VNG using infrared video recordings offer several advantages in terms of patient flow and cost effectiveness. The most obvious is the reduction in time needed to complete an ENG examination. In our office, an average of about 60 minutes is required per patient with electrode-based ENG and 45 to 50 minutes per patient with infrared video VNG.
Another benefit of infrared video is that during the initial physical examination a quick screening for obvious spontaneous, gaze, or positional nystagmus is typically performed. Based on current Medicare reimbursement policies (which are subject to change), inspection for gaze or spontaneous or positional nystagmus is not reimbursable unless it is accompanied by a hard-copy recording. By performing this examination through infrared goggles with recording capabilities, the provider can be reimbursed. Of course, electrode-based recordings are also reimbursed, but the practitioner must take the time to perform skin preparation, apply electrodes, and allow darkness adaptation time. Infrared video does not require the use of electrodes, which saves a few dollars in cost per test.
The most notable disadvantage to infrared video that in some patients the eye simply cannot be tracked. Older or medicated patients sometimes have difficulty keeping their eyes open while in total darkness or when vertigo is induced. Patients who have small eyes, droopy eyelids or poor contrast between the pupil and the iris and sclera are better suited for electrode-based recordings or ENG. Patients with permanent tatooed eyeliner are sometimes impossible to track consistently.
We invested in a VNG unit that allows us to switch over to electrode-based recording when we need to. We find that we use it infrequently. This adds a bit to the cost of the equipment, so adding this option is a judgment call.
Video-based systems are typically more expensive than electrode-based systems, but overall VNG is the clear winner. According to one leading manufacturer of both VNG and ENG equipment, the vast majority of units sold in the past few years are VNG only, with a handful fitted with the ENG option. No ENG-only units have been manufactured or sold in several years.
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