3D-exoscopic visualization using the VITOM-3D in cranial and spinal neurosurgery. What are the limitations?

Objective: 3D exoscopic visualization in neurosurgical procedures is of interest for several reasons. The VITOM-3D exoscopic system is cheaper compared to the operating microscope (OM) and offers each person involved in the procedure the same image of the operative field. Little is known of limitations of this visualization technique. Patients and methods: : Prospectively, a consecutive series 34 procedures were assessed with focus on the following aspects: intraoperative limitation and the cause for a switch to the OM or endoscopy. A standardized questionnaire was answered by each individual involved in the procedure to assess the image quality, illumination, and magnification of the operative field. Intraoperative video recording and pre- and postoperative MRI and CT-scan were analyzed to assess the dimensions of the surgical approach. Results: Sixteen cranial and 18 spinal procedures (10 intra-axial, 6 extra-axial, 6 cervical, and 12 lumbar) were performed by seven neurosurgical attendings, twelve residents and twelve scrub nurses who all completed a standardized questionnaire after each procedure. Handling and identification of anatomical structures was rated equal or superior to the OM in 62 % and over 80 % of cases, respectively. The illumination and magnification of the operative field on the surface was rate in equal od superior in all cases and on the depth it was rated inferior to the OM over 60 % of cases. In one spinal and five cranial procedures a switch to the OM or endoscope were performed for the following reasons: poor illumination (4 cases), tissue identification (1 case), need for fluorescence imaging (1 case). Conclusion: 3D exoscopic visualization using the VITOM-3D is best suited for spinal procedures and for extraaxial cranial procedures. In case of small approach dimensions, the illumination and magnification of the depth of the operative field is rated inferior to the OM which resulted in difficulty of tissue identification and a switch to the OM.