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Updated: Apr 16, 2026

Microvascular Decompression: Salient Surgical Principles and Technical Nuances
Published on: July 5, 2011
Effects of partial neuromuscular blockade on lateral spread response monitoring during microvascular decompression
Yang Hoon Chung1, Won Ho Kim2, Ik Soo Chung1
1Department of Anaesthesiology and Pain Medicine, Samsung Medical Centre, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea.
Objective:
We 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.
Methods:
Patients 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.
Results:
The 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.
Conclusions:
Partial 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.
Significance:
We suggested the availability of partial NMB for intraoperative LSR monitoring.
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