoid hyperkalemia. For maintenance of general anesthesia, total intravenous anesthesia using propofol, dexmedetomidine, and remifentanil was selected. The reason for this was two-fold: avoidance of inhalational anesthetics to minimize the theoretical risks of malignant hyperthermia and potentiation of neuromuscular blockade as well as to prevent postoperative nausea and vomiting as this patient had a prior history. The BIS monitor and twitch monitor were used throughout the entire intraoperative period to keep the patient deeply anesthetized (BIS goal of 40-50) and limit frequent redosing of paralytic. The patient was also monitored for hypothermia to decrease the risk of neuromuscular blockade potentiation. Both objective and subjective measures of neuromuscular blockade reversal were utilized. Upon emergence from anesthesia, patient was administered 200mg of sugammadex for neuromuscular blockade reversal with continuous quantatative twitch monitoring. The patient was also strength tested by the anesthesiologist throughout the extubation process and also after extubation before transporting to the recovery room.
Results: The intraoperative and postoperative course were uneventful and without complications. The patient experienced no myotonic episodes on induction or emergence. Full neuromuscular blockade reversal was achieved without residual weakness at the end of the case confirmed with adequate strength testing prior to extubation and after extubation. Patient was transported to the recovery room in stable condition.
Discussion/Conclusion: Patients with rare neuromuscular diseases such as myotonia congenita present unique anesthetic challenges given the risk for multiple life-threatening complications throughout the anesthetic process. Anesthesiologists must be aware of these patients and perform a thorough preoperative evaluation noting the severity of the condition and formulating an anesthetic plan that minimizes risks at all stages of anesthetic administration. The risks that patients with neuromuscular diseases pose could be potentially catastrophic in the operating room. While rare, fatal hyperkalemia, malignant hyperthermia, and residual muscular blockade are all possible risks that must be affronted with the proper anesthetic technique to ensure the safety of these patients while undergoing general anesthesia.