The novel prognostic value of postoperative follow-up lateral spread response after microvascular decompression for hemifacial spasm

Abstract

OBJECTIVE The lateral spread response (LSR) is an aberrant electrophysiological response in which a stimulus on one branch of the facial nerve spills over to other branches of the nerve, which can be captured by electrodes near each branch. The authors performed this study to evaluate the prognostic value of the follow-up LSR with a sufficient time interval from intraoperative LSR (IO-LSR) after microvascular decompression (MVD) for hemifacial spasm (HFS), excluding the interference of various intraoperative situations. METHODS A total of 247 patients treated with MVD for HFS between June 2011 and March 2019 were enrolled in this study. The IO-LSR was routinely evaluated in all patients. The LSR was checked again on postoperative day (POD) 2 after surgery (POD2-LSR). A total of 228 patients (92.3%) were considered cured at the last clinical follow-up. RESULTS The IO-LSR disappeared in 189 patients (76.5%), and among them, 181 patients (95.8%) were cured 1 year after surgery. The POD2-LSR disappeared in 193 patients (78.1%), and 185 patients (95.9%) among them were cured. Among the 189 patients in which the IO-LSR disappeared, the POD2-LSR reappeared in 26 patients (13.8%). In contrast, the POD2-LSR disappeared in 30 (51.7%) of 58 patients for whom the IO-LSR continued at the end of surgery. When classified into groups according to the status of the IO-LSR and POD2-LSR, in the group of patients in whom both LSRs disappeared, the cure rate was 98.2%, which was significantly higher than that of the other 3 groups (p < 0.05, Cochran-Armitage trend test). The use of both LSRs was found to be significantly associated with better predictability (p < 0.05, McNemar’s test). CONCLUSIONS Postoperative follow-up LSR examination may be beneficial in predicting clinical outcomes after MVD for HFS, especially when considered together with IO-LSR.

Prognostic Value of Lateral Spread Response Recorded 1 Month After Microvascular Decompression for the Treatment of Hemifacial Spasm

“…A similar pattern of LSR reappearance (10.5%, 26 of 247) and delayed disappearance (12.1%, 30 of 247) has been previously reported. 13 We suspected that this phenomenon of postoperative LSR change occurs over several days or more. Therefore, on the basis of our observations of the LSR change in the postoperative period, we cautiously suggest that IONM or LSR recorded during the immediate postoperative period may not be an adequate prognostic factor.…”

“…To date, few studies have focused on the postoperative follow-up LSR and its clinical implications. 13 Hence, we aimed to analyze the pattern of LSR changes postsurgery using the LSR measured 1 month postoperatively and determine its prognostic value up to 1 year postsurgery to assess the necessity of postoperative LSR measurement.…”

Lateral Spread Response: Unveiling the Smoking Gun for Cured Hemifacial Spasm

“…However, continuous administration of these agents can affect the precise detection of LSR. Therefore, careful titration of NMB is necessary, and many anesthesiologists prefer to delay its administration until the end of the surgery [ 6 ]. It is generally recommended that a train-of-four count of more than two be maintained, for accurate monitoring.…”

Intraoperative Monitoring of the Facial Nerve during Microvascular Decompression for Hemifacial Spasm

“…The intraoperative disappearance of the LSR has been associated with favorable clinical outcomes in the postoperative period, although its relationship with long-term outcomes remains uncertain [12,13,45,46]. However, recent studies indicate that the postoperative disappearance or reappearance of the LSR may serve as an indicator of long-term outcomes [42,47].…”

“…Recently, studies have been published suggesting that long-term outcomes can be predicted by measuring the LSR in the postoperative period rather than IONM [47]. Among patients with intraoperative LSR loss, 13.8% showed LSR reappearance on postoperative day 2, while 51.7% of patients without intraoperative LSR loss showed LSR disappearance on the same day.…”