Navigational Surgery of the Skull Base and Other Vital Area Lesions Using the Mehrkoordinaten Manipulator (MKM) System

After introduction of the Mehrkoordinaten Manipulator (MKM; multicoordinate manipulator) system (Zeiss, Oberkochen, Germany) for frameless stereotactic microneurosurgery, we could determine the target point and the access route to the lesion preoperatively and outline the lesion and critical areas at a computer workstation. The system integrates stereotactically oriented computed tomography and magnetic resonance imaging with optical visualization by the microscope, displaying the spatial location of the point of focus in three sectional images. Additionally, the system superimposes the access route to the lesion, the target point with its location and direction, and the outline of the lesion and critical areas in the microscope. MKM-guided stereotactic microneurosurgery was performed in 14 patients with lesions involving the skull base, brain stem, and other deep sites. Because the lesion and surrounding structures of the skull base and brain stem maintained constant anatomical relationships during surgery, MKM-guided surgery provided easier access to the lesion, safer skull-base drilling, and better surgical results than classical microsurgical techniques. For small deep-seated lesions, the system could provide frameless stereotactic access to the lesion, but the outline of the lesion was not precisely superimposed because of displacement of the lesion and surrounding structures by cerebrospinal fluid outflow, brain retraction, and resection. The MKM system is very useful in its present configuration for lesions involving the skull base and brain stem. In the future, the MKM computer workstation should be given capability to interact with real-time intraoperative imagings to display small deep-seated lesions more accurately.