Preservation of facial nerve function is a major concern during ear surgery. Facial nerve monitoring may offer intangible advantages to the experienced or attending surgeon that allow surgery to proceed more rapidly and with a greater sense of confidence.
The Silverstein Model S8 is a non-invasive monitoring system ideal for routine ear surgery.
- Easily managed by operating room staff
- Rapid set-up
- Low cost per case
Monitoring is accomplished with a tactile monitor (Cheek Muscle Movement Sensor) placed on the patient’s cheek, and an audible alarm is given when muscle movement is detected.
LOCATING THE FACIAL NERVE
To locate distance from the nerve, it is useful to use the stimulator and monitor while drilling to estimate the depth of bony covering. Dr. Herbert Silverstein et al¹ estimated that there is an approximate relationship of one milliamp of current per one millimeter of bone. While not absolute, ‘one-milliamp-to-one-millimeter’ is a useful rule of thumb.
Constant-current, pulsed stimulation is delivered from two probe options; a monopolar disposable and a Remote Probe, which is monopolar. The Remote Probe has buttons on the hand piece, and lets the surgeon control the level of current intensity being delivered to the patient.
Silverstein H, Smouha E, Jones R: Routine identification of the facial nerve using electrical stimulation during ontological and neurotological surgery. Laryngoscope 98:726-730, 1988