Heads-up intraoperative endoscopic imaging: a prospective evaluation of techniques and limitations.

Abstract

Endoscopes have been used adjunctively for spinal and cranial microsurgical procedures and directly for ventricular exploration, fenestration, and catheterization. Technological advances now allow for multi-imaging technologies, including a so-called "heads-up display," allowing the surgeon to view the operative field and the endoscopic image simultaneously. A high-resolution, active matrix liquid crystal display is built into the frame of the eyewear, with a display density of 182,000 pixels (280 x 650 pixels) and a resolution of 200 lines. The display occupies approximately 20% of the visual field. The headgear weighs 4 oz, with dimensions of 9 x 18 x 17 cm. The modular interface weighs 7 oz. Two different visualization systems can be used. The first uses a single integrated interface (IM 300), whereas the second (remote 900) is a 900-MHz frequency modulation wireless system that provides for a line-of-sight link between the NTSC source and the modular interface (range = 100 ft). Heads-up adjunctive endoscopy was used in 60 patients during 18 months. The procedures included 16 craniotomies, 1 intradural lumbar biopsy, and 42 ventriculoperitoneal shunt placements. Follow-up was obtained at a minimum of 1 year. Patient age ranged from 1 month to 58 years. The only complication was a transient loss of auditory evoked potentials after contact of the eighth nerve by the endoscope. We describe a portable, light-weight heads-up display imaging system, which we have used in 60 operative procedures. Benefits of the heads-up system include portability and a high-resolution digital monocular image, which reduces eye strain and vertigo. The ideal headgear will likely be an extremely high-resolution liquid crystal display-based or cathode ray tube-based semi-immersive system, with all of the benefits currently described for two-dimensional heads-up systems (i.e., light weight, portability, image quality, and the avoidance of complications associated with immersive systems).