Alexandra Chabrerie

Clinical Experience with a Hich Precision Image-Guided Neurosurgery System

We describe an image-guided neurosurgery system which we have successfully used on 70 cases in the operating room. The system is designed to achieve high positional accuracy with a simple and efficient interface that interferes little with the operating room’s usual procedures, but is general enough to use on a wide range of cases. It uses data from a laser scanner or a trackable probe to register segmented MR imagery to the patient’s position in the operating room, and an optical tracking system to track head motion and localize medical instruments. Output visualizations for the surgeon consist of an “enhanced reality display,” showing location of hidden internal structures, and an instrument tracking display, showing the location of instruments in the context of the MR imagery. Initial assessment of the system in the operating room indicates a high degree of robustness and accuracy.

Three-Dimensional Reconstruction and Surgical Navigation in Pediatric Epilepsy Surgery

We have used MRI-based three-dimensional (3D) reconstruction and a real-time, frameless, stereotactic navigation device to facilitate the removal of seizure foci in children suffering from intractable epilepsy. Using this system, the location of subdural grid and strip electrodes is recorded on the 3D model to facilitate focus localization and resection. Ten operations were performed, including 2 girls and 8 boys ranging in age from 3 to 17, during which 3D reconstruction and surgical instrument tracking navigation was used. In all the cases, the patients tolerated the procedure well and showed no postoperative neurological deficits. We believe this to be a valuable tool for a complete and safe resection of seizure foci, thereby reducing the incidence of postoperative neurological deficits and significantly improving the overall quality of life of the patients.

Decreases in ventricular volume correlate with decreases in ventricular pressure in idiopathic normal pressure hydrocephalus patients who experienced clinical improvement after implantation with adjustable valve shunts.

OBJECTIVE:This retrospective study examined whether changes in ventricular volume correspond with changes in adjustable valve pressure settings in a cohort of patients who received shunts to treat idiopathic normal pressure hydrocephalus. We also examined whether these pressure–volume curves and other patient variables would co-occur with a positive clinical response to shunting. METHODS:We selected 51 patients diagnosed with idiopathic normal pressure hydrocephalus who had undergone implantation of a Codman Hakim programmable valve (Medos S.A., Le Locle, Switzerland). Clinical data were gathered from the patients’ records and clinical notes by an investigator blinded to patients’ ventricular volumes. Ventricular volume was measured using 3D Slicer, an image analysis and interactive visualization software package developed and maintained at the Surgical Planning Laboratory at Brigham and Women’s Hospital. RESULTS:Eighty-six percent of patients with gait disturbance at presentation showed improvement of this symptom, 70% experienced improvement in incontinence, and 69% experienced improvement in dementia. For the group showing 100% clinical improvement, the correlation coefficient of average changes in valve pressure over time (ΔP/ΔT) and average changes in ventricular volume over time (ΔV/ΔT) were high at 0.843 (P < 0.05). For the group experiencing no or only partial improvement, the correlation coefficient was 0.257 (P = 0.32), indicating no correlation between average ΔV/ΔT and average ΔP/ΔT for each patient. CONCLUSION:This was a carefully analyzed modeling study of idiopathic normal pressure hydrocephalus treatment made possible only by adjustable valve technology. With careful volumetric analysis, we found that changes in ventricular volume correlated with adjustments in valve pressure settings for those patients who improved clinically after shunting. This suggests that positive clinical responders retained parenchymal elasticity, emphasizing the importance of dynamic changes in this cohort.

Three-Dimensional Reconstruction for Cortical Surgery: The Brigham and Women's Hospital Experience

Abstract: This article describes the use of 3D reconstruction for preoperative surgical planning and intraoperative navigation for cortical surgery. Before each surgical procedure, a detailed structural and functional model is reconstructed from magnetic resonance imaging scans and functional mapping modalities. These models, when integrated with direct intraoperative cortical mapping, create an integral 3D map of the cortical surface surrounding the lesion and its relation to the whole brain anatomy. A navigation system is coupled to the surgical field using skin-to-skin registration involving infrared light-emitting diode instrument tracking. This allows accurate guidance in the mapped 3D space. These detailed, patient-specific 3D maps of the brain are used as a method of accurately assessing the surgical approach, determining the potential neurologic risks, and navigating within the brain. One hundred fifty-five patients have been treated with this system for either preoperative planning or surgical navigation.

Excision of Cortical Dysplasia in the Language Area with Use of a Surgical Navigator: A Case Report

Summary: Purpose: We have developed an intraoperative optical tracking‐based navigational system that allows localization in the operative space. Using three‐dimensional reconstruction, this system has provided precise spatial information for intraoperative cortical mapping in patients with intractable epilepsy in whom the lesion lies close to eloquent cortex.