Serum levels of glial fibrillary acidic protein correlate to tumour volume of high-grade gliomas.

OBJECTIVES: To investigate serum levels of glial fibrillary acidic protein (GFAP) and S-100B in patients with newly diagnosed high-grade gliomas. MATERIALS AND METHODS: GFAP and S-100B were measured by enzyme-linked immunosorbent assay techniques in preoperative serum from 31 patients with high-grade gliomas. A database with clinical, radiological and histological variables was created for statistical analyses. RESULTS: Mean serum levels of 239 ng/l (range 30-1210 ng/l) for GFAP and 58.3 ng/l (range 22-128 ng/l) for S-100B were found. Of the 31 patients, 16 had elevated levels of GFAP while only two showed increased S-100B concentrations. Tumour size was the only variable significantly associated with serum levels of GFAP (P < 0.0001) with a linear correlation coefficient of 0.67. CONCLUSIONS: Serum levels of GFAP demonstrated a linear correlation to tumour volume in patients with high-grade gliomas. GFAP seems to be a more reliable biomarker in patients with high-grade gliomas than the commercially available S-100B.

Does imprint cytology of brain tumours improve intraoperative diagnoses?

OBJECTIVES: To evaluate the diagnostic accuracy using frozen sections only and a combination of imprint cytology and frozen sections. MATERIAL AND METHODS: After introduction of imprint cytology as a supplement to frozen sections in 1999, 153 patients with brain tumours underwent stereotactic or open surgery. An equal number of cases prior to 1999 were chosen for comparison. Intraoperative diagnoses were compared with final diagnoses based on paraffin sections of the same tissue samples. The number of delayed intraoperative diagnoses was noted in each patient group. RESULTS: The combined use of the two techniques improved intraoperative diagnostic accuracy from 87 to 91% while the delayed intraoperative diagnoses were significantly reduced from 30 to 8. The choice of surgical procedure did not affect the outcome of the pathological investigations. CONCLUSION: A combination of frozen sections and imprints significantly reduced the number of delayed intraoperative diagnoses. Intraoperative diagnostic accuracy was improved, although not to a statistically significant level. Choice of surgical procedure did not affect the diagnostic outcome.

A four-year experience with a stereotactic computer in a small neurosurgical department.

BACKGROUND: A stereotactic computer with a mechanical, proprioceptive arm was acquired in 1996. The aim of this report is to review the 4-year experience with frameless, computer-aided stereotaxy in a small neurosurgical department. METHODS: From 1996 to 1999 the computer was used for 121 operations. The surgical files from these operations were either retrospectively or prospectively registered. Patient and computer data, type of surgery, complications and number of surgeons were noted. The versatility, benefits, and drawbacks of the stereotactic computer were evalued based on these findings. RESULTS: Seven surgeons performed a total of 121 computer-assisted operations. The procedures consisted of 63 stereotactic tissue samplings, 44 craniotomies, 7 abscess punctures and 3 insertions of intracerebral devices (shunts and microelectrodes). Technical complications were seen in 6 cases (4.8%), but this did not affect the surgical outcome. CONCLUSIONS: The stereotactic computer has enabled the department to broaden its spectrum of procedures. High precision surgery such as stereotactic biopsy has been possible without the use of a framebased system. The results indicate that even small neurosurgical units with a limited number of procedures can safely and successfully implement neuronavigation in daily routines.

A new procedure for frameless computer navigated stereotaxy.

OBJECTIVE: Stereotactic procedures using frame-based systems have become well established in neurosurgery. Later, stereotactic computers have provided the neurosurgeon with a broader range of applications. A new, frameless stereotactic guide which utilizes the navigational abilities of a computer has been developed. This clinical study evaluates the accuracy and safety of the system when applied for puncture of tumours and abscesses in the cerebrum. METHODS: Using a frameless setup 36 patients were operated on for a total of 39 intracranial processes over a period of two years. Three patients were operated on twice. Computer data, time of surgery, anesthesia, complications, tumour localization and tissue examinations were recorded. RESULTS: Biopsies were obtained from all lobes of the cerebrum and a diagnosis established in all cases except two. Mean age and total range was 52 years and 15-82 years, respectively. Median time of surgery was approximately 60 minutes including positioning of the patient and the registration process on the stereotactic computer. Local anesthesia was used for 25 operations and general anesthesia for 14 operations. There was one postoperative abscess formation in a previously immunosuppressed patient and a per-operative epileptic seizure caused by electrocoagulation of the dura in a second patient. CONCLUSIONS: Based on this clinical study a new procedure for obtaining stereotactic biopsies of intracranial processes is introduced. All tumours were successfully reached with two cases of complications.

Mechanical accuracy of a new stereotactic guide.

OBJECTIVE: A new stereotactic guide using a navigational computer is developed for stereotactic procedures. In order to compare the mechanical accuracy of the guide to frame based systems, an error analysis study was designed. METHODS: A biopsy procedure was simulated using a phantom model. Targets with known co-ordinates in a three-dimensional Cartesian co-ordinate system were positioned inside the skull model. A biopsy needle was inserted along computer set trajectories from three different entry points. The position of the biopsy needle in the co-ordinate system was measured. Distance from needle tip to target was calculated and defined as the error of the system for each trial. The results were statistically analyzed for precision and biasedness. RESULTS: A total of 242 accuracy measurements (182 on two MRI scans, 60 on one CT scan) were carried out. Mean incision length along the trajectories was 59 mm. Mean error using MRI scans was 3.8 mm and for the CT scan 2.9 mm. The error of the stereotactic computer was found to be 1.0 mm with both MR and CT imaging. The main cause of error for the MRI based trials was distortion of the magnetic field. CONCLUSION: The results indicate a stereotactic system with high degree of accuracy. This is confirmed by a clinical study of 39 biopsies where all tumours were reached. MRI affected the mechanical accuracy significantly due to distortion of the magnetic field. The accuracy is comparable to other studies performed on both stereotactic computers and frame based systems.

[Primary lymphoma of the central nervous system]. / Primaert lymfom i sentralnervesystemet.

Primary lymphoma of the central nervous system is an important diagnosis to consider in any patient with an expansive lesion of unknown origin. The incidence of this cancer is reported to be increasing. We collected retrospective data from the files on all patients with brain tumours treated surgically at the University Hospital of Tromsø in the 1986-98 period (n = 513). Of 283 patients operated for brain tumours from 1986 to 1994, only one (0.4%) had a primary lymphoma. Of 230 patients treated from 1995 to 1998 seven (3%) suffered from the same condition. Two of the eight patients had T-cell lymphomas. Primary lymphoma of the central nervous system is a highly invasive tumour and should preferably be treated with chemotherapy and irradiation. The use of surgery is controversial. In most cases, surgery should be restricted to biopsy only.