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Jeffrey R Balzer - One of the best experts on this subject based on the ideXlab platform.
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intraoperative neurophysiological monitoring during Microvascular Decompression of cranial nerves
2020Co-Authors: Carla Araujo Ferreira, Parthasarathy D Thirumala, Donald J Crammond, Raymond F Sekula, Jeffrey R BalzerAbstract:Abstract Since the inception of Microvascular Decompression (MVD), the techniques have evolved. Neurophysiology has come to play a prominent role for both complication avoidance and demonstration of surgical success. This chapter provides a historical review of the various pathologies, monitoring techniques, as well as our current approach to intraoperative neurophysiology for MVD including the principles, technical aspects, interpretation, and limitations of each of the different electrophysiological modalities.
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estimation of intraoperative stimulation threshold of the facial nerve in patients undergoing Microvascular Decompression
Skull Base Surgery, 2019Co-Authors: Rafey Feroze, Parthasarathy D Thirumala, Jeffrey R Balzer, Donald J Crammond, Michael M Mcdowell, Raymond F SekulaAbstract:Introduction Facial weakness can result from surgical manipulation of the facial nerve. Intraoperative neuromonitoring reduces functional impairment but no clear guidelines exist regarding interpretation of intraoperative electrophysiological results. Most studies describe subjects with facial nerves encumbered by tumors or those with various grades of facial nerve weakness. We sought to obtain the neurophysiological parameters and stimulation threshold following intraoperative facial nerve triggered electromyography (t-EMG) stimulation during Microvascular Decompression for trigeminal neuralgia to characterize the response of normal facial nerves via t-EMG. Methods Facial nerve t-EMG stimulation was performed in seven patients undergoing Microvascular Decompression for trigeminal neuralgia. Using constant current stimulation, single stimulation pulses of 0.025 to 0.2 mA intensity were applied to the proximal facial nerve. Compound muscle action potentials, duration to onset, and termination of t-EMG responses were recorded for the orbicularis oculi and mentalis muscles. Patients were evaluated for facial weakness following the surgical procedure. Results Quantifiable t-EMG responses were generated in response to all tested stimulation currents of 0.025, 0.05, 0.1, and 0.2 mA in both muscles, indicating effective nerve conduction. No patients developed facial weakness postoperatively. Conclusions The presence of t-EMG amplitudes in response to 0.025 mA suggests that facial nerve conduction can take place at lower stimulation intensities than previously reported in patients with tumor burden. Proximal facial nerve stimulation that yields responses with thresholds less than 0.05 mA may be a preferred reference baseline for surgical procedures within the cerebellopontine angle to prevent iatrogenic injury.
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reduction in high frequency hearing loss following technical modifications to Microvascular Decompression for hemifacial spasm
Journal of Neurosurgery, 2015Co-Authors: Parthasarathy D Thirumala, Miguel Habeych, Jeffrey R Balzer, Donald J Crammond, Yuefang Chang, A M Frederickson, Raymond F SekulaAbstract:OBJECT Microvascular Decompression is a safe and effective procedure to treat hemifacial spasm, but the operation poses some risk to the patient’s hearing. While severe sensorineural hearing loss across all frequencies occurs at a low rate in experienced hands, a recent study suggests that as many as one-half of patients who undergo this procedure may experience ipsilateral high-frequency hearing loss (HFHL), and as many as one-quarter may experience contralateral HFHL. While it has been suggested that drill-related noise may account for this finding, this study was designed to examine the effect of a number of techniques designed to protect the vestibulocochlear nerve from operative manipulation on the incidence of HFHL. METHODS Pure-tone audiometry was performed both preoperatively and postoperatively on 67 patients who underwent Microvascular Decompression for hemifacial spasm during the study period. A change of greater than 10 dB at either 4 kHz or 8 kHz was considered to be HFHL. Additionally, the a...
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appropriate time to establish baseline responses for brain stem auditory evoked potentials during Microvascular Decompression for hemifacial spasm
Journal of Clinical Neurophysiology, 2014Co-Authors: Santhosh Kumar Mohanraj, Parthasarathy D Thirumala, Miguel Habeych, Donald J Crammond, Jeffrey R BalzerAbstract:Purpose:To evaluate the appropriate time to establish baseline responses for brain stem auditory evoked potentials (BAEPs) during Microvascular Decompression for hemifacial spasm and its implications on the alarm criteria and outcomes.Methods:Overall, 61 patients who had intraoperative monitoring wi
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analysis of wave iii of brain stem auditory evoked potential waveforms during Microvascular Decompression of cranial nerve vii for hemifacial spasm
Journal of Clinical Neurophysiology, 2014Co-Authors: Parthasarathy D Thirumala, Miguel Habeych, Donald J Crammond, Balaji Krishnaiah, Jeffrey R BalzerAbstract:Introduction:Intraoperative monitoring of brain stem auditory evoked potential during Microvascular Decompression (MVD) prevent hearing loss (HL). Previous studies have shown that changes in wave III (wIII) are an early and sensitive sign of auditory nerve injury.Objective:To evaluate the changes of
Parthasarathy D Thirumala - One of the best experts on this subject based on the ideXlab platform.
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intraoperative neurophysiological monitoring during Microvascular Decompression of cranial nerves
2020Co-Authors: Carla Araujo Ferreira, Parthasarathy D Thirumala, Donald J Crammond, Raymond F Sekula, Jeffrey R BalzerAbstract:Abstract Since the inception of Microvascular Decompression (MVD), the techniques have evolved. Neurophysiology has come to play a prominent role for both complication avoidance and demonstration of surgical success. This chapter provides a historical review of the various pathologies, monitoring techniques, as well as our current approach to intraoperative neurophysiology for MVD including the principles, technical aspects, interpretation, and limitations of each of the different electrophysiological modalities.
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estimation of intraoperative stimulation threshold of the facial nerve in patients undergoing Microvascular Decompression
Skull Base Surgery, 2019Co-Authors: Rafey Feroze, Parthasarathy D Thirumala, Jeffrey R Balzer, Donald J Crammond, Michael M Mcdowell, Raymond F SekulaAbstract:Introduction Facial weakness can result from surgical manipulation of the facial nerve. Intraoperative neuromonitoring reduces functional impairment but no clear guidelines exist regarding interpretation of intraoperative electrophysiological results. Most studies describe subjects with facial nerves encumbered by tumors or those with various grades of facial nerve weakness. We sought to obtain the neurophysiological parameters and stimulation threshold following intraoperative facial nerve triggered electromyography (t-EMG) stimulation during Microvascular Decompression for trigeminal neuralgia to characterize the response of normal facial nerves via t-EMG. Methods Facial nerve t-EMG stimulation was performed in seven patients undergoing Microvascular Decompression for trigeminal neuralgia. Using constant current stimulation, single stimulation pulses of 0.025 to 0.2 mA intensity were applied to the proximal facial nerve. Compound muscle action potentials, duration to onset, and termination of t-EMG responses were recorded for the orbicularis oculi and mentalis muscles. Patients were evaluated for facial weakness following the surgical procedure. Results Quantifiable t-EMG responses were generated in response to all tested stimulation currents of 0.025, 0.05, 0.1, and 0.2 mA in both muscles, indicating effective nerve conduction. No patients developed facial weakness postoperatively. Conclusions The presence of t-EMG amplitudes in response to 0.025 mA suggests that facial nerve conduction can take place at lower stimulation intensities than previously reported in patients with tumor burden. Proximal facial nerve stimulation that yields responses with thresholds less than 0.05 mA may be a preferred reference baseline for surgical procedures within the cerebellopontine angle to prevent iatrogenic injury.
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reduction in high frequency hearing loss following technical modifications to Microvascular Decompression for hemifacial spasm
Journal of Neurosurgery, 2015Co-Authors: Parthasarathy D Thirumala, Miguel Habeych, Jeffrey R Balzer, Donald J Crammond, Yuefang Chang, A M Frederickson, Raymond F SekulaAbstract:OBJECT Microvascular Decompression is a safe and effective procedure to treat hemifacial spasm, but the operation poses some risk to the patient’s hearing. While severe sensorineural hearing loss across all frequencies occurs at a low rate in experienced hands, a recent study suggests that as many as one-half of patients who undergo this procedure may experience ipsilateral high-frequency hearing loss (HFHL), and as many as one-quarter may experience contralateral HFHL. While it has been suggested that drill-related noise may account for this finding, this study was designed to examine the effect of a number of techniques designed to protect the vestibulocochlear nerve from operative manipulation on the incidence of HFHL. METHODS Pure-tone audiometry was performed both preoperatively and postoperatively on 67 patients who underwent Microvascular Decompression for hemifacial spasm during the study period. A change of greater than 10 dB at either 4 kHz or 8 kHz was considered to be HFHL. Additionally, the a...
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appropriate time to establish baseline responses for brain stem auditory evoked potentials during Microvascular Decompression for hemifacial spasm
Journal of Clinical Neurophysiology, 2014Co-Authors: Santhosh Kumar Mohanraj, Parthasarathy D Thirumala, Miguel Habeych, Donald J Crammond, Jeffrey R BalzerAbstract:Purpose:To evaluate the appropriate time to establish baseline responses for brain stem auditory evoked potentials (BAEPs) during Microvascular Decompression for hemifacial spasm and its implications on the alarm criteria and outcomes.Methods:Overall, 61 patients who had intraoperative monitoring wi
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analysis of wave iii of brain stem auditory evoked potential waveforms during Microvascular Decompression of cranial nerve vii for hemifacial spasm
Journal of Clinical Neurophysiology, 2014Co-Authors: Parthasarathy D Thirumala, Miguel Habeych, Donald J Crammond, Balaji Krishnaiah, Jeffrey R BalzerAbstract:Introduction:Intraoperative monitoring of brain stem auditory evoked potential during Microvascular Decompression (MVD) prevent hearing loss (HL). Previous studies have shown that changes in wave III (wIII) are an early and sensitive sign of auditory nerve injury.Objective:To evaluate the changes of
Peter J Jannetta - One of the best experts on this subject based on the ideXlab platform.
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Microvascular Decompression of cranial nerves lessons learned after 4400 operations
Journal of Neurosurgery, 1999Co-Authors: Mark R Mclaughlin, Brent L Clyde, Peter J Jannetta, Brian R Subach, Christopher H Comey, Daniel K ResnickAbstract:Object. Microvascular Decompression has become an accepted surgical technique for the treatment of trigeminal neuralgia, hemifacial spasm, glossopharyngeal neuralgia, and other cranial nerve rhizopathies. The senior author (P.J.J.) began performing this procedure in 1969 and has performed more than 4400 operations. The purpose of this article is to review some of the nuances of the technical aspects of this procedure. Methods. A review of 4415 operations shows that numerous modifications to the technique of Microvascular Decompression have occurred during the last 29 years. Of the 2420 operations performed for trigeminal neuralgia, hemifacial spasm, and glossopharyngeal neuralgia before 1990, cerebellar injury occurred in 21 cases (0.87%), hearing loss in 48 (1.98%), and cerebrospinal fluid (CSF) leakage in 59 cases (2.44%). Of the 1995 operations performed since 1990, cerebellar injuries declined to nine cases (0.45%), hearing loss to 16 (0.8%), and CSF leakage to 37 (1.85% p < 0.01, test for equality of...
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delayed facial weakness after Microvascular Decompression of cranial nerve vii
Surgical Neurology, 1998Co-Authors: Thomas J Lovely, Christopher C Getch, Peter J JannettaAbstract:Abstract Background Retromastoid craniectomy and Microvascular Decompression of cranial nerve VII for hemifacial spasm is a well accepted and effective treatment. Risks of the operation relate to the surgical approach in general and to the seventh nerve in particular. Delayed facial weakness is an unusual and little-described complication of the procedure. The purpose of this review is to describe this complication and the characteristics of the patients so affected. Methods Between 1972 and 1996, 985 patients have undergone Microvascular Decompression for hemifacial spasm. During this time, 28 patients (2.8%) undergoing Decompression of the facial nerve and 1 patient undergoing Decompression of the cochlear nerve for tinnitus developed delayed facial palsy. Results The weakness was at least a House Grade III or worse and was complete in 11 of the patients. The time to occurrence averaged 12 days, with a tight range of 7 to 16 days. There were no factors such as duration of symptoms, intraoperative findings, or preoperative botulinum injections that were predictive of this postoperative weakness. In all patients there was almost complete recovery (House Grade I or II). Conclusions Delayed facial weakness after MVD of CN VII can occur in up to 3% of cases. The onset of weakness after operation is consistent in its timing, occurring on average 12 days after the procedure. Although the etiology of this complication is uncertain, the palsy spontaneously resolves with a good or excellent outcome.
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Microvascular Decompression of the left lateral medulla oblongata for severe refractory neurogenic hypertension
Neurosurgery, 1998Co-Authors: Elad I. Levy, Brent L Clyde, M R Mclaughlin, Peter J JannettaAbstract:OBJECTIVE: To demonstrate that Microvascular Decompression of the left medulla oblongata is a safe and effective modality for treating elevated blood pressure in patients with severe medically refractory "essential" hypertension (HTN). METHODS: Twelve patients with medically intractable HTN with or without autonomic dysreflexia underwent Microvascular Decompression of the left rostral ventrolateral medulla oblongata. Causes such as pheochromocytoma, carcinoid syndrome, and renal disease were ruled out before surgery. Indications for surgery included systolic blood pressures greater than 180 mm Hg refractory to three or more medications, severe blood pressure lability, or medically resistant HTN at systolic pressures greater than 160 mm Hg associated with autonomic dysreflexia and/or magnetic resonance images demonstrating left medullary compression. The median age and follow-up duration were 51 years and 4.1 years, respectively. RESULTS: Ten of 12 patients experienced reductions in systolic blood pressure greater than 20 mm Hg. Of these 10 patients, pressure reductions were temporary (6 mo) in two. Seven of eight patients experienced improvement in blood pressure lability and/or autonomic dysreflexia, with five patients showing sustained improvements. CONCLUSION: Microvascular Decompression of the left rostral ventrolateral medulla oblongata may be an effective treatment modality for patients suffering from severe HTN and/or autonomic dysreflexia refractory to medical management.
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the long term outcome of Microvascular Decompression for trigeminal neuralgia
The New England Journal of Medicine, 1996Co-Authors: Fred G Barker, Peter J Jannetta, David J Bissonette, Mark V Larkins, Hae Dong JhoAbstract:Background Several surgical procedures to treat trigeminal neuralgia (tic douloureux) are available, but most reports provide only short-term follow-up information. Methods We describe the long-term results of surgery in 1185 patients who underwent Microvascular Decompression of the trigeminal nerve for medically intractable trigeminal neuralgia. The outcome of the procedure was assessed prospectively with annual questionnaires. Results Of the 1185 patients who underwent Microvascular Decompression during the 20-year study period, 1155 were followed for 1 year or more after the operation. The median follow-up period was 6.2 years. Most postoperative recurrences of tic took place in the first two years after surgery. Thirty percent of the patients had recurrences of tic during the study period, and 11 percent underwent second operations for the recurrences. Ten years after surgery, 70 percent of the patients (as determined by Kaplan–Meier analysis) had excellent final results — that is, they were free of p...
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Microvascular Decompression for spasmodic torticollis
Acta Neurochirurgica, 1995Co-Authors: Hae Dong Jho, Peter J JannettaAbstract:Twenty patients with spasmodic torticollis (ST) were treated by Microvascular Decompression (MVD) of the spinal accessory nerves, the upper cervical nerve roots and the brainstem. Thirteen were female and seven male. Median age was 47 years (range 39 to 70 years). Median duration of symptoms was 5 years (range 4 months to 17 years). Ten had right horizontal; nine, left horizontal; and one, retrocollis ST. Twenty-two operations were performed on twenty patients, suboccipital craniectomy and C_1 laminectomy in 18 and retromastoid craniectomy in 4 operations. The most common compressing blood vessels were the vertebral artery and/or the posterior inferior cerebellar artery. No nerve section was performed. Three patients died of unrelated conditions, 3, 5 1/2, and 6 years postoperatively, respectively. Minimum follow-up period in the rest of the cases is 5 years (range 5 to 10 years). Thirteen (65%) were cured, four (20%) improved with minimal spasm, one (5%) improved with moderate spasm, and two (10%) improved minimally or unchanged. In most cases the cure or improvement was noticed gradually over 6 months to two years following the operation. There was no operative mortality. Postoperative morbidities included transient cerebrospinal fluid leakage through the surgical incision in one case and an apparent multiple small vessel stroke involving periventricular white matter in one reoperation case with full recovery. MVD for ST is a nondestructive benign procedure with high probability of cure or significant improvement.
Donald J Crammond - One of the best experts on this subject based on the ideXlab platform.
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intraoperative neurophysiological monitoring during Microvascular Decompression of cranial nerves
2020Co-Authors: Carla Araujo Ferreira, Parthasarathy D Thirumala, Donald J Crammond, Raymond F Sekula, Jeffrey R BalzerAbstract:Abstract Since the inception of Microvascular Decompression (MVD), the techniques have evolved. Neurophysiology has come to play a prominent role for both complication avoidance and demonstration of surgical success. This chapter provides a historical review of the various pathologies, monitoring techniques, as well as our current approach to intraoperative neurophysiology for MVD including the principles, technical aspects, interpretation, and limitations of each of the different electrophysiological modalities.
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estimation of intraoperative stimulation threshold of the facial nerve in patients undergoing Microvascular Decompression
Skull Base Surgery, 2019Co-Authors: Rafey Feroze, Parthasarathy D Thirumala, Jeffrey R Balzer, Donald J Crammond, Michael M Mcdowell, Raymond F SekulaAbstract:Introduction Facial weakness can result from surgical manipulation of the facial nerve. Intraoperative neuromonitoring reduces functional impairment but no clear guidelines exist regarding interpretation of intraoperative electrophysiological results. Most studies describe subjects with facial nerves encumbered by tumors or those with various grades of facial nerve weakness. We sought to obtain the neurophysiological parameters and stimulation threshold following intraoperative facial nerve triggered electromyography (t-EMG) stimulation during Microvascular Decompression for trigeminal neuralgia to characterize the response of normal facial nerves via t-EMG. Methods Facial nerve t-EMG stimulation was performed in seven patients undergoing Microvascular Decompression for trigeminal neuralgia. Using constant current stimulation, single stimulation pulses of 0.025 to 0.2 mA intensity were applied to the proximal facial nerve. Compound muscle action potentials, duration to onset, and termination of t-EMG responses were recorded for the orbicularis oculi and mentalis muscles. Patients were evaluated for facial weakness following the surgical procedure. Results Quantifiable t-EMG responses were generated in response to all tested stimulation currents of 0.025, 0.05, 0.1, and 0.2 mA in both muscles, indicating effective nerve conduction. No patients developed facial weakness postoperatively. Conclusions The presence of t-EMG amplitudes in response to 0.025 mA suggests that facial nerve conduction can take place at lower stimulation intensities than previously reported in patients with tumor burden. Proximal facial nerve stimulation that yields responses with thresholds less than 0.05 mA may be a preferred reference baseline for surgical procedures within the cerebellopontine angle to prevent iatrogenic injury.
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reduction in high frequency hearing loss following technical modifications to Microvascular Decompression for hemifacial spasm
Journal of Neurosurgery, 2015Co-Authors: Parthasarathy D Thirumala, Miguel Habeych, Jeffrey R Balzer, Donald J Crammond, Yuefang Chang, A M Frederickson, Raymond F SekulaAbstract:OBJECT Microvascular Decompression is a safe and effective procedure to treat hemifacial spasm, but the operation poses some risk to the patient’s hearing. While severe sensorineural hearing loss across all frequencies occurs at a low rate in experienced hands, a recent study suggests that as many as one-half of patients who undergo this procedure may experience ipsilateral high-frequency hearing loss (HFHL), and as many as one-quarter may experience contralateral HFHL. While it has been suggested that drill-related noise may account for this finding, this study was designed to examine the effect of a number of techniques designed to protect the vestibulocochlear nerve from operative manipulation on the incidence of HFHL. METHODS Pure-tone audiometry was performed both preoperatively and postoperatively on 67 patients who underwent Microvascular Decompression for hemifacial spasm during the study period. A change of greater than 10 dB at either 4 kHz or 8 kHz was considered to be HFHL. Additionally, the a...
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appropriate time to establish baseline responses for brain stem auditory evoked potentials during Microvascular Decompression for hemifacial spasm
Journal of Clinical Neurophysiology, 2014Co-Authors: Santhosh Kumar Mohanraj, Parthasarathy D Thirumala, Miguel Habeych, Donald J Crammond, Jeffrey R BalzerAbstract:Purpose:To evaluate the appropriate time to establish baseline responses for brain stem auditory evoked potentials (BAEPs) during Microvascular Decompression for hemifacial spasm and its implications on the alarm criteria and outcomes.Methods:Overall, 61 patients who had intraoperative monitoring wi
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analysis of wave iii of brain stem auditory evoked potential waveforms during Microvascular Decompression of cranial nerve vii for hemifacial spasm
Journal of Clinical Neurophysiology, 2014Co-Authors: Parthasarathy D Thirumala, Miguel Habeych, Donald J Crammond, Balaji Krishnaiah, Jeffrey R BalzerAbstract:Introduction:Intraoperative monitoring of brain stem auditory evoked potential during Microvascular Decompression (MVD) prevent hearing loss (HL). Previous studies have shown that changes in wave III (wIII) are an early and sensitive sign of auditory nerve injury.Objective:To evaluate the changes of
Miguel Habeych - One of the best experts on this subject based on the ideXlab platform.
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reduction in high frequency hearing loss following technical modifications to Microvascular Decompression for hemifacial spasm
Journal of Neurosurgery, 2015Co-Authors: Parthasarathy D Thirumala, Miguel Habeych, Jeffrey R Balzer, Donald J Crammond, Yuefang Chang, A M Frederickson, Raymond F SekulaAbstract:OBJECT Microvascular Decompression is a safe and effective procedure to treat hemifacial spasm, but the operation poses some risk to the patient’s hearing. While severe sensorineural hearing loss across all frequencies occurs at a low rate in experienced hands, a recent study suggests that as many as one-half of patients who undergo this procedure may experience ipsilateral high-frequency hearing loss (HFHL), and as many as one-quarter may experience contralateral HFHL. While it has been suggested that drill-related noise may account for this finding, this study was designed to examine the effect of a number of techniques designed to protect the vestibulocochlear nerve from operative manipulation on the incidence of HFHL. METHODS Pure-tone audiometry was performed both preoperatively and postoperatively on 67 patients who underwent Microvascular Decompression for hemifacial spasm during the study period. A change of greater than 10 dB at either 4 kHz or 8 kHz was considered to be HFHL. Additionally, the a...
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appropriate time to establish baseline responses for brain stem auditory evoked potentials during Microvascular Decompression for hemifacial spasm
Journal of Clinical Neurophysiology, 2014Co-Authors: Santhosh Kumar Mohanraj, Parthasarathy D Thirumala, Miguel Habeych, Donald J Crammond, Jeffrey R BalzerAbstract:Purpose:To evaluate the appropriate time to establish baseline responses for brain stem auditory evoked potentials (BAEPs) during Microvascular Decompression for hemifacial spasm and its implications on the alarm criteria and outcomes.Methods:Overall, 61 patients who had intraoperative monitoring wi
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analysis of wave iii of brain stem auditory evoked potential waveforms during Microvascular Decompression of cranial nerve vii for hemifacial spasm
Journal of Clinical Neurophysiology, 2014Co-Authors: Parthasarathy D Thirumala, Miguel Habeych, Donald J Crammond, Balaji Krishnaiah, Jeffrey R BalzerAbstract:Introduction:Intraoperative monitoring of brain stem auditory evoked potential during Microvascular Decompression (MVD) prevent hearing loss (HL). Previous studies have shown that changes in wave III (wIII) are an early and sensitive sign of auditory nerve injury.Objective:To evaluate the changes of
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emprical factors associated with brainstem auditory evoked potential monitoring during Microvascular Decompression for hemifacial spasm and its correlation to hearing loss
Acta Neurochirurgica, 2014Co-Authors: Tingting Ying, Parthasarathy D Thirumala, Miguel Habeych, Donald J Crammond, Yuefang Chang, Jeffrey R BalzerAbstract:Background Cranial nerve VIII is at risk during Microvascular Decompression (MVD) for hemifacial spasm (HFS). The primary aim of this study is to evaluate the empirical factors associated with brainstem auditory evoked potential monitoring and its correlation to post operative hearing loss (HL) after MVD for HFS.
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Microvascular Decompression for hemifacial spasm evaluating outcome prognosticators including the value of intraoperative lateral spread response monitoring and clinical characteristics in 293 patients
Journal of Clinical Neurophysiology, 2011Co-Authors: Parthasarathy D Thirumala, Aalap C Shah, Tara Nikonow, Miguel Habeych, Jeffrey R Balzer, Donald J Crammond, Lois Burkhart, Yuefang Chang, Paul A Gardner, Amin B KassamAbstract: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.