Sistema auxiliar para colocar el marco estereotactico en el craneo / Auxiliary system for positioning the stereotactic frame to the skull

En neurocirugía funcional y radioneurocirugía estereotáctica, la fijación de un marco en el cráneo, permite el establecimiento de un sistema tridimensional de coordenadas, para localizar y definir con precisión los objetivos en el cerebro. El montaje se basa en la experiencia y la percepción visual del médico, pero los resultados son subjetivos y la calibración de las coordenadas del marco con respecto al cráneo no siempre es la óptima para el desarrollo del procedimiento quirúrgico. Este estudio evalúa la eficacia y la funcionalidad de un sistema auxiliar diseñado para colocar el marco estereotáctico en el cráneo. La evaluación se realiza por medio de un estudio comparativo de dos grupos de 7 pacientes cada uno sometidos a tratamiento de radioneurocirugía. En el primer grupo no es utilizado el sistema, solo en el segundo, se tomaron 165 imágenes (IRM) en promedio por cada estudio. El empleo del sistema auxiliar disminuye la variación de la inclinación y la rotación del marco con respecto al cráneo hasta un 64%, la apreciación subjetiva del médico es sustituida por una medición objetiva, obteniéndose certidumbre al posicionar el marco sobre el cráneo. Los resultados muestran que el sistema auxiliar diseñado es eficaz y funcional.

In functional neurosurgery and stereotactic radioneurosurgery, the fixation of a frame to the skull allows the establishment of a three-dimensional coordinate system, to locate and precisely defined objectives in the brain. The montage is based on experience and visual perception the doctor, the results obtained and the calibration of the coordinates of the frame with respect to the skull is not always the optimal for developing the surgical procedure. This study evaluates the effectiveness and functionality of an auxiliary system designed to collocate the stereotactic frame to the skull. The evaluation is done by means of a comparative study of two groups of 7 patients each underwent radioneurosurgery treatment. The first group is not using the system, only in the second, were performed on average 165 images (MRI) for each study. The use of auxiliary system reduces the variation of the inclination and rotation of the frame with respect to the skull by 64%, the subjective appreciation the doctor is substituted by an objective measure, thus obtaining certainty to position the frame on the skull. The results show that the auxiliary system designed is effective and functional.

Cortical Localization of Scalp Electrodes on Three-Dimensional Brain Surface Using Frameless Stereotactic Image Guidance System

BACKGROUND: The purpose of this study was to localize the cortical regions reflected by overlying scalp electrodes. METHODS: We enrolled 10 patients with epilepsy (5 males, mean age 29.7 years old). Thin slice coronal T1 weighted MR images were obtained and then scalp EEG electrodes were placed based on an international 10-20 system. Cortical locations of scalp electrodes were determined using a real-time frameless stereotactic image guidance system, Brainsight(R). RESULTS: The locations of 19 scalp electrodes were marked on the 3D rendered cortical surface of one representative patient's MRI; Fp1 (Fp2) on the anterior pole of the middle frontal gyrus, Fz on the mid-point of the interhemispheric fissure in the frontal lobe, F3 (F4) on the mid-portion of the middle frontal gyrus, F7 (F8) on the pars triangularis of the inferior frontal gyrus, Cz on the interhemispheric fissure where a lateral precentral gyrus starts, C3 (C4) scattered around postcentral gyrus, T3 (T4) on the middle temporal gyrus, P3 (P4) on the angular gyrus, Pz on the mid-point of the interhemispheric fissure in the parietal lobe, T5 (T6) on the posterior part of the inferior temporal gyrus, and O1 (O2) on the occipital pole. CONCLUSIONS: The locations of scalp electrodes were well correlated with conventional concepts of their cortical locations. The individual differences of the scalp electrode locations may be due to the different sizes and morphologies of the brains in each of the patients. Real time cortical localization of scalp electrodes using the Frameless Stereotactic Image Guidance System may provide useful information for more accurate localization of focal cerebral activity in partial epilepsy patients.

Comparative Study on Frameless Stereotactic Hematoma Aspiration versus Frame-Based Stereotactic Hematoma Aspiration in Deep Seated Intracerebral Hemorrhage: A Clinical Article / 대한뇌혈관외과학회지

OBJECTIVE: We compare the frameless stereotactic hematoma aspiration (FSA) with frame-based stereotactic hematoma aspiration (FBSA) in intracerebral hemorrhage (ICH) about operative advantage and result. MATERIAL AND METHODS: Between January 2002 and December 2002, we surgically treated 30 patients presenting with spontaneous ICH at our hospital. 15 patients underwent FBSA via Codman-Roberts-Wells system and catheter placement with urokinase infusion and drainage, and 15 patients underwent FSA and catheter placement via neuronavigator with urokinase infusion and drainage. RESULTS: The amount of remaining hematoma and removal rate were from 1 to 26 and 76% in FSA and from 2 to 55 and 60.4% in FBSA. The entry point was selected within 2.03+/-0.85 cm in a frontal direction from Kocher's point and 2.86+/-0.57 cm in lateral direction from Kocher's point and the trajectory was selected toward the distal margin of hematoma along the long axis of hematoma in FSA but the entry point was restricted within Kocher's point and the trajectory was selected toward the center of the maximum axial section of hematoma in FBSA. The mean time of operative preparation was mean 61 minutes in FSA and 78 minutes in FBSA. The number of patients not required with infusion of urokinase was 10 in FSA and 7 in FBSA. The mean duration of urokinase infusion was 3.6 day in FSA and 4.1 day in FBSA. CONCLUSION: FSA is fast, simple and effective procedure. In comparison with FBSA, FSA has advantage in selecting the entry point and the trajectory for hematoma aspiration and catheter placement, and in a less time-consuming procedure.

Clinical Application of Frameless Stereotaxy "Viewing Wand": Its Usefulness and Limitation

The Viewing Wand is a frameless stereotactic device to provide image-based intraoperative navigation, allowing accurate neurosurgical planning and procedures. The authors applied the frameless stereotactic device called "ISG Viewing Wand" to 30 cases of intracranial lesions and evaluated for its usefulness and limitation. The Viewing Wand was used in 3 cases in conjunction with CT and 27 cases with MRI. The actual error of this system after the registration was judged by the operating surgeon to be less than 2mm in CT or MR image. The useful registrations were possible in 25(83%) out of 30 cases. But it was not useful in 5 cases, because of movement of fiducial markers in 2 cases and head movement after registration in 3 cases. In 25 cases having useful registration, the wand was helpful to localize the lesion for designing the scalp incision and bone flap, as well as the extent of surgical resection of lesions. As a whole, the viewing wand was found to be reliable and accurate. The system is a useful navigational aid that allows a direct approach to intracranial pathology without the drawbacks of application and the limitations of a frame-based stereotactic device.