Does Multimodal Neurophysiological Monitoring Influence the Duration of Procedure in CPA?

Introduction: Continuous monitoring of selected neurophysiological functions was introduced as a routine in CPA surgery and some other operations in the petroclival region in our department in 1998. Benefits from this method, such as increase in patient safety, availability of information about dynamical changes in monitored structures, and possibility of localization of cranial nerves, are quite obvious. However, correct placement of many electrodes requires additional time after induction of anesthesia but before beginning of surgery. Material and Methods: The statistical analysis of the duration of preparation time, time of anesthesia, and time of operation in 197 procedures of CPA tumors in the period 1986 to 2002, performed with intraoperative monitoring (group M) and without monitoring (before 1998, group NM), was performed. Subgroups according to histological type of the tumor were evaluated. Group M of 118 procedures consisted of 70 operations of acoustic neurinomas, 19 meningiomas, 10 cases of epidermal cyst, and 19 other neoplastic lesions in the CPA region. Group NM consisted of 79 operations; among them there were 57 cases of acoustic neurinoma, 4 cases of meningioma, 8 cases of epidermal cyst, and 10 other lesions. Results: We found statistically significant lengthening of the preparing time in group M, compared to group NM, in cases of acoustic neurinoma and other tumors; also lengthening of time of anesthesia in the acoustic neurinoma subgroup was present. No statistically significant differences in duration of the operation time in any subgroups were found. The highest percentage of radical procedures, better facial nerve status, and hearing preservation in group M were statistically proved. Conclusions: In our opinion benefits of monitoring are more important than the length of the procedure.