Neurosurgery
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A VIRTUAL REALITY system has been devised to superimpose a computer-generated rendering of a volumetric target to be surgically approached or resected on a real-time video image of the surgical field. A stereotactic frame is used to register the image from the video camera with the image of the target volume for accurate localization. The volumetric target is obtained from preoperative imaging studies and can be modified to adjust the intended line of resection or to avoid eloquent vascular or neural tissue. ⋯ To date, 74 intracranial tumor resections have been performed under video virtual reality guidance. Postoperative scanning corresponds in every case with preoperative planning. This system is also designed to be adapted to frameless guidance, which can be further enhanced by the incorporation of an audible tone to signal the relationship of the tip of the resection instrument to the line of resection.
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Comparative Study
Transcranial Doppler grading criteria for basilar artery vasospasm.
Transcranial Doppler (TCD) criteria for basilar artery (BA) vasospasm are poorly defined, and grading criteria for vertebrobasilar vasospasm are unavailable. The purpose of the present study was to define TCD grading criteria for BA vasospasm on the basis of the absolute flow velocities and the intracranial to extracranial flow velocity ratios for the posterior circulation, and to improve the sensitivity and specificity of TCD for diagnosis of BA vasospasm. ⋯ The BA/VA ratio improves the sensitivity and specificity of TCD detection of BA vasospasm. On the basis of the BA/VA ratio and BA mean velocities, we suggest new TCD grading criteria for BA vasospasm.
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The restricted radiation tolerance of the anterior visual pathways represents a unique challenge for ablating adjacent lesions with single-session radiosurgery. Although preliminary studies have recently demonstrated that multisession radiosurgery for selected perioptic tumors is both safe and effective, the number of patients in these clinical series was modest and the length of follow-up limited. The current retrospective study is intended to help address these shortcomings. ⋯ Multisession radiosurgery resulted in high rates of tumor control and preservation of visual function in this group of perioptic tumors. Ninety-four percent of patients retained or improved preradiosurgical vision. This intermediate-term experience reinforces the findings from earlier studies that suggested that multisession radiosurgery can be a safe and effective alternative to either surgery or fractionated radiotherapy for selected lesions immediately adjacent to short segments of the optic apparatus.
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In this study, we evaluated patients' clinical outcome and recurrence rates at long-term follow-up after aggressive microsurgical resection of cranial base chordomas. ⋯ Aggressive microsurgical resection of chordomas can be followed by long-term, tumor-free survival with good functional outcome. A more conservative strategy is recommended in reoperation cases, especially after previous radiotherapy, to reduce postoperative complications.
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The aim of the study was to correlate absolute cerebral blood flow (CBF) and mean transient time (MTT) measured by dynamic perfusion computed tomographic (PCT) scanning with the clinical course, vasospasm severity, and perfusion abnormality in patients with cerebral vasospasm after aneurysmal subarachnoid hemorrhage. ⋯ The present study suggests that, in general, quantitative measurements of rCBF and regional MTT by PCT show high concordance rates with the clinical course, vasospasm severity, and hemodynamic impairments in patients with cerebral vasospasm aneurysmal subarachnoid hemorrhage.