[External Ocular Movement(EOM)Monitoring].

The intraoperative monitoring of extraocular motor nerves allows optimal skull base surgery by protecting the cranial nerves. For detecting cranial nerve function, several methods, such as external ocular movement monitoring with an electrooculogram(EOG), electromyogram(EMG), and piezoelectric device sensors, are present. While being valuable and useful, several problems related to its accurate monitoring persist when scanning from inside the tumor, which might be far from the cranial nerves. Here, we described three modalities, free-run EOG monitoring, trigger EMG monitoring, and piezoelectric sensor monitoring for monitoring external ocular movement. Improvement of these processes is essential for appropriately conducting these procedures during neurosurgical operations without harming the extraocular motor nerves.