gms | German Medical Science

Objective: To assess visual field, magnification, illumination, ergonomics, depth effect and 3D-impression of the prototype of a 3D-Exoscope in comparison to a standard operating microscope.

Method: A pterional approach was performed in 3 ETOH fixed specimens (6 sides) in the anatomical lab using a Mayfield headholder and standard neurosurgical equipment (Aesculap). A standard operating microscope (FA Zeiss, Pentero) was compared to a 3D- Exoscope prototype (FA Aesculap). Dimensions like visual field, magnification, illumination, ergonomics, depth effect and 3D impression were compared by 3 neurosurgeons and one anatomist and rated in a verbal scale: very bad (--), bad (-), neutral (0), good (+), very good (++).

Results: In all approaches the structures of interest ICA, ACA, MCA, ipsi-and contralateral optic nerve, optic chiasm, pituitary stalk, ipsilateral olfactory nerve, and oculomotor nerve could be clearly visualized with both devices (++). Magnification showed similar results (+). The Exoscope had more magnification potential whereas the visual quality got worse in higher magnification levels. The illumination showed better results in the microscope with direct illumination of the working field (++), whereas the Exoscope needed an additional light source in higher magnifications (-). Surgeons were more comfortable with the 3D Exoscope (ergonomics ++) because all structures could be clearly visualized and reached by movement of the exoscope without changing sitting-, spine-, or head-position. Visualizing of contralateral structures was linked to extensive changes in spine-, head- and neck-position using the microscope (-). Depth effect and 3D impression showed similar results (++). None of the surgeons felt uncomfortable or had the impression to endanger sensitive structures using the exoscope.

Conclusions: The operating microscope is the gold standard visualization tool in neurosurgery due to its illumination, stereoscopy and magnification. Nevertheless, it causes ergonomic problems because of its size and localization between the surgeon and the operating field. The prototype of a 3D Exoscope showed comparable features in visual field, stereoscopic impression and magnification with a clear benefit concerning the ergonomic possibilities. With further development of light sources and 3D camera resolutions the 3D exoscope seems to have the potential to be an equivalent valid alternative to the operating microscope in neurosurgical practice.