To the Editor.—We read in the Medical News section of the February issue of the Archives1 a note about a new device for locating the facial nerve during removal of acoustic tumors. According to the description in the Archives, the device seems practically identical to a device that we developed more than three years ago. The instrument made use of a monopolar stimulator, and the facial electromyogram is made audible while the stimulus artifacts are suppressed, thus identical features as the one described in the February issue. Our instrument was fully described in the Journal of Neurosurgery2 two years ago, including circuit diagrams. The device and its use was also described at the annual meeting of the Neurosurgical Society of America held in Coronado, Calif, May 13 to 16, 1984.3
A commercial version of the device that we developed has been available for more than a