Astrocytoma resection using an interactive frameless stereotactic wand: an early experience

Multimodality image-guided surgery for the treatment of medically refractory epilepsy

OBJECT

The aim of this study was to review seizure outcome, imaging modalities used, and complications following surgery in patients with epilepsy who had undergone multimodality image-guided surgery at our institution.

METHODS

Data from patients with epilepsy who had undergone surgery between April 1999 and October 2001 were reviewed. During this time period, 116 operations were performed in 109 patients with medically refractory epilepsy. Among these patients, 22 were selected to undergo multimodality image-guided surgery primarily on the basis of whether they had no lesion visible on conventional magnetic resonance (MR) imaging sequences, multiple lesions, or one very large lesion that could not be completely resected without the risk of significant postoperative morbidity. A fourth group of patients in whom there was a single lesion in the eloquent cortex, a location associated with a significant risk of postoperative morbidity, was also included in the analysis. This latter group was assessed with the aid of intracranial grid electrodes that were coregistered to the MR image and were used intraoperatively to minimize electrode position error. Other imaging modalities used included positron emission tomography (PET), fluid-attenuated inversion recovery (FLAIR) MR imaging, and subtracted ictal-interictal single-photon positron emission computerized tomography (SPECT) coregistered with MR imaging (SISCOM). After coregistration, images were then downloaded onto an image-guided surgical system and the epileptogenic area was then resected. The mean patient age was 33 years (range 17-46 years), and there was a mean follow up of 27 months (range 14-41 months). Multimodality coregistrations used were as follows: nine PET scans, seven subdural electrode grids, four SISCOM studies, one FLAIR MR image, and one combined PET/subdural grid. Seizure outcome was excellent in 17 patients (77%) and not excellent in five (23%), or favorable in 19 (86%) and unfavorable in three (14%). Six patients (27%) had a transient neurological deficit, one patient (5%) a permanent major deficit, and three patients (15%) a permanent minor deficit. Five patients (24%) had a transient psychiatric problem postoperatively.

CONCLUSIONS

Multimodality image-guided surgery offers a new perspective in surgery for epilepsy. Functional imaging modalities previously lateralized and often localized a seizure focus, but did not provide enough anatomical information to resect the epileptogenic zone confidently and safely. The coregistration of these modalities to a volumetric MR image and their incorporation into an image-guided system has allowed surgeons to offer surgery to patients who may not previously have been considered eligible, with outcomes comparable to those in patients with more straightforward lesional epilepsy.

Intracranial navigation by using low-field intraoperative magnetic resonance imaging: preliminary experience

OBJECT

Intracranial navigation by using intraoperative magnetic resonance (iMR) imaging allows the surgeon to reassess anatomical relationships in near-real time during brain tumor surgery. The authors report their initial experience with a novel neuronavigation system coupled to a low-field iMR imaging system.

METHODS

Between October 2000 and December 2001, 70 neurosurgical procedures were performed using the mobile 0.12-tesla PoleStar N-10 iMR imaging system. The cases included 38 craniotomies, 15 brain biopsies, nine transsphenoidal approaches, and one drainage of a subdural hematoma. Tumor resection was performed using the awake method in seven of 38 cases. Of the craniotomies, image-confirmed complete or radical tumor resection was achieved in 28 cases, subtotal resection in eight cases, and open biopsies in two cases. Tumor resection was controlled with the use of image guidance until the final intraoperative images demonstrated that there was no residual tumor or that no critical brain tissue was at risk of compromise. In each stereotactic biopsy the location of the biopsy needle could be verified by intraoperative imaging and diagnostic tissue was obtained. Complications included a case of aseptic meningitis after a biopsy and one case of temporary intraoperative failure of the anesthesia machine. Awake craniotomies were performed successfully with no permanent neurological complications.

CONCLUSIONS

Intraoperative MR image-based neuronavigation is feasible when using the Odin PoleStar N-10 system for tumor resections that require multiple other surgical adjuncts including awake procedures, cortical mapping, monitoring of somatosensory evoked potentials, or electrocorticography. Use of the system for brain biopsies offers the opportunity of immediate verification of the needle tip location. Standard neurosurgical drills, microscopes, and other equipment can be used safely in conjunction with this iMR imaging system.

The role of image-guided technology in the surgical planning and resection of gliomas

Today's image-guided techniques provide the surgeon with new tools to plan and execute surgery on gliomas. When coupled with good judgment, they can extend what is safely operable and may maximize the extent of surgical resection. Intraoperative imaging such as ultrasonography or MRI may expand the utility of these systems in the foreseeable future.

Outcome in elderly patients undergoing definitive surgery and radiation therapy for supratentorial glioblastoma multiforme at a tertiary care institution

PURPOSE

To determine the efficacy of definitive surgery and radiation in patients aged 70 years and older with supratentorial glioblastoma multiforme.

METHODS AND MATERIALS

We selected elderly patients (> or = 70 years) who had primary treatment for glioblastoma multiforme at our tertiary care institution from 1977 through 1996. The study group (n = 102) included 58 patients treated with definitive radiation, 19 treated with palliative radiation, and 25 who received no radiation. To compare our results with published findings, we grouped our patients according to the applicable prognostic categories developed by the Radiation Therapy Oncology Group (RTOG): RTOG group IV (n = 6), V (n = 70), and VI (n = 26). Patients were retrospectively assigned to prognostic group IV, V, or VI based on age, performance status, extent of surgery, mental status, neurologic function, and radiation dose. Treatment included surgical resection and radiation (n = 49), biopsy alone (n = 25), and biopsy followed by radiation (n = 28). Patients were also stratified according to whether they were optimally treated (gross total or subtotal resection with postoperative definitive radiation) or suboptimally treated (biopsy, biopsy + radiation, surgery alone, or surgery + palliative radiation). Patients were considered to have a favorable prognosis (n = 39) if they were optimally treated and had a Karnofsky Performance Status (KPS) score of at least 70.

RESULTS

The median survival for patients according to RTOG groups IV, V, and VI was 9.2, 6.6, and 3.1 months, respectively (log-rank, p < 0.0004). The median overall survival was 5.3 months. The definitive radiation group (n = 58) had a median survival of 7.3 months compared to 4.5 months in the palliative radiation group (n = 19) and 1.2 months in the biopsy-alone group (p < 0.0001). Optimally treated patients had a median survival of 7.4 months compared to 2.4 months in those suboptimally treated (p < 0.0001). The favorable prognosis group had an 8.4-month median survival compared to 2.4 months in the unfavorable group (p < 0.0001). On multivariate analysis, the KPS, RTOG group, favorable/unfavorable prognosis, and optimal treatment/suboptimal treatment were significant predictors of survival.

CONCLUSION

Elderly patients with good performance status (> or = 70 KPS) when treated aggressively with maximal resection and definitive radiation had longer survival than those treated with palliative radiation and biopsy. Aggressive treatment in such patients should be considered.

A simple method of scalp localization using multiplanar reconstruction of MR images

BACKGROUND

Image-based scalp localization methods currently used are complex and not standardized. The authors have developed a simple yet accurate method for craniotomy localization using multiplanar reconstruction (MPR) algorithms.

METHODS

In this method, the goal is to localize a projected point (defined as T) of the center of the lesion on the scalp. An oblique coronal plane is reformatted using a patient's magnetic resonance (MR) images with MPR algorithms to include both the center of the lesion and bilateral external auditory meati. Then the distance between T and the ipsilateral external auditory meatus or sagittal suture (defined as S) is measured along the scalp contour in the plane. The distance between the bregma and S is also measured. These distances are used for scalp localization, using a tape measure in the operating room.

RESULTS

We have had successful scalp localization in six clinical cases. It took about 3 min to measure each distance on the MR console.

CONCLUSION

This method for craniotomy planning using MPR algorithms is simple and sufficiently accurate.

Computer-aided endoscopic sinus surgery

OBJECTIVES

To examine four different types of computer-aided endoscopic sinus surgical devices--the ISG Viewing Wand, the ISG infrared OptoTrak, the IGT FlashPoint 5000, and the VTI InstaTrak--with emphasis on their accuracy and ease of use.

STUDY DESIGN

Prospective study utilizing laboratory experiments and intraoperative data collection.

METHODS

A review of the literature is presented. Patients undergoing endoscopic sinus surgery during the study period were enlisted under FDA protocols with IRB consent. Groups of patients had surgery performed with each of the above devices--except the FlashPoint 5000. Accuracy measurements were recorded, and user and operating staff comments about ease of use were collected. The FlashPoint 5000 was used exclusively in the laboratory setting, where accuracy measurements were obtained on a cadaver skull.

RESULTS

The systems all demonstrated accuracy to within 2.00 mm. Ease of use was somewhat variable, but following a learning curve by the surgeon and operating department personnel, all of the units were considered to be relatively user friendly.

CONCLUSIONS

Computer-aided endoscopic sinus surgery appears to be the wave of the future. Nevertheless, the modern endoscopic sinus surgeon must have thorough training in the basic anatomy of the paranasal sinuses as well as the various surgical techniques.