Use of intraoperative MRI for resection of gliomas

Literature has shown that extent of tumor resection has an impact on quality of life and survival of patients with gliomas. Intraoperative MRI has been used to increase resection while preserving procedure's safety. METHOD: The first five patients with gliomas operated on at the University of São Paulo using intraoperative MRI are reported. All but one patient had Karnofsky Performance Status of 100% before surgery. Presentation symptoms were progressive headache, seizures, behavior disturbance, one instance of hemianopsia, and another of hemiparesis. RESULTS: Gross total removal was achieved in two patients. Surgical resection was limited by tumor invasion of critical areas like the internal capsule or the mesencephalon in the remaining patients. CONCLUSION: Intra-operative MRI is an important tool that helps surgeons to remove glial tumors, however, knowledge of physiology and functional anatomy is still fundamental to avoid morbidity

Prospective analysis of bedside percutaneous subdural tapping for the treatment of chronic subdural haematoma in adults.

OBJECTIVES: Although there is general agreement that surgery is the best treatment for chronic subdural haematoma (CSDH), the extent of the surgical intervention is not well defined. METHODS: The less invasive surgical technique of bedside percutaneous subdural tapping and spontaneous haematoma efflux after twist drill craniostomy under local anaesthesia was prospectively analysed in 118 adult patients, 99 with unilateral and 19 with bilateral CSDH. RESULTS: The mean number of subdural tappings was 3.2. Ninety two of the patients with unilateral CSDH were successfully treated by up to five subdural tappings, 95% of the patients with bilateral CSDH were successfully treated by up to 10 subdural tappings. The mean duration of inpatient treatment was 12 days. In 11 patients (9%) the treatment protocol had to be abandoned because of two acute subdural bleedings, two subdural empyemas, and seven cases of insufficient haematoma efflux and no neurological improvement. The only significant predictor for failure of the described treatment protocol was septation visible on preoperative CT. CONCLUSIONS: The described therapy protocol is-apart from a purely conservative treatment-the least invasive presently available surgical technique for treating chronic subdural haematoma. Its results are comparable with other modern treatment protocols. Thus, it can be recommended in all patients as a first and minimally invasive therapy, especially in patients in a poor general condition. Patients with septation visible on preoperative CT should be excluded from this form of treatment

Virtual pointer projection of the central sulcus to the outside of the skull using frameless neuronavigation -- accuracy and applications.

BACKGROUND:The purpose of this prospective study was to localize the central sulcus by frameless neuronavigation and to project this anatomical structure to the outside of the skull on the skin. This method was analyzed in respect to its practicability, accuracy, and potential applications. METHOD: In 27 patients investigated (28 unaffected hemispheres), the central sulcus was virtually projected to the outside of the skull using frameless neuronavigation and a virtual pointer elongation of 15 or 20 mm. The following parameters were measured on the scalp: 1. the distance between the bregma and the midline junction of the central sulcus, and 2. the angle between the central sulcus and the midline. These dada were compared with measurements based on the original axial MR images of these patients. Finally, a laboratory phantom study was designed in analogy to a patient's examination for estimation of the overall accuracy of the neuronavigation system in the experimental setup used in this study. FINDINGS: Virtual pointer projection of the central sulcus to the outside of the skull using frameless neuronavigation was found to be easily possible. The distance between the bregma and the midline junction of the central sulcus amounted to a mean of 55 mm on the left and 56 mm on the right. The angle between the central sulcus and the midline reached a mean of 63 degrees on the left and 60 degrees on the right. These data confirmed results of other studies with no frameless neuronavigation devices. The phantom study revealed a mean overall inaccuracy of 0.9 mm at a virtual pointer elongation of 15 mm. At a virtual pointer elongation of 20 mm, the mean overall inaccuracy of our study was 1.1 mm. These results correspond to the inaccuracy of frame based stereotaxy. INTERPRETATION: It is easily possible, valid, and reliable to virtually project the central sulcus to the outside of the skull with an acceptably low inaccuracy using frameless neuronavigation. This is important for research studies that correlate and integrate different functional imaging methods with the aid of frameless neuronavigation

Is the head position during preoperative image data acquisition essential for the accuracy of navigated brain tumor surgery?

OBJECTIVE: To analyze the influence of head positioning during preoperative image data acquisition on intraoperative accuracy of modern neuronavigation systems. MATERIAL AND METHODS: All measurements were performed preoperatively before opening the head. In 24 patients, preoperative MR image data acquisition was performed twice on a 0.5 T scanner using a contrast-enhanced T1-weighted sequence; first in the neutral head position, and thereafter in the surgical head position for pterional craniotomy. For both data sets, the Sylvian fissure, the central sulcus, and the superior and inferior temporal sulci were depicted on the patient's scalp using the frameless neuronavigation system EasyGuide Neurotrade mark. At the beginning of surgery, with the head fixed in a Mayfield clamp and an articulated instrument holder being used for fixation of the navigation system's pointer, the distances of 10 correlating points of the sulci for the two data sets were measured. To evaluate the accuracy of the navigation system in this experimental set-up, a phantom study was also performed. RESULTS: The phantom study revealed a mean inaccuracy of 1.6 mm (range 0.1-2.3 mm, standard deviation 0.6 mm). The patient study revealed a mean inaccuracy of 1.8 mm (range 0.4-2.8 mm, standard deviation 0.5 mm). CONCLUSIONS: The data suggest that the positioning of the patient's head during preoperative imaging plays no relevant role in intraoperative accuracy of neuronavigation. However, further studies and a larger number of patients with various pathologies in different regions of the brain are necessary to obtain a better understanding of the problem of brain shift in neuronavigation due to patient positioning alone, and to avoid procedure-related operative morbidity