Intraoperative magnetic resonance-guided frameless stereotactic biopsies - initial clinical experience.

BACKGROUND AND PURPOSE: We present our early experience in intraoperative magnetic resonance (iMRI)-guided stereotactic frameless biopsies with special regard to its safety, efficacy and diagnostic value. MATERIAL AND METHODS: The records of patients who underwent frameless stereotactic iMRI-guided biopsies between June 2009 and April 2011 were analysed prospectively. All the operations were performed under local anaesthesia, with the use of a passive side-cutting biopsy needle. The needle was introduced into the pathological lesion with the help of optic neuronavigation system guidance. The iMRI scans served as reference images. We analysed the patients' demographic and epidemiological data, the preparation and surgery times, diagnostic values of collected specimens, lengths of the hospital stay (LOS) and the complication rate. RESULTS: Fifteen iMRI-guided stereotactic biopsies were performed in the analysed period. The mean patient age was 52 ± 18 yrs, the median WHO score was 2 (range: 1-3), there were 9 (60%) males in the study group. The average preparation time was 53 ± 24 minutes and the operation time 69 ± 25 minutes. No major complications were noted. The median total length of hospital stay was 5 days. The histopathological diagnoses were as follows: glioblastoma multiforme - 6 cases, low-grade gliomas - 4 cases, lymphomas - 3 cases, and other pathologies - 2 cases. In all the cases biopsy material allowed specified histopathological diagnoses to be obtained. CONCLUSIONS: Frameless stereotactic iMRI-guided brain tumour biopsy is a safe and diagnostically effective procedure. The use of iMRI might increase the diagnostic value and safety of stereotactic biopsy and positively influence its economic balance.

Awake craniotomy with dexmedetomidine during resection of brain tumours located in eloquent regions.

INTRODUCTION: An awake craniotomy (AC) is the gold standard for the resection of supra-tentorial brain tumours in eloquent areas. Intraoperative monitoring "on-demand" of essential eloquent brain functions and the increasing need to preserve higher intellectual functions during surgery requires a unique anaesthetic approach during AC. Dexmedetomidine is considered the first-choice pharmacological agent for sedation during AC. MATERIAL AND METHODS: Twenty-six patients with a single brain tumour located in areas of eloquent brain function were enrolled in this prospective study. The patients underwent AC under conscious sedation. Motor-evoked potentials and brainstem-evoked auditory potentials were measured using neurophysiological tests during surgery to assess brain potentials. Intraoperative brain relaxation was reached using a modified Bristow scale. Neuromonitoring and psychological tests were maintained until meningeal closure. RESULTS: All operations were carried out successfully, and no reoperations were needed. No significant impact on circulatory and respiratory parameters was observed during conscious sedation based on dexmedetomidine. Neither instrumental airway support nor conversion to general anaesthesia was necessary. Brain relaxation was good in 84% of cases. Intraoperative epileptic episodes were observed in 15% of the patients. Neuro-logical and psychological monitoring was satisfactory. Unaltered muscle force was observed postoperatively in 88% of the patients. CONCLUSIONS: AC performed under conscious sedation, and dexmedetomidine infusion without instrumental airway support, was safe and well-tolerated by patients with comfortable physiological sleep for most of the procedure. This approach to AC was associated with minimal risk of perioperative adverse events and may be particularly beneficial in patients with severe comorbidities.

Prospective study on the efficacy of low-field intraoperative magnetic resonance imaging in neurosurgical operations.

BACKGROUND AND PURPOSE: The application of intraoperative magnetic resonance imaging (iMRI) is related to a series of challenges of both a technical and an organizational nature. We present our experience in the application of low-field iMRI in everyday neurosurgical practice. MATERIAL AND METHODS: A group of 58 patients operated on using low-field iMRI was subject to prospective controlled observation. The significance of differences in the range of preparation time, duration and direct operation results between the iMRI group and controls was analysed. The influence of epidemiological and demographic factors and technical aspects related to iMRI application on direct outcome of the surgery was assessed. RESULTS: Twenty-eight tumour resections using craniotomy, 17 transsphenoidal resections of pituitary adenomas and 13 stereotactic procedures were conducted in the group of 24 men and 34 women operated on using iMRI. The control group was not significantly different in terms of epidemiological and demographic factors. The preparation and operation times were significantly longer in the iMRI group (p < 0.001 and p = 0.002, respectively). Longer duration of the surgery was not related to an increased frequency of complications. A higher percentage of postoperative improvement in neurological status (31% vs. 14%, p = 0.045), lower complication percentage (10% vs. 28%, p = 0.03) and a similar time of hospitalization (13 ± 7 vs. 12 ± 4 days, p = 0.33) were noted in the iMRI group. CONCLUSIONS: The application of low-field iMRI prolongs the duration of neurosurgical procedures but does not negatively influence their safety. It is associated with above-average functional results and a lower percentage of total complications.