(Polenov Research Neurosurgical Institute, Saint Petersburg
Saint Petersburg Medical Academy of Postgraduate Education)
The goal of the study was to estimate potentialities of intraoperative ultrasonic navigation (USN) in verifying a character of intracranial formation growth, control of efficacy of neoplasm removal in different localization of a target and prevention of ischemic postoperative complications.
USN was used in 46 cases with a cerebral mass. Their age varied from 1.3 up to 67 years (28.5 years on the average). Pathology distribution was as follows: cysts – 3 (6.5%); glial tumors – 18 (39%); cavernous malformations – 11 (23%); craniopharyngiomas – 3 (6.5%); meningiomas, germinomas and dermoid cyst – 2 cases each (4.3%); fibromas, neurinomas and choriopapillomas – 1 case each; metastases – 2 (4.3%). The patients were divided into 2 groups in accordance with an approach character. The first group included cases (35) with supratentorial formations. The second group comprised patients with cerebellar tumors and neoplasms, adjacent to the brain stem. An approach via structures of the posterior cranial fossa (PCA) was performed in all 11 cases. The control group consisted of 49 patients with supratentorial and subtentorial neoplasms, who were not subject to USN.
Transdural transcortical visualization of pathologic objects was carried out, using Siemens Sonoline Versa Plus apparatus with 5.0 P and 7.5 L probes (B and B-color modes) or Concept 2000 device with 5.0 S and 5.0 L probes. A target position in relation to main ultrasonic landmarks and major vessels was estimated. A place of dura incision and encephalotomy direction were chosen on the basis of a place and depth of a target location. Such criteria of nodular neoplasm as even edges, clear outlines and an regular form were determined. A tumor with infiltrative growth was characterized by unclear outlines, uneven edges and an irregular form. A puncture under USN control was made in 6 cases with cystic tumors (17%), referred to the first group. It was necessary to puncture ventricles in 4 cases (11%). Criteria of AVM were ascertained. It looked like a formation with high-speed different-direction flows, when color Doppler mapping was used. A size of a malformation body, measured during ultrasonic examination, coincided with that of removed malformation. Discrete ultrasonic monitoring of manipulations and control of efficacy of removal of pathologic tissue were carried out. Control of tumor removal revealed areas of incomplete resection in 9 cases (26%). There was no infiltrative growth in 4 of them (11%). Use of USN in the second group demonstrated a growth of tumor into the stem and the IVth ventricle in 7 cases (78%).
Estimation of the nearest postoperative period in patients of the first group, operated with use of USN, showed, that focal symptoms regressed or remained at a preoperative level in 85% of cases. The same index in the control group was 48%. A state deterioration, caused by brain edema or ischemia, was watched in 1 patient, operated with USN. It was typical of 7 cases (33%) of the control group. As for the second group, there was 1 case with ischemic complications both in the main and control groups. However, improvement of a state in an early postoperative period was watched in 67% of cases of the main group, whereas this figure in the control group was 56%.
Thus, use of USN allows to determine a type of neoplasm growth, to get more precise information on a degree of resection efficacy and to optimize a process of removal of intracranial neoplasm.