Effect of the type of image study (CT or MRI) on some parameters of neuronavigation-assisted procedures.

AIM: The aim of this study was to determine the effect of the applied method of image investigation (CT or MRI) on the following parameters of the neuronavigation (NN) assisted procedure: "number of attempts for registration", "duration of registration" and "registration accuracy". PATIENTS AND METHODS: A total of 195 patients with various cranial pathological lesions underwent neuronavigation-assisted surgery between March 2003 and December 2005 at the Clinic of Neurosurgery of St. I. Rilsky University Hospital, Medical University, Sofia. All of them were included in our study. CT based registration was realized in 81 patients of our series and MR based registration--in 114 patients. The patients were examined and followed up in a standardized manner. We conducted a prospective study on the effect of the type of image investigation (either CT or MRI) on the parameters registration accuracy, number of attempts for registration and duration of registration. Statistical analysis was performed using a one-factor non-parametric rank analysis (Friedman ANOVA) with a factor "type of image study" which had four sublevels: "MR I", "CT", MRI+MRI Angiography" and "MRI+CT". Multiple Hotelling F-contrasts were applied; the level of statistical significance was 95% (Statistica 6.0, 2001, Statsoft, Tulsa, USA). RESULTS: In the series, the best (the lowest digital expression) mean registration accuracy was demonstrated in MRI based neuronavigation (1.6 mm). Besides that, in MRI-NN the number of attempts for registration was smaller and the time necessary for registration was shorter in comparison with CT-NN. In the "MR I+CT" subgroup the mean values of the investigated parameters were lower in comparison with the other three subgroups. Nevertheless, the differences were not statistically significant because of the wide statistical dispersions of the obtained results and the small number of patients investigated in this subgroup. ANOVA did not show statistically significant difference between the number of attempts for registration, the duration of registration and the registration accuracy in CT and MR-based neuronavigation-assisted procedures. CONCLUSION: We did not found any statistically significant differences between CT- and MRI-based neuronavigation with respect to the accuracy and reliability of the methods. The type of image study that should be used for neuronavigation depends on the specific characteristics of the corresponding pathological lesion.

Neuronavigated surgery of intracranial cavernomas--enthusiasm for high technologies or a gold standard?

AIM: The aim of this study was to investigate the effect of neuronavigation on the following parameters: "skin incision", "craniotomy", "intraoperative anatomical orientation", "dissection guiding", "localization of the pathological formation", "assessment of the degree of resection" and "duration of surgical procedure" in resections of intracranial cavernomas and to specify the indications for neuronavigation in their surgical treatment. PATIENTS AND METHODS: The present prospective study included 20 patients with intracranial cavernomas who underwent neuronavigated surgery between March 2003 and December 2005 at the Clinic of Neurosurgery of the "St. I. Rilsky" University Hospital, Medical University, Sofia. The female/male ratio in the series was 9/11 (45%-55%). The patients' mean age was 27.96 +/- 11.61 years (age range 1.2 to 44 years). The patients were examined and followed up in a standard manner. RESULTS: Cavernous malformations were totally removed in 19 patients. One patient with thalamic cavernoma underwent navigated endoscopic biopsy. There was no morbidity or mortality associated with the method. Neuronavigation allowed precise localization and individual design of the skin incision and craniotomy. Neuronavigated intraoperative anatomical orientation, dissection guiding, localization of the pathological formation, and assessment of degree of resection were evaluated as markedly useful. They resulted in excellent surgery results and reduced operation time in comparison with the conventional surgery. CONCLUSION: In intracranial cavernomas frameless stereotaxy provides the surgeon with useful feedback in the preoperative anatomical orientation, the planning and simulation of surgical approach, the intraoperative navigation, in avoiding vital neurovascular structures, in the assessment of the degree of resection and the identification of possible residual parts. That is why cavernous malformations are among the most common indications for cranial neuronavigation.

Cranial neuronavigation--a step forward or a step aside in modern neurosurgery.

Neuronavigation is a result of the introduction and integration of high technologies into modern neurosurgery. The method is becoming increasingly available, and more than ever, its "fashionable", ungrounded application (literally, in each neurosurgical procedure) requires objective evaluation of its real usefulness. The aim of the present survey was to analyze the use of neuronavigation in the general fields of modern cranial neurosurgery. The reliability of the classical method of brain lesion localization was compared to neuronavigated localization. We studied the neuronavigation assisted interventions in tumor surgery, skull-base surgery, biopsies, neuroendoscopy, functional neurosurgery, vascular neurosurgery and surgical procedures in the proximity of functionally important cortical zones. We showed the modern tendencies in neuronavigation and outlined the social and economic aspects of neuronavigation-assisted neurosurgery. A summary of the advantages and disadvantages of frameless stereotaxy is made.

Role of neuronavigation in the resection of intracranial arteriovenous malformations.

AIM: The aim of this study was to investigate the effect of neuronavigation on the following parameters: "skin incision", "craniotomy", "intraoperative anatomical orientation", "dissection guiding", "localization of the pathological formation", "assessment of the degree of resection" and "duration of surgical procedure" in the resection of intracranial arteriovenous malformations (AVMs) and to specify the indications for application of neuronavigation in the surgical treatment of AVMs. METHODS: Five neuronavigation-assisted resections of intracranial AVMs were performed between March 2003 and December 2005 at the Clinic of Neurosurgery of St. I. Rilsky University Hospital, Medical University, Sofia. The female/male ratio in the series was 2:3 (40%:60%). The patients' mean age was 28.2 +/- 18.27 (range 10 to 56) years. The study was prospective in design. Patients were examined and followed in a standardized manner. RESULTS: Arteriovenous malformations were totally removed in all 5 cases of neuronavigation-assisted resections. We did not observe any morbidity or mortality associated with the method. Neuronavigation allowed precise localization and individual design of the skin incision and craniotomy. Neuronavigation facilitated the surgeon during intraoperative anatomical orientation. Dissection guiding, localization of the formation and assessment of the degree of resection were assessed as markedly useful. This resulted in reduced duration of surgery compared to conventional neurosurgery. CONCLUSIONS: In AVMs resection neuronavigation optimizes surgical approach by visualizing the relationship ofAVMs to the skull and various critical anatomical structures. Deep vessel components and nidus margins, especially in the vicinity of the ventricles can be identified precisely. Neuronavigation can improve the early post-operative results in cerebral AVMs reducing operating time and blood loss.

Primary spinal melanoma with bilateral papilledema.

A case of primary leptomeningeal malignant melanoma localized in the cervical region in a 41-year-old woman is presented. The only clinical finding was intracranial hypertension with papilledema. A diagnosis of primary CNS melanoma was made after dermatological and ophthalmological consultations, ruled out a metastatic lesion. Primary leptomeningeal melanoma is an extremely rare spinal tumor. Its clinical presentation with signs of increased intracranial pressure but without cord symptoms is unusual. Clinical features of this case including the radiological and histologic findings are described. Diagnosis as well as management are discussed.