Craniotomy tools: description of a test model for the evaluation of craniotome blade efficiency.

Craniotomes have shown to be fast and precise in performing bone flaps. Nevertheless, in everyday practice, the neurosurgeon can experience breakage of the blade and other complications like dural tears during cutting of the bone. We developed a test procedure for craniotomies and used it to compare two blade types. We used bovine scapulae to perform three tests. Five testers carried out every trial. Test 1: a 4-cm straight line was performed with both blades. Test 2: each tester performed a spiral cut. Test 3: a zig-zag cut with angles of 90° was performed by all testers with both blade types. The mean time needed to achieve the 4-cm cut in test 1 was 29.50 and 17.88 s, respectively, for the previous and new blade. In test 2, the calculated mean speed (cm/s) was 0.138 using the previous blade model and 0.178 using the new one. In test 3, the mean number of 90° angles per second performed with both blades is comparable with values of 0.058 and 0.063, respectively, for the previous and new blade. The variable considered: speed of cutting and resistance to breakage shows that the novel blade is faster in performing all the three types of cut and has higher compliance with stress.

Patient acceptance of awake craniotomy.

OBJECTIVES: The aim of this study was to objectively assess the patients' acceptance for awake craniotomy in a group of neurosurgical patients, who underwent this procedure for removal of lesions in or close to eloquent brain areas. PATIENTS AND METHODS: Patients acceptance for awake craniotomy under local anesthesia and conscious sedation was assessed by a formal questionnaire (PPP33), initially developed for general surgery patients. The results are compared to a group of patients who had brain surgery under general anesthesia and to previously published data. RESULTS: The awake craniotomy (AC) group consisted of 37 male and 9 female patients (48 craniotomies) with age ranging from 18 to 71 years. The general anesthesia (GA) group consisted of 26 male and 15 female patients (43 craniotomies) with age ranging from 26 to 83 years. All patients in the study were included in the questionnaire analysis. In comparison to GA the overall PPP33 score for AC was higher (p=0.07), suggesting better overall acceptance for AC. The subscale scores for AC were also significantly better compared to GA for the two subscales "postoperative pain" (p=0.02) and "physical disorders" (p=0.01) and equal for the other 6 subscales. The results of the overall mean score and the scores for the subscales of the PPP33 questionnaire verify good patients' acceptance for AC. CONCLUSION: Previous studies have shown good patients' acceptance for awake craniotomy, but only a few times using formal approaches. By utilizing a formal questionnaire we could verify good patient acceptance for awake craniotomy for the treatment of brain tumors in or close to eloquent areas. This is a novel approach that substantiates previously published experiences.

Identification of venous variants in the pineal region with three-dimensional preoperative magnetic resonance imaging navigation in patients harbouring tumors in this area: significance for surgical approach to the lesion.

OBJECT: The purpose of this study was to identify the anatomy of pineal region venous complex using neuronavigation software when distorted by the presence of a space-occupying lesion and to describe the anatomical relationship between lesion and veins. Moreover we discuss its influence on the choice of the surgical strategy. METHODS: Of the 33 patients treated at our Institute for pineal region tumors between 2003 and 2008 we used the neuronavigation software to depict the venous system of the pineal region in 14 patients. We focused on depiction of the basal vein of Rosenthal (BV), the internal cerebral vein (ICV) and the vein of Galen: connection patterns between the veins and the type of anatomical distortion caused by the lesion were investigated and classified. RESULTS: Using the neuronavigation software for three-dimensional (3D) reconstruction of MRI images the ICV was clearly depicted in all patients on both sides (100%). Last segment of the BV was identified in 25 sides on a total of 28 (89.3%) and absent in 3 of the 28 sides (10.7%). Studying the distortion effect of the tumor on the galenic venous system, three directions of displacement were observed: craniocaudal, anteroposterior and lateral. Seven patients presented a cranial dislocation, 5 patients caudal dislocation and there was no craniocaudal shift in 2 patients. Considering the anteroposterior displacement: 3 subjects showed an anterior shift of the veins, 5 subjects posterior shift and no anterioposterior shift was present in 6 patients. Only 2 of the 14 patients presented lateral displacement of the veins. The principal approaches used in this series were: supracerebellar infratentorial and interhemispheric parieto-occipital. The craniocaudal displacement of the pineal veins seems to be the most important for the choice of the approach. CONCLUSION: The galenic venous system has a central role in the surgery pineal region tumors. Our study demonstrates that the architecture of the pineal veins and their anatomical relationship with the lesion can be depicted with great accuracy by using 3D neuronavigation software in order to facilitate surgical planning and intraoperative orientation.

Optic radiation fiber tracking using anteriorly angulated diffusion tensor imaging: a tested algorithm for quick application.

BACKGROUND: Fiber tracking (FT) of the optic pathways (OPs) is difficult because there is no standard for the parameters of diffusion tensor imaging (DTI), placement of seed volumes, or interpreting the results. OBJECTIVE: To determine optimal conditions and parameters for DTI and FT of the optic radiation under intraoperative conditions, we performed a multivariate prospective study. METHODS: A healthy man underwent magnetic resonance imaging and DTI scans using various scan parameters. The slice thicknesses were 2.7 mm, 5 mm, and 7 mm, and the gantry of the slices was 0 degrees and 44 degrees. The OPs were tracked using different settings for focal anisotropy and minimal length of the visualized fibers. The time needed for DTI, image processing, and uploading as well as the difficulty of depicting the OPs, the time needed for FT, quality, and volume of the tracked fiber object were registered and analyzed. RESULTS: The DTI took between 2 minutes 14 seconds for the axial scan with 7-mm slice thickness and 6 minutes 14 seconds for the 44-degree angulated scan with 2.7-mm slice thickness. Splitting the data into a 3-dimensional mosaic data set took between 1 minute 42 seconds (44 degrees, 7 mm; 0 degrees, 7 mm) and 4 minutes 21 seconds (44 degrees, 2.7 mm). The best results were achieved using 44-degree, 2.7-mm DTI. The optimal setting for focal anisotropy was 0.1 and 11 mm for minimal length. Using these parameters, tracking of the OPs was possible in 1 minute 22 seconds and with high quality and correlating with anatomic studies. CONCLUSION: The use of anteriorly angulated DTI improves the FT work flow and the results of tractography of the OP. The quality of the resulting objects can be judged by anatomic landmarks.

Fat implant is superior to muscle implant in vestibular schwannoma surgery for the prevention of cerebrospinal fluid fistulae.

OBJECTIVE: Meticulous sealing of opened air cells in the petrous bone is necessary for the prevention of cerebrospinal fluid (CSF) fistulae after vestibular schwannoma surgery. We performed a retrospective analysis to determine whether muscle or fat tissue is superior for this purpose. METHODS: Between January 2001 and December 2006, 420 patients underwent retrosigmoidal microsurgical removal by a standardized procedure. The opened air cells at the inner auditory canal and the mastoid bone were sealed with muscle in 283 patients and with fat tissue in 137 patients. Analysis was performed regarding the incidence of postoperative CSF fistulae and correlation with the patient's sex and tumor grade. RESULTS: The rate of postoperative CSF leak after application of fat tissue was lower (2.2%) than after use of muscle (5.7%). Women had less postoperative CSF leakage (3.4%) than men (5.6%). There was an inverse correlation with tumor grade. Patients with smaller tumors seemed to have a higher rate of CSF leakage than those with large tumors without hydrocephalus. Only large tumors with severe dislocation of the brainstem causing hydrocephalus showed a higher incidence of CSF leaks. CONCLUSION: Fat implantation is superior to muscle implantation for the prevention of CSF leakage after vestibular schwannoma surgery and should, therefore, be used for the sealing of opened air cells in cranial base surgery.

Identification of venous variants in the pineal region with 3D preoperative computed tomography and magnetic resonance imaging navigation. A statistical study of venous anatomy in living patients.

OBJECT: The purpose of this study was to determine the ability of software-assisted 3D reconstruction performed using a neuronavigation system to delineate the anatomy and variation patterns of the pineal region venous complex, and then to compare these data with previous anatomical findings. METHODS: The authors retrospectively reviewed the neuroimages obtained in 100 patients with intracranial lesions (50 computed tomography [CT] scans obtained with contrast agents and 50 magnetic resonance [MR] images obtained with gadolinium) by using a neuronavigation workstation for 3D reconstruction. Particular attention was given to the internal cerebral vein, basal vein (BV), and the vein of Galen. The various connection patterns between the major vessels were classified and statistically analyzed. CONCLUSIONS: The venous system of the pineal region shows a wide range of sex-related variations. In the female patient the absence of a BV (Type 0) is significantly more frequent than in the male. In this study the authors illustrate the ability to depict the venous drainage patterns in the pineal region for all cases studied by using 3D neuronavigation software without the need for additional examinations. This simple tool provides important information for surgical planning and may be of significant help intraoperatively.

The endoscopic endonasal approach to the lateral recess of the sphenoid sinus via the pterygopalatine fossa: comparison of endoscopic and radiological landmarks.

OBJECTIVE: The endoscopic endonasal approach offers the opportunity to reach the pterygopalatine fossa, the lateral recess of the sphenoid sinus, and other areas of the cranial base through a minimally invasive approach. This study compares the anatomy of these areas when observed through an endoscopic endonasal view with the anatomy of the same regions as they appear in computed tomographic scans. The aim was to identify and correlate the corresponding anatomic structures, providing the surgeons with anatomic landmarks to guide them when operating in these areas through an endoscopic endonasal approach. METHODS: An anatomic dissection of six fixed cadaver heads was performed by an endoscopic endonasal approach. A step-by-step comparison of endoscopic and radiological images was made to identify the landmarks of the surgical field. RESULTS: The step-by-step comparison of endoscopic and radiological images acquired during the endoscopic endonasal approach to the lateral recess of the sphenoid sinus via the pterygopalatine fossa allowed the identification of all the relevant anatomic landmarks of the procedure. CONCLUSION: The endoscopic endonasal approach via the pterygopalatine fossa offers direct, minimally invasive access to the lateral recess of the sphenoid sinus, which can be monitored in each phase through consistent radiological imagery.

Nausea and dizziness after vestibular schwannoma surgery: a multivariate analysis of preoperative symptoms.

OBJECTIVE: Nausea and dizziness are very discomforting for patients after vestibular schwannoma surgery and they impair recovery. METHODS: To identify preoperative symptoms and conditions that increase the risk of development of nausea after vestibular schwannoma surgery, a multivariate analysis was performed. One hundred fifteen patients with vestibular schwannoma had a microsurgical tumor removal in a standardized procedure in 2001 and 2002. Eighteen patients were excluded from the study because of previous surgery (recurrent tumors, 7 patients) or bilateral tumor occurrence (neurofibromatosis, 11 patients). Analysis was performed regarding postoperative amount of antiemetic medication, vomiting, and subjective feeling of the patient. Tumor grading, body mass index, sex, previous complaints, examination at admission, and side of the tumor were taken in consideration. RESULTS: Women had significant longer postoperative complaints (mean, 3.0 d; standard error, 0.47) and needed longer antiemetic therapy (mean, 3.3 d; standard error, 0.49) than men (mean, 1.72 d; standard error, 0.21). Patients developing no significant postoperative complaints were all in the higher tumor grading group, Grades 3a, 4a, and 4b. There was a significant difference in the duration of antiemetic therapy between tumors graded 1 and tumors graded 3 or 4. Patients with a positive stepping test preoperatively had a tendency to demand less antiemetic medication. Women with small tumors are most likely to develop significant complaints after vestibular schwannoma surgery. CONCLUSION: It is possible to identify patients with a higher risk of postoperative nausea and dizziness after vestibular schwannoma surgery. This allows one to inform these patients preoperatively and to initiate an early postoperative drug therapy to ease their symptoms.

Seeding of malignant meningioma along a surgical trajectory on the scalp. Case report and review of the literature.

The authors report the case of an 11-year-old boy with a malignant meningioma of the right frontal meninges. The tumor was asymptomatic, despite visible exophytic extracranial growth. Neuroimaging demonstrated an en plaque meningioma bulging into the brain. Six months after the tumor had been totally removed by surgery, an isolated subcutaneous metastasis developed at the right preauricular area of the scalp, originating at the scar left by the first surgery. After removal of this metastasis, radiotherapy was conducted. To date the follow-up examinations have not revealed any additional metastases. To the best of the authors' knowledge, this is the first report of a seeding of a subcutaneous metastasis in a child with a malignant meningioma. The authors review the literature with reference to malignant meningiomas and their formation of metastasis. In cases of malignant meningiomas, piecemeal tumor removal carries the risk of iatrogenic cell dissemination even when precautions are taken.