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

OBJECTIVE: 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. INSTRUMENTATION: 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). RESULTS: 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. CONCLUSION: 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).