Andrea Cardia

Degenerative lumbar spinal stenosis : analysis of results in a series of 374 patients treated with unilateral laminotomy for bilateral microdecompression

OBJECT Surgical decompression is the recommended treatment in patients with moderate to severe degenerative lumbar spinal stenosis (DLSS) in whom symptoms do not respond to conservative therapy. Multilevel disease, poor patient health, and advanced age are generally considered predictors of a poor outcome after surgery, essentially because of a surgical technique that has always been considered invasive and prone to causing postoperative instability. The authors present a minimally invasive surgical technique performed using a unilateral approach for lumbar decompression. METHODS A retrospective study was conducted of data obtained in a consecutive series of 473 patients treated with unilateral microdecompression for DLSS over a 5-year period (2000-2004). Clinical outcome was measured using the Prolo Economic and Functional Scale and the visual analog scale (VAS). Radiological follow-up included dynamic x-ray films of the lumbar spine and, in some cases, computed tomography scans. RESULTS Follow-up was completed in 374 (79.1%) of 473 patients--183 men and 191 women. A total of 520 levels were decompressed: 285 patients (76.2%) presented with single-level stenosis, 86 (22.9%) with two-level stenosis, and three (0.9%) with three-level stenosis. Three hundred twenty-nine patients (87.9%) experienced a clinical benefit, which was defined as neurological improvement in VAS and Prolo Scale scores. Only three patients (0.8%) reported suffering segmental instability at a treated level, but none required surgical stabilization, and all were successfully treated conservatively. CONCLUSIONS Evaluation of the results indicates that unilateral microdecompression of the lumbar spine offers a significant improvement for patients with DLSS, with a lower rate of complications.

Spinal navigation: Standard preoperative versus intraoperative computed tomography data set acquisition for computer-guidance system: Radiological and clinical study in 100 consecutive patients

Study Design. A retrospective clinical and radiological study. Objective. To compare the safety and accuracy of pedicle screw insertion using two different computed tomography (CT) data set acquisitions (preoperative and intraoperative) for computer-guidance systems in a series of 100 consecutive patients. Summary of Background Data. Misplacement and pedicle cortical violation occurs in over 20% of screw placements and can result in potential neurovascular complications. Many technological innovations have been described to help reduce this range of error, such as image-guided surgery using fluoroscopy or CT-based image guidance. However, these techniques are not without their drawbacks. The next technological evolution is the use of an intraoperative CT scan, which would allow us to solve some of the critical phases of spinal navigation, such as position-dependent changes, thus granting a higher accuracy of the navigation system. The authors have compared and discussed the results of a preoperative and intraoperative CT data set acquisition mode for spinal navigation. Methods. One hundred consecutive patients with a diagnosis of lumbar degenerative spondylolisthesis who underwent a surgical approach of lumbar pedicle screw fixation using a CT-based computer-guidance system were evaluated. The population was divided into two groups: in group I, a preoperative CT scan was used for the navigation system; whereas in group II, an intraoperative CT scan acquired during surgery was used. Epidemiological and surgical data of the patients in the two groups were then analyzed and compared. The Pearson &khgr;2 test was used for comparisons between groups (significance level 0.05). The evaluation and classification of the screw positioning was performed on the basis of a control CT scan according to the classification proposed by Laine. Results. Out of 504 screws, 471 were correctly inserted into the pedicles (93.5%): the accuracy of group I was of 91.8%, whereas in group II it was 95.2% (no statistical significance). The overall rate of perforation was 6.5% (33 screws): 21 in group I and 12 in group II. Twenty-eight screws had a perforation of the pedicle less than 2 mm (Grade I), three comprised from 2 to 4 (Grade II), and only two more than 4 mm and less than 6 mm (Grade III). Out of 33 misplaced screws only one was replaced (graded as III in group II). Surgical time was shorter for group II, with a statistically significant difference. This result is mainly because of the automatic recognition and merging of the intraoperative images with the surgical anatomy that avoided the phase of registration with a paired-point technique. Conclusion. The results of this study suggest that the CT-based computer-assisted surgical navigation systems are precise, granting an elevated accuracy in pedicle screw positioning.

Primary stability of pedicle screws depends on the screw positioning and alignment

BACKGROUND CONTEXT There is no universal consensus regarding the biomechanical aspects and relevance on the primary stability of misplaced pedicle screws. PURPOSE The study is aimed to the determination of the correlation between axial pullout forces of pedicle screws with the possible screw misplacement, including mild and severe cortical violations. METHODS Eighty-eight monoaxial pedicle screws were implanted into 44 porcine lumbar vertebral bodies, paying attention on trying to obtain a wide range of placement accuracy. After screw implantation, all specimens underwent a spiral computed tomography scan, and the screw placements were graded following the scales of Laine et al. and Abul Kasim et al. Axial pullout tests were then performed on a servohydraulic material testing system. RESULTS Decreasing pullout forces were determined for screws implanted with increasing cortical violation. A smaller influence of cortical violations in the medial direction with respect to the lateral direction was observed. Screws implanted with a large cortical violation and misplacement in the craniocaudal direction were found to be significantly less stable than screws having comparable cortical violation but in a centered sagittal position. CONCLUSIONS These results provide adjunctive criteria to evaluate more accurately the fate of a spine instrumentation. Particular care should be placed in the screw evaluation regarding the craniocaudal positioning and alignment.

Economic study: a cost-effectiveness analysis of an intraoperative compared with a preoperative image-guided system in lumbar pedicle screw fixation in patients with degenerative spondylolisthesis.

BACKGROUND CONTEXT In spinal surgery, newly developed technology seems to play a key role, especially with the use of computer-assisted image-guided navigation, giving excellent results. However, these tools are expensive and may not be affordable for many facilities. PURPOSE To compare the cost-effectiveness of preoperative versus intraoperative CT (computed tomography) guidance in spinal surgery. STUDY DESIGN A retrospective economic study. METHODS A cost-effectiveness study was performed analyzing the overall costs of a population of patients operated on for lumbar degenerative spondylolisthesis using an image-guided system (IGS) based on a CT scan. The population was divided into two groups according to the type of CT data set acquisition adopted: Group I (IGS based on a preoperative spiral CT scan), Group II (IGS based on an intraoperative CT scan-O-Arm system). The costs associated with each procedure were assessed through a process analysis, where clinical procedures were broken down into single phases and the related costs from each phase were evaluated. No benefits in any form have been or will be received from commercial parties directly or indirectly related to the subject of this article. RESULTS Four hundred ninety-nine patients met the criteria for this study. In total, 2,542 screws were inserted with IGS. Baseline data were similar for the two groups, as were hospitalization and complications. The surgical time was 119±43 minutes in Group I and 92±31 minutes in Group II. The full cost of the two procedures was analyzed: the mean cost, using the O-Arm system (Group II), was found to be €255.83 (3.80%) less than the cost of Group I. Moreover, the O-Arm system was also used in other surgical procedures as an intraoperative control, thus reducing the final costs of radiologic examinations (a reduction of around 550 CT scans/year). CONCLUSIONS In conclusion, the authors of the study are of the opinion that the surgical procedure of pedicle screw fixation, using a CT-based computer-guidance system with support of the O-Arm system, allows a shortening of procedure time that might improve the clinical result. However, the present study failed to determine a clear cost-effectiveness with respect to other CT-based IGS.

Computed tomography-based image-guided system in spinal surgery: state of the art through 10 years of experience

BACKGROUND: Image-guided navigation systems (IGS) grant excellent clinical and radiological results, minimizing risks correlated with spinal instrumentation. However, there is some concern regarding the real need for IGS and its indications. OBJECTIVE: To analyze the accuracy, technical aspect, and radiation exposure data of the principal IGS based on computed tomography (CT) imaging. METHODS: The data of all patients treated for spinal instrumentation with the aid of an IGS system from January 2003 to March 2013 were retrospectively analyzed. We defined 2 groups: group I with an IGS system based on a preoperative CT scan; group II relied on an intraoperative CT scan. Screw accuracy was assessed with a postoperative CT scan control. Radiation dosage for patients was defined by using the technical parameters and dose report data. Statistical analysis was performed using the Fisher exact test with a significance of 5% (P value < .05). RESULTS: Two thousand twenty patients and 11 144 screws were analyzed. Group I had 794 patients (4246 screws); the accuracy was 96.1%. Group II had 1226 patients (6898 screws) treated, with 98.5% accuracy (P = .001). The radiation dose analysis showed better results in group II, with significant reduction of the effective dose to the patient. CONCLUSION: The IGS based on an intraoperative CT scan grants excellent results, eliminating the rate of reoperation for misplaced instrumentations (screws, plate, and cage) or for inadequate bone decompression. However, this technology cannot replace the surgical skills, experience, and knowledge necessary for spine surgery. ABBREVIATIONS: CTDI, Computed Tomography Dose Index DLP, dose-length product IGS, image-guided system

Management of C1-2 traumatic fractures using an intraoperative 3D imaging-based navigation system.

OBJECT Fractures of C-1 and C-2 are complex and surgical management may be difficult and challenging due to the anatomical relationship sbetween the vertebrae and neurovascular structures. The aim of this study was to evaluate the role, reliability, and accuracy of cervical fixation using the O-arm intraoperative 3D image-based navigation system. METHODS The authors evaluated patients who underwent a navigation system-based surgery for stabilization of a fracture of C-1 and/or C-2 from August 2011 to August 2013. All of the fixation screws were intraoperatively checked and their position was graded. RESULTS The patient population comprised 17 patients whose median age was 47.6 years. The surgical procedures were as follows: anterior dens screw fixation in 2 cases, transarticular fixation of C-1 and C-2 in 1 case, fixation using the Harms technique in 12 cases, and occipitocervical fixation in 2 cases. A total of 67 screws were placed. The control intraoperative CT scan revealed 62 screws (92.6%) correctly placed, 4 (5.9%) with a minor cortical violation (<2 mm), and only 1 screw (1.5%) that was judged to be incorrectly placed and that was immediately corrected. No vascular injury of the vertebral artery was observed either during exposition or during screw placement. No implant failure was observed. CONCLUSIONS The use of a navigation system based on an intraoperative CT allows a real-time visualization of the vertebrae, reducing the risks of screw misplacement and consequent complications.

VITOM 3D: Preliminary Experience in Cranial Surgery

BACKGROUND Optimal vision and ergonomics are important factors contributing to achievement of good results during neurosurgical interventions. The operating microscope and the endoscope have partially filled the gap between the need for good surgical vision and maintenance of a comfortable posture during surgery. Recently, a new technology called video-assisted telescope operating monitor or exoscope has been used in cranial surgery. The main drawback with previous prototypes was lack of stereopsis. We present the first case report of cranial surgery performed using the VITOM 3D, an exoscope conjugating 4K resolution view and three-dimensional technology, and discuss advantages and disadvantages compared with the operating microscope. CASE DESCRIPTION A 50-year-old patient with vertigo and headache linked to a petrous ridge meningioma underwent surgery using the VITOM 3D. Complete removal of the tumor and resolution of symptoms were achieved. The telescope was maintained over the surgical field for the duration of the procedure; a video monitor was placed at 2 m from the surgeons; and a control unit allowed focusing, magnification, and repositioning of the camera. CONCLUSIONS VITOM 3D is a video system that has overcome the lack of stereopsis, a major drawback of previous exoscope models. It has many advantages regarding ergonomics, versatility, and depth of field compared with the operating microscope, but the holder arm and the mechanism of repositioning, refocusing, and magnification need to be ameliorated. Surgeons should continue to use the technology they feel confident with, unless a distinct advantage with newer technologies can be demonstrated.

Treatment of spondylotic cervical myelopathy: Anterior cervical discectomy and fusion with a modular plate-cage system (PCB) in the singlelevel and multilevel cervical myelopathy

Study Design:A retrospective, clinical, and radiographic study. Objective:To evaluate the clinical and radiologic outcome of patients treated for cervical spondylosis by anterior cervical discectomy and fusion with the plate-cage system (PCB). Summary of Background Data:Cervical spondylosis and its clinical manifestations are common pathologic entities. The goal of surgical treatment is to decompress the cervical spinal canal and achieve an arthrodesis of the treated levels. Several factors must be considered in choosing the best approach, and to date, there has not been any universal consensus. Methods:A total of 152 consecutive patients with cervical spondylotic myelopathy underwent anterior cervical discectomy and fusion surgery with the PCB, between 2000 and 2007, with a minimum follow-up of 12 months (range, 12 to 70 mo; mean: 47.4). All patients were evaluated preoperatively and postoperatively using magnetic resonance imaging, dynamic x-ray, Nurick, and the modified Japanese Orthopedic Association score. Results:Out of the entire group of patients, 112 cases presented with a single-level compression whereas 40 patients were affected by multilevel (2 or 3 levels) cervical stenosis. The postoperative clinical follow-up showed an improvement in 126 cases (82.9%), with no changes in 16 (10.5%) but a worsening in 10 (6.6%). Conclusions:Anterior decompression and PCB plate-cage fixation for singlelevel or multilevel cervical stenosis represent a safe, simple, fast, and less invasive technique with excellent neuroradiological and clinical postoperative results. Moreover, this particular anterior technique reduced the mean hospital stay and the rate of intraoperative and postoperative complications.

Unruptured Versus Ruptured AVMs: Outcome Analysis from a Multicentric Consecutive Series of 545 Surgically Treated Cases

BACKGROUND Recent literature strongly challenged indications to perform preventive surgery in unruptured arteriovenous malformation (AVM) claiming that invasive AVM treatment is associated with a significant risk of complications and thus conservative management may be a preferable alternative in many patients. On the other hand, the recent improvement of surgical instrumentation and treatment strategies (both surgical and interventional) yielded better outcomes than those achieved only a decade ago. Therefore, even among specialists, a wide variety of opinions, concerning the treatment of unruptured AVM, can be found. METHODS This multicenter retrospective study analyzes a consecutive series of 545 surgically treated AVMs in 10 different hospitals in Italy. RESULTS Patients with AVMs treated after hemorrhage had an unfavorable (modified Rankin Scale score >1) outcome in more than one third (37.69%) of the cases. Conversely, with proper indications, unruptured AVMs treated preventively have a good outcome in 93.8% of cases, increasing to 95.7%, with no death, if only Spetzler-Martin grades 1-3 are considered (P < 0.05). Outcomes on discharge significantly (P < 0.05) improve at 6 months with the disappearance of many of the initial neurologic deficits that turn out to be transient. CONCLUSIONS In unruptured low-risk AVMs (Spetzler-Martin grades 1-3), over time, the risk of surgery-associated neurologic deficits becomes lower than that linked to spontaneous hemorrhage, with a crossover point at 6.5 years. Because the average bleeding age is less than 45 years, preventive surgery can be advocated to safeguard the patient and overcome the risks associated with the natural history of AVMs.

Localizzazione di linfoma non Hodgkin B in paziente con apparente ricrescita di macroadenoma ipofisario non secernente

media taglia. Frazione di crescita (anticorpo Mib1): 30%. La successiva stadiazione con tomografia assiale computerizzata (TAC) torace-addome e tomografia a emissione di positroni (PET) total body evidenziava multiple localizzazioni adenopatiche sovrae sottodiaframmatiche e la RMN encefalo post-operatoria mostrava persistenza di tessuto patologico in loco e nel seno cavernoso sinistro. Si programmava pertanto un ricovero in EmatoOncologia per I ciclo di terapia sistemica ed eventuale biopsia TAC guidata di adenopatie addominali per meglio caratterizzare il linfoma. In conclusione, la nuova diagnosi è di linfoma ipofisario. Si tratta di una localizzazione rarissima di cui sono stati segnalati in letteratura circa 40 casi negli ultimi 20 anni. Sig.ra A.P., 74 anni, in anamnesi intervento di cataratta in occhio sinistro e protesi d’anca bilaterale. Nel marzo 2007 intervento di asportazione di macroadenoma non secernente, con persistenza di residuo di malattia a livello del seno cavernoso sinistro, determinante quadro di ipopituitarismo per il quale era in terapia sostitutiva con levotiroxina sodica 75 μg e cortisone acetato 1/2 cp 2 volte al giorno. La paziente si presentava alla nostra attenzione nel maggio 2011 per il riscontro a una risonanza magnetica nucleare (RMN) di controllo di ricrescita dell’adenoma, che giungeva a contatto con il nervo ottico di destra. In funzione della progressiva crescita della lesione e della vicinanza con le strutture nervose del basicranio, si poneva indicazione a intervento di asportazione della recidiva, seguito da trattamento radiochirurgico sul probabile residuo. La paziente veniva quindi sottoposta a intervento per via nasosfenoidale con ausilio di neuro-navigatore, in endoscopia 3D con asportazione subtotale del tessuto patologico. Il referto istologico segnalava reperto morfo-fenotipico compatibile con localizzazione di linfoma non Hodgkin B con cellule di piccola e Localizzazione di linfoma non Hodgkin B in paziente con apparente ricrescita di macroadenoma ipofisario non secernente