Introduction: The accuracy of existing frameless neuronavigation systems and the possibility of their use for stereotactic guidance largely depend on the method of registration. It is known that the highest accuracy is provided with registration using bone-implanted fiducials, but the disadvantage of this method is the invasiveness.

Methods: Alternative option for bone fixation of fiducials is detachable fixing of markers to the teeth of the upper jaw of a patient using the dental impression. This method provides a rigid immobility of the markers relative to the skull and the reproducibility of their spatial position during repeated biting of dental impression. As the support for fiducials we use device consisting of an aluminum arc and four rods with standard toroidal markers for CT and MRI. During a preoperative scanning and further surgery at the time of registration this device is reproducibly fixed to the patient's head with individual tooth impression. For navigation we use Medtronic StealthStation S7, supplemented with neurosurgical manipulator of stereotactic system POANIC, allowing for mutually perpendicular movements of a stereotactic instrument. For targeting we use the function "virtual extensing of the instrument" provided by the navigation station.

Results: We performed a series of phantom tests using this methodology. Results showed an average targeting error of 0.87 ± 0.33 mm for CT and 0.91 ± 0.56 mm for MRI-guidance. In clinical practice, this method has been engaged by us when performing operations in 10 patients with bilateral DBS of STN and GPI, 5 patients with stereoEEG and 19 patients with biopsy and stereotactic cryoablation of deep-seated gliomas. In patients with implanted electrodes, the average error of implantation was 1.66 ± 0.72 mm.

Conclusions: The introduced method allows to achieve accuracy corresponding to the use of bone-implanted markers, but it is less invasive and provides more comfortable conditions of frameless stereotactic procedure for patients.

Patient Care: Improving the efficiency of operations by increasing the accuracy of stereotactic guidance; painlessness of the procedure, reducing the risk of infection; lack of necessary of shaving the patient's head, reducing the cost of the procedure for eliminating of costly expendable materials.

Learning Objectives: None

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