Author(s)
Haley C. Sibley, MD
Ayaka J. Iwata, MD, MS
Michael C. Singer, MD, FACS, FACE
Affiliation(s)
Henry Ford Health System;
Abstract:
Educational Objective: At the conclusion of this presentation, the participants should be able to recognize pseudocholinesterase deficiency as a rare but potential confounding factor when using nerve monitoring for thyroid and parathyroid surgery. Objectives: Pseudocholinesterase deficiency (PD) is a condition characterized by prolongation of choline ester induced neuromuscular blockade. This inherited disease often manifests as prolonged recovery of muscular twitches after use of these agents, including succinylcholine. While widely recognized, it only occurs in 3 out of 5,000 people. We present two consecutive cases of patients undergoing thyroid surgery diagnosed with PD, after their recurrent laryngeal nerve (RLN) failed to stimulate with neuromonitoring. Study Design: Case report. Methods: Chart review. Results: A 53 year old woman with a toxic thyroid nodule underwent a left hemithyroidectomy. Intraoperatively, the left RLN was identified and preserved. At no point did it stimulate nerve monitoring. Upon emergence from anesthesia, the patient had no twitches on train of four and was suspected of having PD. After regaining muscular function, she was extubated two hours later in the recovery room. Testing for serum pseudocholinesterase revealed a level of 75 units per liter (normal range 2900-7100 U/L). Normal vocal cord function was seen on laryngoscopy postoperatively. In the next case, a 71 year old female underwent a four gland parathyroid gland exploration. After exploring the first side, vagal nerve stimulation did not elicit a response. Given the prior case, PD was immediately considered and confirmed by absent train of four assessment. She too was extubated two hours later and found to have normal laryngeal function. Her pseudocholinesterase level was 959 U/L. Conclusions: In both cases, neuromonitoring was ineffective due to PD. Although a rare condition, it is important to recognize PD as a potential confounding factor when using nerve monitoring in thyroid and parathyroid surgery.