V.E. Parfenov, D.V. Svistov, A.V. Savello, R.A. Lapshin, A.B. Tsibirov
Clinic of Neurosurgery, Medicomilitary Academy, Saint Petersburg, Russia
Intraoperative ultrasonic navigation was used in 62 cases with brain tumors, who were treated in the Clinic of Neurosurgery of the Medicomilitary Academy in 2002-2004.There were 38 males and 24 females, aged 29-77. A mean age was 34 years. All the patients were divided into two groups in compliance with a growth character and a histological structure. The first group included 45 patients (72.5%) with intracerebral tumors. They were as follows: fibrillar astrocytomas - 10 (16%), anaplastic astrocytomas - 7 (11%), multiform glioblastomas - 9 (14%), anaplastic oligodendrogliomas - 3 (5%), neurocytomas - 1 (1.5%), metastasis - 10 (16%), choriopappilomas - 3 (5%), CNS lymphomas - 1 (1.5%), teratomas - 1 (1.5%). The second group consisted of 17 patients (27.5 %) with extracerebral tumors. Meningiomas and menigosarcomas were present in 16 (26%) and 1 (1.5%) of them respectively.
Primary operations were performed in 53 patients (85.5%); 9 cases (14.5%) were operated for a prolonged growth. Osteoplastic and decompressive trephination was made in 50 (80.6%) and 12 (19.4%) of cases respectively. Operations consisted in total, subtotal (more than 75%) and partial (50-70%) removal of a tumor.
The Aloka and Siemens apparatus were used (probes with a frequency of 5.0-7.5 MHz; 2-D modes, color power Doppler). Neurosonographic study was carried out through dura before its opening; then the information was obtained from the brain surface during and after tumor removal.
Intraoperative sonography showed, that as a rule glial tumors were hyperechogenic; a cystic component of tumor looked like a hypo-unechogenic zone, having no distinct boundaries. Meningiomas were usually hyperechogenic and had clear boundaries; one could see their own vessels. Relationship with major arteries and veins, sources of possible blood supply were estimated. We managed to determine localization of a tumor matrix almost in all cases. Stage-by-stage navigation was used during tumor removal. A wound canal was filed with isotonic solution; then a volume of a removed tumor was determined.
Efficacy of surgical treatment was controlled by intraoperative ultrasonic scanning and postoperative CT- and MRI-examinations of the brain with enhancing. Intervention efficacy in the first group (45 patients) was as follows: total removal - 22 cases (53%), subtotal removal - 14 cases (31%) and partial removal - 7 cases (16%). As for the second group (17 patients) total and subtotal removals were performed in 15 (88%) and 2 (12%) of cases respectively.
Ultrasonic navigation allowed to obtain intraoperative visualization of a cerebral tumor in all the patients, to estimate its size and structure (including angioarchitectonics), to assess blood flow in tumor vessels and, thus, to make supposition on a degree of malignancy (arteriovenous anastomoses), to evaluate relationship between a tumor and adjacent cerebral structures, big arteries and veins and to get information on a state of a ventricular system and brain parenchyma.
A peculiar feature of ultrasonic navigation is possibility of estimating a state of the brain and tumor in an on-line mode, as well as removal efficacy.
Thus, use of intraoperative navigation permitted not only to lessen a degree of surgical trauma of the brain, to reduce time of surgical intervention and to increase its efficacy, but also to minimize a risk of damaging intact zones and cerebral vessels.
Intraoperative ultrasonic navigation ensures effective intraoperative orientation, which is of particular importance in low-grade gliomas, located in eloquent areas of the brain.