Related Experiment Video
Updated: Feb 12, 2026

Measurement of Myocardial Lactate Production for Diagnosis of Coronary Microvascular Spasm
Published on: September 17, 2021
A new method for monitoring abnormal muscle response in hemifacial spasm: A prospective study
Seunghoon Lee1, Sang-Ku Park2, Jeong-A Lee1
1Department of Neurosurgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
Objective:
To examine a new abnormal muscle response (AMR) monitoring method during microvascular decompression (MVD) for hemifacial spasm.
Methods:
486 patients with hemifacial spasm were monitored for an AMR during MVD with a new method involving preoperative mapping and intraoperative centrifugal stimulation of the facial nerve. For the last 62 patients, we performed the AMR monitoring using both, the new and conventional methods simultaneously.
Results:
Preoperative facial nerve mapping showed that the maximal AMR was detected most frequently (66.9%) at the "F" location (the direction towards the frontalis muscle). An intraoperative AMR was observed in 86.2% of the patients, which disappeared after MVD in 96.4% of the patients. A comparison of the new and conventional methods respectively showed that AMR disappearance after MVD was observed in 98.2% and 61.8% of the patients, no AMR in 0% and 9.1%, and persistent AMR after MVD in 1.8% and 29.1%.
Conclusions:
The new AMR monitoring method demonstrated greater AMR monitoring efficacy and supports the finding that disappearance of an AMR is a good indicator of effective decompression during MVD surgery.
Significance:
Preoperative mapping and intraoperative centrifugal stimulation of the facial nerve during MVD surgery in HFS patients showed greater efficacy of AMR monitoring.
Related Concept Videos
Vascular Spasm
Design Example: Frog Muscle Response
When the switch connecting the RL circuit is closed, a brief muscle contraction is observed. This is because, at a steady state, the inductor acts like a short...
Abnormal Proliferation
Cardiovascular System Abnormal Findings I: Inspection and Palpation
Abnormal findings observed during an inspection
Respiratory System Abnormal Finding I: Inspection and Percussion
Inspection Findings
During an inspection, several findings may suggest the presence of respiratory distress or disease. Pursed-lip breathing, where exhalation is slowed by...
Cardiovascular System Abnormal Findings II: Auscultation
Abnormal Heart Sounds
Gallops:

