Lateral Spread Response Monitoring Research Articles

Optimal method for reliable lateral spread response monitoring during microvascular decompression surgery for hemifacial spasm

In this study, we propose an optimal method for monitoring the key electrophysiological sign, the Lateral Spread Response (LSR), during microvascular decompression (MVD) surgery for hemifacial spasm (HFS). Current monitoring methods and interpretations of LSR remain unclear, leading to potential misinterpretations and undesirable outcomes." We prospectively collected data from patients undergoing MVD for HFS, including basic demographics, clinical characteristics, and surgical outcomes. Stimulation intensity was escalated by 1 mA increments to identify the optimal range for effective LSR. We designated the threshold at which we can observe LSR as THR1 and THR2 for when LSR disappears, with high-intensity stimulation (30 mA) designated as THR30. Subsequently, we compared abnormal muscle responses (AMR) between the optimal range (between THR1 and THR2) and THR30. Additionally, we conducted an analysis to identify and assess factors associated with artifacts and their potential impact on clinical outcomes. As stimulation intensity increases, the onset latency to detect AMR was shortened. The first finding of the study was high intensity stimulation caused artifact that mimic the wave of LSR. Those artifacts were observed even after decompression thus interfere interpretation of disappearance of LSR. Analyzing the factors related to the artifact, we found the AMR detected at onset latency below 9.6 ms would be the lateral spreading artifact (LSA) rather than true LSR. To avoid false positive LSR from LSA, we should stepwise increase stimulation intensity and not to surpass the intensity that cause LSR onset latency below 10 ms.

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.

Hemifacial Spasm Caused by Distal Neurovascular Compression Confirmed by Lateral Spread Response Monitoring.

Primary hemifacial spasm (HFS) is likely related to a vascular compression of the facial nerve at its distal cisternal portion root exit Zone that has been reported during recent years. Most of these cases were found during secondary surgery or intraoperative monitoring of lateral spread response (LSR). Here we reported 2 patients with typical HFS caused by distal neurovascular compression that were successfully treated with microvascular decompression. Magnetic resonance imaging in both cases suggested that there was a contact between the vessel in cisternal segment and the facial nerve. LSR immediately disappeared after decompression of distal neurovascular compression. Resolution of spasm after the operation was achieved in both of these cases, with a short duration of vertigo and mild facial paralysis in case 1. Reviewing the literature, the majority of cases of distal neurovascular compression are found under the following 2 conditions:(1) When patients underwent a second operation. (2) When surgeons explored the distal part, the cisternal portion, after exploring the traditional root exit Zone without LSR disappearing. Therefore, it is the distal neurovascular compression at cisternal segment that may also be the cause of HFS. As for this kind of special HFS, these patients may also present with cranial nerve symptoms of VIII. In addition, magnetic resonance imaging can provide some information about compression sites. When we perform microvascular decompression, we should carefully pay attention to having an entire-root-exploration with intraoperative electrophysiology to find and decompress the real neurovascular compression.

Predicting Early Loss of Lateral Spread Response before Decompression in Hemifacial Spasm Surgery.

Recent studies have shown the evocation of lateral spread response (LSR) due to the compression of the facial nerve in hemifacial spasm (HFS). Intraoperative monitoring (IOM) of LSR could help locate neurovascular conflicts and confirm adequate micro-vascular decompression (MVD) while treatment of hemifacial spasm (HFS). However, studies on early LSR loss before decompression in HFS surgery are sparse, indicating the need to understand various perceptions on it. Therefore, we retrospectively analyzed 50 adult HFS patients who underwent MVD during the period of September 2018–June 2021. We employed IOM combining traditional LSR (tLSR) and dual LSR (dLSR). One patient was excluded owing to the lack of LSR induction throughout the surgery, while 49 were divided into groups A (n = 14) and B (n = 35), designated as with or without early LSR loss groups, respectively, and offending vessels were analyzed. The mean age of group A patients was significantly younger (47.8 ± 8.6) than that of group B (53.9 ± 10.6) (p = 0.0393). The significant predominating offending vessel in group A was the anterior inferior cerebellar artery (AICA, 78.57%). However, group B included those with AICA (28.57%), posterior inferior cerebellar artery (PICA, 22.86%), vertebral artery (VA) involved (25.71%), and combined AICA and PICA (22.86%). Group B exhibited poorer clinical outcomes with more complications. Conclusively, early LSR loss might occur in the younger population, possibly due to the AICA offending vessel. The compression severity of offending vessels may determine the occurrence of early LSR loss.

Intraoperative neurophysiologic monitoring in microvascular decompression for hemifacial spasm

The majority of primary hemifacial spasm (HFS) patients are related to a vascular compression of the facial nerve root at its entry zone. Non-surgical treatment methods of HFS are anti-epileptic drugs and local botulinum toxin injection, but their outcomes are often not satisfactory in relieving symptoms. Microvascular decompression (MVD) is a surgical treatment method of HFS. Nowadays, intraoperative neurophysiologic monitoring is being used during MVD for two main objectives. The first and main objective is to prevent and reduce the risk of hearing impairment. Brainstem auditory evoked potentials (BAEPs) is monitored during surgery, to monitor the cranial nerve VIII and determine hearing sense preservation. Researches on BAEPs has enabled near real-time and safe monitoring, as warning indicators and advanced techniques to get results faster has been discovered. The second objective is to optimize the effectiveness of surgery. Despite the surgery, some patients had persisted symptoms or recurrence of spasm for some reasons, in few cases. The lateral spread response (LSR) monitoring is performed to guide the operator during surgery. LSR shows modest sensitivity. Nevertheless, it shows high specificity in predicting the symptom-free status after MVD. Low sensitivity precluded the use of the LSR monitoring as an exclusive solitary diagnostic modality. The disappearance of LSR during MVD appears to be not effectively in predicting long-term outcomes, but it demonstrated limited prognostic values in predicting favorable short-term outcomes. These results implements that, intraoperative monitoring of LSR during MVD can provide considerable value for investigating the adequacy of MVD before cranial bone closure.

The Utility of Intraoperative Lateral Spread Recording in Microvascular Decompression for Hemifacial Spasm: A Systematic Review and Meta-Analysis.

Microvascular decompression (MVD) is the surgical treatment of choice for hemifacial spasm (HFS). During MVD, monitoring of the abnormal lateral spread response (LSR), an evoked response to facial nerve stimulation, has been traditionally used to monitor adequacy of cranial nerve (CN) VII decompression. To assess the utility of LSR monitoring in predicting spasm-free status after MVD postoperatively. We searched PubMed, Web of Science, and Embase for relevant publications. We included studies reporting on intraoperative LSR monitoring during MVD for HFS and spasm-free status following the procedure. Sensitivity of LSR, specificity, diagnostic odds ratio, and positive predictive value were calculated. From 148 studies, 26 studies with 7479 patients were ultimately included in this meta-analysis. The final intraoperative LSR status predicted the clinical outcome of MVD with the following specificities and sensitivities: 89% (0.83- 0.93) and 40% (0.30- 0.51) at discharge, 90% (0.84-0.94) and 41% (0.29-0.53) at 3 mo, 89% (0.83-0.93) and 40% (0.30-0.51) at 1 yr. When LSR persisted after MVD, the probability (95% CI) for HFS persistence was 47.8% (0.33-0.63) at discharge, 40.8% (0.23-0.61) at 3 mo, and 24.4% (0.13-0.41) at 1 yr. However, when LSR resolved, the probability for HFS persistence was 7.3% at discharge, 4.2% at 3 mo, and 4.0% at 1 yr. Intraoperative LSR monitoring has high specificity but modest sensitivity in predicting the spasm-free status following MVD. Persistence of LSR carries high risk for immediate and long-term facial spasm persistence. Therefore, adequacy of decompression should be thoroughly investigated before closing in cases where intraoperative LSR persists.

Predictive value of intraoperative blink reflex monitoring for surgical outcome during microvascular decompression for hemifacial spasm

ObjectiveTo investigate the prognostic and predictive value of intraoperative blink reflex (BR) monitoring during microvascular decompression (MVD) for hemifacial spasm (HFS). MethodsWe retrospectively reviewed 41 patients with HFS undergoing MVD with intraoperative BR and lateral spread response (LSR) monitoring. Facial spasm was evaluated for six months postoperatively. ResultsThe BR resolved in 38 patients and persisted in three after MVD. For patients who exhibited BR resolution, 1-day, 1-month, and 6-month follow-ups revealed that 35 (92.1%), 35 (92.1%), and 38 (100%) patients had spasm resolution, respectively. However, of the three patients with persistent BR, one (33.3%), one (33.3%), and zero (0%) patients exhibited spasm resolution at the three corresponding follow-ups. We found a statistically significant difference in spasm resolution between the persistent and resolved BR groups at six months postoperatively. A comparison between intraoperative BR and LSR monitoring revealed that BR was a better predictor of clinical outcomes. ConclusionsIntraoperative BR monitoring is a potentially useful tool to help facilitate an adequate decompression and is a reliable prognostic predictor of surgical outcome. SignificanceThis study is the first to document the relationship between intraoperative BR monitoring and surgical outcome in patients with HFS.

Fully endoscopic microvascular decompression for hemifacial spasm

Hemifacial spasm (HFS) is characterized by involuntary tonic and/or clonic contractions of facial nerve muscles. Fully endoscopic microvascular decompression (E-MVD) for HFS has not been widely adopted. This paper aims to illustrate the safety and efficacy of the fully endoscopic technique for HFS treatment. The authors conducted a single-center retrospective study of 27 patients (28 separate E-MVD cases; 1 patient had bilateral E-MVD) diagnosed with HFS who underwent fully E-MVD from January 2013 to October 2016. Intraoperative brainstem auditory evoked potentials and lateral spread resolution were reviewed. Outcome was based on the clinical status of the patient at the last contact point with the senior author. Complications were categorized as facial weakness, hearing loss, ataxia, dysphagia, or any adverse event able to be attributed to the surgical procedure. HFS was relieved either completely or partially in the majority of cases (24 of 28, 85.7%). Of the 28 separate procedures, 17 (60.7%) resulted in complete resolution of symptoms, 4 (14.3%) resulted in near-complete resolution, 2 (7.1%) resulted in 50% reduction of symptoms, 1 (3.6%) resulted in minimal reduction, and 4 (14.3%) resulted in no relief. Of the 27 patients, 26 (96%) had no permanent postoperative complications. In multivariate logistic regression, the best predictor of greater than 50% resolution of spasm was resolution of intraoperative lateral spread response. A fully E-MVD for HFS provides a safe and comprehensive view of the neurovascular conflict. Exclusive use of the endoscope in MVD is both safe and feasible in the treatment of HFS. Attention to lateral spread response monitoring remains an integral part of comprehensive neurosurgical management.

Effect of partial neuromuscular blockade on efficacy and safety of nerve monitoring during microvascular decompression of facial nerve

Objective To evaluate the effect of partial neuromuscular blockade (NMB) on the efficacy and safety of nerve monitoring during microvascular decompression (MVD) of facial nerve. Methods Seventy American Society of Anesthesiologists physical status Ⅰ or Ⅱ patients of both sexes, aged 39-78 yr, weighing 44-84 kg, scheduled for elective MVD, were divided into 2 groups (n=35 each) using a random number table method: control group and partial NMB group.Anesthesia was induced by intravenous injection of 3-fold ED95 cisatracurium.In control group, muscle relaxants were not used after intubation.In partial NMB group, cisatracurium was continuously infused intravenously to maintain partial NMB, and the T1/Tc ratio was maintained at 20%-40%.Intraoperative neuroelectrophysiological monitoring was performed using lateral spread response (LSR). The success rates of LSR monitoring, occurrence of body movement, requirement for anesthetics and cardiovascular agents were recorded during operation, and the patients were followed up on day 7 after surgery, and the therapeutic efficacy and occurrence of neurological complications were recorded. Results Compared with control group, the incidence of intraoperative body movement was significantly decreased, the intraoperative consumption of propofol and remifentanil was decreased, and the intraoperative requirement for vasopressors was decreased in partial NMB group (P 0.05). Conclusion Partial NMB (T1/Tc=20%-40%) can be effectively used for MVD monitored by LSR, decrease the occurrence of the body movement, and raise the perioperative safety in patients. Key words: Muscle relaxation; Facial nerve; Microvascular decompression surgery; Monitoring, intraoperative

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

ObjectiveThis study aimed to investigate the prognostic value of the lateral spread response (LSR) for predicting surgical outcomes following microvascular decompression (MVD) in patients with hemifacial spasm.MethodsSeventy-three patients with hemifacial spasm underwent MVD with intraoperative LSR monitoring. Surgical outcomes were evaluated 1 week and 1 year after MVD and correlations between LSR characteristics and surgical outcomes were analyzed.ResultsThe LSR disappeared completely in 61 patients during surgery (Group A; prior to insertion of Teflon felt pledgets in 11, after insertion of pledgets in 50), disappeared partially in nine patients (Group B), and remained unchanged in three patients (Group C). Fifty-five patients showed short-term and 61 patients showed long-term clinical cures during the follow-up period. The short-term and long-term cure rates were significantly higher in Group A than in Group C. There was no correlation between the time of complete LSR disappearance and surgical outcomes.ConclusionsDisappearance of the LSR during MVD is correlated with the surgical outcomes. Intraoperative LSR monitoring is a reliable approach for predicting the prognosis of hemifacial spasm following MVD, but the time at which LSR disappears is not a prognostic indicator.

Platform Session – Evoked potentials & NIOM: Prognostic value of intra- and extra-operative lateral spread responses in microvascular decompression surgeries of hemifacial spasm

Introduction Lateral spread response is observed in patients with hemifacial spasm (HFS) by eletrically stimulating one branch of the facial nerve activates facial muscles innervated by other branches of the facial nerve by electromyography. Nowadays, LSR has been used to confirm adequacy of microvascular decompression (MVD). The aim of this study was to evaluate the prognostic value of intra- and extra-operative lateral spread response (LSR) in microvascular decompression (MVD) surgeries of hemifacial spasm (HFS). Methods A retrospective review was made of consecutive 25 patients who underwent continuous intraoperative monitoring during MVD. LSR and continuous electromyography were monitored in the frontalis, orbicularis oculi, and mentalis muscles. Extra-operative LSRs were done pre- and postoperatively. The neurological status of each patient was evaluated before and immediately after surgery, on discharge, and at 3 months after surgery. Results Intraoperative neurophysiologic monitorings were successful in all patients. On admission and discharge, extra-operative LSR recordings were done in 23 patients. Twenty-one patients completed a follow- up evaluation. In 17, the intraoperative LSRs disappeared during surgery. In 5, the intraoperative LSRs were absent before incision and remained the same until the end of surgery. In one, the intraoperative LSR were present before incision and persisted despite MVD. For extra-operative LSRs, they disappeared after surgery in 10. LSRs were absent before and after surgery in 7. In 6, LSRs were present before surgery and persisted after MVD. For 5, intraoperative LSRs disappeared during surgery but extra-operative LSRs were persisted despite adequate MVD. In one, intraoperative LSRs were absent before incision and remained during the surgery. But extra-operative LSRs were present before surgery and disappeared after adequate MVD. Statistically, the extra-operative disappearance of LSR was correlated with the HFS relief in 4 days after surgery and the 3-month follow up period. (P = 0.049 and 0.044). However, the intaroperative disapearance of LSR was not. Conclusion In our study, extra-operative LSR monitoring may be more predictive of the surgical outcome compared with intraoperative LSR during the 3-month follow up.

Microvascular decompression for hemifacial spasm: can intraoperative lateral spread response monitoring improve surgical efficacy?

OBJECTIVE The purpose of this study was to evaluate whether intraoperative monitoring of lateral spread response (LSR) improves the efficacy of microvascular decompression (MVD) for hemifacial spasm (HFS). METHODS In this prospective study, patients undergoing MVD for HFS were assigned to one of 2 groups, Group A (MVD with intraoperative LSR monitoring) or Group B (MVD without LSR monitoring). Clinical outcome at 12 months after surgery was assessed through telephone survey. Data analysis was performed to investigate the effect of intraoperative LSR monitoring on efficacy of MVD. RESULTS A total of 283 patients were enrolled in the study, 145 in Group A and 138 in Group B. There was no statistically significant difference between the 2 groups with respect to the percentage of patients who had spasm relief at either 1 week (Group A 87.59% vs Group B 83.33%; p = 0.317) or 1 year (93.1% vs 94.2%; p = 0.809) after surgery. A clear-cut elimination of LSR during surgery was observed in 131 (90.34%) of 145 patients; LSR persisted in 14 patients (9.66%) at the end of the surgical procedure. Disappearance of LSR correlated with spasm-free status at 1 week postoperatively (p = 0.017) but not at 1 year postoperatively (p = 0.249). CONCLUSIONS Intraoperative LSR monitoring does not appear to provide significant benefit with respect to the outcome of MVD for HFS in skilled hands. Persistence of LSR does not always correlate with poor outcome, and LSR elimination should not be pursued in all patients after verification of complete decompression.

Prognostic ability of intraoperative electromyographic monitoring during microvascular decompression for hemifacial spasm to predict lateral spread response outcome.

OBJECTIVE Abnormal lateral spread response (LSR) is a typical finding in facial electromyography (EMG) in patients with hemifacial spasm (HFS). Although intraoperative monitoring of LSR has been widely used during microvascular decompression (MVD), the prognostic value of this monitoring is still debated. The purpose of this study was to determine whether such monitoring exhibits prognostic value for the alleviation of LSR after treatment of HFS. METHODS Between January 2009 and December 2013, a total of 582 patients underwent MVD for HFS with intraoperative EMG monitoring at Kyung Hee University Hospital. The patients were categorized into 1 of 2 groups according to the presence of LSR at the conclusion of surgery (Group A, LSR free; Group B, LSR persisting). Patients were assessed for the presence of HFS 1 day, 6 months, and 1 year after surgery. Various parameters, including age, sex, symptom duration, offending vertebral artery, and offending perforating artery, were evaluated for their influence on surgical and electrophysiological results. RESULTS Overall, HFS was alleviated in 455 (78.2%) patients 1 day after MVD, in 509 (87.5%) patients 6 months after MVD, and in 546 (93.8%) patients 1 year after MVD. Patients in Group B were significantly younger than those in Group A (p = 0.022). Patients with a symptom duration of less than 1 year were significantly more likely to be classified in Group A than were patients whose symptoms had persisted for longer than 10 years (p = 0.023); however, analysis of the entire range of symptom durations did not reveal a significant effect (p = 0.132). A comparison of Groups A and B according to follow-up period revealed that HFS recovery correlated with LSR alleviation over a shorter period, but the same was not true of longer periods; the proportions of spasm-free patients were 80.6% and 71.1% (p = 0.021), 89.4% and 81.9% (p = 0.022), and 93.5% and 94.6% (p = 0.699) 1 day, 6 months, and 1 year after surgery in Groups A and B, respectively. CONCLUSIONS Although intraoperative EMG monitoring during MVD was beneficial for identifying the offending vessel and suggesting the most appropriate surgical end point, loss of LSR did not always correlate with long-term HFS treatment outcome. Because the HFS cure rate improved over time, revision might be considered for persistent LSR when follow-up has been performed for more than 1 year and the spasm remains despite adequate decompression.

The value of lateral spread response monitoring in predicting the clinical outcome after microvascular decompression in hemifacial spasm: a prospective study on 100 patients.

Microvascular decompression represents an effective treatment for hemifacial spasm. The use of lateral spread response (LSR) monitoring remains a useful intraoperative tool to ensure adequate decompression of the facial nerve. The aim of this study was to assess the value of LSRs intraoperative monitoring as a prognostic indicator for the outcome of microvascular decompression in hemifacial spasm. Our study included 100 patients prospectively. The patients were classified into four groups whether LSRs were totally, partially, not relieved, or not detected from the start. According to clinical outcome, the patients were classified into four groups depending on the clinical course after surgery and the residual symptoms if any. Then, correlations were made between LSR events and treatment outcome to detect its reliability as a prognostic indicator. LSRs were relieved totally in 56% of the patients, partially relieved in 14%, not relieved in 10%, and were not detected in 20% of the patients from the start. HFS was relieved directly after operation in 62% with clinical improvement of 90-100%. Thirty-one percent described 50-90% improvement over the next 3months after surgery. Almost all of these 31% (28 out of 31 patients) reported further clinical improvement of 90-100% within 1year after surgery. Three percent suffered from a relapse after a HFS-free period, and 4% reported minimal or no improvement describing 0-50% of the preoperative state. The percentage of the satisfied patients with the clinical outcome who reported after 1year a clinical improvement of 90-100% was 90%. Statistical analysis did not find a significant correlation between the relief of LSRs and clinical outcome. LSRs may only represent an intraoperative tool to guide for an adequate decompression but failed to represent a reliable prognostic indicator for treatment outcome.

Effects of partial neuromuscular blockade on lateral spread response monitoring during microvascular decompression surgery

ObjectiveWe evaluated the effect of partial neuromuscular blockade (NMB) and no NMB on successful intraoperative monitoring of the lateral spread response (LSR) during microvascular decompression (MVD) surgery. MethodsPatients were randomly allocated into one of three groups: the TOF group, the NMB was targeted to maintain two counts of train-of-four (TOF); the T1 group, maintain the T1/Tc (T1: amplitude of first twitch, Tc: amplitude of baseline twitch) ratio at 50%; and the N group, no relaxants after tracheal intubation. Successful LSR monitoring was defined as effective baseline establishment and maintenance of the LSR until dural opening. ResultsThe success rate of LSR monitoring was significantly lower in the TOF group. But, there was no significant difference between T1 and N. The detection rate of spontaneous free-run electromyography (EMG) activity was significantly higher in the N group compared with the TOF and T1 groups. ConclusionsPartial NMB with a target of T1/Tc ratio at 50% allows good recording of LSR with same outcome as surgery without NMB, and reduced spontaneous EMG activity. SignificanceWe suggested the availability of partial NMB for intraoperative LSR monitoring.

Monitoring der lateralen Ausbreitungsreaktion während mikrovaskulärer Dekompression bei heimfazialem Spasmus

The aim of the present study was to determine (1) whether successful intraoperative electromyography monitoring for lateral spread response (LSR) is possible with partial neuromuscular blockade (NMB) in subjects undergoing microvascular decompression (MVD) for hemifacial spasm and (2) the adequate level of NMB to achieve that goal. A total of 61 patients in whom LSR was monitored during MVD were enrolled in the study. Patients were randomly allocated to two groups: group TOF in which the NMB target was maintenance of two train-of-four (TOF) counts and group T1 in which the NMB target was maintenance of a T1/Tc ratio of 50 % (T1: first twitch height of TOF and Tc: control twitch height). The adductor pollicis brevis muscle was used to monitor TOF responses. The frequency of successful LSR monitoring, defined as successful baseline establishment and maintenance of LSR until surgical decompression, was compared between the two groups. Of the 61 patients 2 were excluded from the study so that 30 patients in group TOF and 29 patients in group T1 were analyzed. The success rate of LSR monitoring was clinically acceptable and significantly higher in group T1 than in group TOF, i.e. n = 15 (50.0 %) in group TOF versus n = 24 (82.8 %) in group T1 (P = 0.008), corresponding to a 32.8 % higher success rate in group T1 than group TOF (95 % CI: 13.9-51.7 %). Mean vecuronium infusion dose was smaller and mean TOF count was higher in group T1 than group TOF with a TOF count = 2 (1) in group TOF versus 3 (1) in group T1 (P = 0.003). Mean sevoflurane and remifentanil infusion doses were not different between groups. There was no incidence of spontaneous movement during microscopy in either group. Maintenance of partial NMB with a target T1/Tc ratio of 50 % resulted in a clinically acceptable success rate of LSR monitoring and surgical condition during MVD. Maintenance of partial NMB with a target T1/Tc ratio of 50 % rather than TOF count of two during LSR monitoring for MVD can therefore be recommended.

Microvascular Decompression for Hemifacial Spasm: Evaluating Outcome Prognosticators Including the Value of Intraoperative Lateral Spread Response Monitoring and Clinical Characteristics in 293 Patients

Hemifacial spasm is a socially disabling condition that manifests as intermittent involuntary twitching of the eyelid and progresses to muscle contractions of the entire hemiface. Patients receiving microvascular decompression of the facial nerve demonstrate an abnormal lateral spread response (LSR) in peripheral branches during facial electromyography. The authors retrospectively evaluate the prognostic value of preoperative clinical characteristics and the efficacy of intraoperative monitoring in predicting short- and long-term relief after microvascular decompression for hemifacial spasm. Microvascular decompression was performed in 293 patients with hemifacial spasm, and LSR was recorded during intraoperative facial electromyography monitoring. In 259 (87.7%) of the 293 patients, the LSR was attainable. Patient outcome was evaluated on the basis of whether the LSR disappeared or persisted after decompression. The mean follow-up period was 54.5 months (range, 9-102 months). A total of 88.0% of patients experienced immediate postoperative relief of spasm; 90.8% had relief at discharge, and 92.3% had relief at follow-up. Preoperative facial weakness and platysmal spasm correlated with persistent postoperative spasm, with similar trends at follow-up. In 207 patients, the LSR disappeared intraoperatively after decompression (group I), and in the remaining 52 patients, the LSR persisted intraoperatively despite decompression (group II). There was a significant difference in spasm relief between both groups within 24 hours of surgery (94.7% vs. 67.3%) (P < 0.0001) and at discharge (94.2% vs. 76.9%) (P = 0.001), but not at follow-up (93.3% vs. 94.4%) (P = 1.000). Multivariate logistic regression analysis demonstrated independent predictability of residual LSR for present spasm within 24 hours of surgery and at discharge but not at follow-up. Facial electromyography monitoring of the LSR during microvascular decompression is an effective tool in ensuring a complete decompression with long-lasting effects. Although LSR results predict short-term outcomes, long-term outcomes are not as reliant on LSR activity.

Influence of distal portion compression of facial nerve in hemifacial spasm surgery

Objectiye To study the influence of distal portion compression of the facial nerve in hemifacial spasm surgery.Method 120 hemifacial spasm patients were undergone lateral spread response monitoring during microvascular decompression surgery.39 patients＇ LSR remained after decompression of the root exit zone of the facial nerve.After exploring the full length of distal portion of the facial nerve in the subarachnoid space, 19 patients were found distal portion vascular compression and were fully decompressed.The monitoring records as long as the surgical results were analyzed post - operatively.Results At the end of operations, 15 patients＇ LSR disappeared and 4 remained.The HFS disappeared immediately in 13patients.The post - operative spasm was weaker in 6 patients.After follow - up period of 8 - 14 months （ mean duration 12.7 months）, all patients were spasm free and no reoccurrence case.Post - operative complications included：2 cases of transient moderate facial paralysis, 1 case of hearing loss, 3 cases of transient hearing impairment and 1 case of intracranial infection.Conclusions Distal portion compression of the facial nerve has influence on the result of microvascular decompression surgery.Distal decompression which identified by intraoperative monitoring can decrease the occurrence of delayed resolution and minimize the complications related with decompression of the vascular attached to the Ⅶ and Ⅷ nerve. Key words: Hemifacial spasm; Monitoring, intraoperative; Microvascular decompression; Distalcompression

A reappraisal of the value of lateral spread response monitoring in the treatment of hemifacial spasm by microvascular decompression

Background:Lateral spread response (LSR) to the electrical stimulation of a facial nerve branch is a specific electrophysiological feature of primary hemifacial spasm (HFS). The curative treatment of HFS is based...

Prognostic value of intra-operative lateral spread response monitoring during microvascular decompression in patients with hemifacial spasm

Hemifacial spasm (HFS) has characteristic and specific electrophysiological features, primarily the lateral spread response (LSR). The aim of this study was to evaluate the correlation between changes in the lateral spread response during microvascular decompression (MVD) and the clinical outcome after MVD. Seventy-two patients with HFS who were treated with MVD were included in this study. Intra-operative facial electromyography (EMG) was performed and brainstem auditory evoked potentials were monitored. In 32 (44.4%) patients, the LSR persisted after MVD. Among these 32 patients, 11 had mild HFS at discharge and six had mild HFS at the 6 month follow up. Out of the 40 patients in whom the LSR disappeared intra-operatively after MVD, five had mild HFS at discharge and four had mild HFS at the 6-moth follow up. The clinical outcome of HFS after MVD does not always correlate with intra-operative EMG abnormality. Therefore, the prognostic value of intra-operative LSR monitoring with respect to long-term results is questionable.