| Περίληψη: | Stereotaxy was the first well-established and traditionally the gold standard method of targeting intracranial structures. The extensive refinement of the stereotactic devices along with the development of MRI in the 1990s and a large number of relevant publications with consistent results rendered the frame-based stereotactic brain biopsy the gold standard technique for brain biopsies, too. (Hall 1998, Yu, Liu et al. 2000, Heper, Erden et al. 2005) However, the stereotactic method is characterized by various important disadvantages: 1) the patient’s discomfort, 2) the necessity of a new CT/MRI scan immediately preoperatively, 3) the requirement of calculating and verifying the coordinates, 4) the head frames themselves, which may restrict both the anesthesiologist and the surgeon, and 5) the fact that biopsy specimens can be acquired intraoperatively only from the targets defined preoperatively. (Goldstein, Gumerlock et al. 1987, Matsumoto, Tomita et al. 1995, Lozano, Gildenberg et al. 2009, Shooman, Belli et al. 2010)
Modern intraoperative navigation systems provide several significant advantages, e.g. multiplanar image reconstruction (axial, coronal, sagittal, probe’s eye view) and 3D pre- and intra-operative planning, real-time intraoperative surgical instrument guidance, and precise localization of intracranial targets. (Bale, Laimer et al. 2006, Georgiopoulos, Ellul et al. 2014) Moreover, in the case of brain biopsies they are combined with miniframe stereotactic devices. As a result, the various disadvantages of the stereotactic methods and apparatuses (e.g. Cosman-Roberts-Wells (CRW) or Leksell systems) can be avoided.
In order to perform a brain biopsy, a biopsy needle must be inserted accurately and safely into the selected target. Therefore, a reliable targeting device (stereotactic apparatus or navigation system) is necessary, as well as a device that holds steadily the needle in the pre-specified trajectory as it is inserted, i.e. a needle guide attached on the stereotactic device or a miniframe device.
Regarding Trigeminal Neuralgia (TGN), percutaneous balloon compression (PBC) is a very reliable technique, which along with radiofrequency thermo-coagulation (RFT), they are the most effective percutaneous methods in the long term. Additionally, it is characterized by a relatively lower and milder morbidity than microvascular decompression and RFT (16.1% vs 29.2%), which also includes avoidance of anesthesia dolorosa and keratitis, while it is appropriate for involvement of the ophthalmic division. (Lopez, Hamlyn et al. 2004, Tatli, Satici et al. 2008, Toda 2008) Moreover, the patients are not obligated to cooperate, while they are sedated avoiding pain and stress. However, failure to cannulate the foramen ovale (FO) (with any of the percutaneous methods) using only fluoroscopy is a significant problem in some cases, due to various possible reasons, i.e. inadequate visualization of the FO, presence of anatomical variations (smaller size, intraforaminal bony ridges or ossified pterygospinous/pterygoalar ligament) or in the case of PBC, the thick Tuohy needle. In addition, the exposure to radiation might be significant for the surgeon, while multiple attempts of cannulation could increase the risk of complications. (Georgiopoulos, Ellul et al. 2014)
The first purpose of the present thesis was to compare the characteristics, i.e. efficacy, duration of each procedure, safety and length of hospitalization, of a frameless fiducial-less brain biopsy method with those of the standard frame-based stereotactic technique. Secondly, in this thesis, we have also suggested a treatment alternative: the use of an optical navigation system (StealthStation® S7™, Medtronic Inc., Minneapolis, MN, USA) for the guidance of PBC for TGN, in cases of reoperation after prior failure to cannulate the FO under fluoroscopy only. Overall, the purpose of the present thesis was to evaluate the anatomical accuracy of the neuronavigation system StealthStation in neurosurgical operations, specifically in brain biopsy and PBC procedures; by assessing the efficacy, the targeting accuracy and the safety of the StealthStation navigated operations, compared with the standard respective techniques.
Brain biopsies, Patients/Materials and Methods: In the present prospective cohort study were enrolled 56 adult patients: 1) for whom no conclusive diagnosis could be settled in a noninvasive manner; and 2a) who also had lesions involving deeply seated and eloquent areas, or multifocal lesions, or lesions for which the probable diagnosis is a contraindication for craniotomy, or 2b) were poor candidates for craniotomy (over 80 years old or serious comorbidities that were considered contraindications for craniotomy). 28 patients were operated on with each method. Regarding the frameless biopsy technique, we used an optical navigation system (StealthStation® S7™) without fiducials in combination with the Navigus miniframe device (burr-hole-mounted, ball-and-socket device). Concerning the frame-based stereotactic method we used the CRW stereotactic system and planning software (FrameLink™ Stereotactic Planning Software).
Brain biopsies, Results: Failure of diagnosis was recorded in 4 cases (14.3%) of the frame-based method group and 3 cases (10.7%) of the frameless fiducial-less method group, in spite of the accurate targeting, without a statistically significant difference (p= 1.0). The smallest maximal diameter of a lesion successfully targeted, acquiring samples which led to a diagnosis, was 15mm for both groups. The mean duration of the overall procedure was 111.3min for the frame-based method and 79.1min for the frameless method, which was clearly a statistically significant difference (p= 0.001). Both the duration of the preparatory steps overall and of the preparation inside the operating room (OR) concerning the frame-based technique were significantly longer than the duration of the preparation overall – inside the OR of the frameless method. However, there was not a statistically significant difference between the two groups regarding either the operation’s duration (“skin-to-skin”) or the time spent inside the OR overall. Concerning neurologic morbidity, new abnormal findings in the postoperative head CT scan (p= 1.0) and postoperative hospital stay (p= 0.66) the two methods did not differ significantly.
Navigated PBC, Patients/Materials and Methods: A total of 174 patients underwent PBC for TGN from 2003 to 2012. In 9 cases the penetration of the FO was not accomplished. Five of those patients were re-operated for PBC using navigation. Preoperatively, a head CT scan is performed and the acquired images are imported into the navigation system (StealthStation® S7™). Intraoperatively, a small reference frame is strapped firmly to the patient’s forehead, the CT images are registered, and cannulation is performed under the guidance of the navigation system and then confirmed by fluoroscopy.
Navigated PBC, Results: In all patients, the operation overall was completed successfully. Moreover, all patients reported complete pain relief immediately postoperatively and no complications were recorded.
The frameless fiducial-less brain biopsy method, described in the present thesis, was shown to be equally efficacious and safe, compared with the standard stereotactic frame-based technique, in terms of diagnostic yield, neurologic complications, and new abnormal findings in the postoperative head CT scan. In addition, the frameless fiducial-less method was associated with a shorter duration of the overall procedure and of the preparation overall – inside the OR, in comparison with the frame-based technique. Finally, the two methods resulted in similar duration of postoperative hospitalization. (Georgiopoulos, Ellul et al. 2017) Furthermore, the frameless fiducial-less technique does not involve the aforementioned disadvantages of the frame-based technique, while it is more flexible preoperatively and intraoperatively. Consequently, it could be hypothesized that it is friendlier to the patient and more comfortable for the surgeon, and seems to provide a more simplified workflow for both the operating room and the hospital overall.
Secondly, the surgical management of unsuccessful PBC, and percutaneous treatments in general, due to various reasons remains controversial. In this thesis, we suggest the use of navigation for the guidance of the cannulation of the FO during PBC, in cases of prior failure to penetrate into the FO under fluoroscopy only. At least when our study was published, we had not encountered any other paper analyzing the application of a navigation system, without impractical special targeting/navigation devices/adjuncts, intraoperative imaging systems or immobilization of the head, specifically for PBC and TGN, after prior failure to cannulate the FO under fluoroscopy only. (Georgiopoulos, Ellul et al. 2014) This technique involves technology with significant advantages helping the successful cannulation of the FO and seems more convenient, more efficient and safer.
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