Prognostic value of lateral spread response during microvascular decompression for hemifacial spasm

Comparison of Ciprofol-Based and Propofol-Based Total Intravenous Anesthesia on Microvascular Decompression of Facial Nerve with Neurophysiological Monitoring: A Randomized Non-Inferiority Trial

Purpose

Ciprofol is a recently developed short-acting gamma-aminobutyric acid receptor agonist with a higher potency than that of propofol. As a new sedative drug, there are few clinical studies on ciprofol. We sought to examine the safety and efficacy of ciprofol use for general anesthesia in neurosurgical individuals undergoing neurosurgical surgery with intraoperative neurophysiological monitoring (IONM).

Patients and Methods

This single-center, non-inferiority, single-blind, randomized controlled trial was conducted from September 13, 2022 to September 22, 2023. 120 patients undergoing elective microvascular decompression surgery (MVD) with IONM were randomly assigned to receive either ciprofol or propofol. The primary outcome of this study was the amplitude of intraoperative compound muscle action potential decline, and the secondary outcome included the indexes related to neurophysiological monitoring and anesthesia outcomes.

Results

The mean values of the primary outcome in the ciprofol group and the propofol group were 64.7±44.1 and 53.4±35.4, respectively. Furthermore, the 95% confidence interval of the difference was -25.78 to 3.12, with the upper limit of the difference being lower than the non-inferiority boundary of 6.6. Ciprofol could achieve non-inferior effectiveness in comparison with propofol in IONM of MVD. The result during anesthesia induction showed that the magnitude of the blood pressure drop and the incidence of injection pain in the ciprofol group were significantly lower than those in the propofol group (P<0.05). The sedative drug and norepinephrine consumption in the ciprofol group was significantly lower than that in the propofol group (P<0.05).

Conclusion

Ciprofol is not inferior to propofol in the effectiveness and safety of IONM and the surgical outcome. Concurrently, ciprofol is more conducive to reducing injection pain and improving hemodynamic stability, which may be more suitable for IONM-related surgery, and has a broad application prospect.

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

Hemifacial spasm (HFS) is a rare disorder characterized by involuntary facial muscle contractions. The primary cause is mechanical compression of the facial nerve by nearby structures. Lateral spread response (LSR) is an abnormal muscle response observed during electromyogram (EMG) testing and is associated with HFS. Intraoperative monitoring of LSR is crucial during surgery to confirm successful decompression. Proper anesthesia and electrode positioning are important for accurate LSR monitoring. Stimulation parameters should be carefully adjusted to avoid artifacts. The disappearance of LSR during surgery is associated with short-term outcomes, but its persistence does not necessarily indicate poor long-term outcomes. LSR monitoring has both positive and negative prognostic value, and its predictive ability varies across studies. Early disappearance of LSR can occur before decompression and may indicate better clinical outcomes. Further research is needed to fully understand the implications of LSR monitoring in HFS surgery.

Usefulness of intraoperative monitoring in microvascular decompression for hemifacial spasm: a systematic review and meta-analysis

OBJECTIVE

To review the diagnostic accuracy and possible added value of Brainstem Auditory Evoked Potentials (BAEP) monitoring and Lateral Spread Response (LSR) monitoring in microvascular decompression surgery for hemifacial spasms.

METHODS

For this systematic review we followed the PRISMA guidelines. We searched different databases and bibliographies of articles. We included studies on BAEP and LSR monitoring that reported data on hearing outcome or efficacy. Selected studies were assessed for bias using the MINORS tool.

RESULTS

64 articles were selected for qualitative synthesis, 42 met inclusion criteria for meta-analysis. The overall incidence of hearing loss was 3.4%. For BAEP monitoring AUC and pooled OR with 95% confidence interval were 0.911 (0.753-0.933) and 7.99 (3.85-16.60) respectively. Short-term data on LSR monitoring showed an overall spasm relief rate of 89% with pooled OR, sensitivity and specificity with a 95% confidence interval of 8.80 (4.82-16.08), 0.911 (0.863-0.943) and 0.451 (0.342-0.564) respectively. Long-term data on LSR monitoring showed an overall spasm relief rate of 95% with pooled OR, sensitivity and specificity with a 95% confidence interval of 4.06 (2.15-7.64), 0.871 (0.817-0.911) and 0.39 (0.294-0.495) respectively.

CONCLUSION

The alarm criteria, a wave V latency prolongation of 1ms or a wave V amplitude decrement of 50%, proposed by the 'American Clinical Neurophysiology Society' are a sensitive predictor for postoperative hearing loss. Other BAEP wave changes, for example, complete loss of wave V, are more specific but correspond to irreversible damage and are therefore not useful as warning criteria. LSR monitoring has high diagnostic accuracy at short-term follow-up. At long-term follow-up, diagnostic accuracy decreases because most patients get spasm relief regardless of their LSR status. LSR persistence after surgery has a good long-term outcome, as long as an extensive exploration of the facial nerve has been performed.

Predicting outcome of hemifacial spasm after microvascular decompression with intraoperative monitoring: A systematic review

BACKGROUND

Microvascular decompression has been established as a primary treatment for hemifacial spasm. Intraoperative monitoring is used during the surgery to guide neurosurgeons to determine whether the decompression of facial nerve from the vessel is sufficient. We performed a systematic review to assess the role of lateral spread response (LSR) monitoring in predicting hemifacial spasm outcomes after microvascular decompression.

METHOD

A systematic search of PubMed, ScienceDirect, Cochrane, and Google Scholar was conducted. We included studies that performed microvascular decompression surgery with intraoperative monitoring analyzing the correlation between lateral spread response and spasm relief. A critical appraisal was conducted for selected studies.

RESULT

Twenty-two studies comprising 6404 cases of hemifacial spasm, which underwent microvascular decompression surgery with intraoperative monitoring, were included. Of 15 articles that assessed symptoms shortly after surgery, 12 studies showed a significant correlation between lateral spread response resolution and disappearance of spasm. Four of six studies that evaluated the outcome at 3-month follow-up showed significant relationship between LSR and outcome, so did five of six articles that assessed spasm relief at 6-month follow-up. As much as 62.5% of studies (10 of 16) showed the result at long-term follow-up (≥1-year) was not significant.

CONCLUSION

Intraoperative monitoring during microvascular decompression surgery can be a useful tool to predict hemifacial spasm resolution. Though long-term outcomes of patients with LSR relief and persistence are similar, resolution of symptoms shortly after surgery will provide comfort to patients thereby improving their quality of life.