OBJECTIVE The O-arm system in spine surgery allows greater accuracy, lower rate of screw misplacement, and reduced surgical time. Some concerns have been postulated regarding the radiation doses to patients and surgeons. To the best of the authors' knowledge, most of the studies in the literature were performed with the use of phantoms. The authors present data regarding radiation exposure of the surgeon and operating room (OR) staff in a consecutive series of patients undergoing spine surgery. METHODS Radiation exposure data were collected in a series of 107 patients who underwent spine surgery using the O-arm system. The doses received by the surgeon and the staff were collected using electronic dosimeters. RESULTS All patients underwent 1–3 scans. The mean radiation dose to the patients was 5.15 mSv (range 1.48–7.64 mSv). The mean dose registered for the scan operator was 0.005 μSv (range 0.00–0.03 μSv) while the other members of the surgical team positioned outside the OR received 0 μSv. CONCLUSIONS The O-arm system exposes patients to a higher radiation dose than standard fluoroscopy. However, considering the clear advantages of this system, this adjunctive dose can be considered acceptable. Moreover, the effective dose to the patient can be reduced using collimation or minimizing the parameters of the O-arm system used in this paper. The exposure to operators is essentially negligible when radioprotective garments and protocols are adopted as recommended by the International Commission on Radiological Protection.

Purpose To identify potential prognostic factors predicting functional outcome and survival after surgery followed by radiotherapy for metastatic spinal cord compression due to solid tumors. Methods 531 consecutive patients with metastatic epidural spinal cord compression (MESCC) were treated at our institution. Surgery followed by radiation therapy was performed in 151 patients (30%) with various histological diagnoses. Three different surgical procedures were performed: minimal resection with or without instrumented fixation, curettage, and total tumorectomy. Within 1 month after surgery, RT was performed, delivering a total dose of 30-36 Gy (3 Gy per fraction). Ten potential prognostic factors were investigated for relationship with functional outcome and survival. Results Clinical remission of pain was obtained in 91% of patients and 94 (62.5%) had recovery of neurological deficit. Recurrence in the same site of treatment occurred in nine (6%) patients. Median survival was 14 months (range 0-52 months); OS at 1, 2, and 3 years was 43.6, 37, and 21.5%, respectively. Survival was significantly associated with the histology of primary tumor (P \ 0.001) and visceral metastases (P \ 0.001) in the whole group; for histology, the prognostic factors statistically significant were other bone metastases in breast cancer, control of primary tumor, and the absence of visceral metastases in NSCLC and kind of surgery in the other. Conclusions The key element for successful treatment of MESCC is multidisciplinary care of the patient, which includes all of those prognostic factors that have been, until now, analyzed and compared. In our set of patients treated for vertebral metastases, PS, time to development of symptoms, and the presence of visceral metastases affected functional outcome and survival.

OBJECTIVEThe goal of this study was to assess the safety and efficacy of stereotactic central lateral thalamotomy with Gamma Knife radiosurgery in patients with neuropathic pain.METHODSClinical and radiosurgical data were prospectively collected and analyzed in patients with neuropathic pain who underwent Gamma Knife central lateral thalamotomy. The safety and efficacy of the lesioning procedure were evaluated by neurological examination and standardized scales for pain intensity and health-related quality of life. Visual analog scale (VAS) for pain, McGill Pain Questionnaire (MPQ), EuroQol–5 dimensions (EQ-5D), and the 36-Item Short Form Health Survey, version 2 (SF-36v2) were measured during baseline and postoperative follow-up evaluations at 3, 6, 12, 24, and 36 months.RESULTSEight patients with neuropathic pain underwent Gamma Knife central lateral thalamotomy. Four patients suffered from trigeminal deafferentation pain, 2 from brachial plexus injury, 1 from central poststroke facial neuropathic pain, and 1 from postherpetic neuralgia. No lesioning-related adverse effect was recorded during the follow-up periods. All patients had pain reduction following thalamotomy. The mean follow-up time was 24 months. At the last follow-up visits, 5 patients reported ≥ 50% VAS pain reduction. The overall mean VAS pain score was 9.4 (range 8–10) before radiosurgery. After 1 year, the mean VAS pain score decreased significantly, from 9.4 (range 8–10) to 5.5 (mean −41.33%, p = 0.01). MPQ scores significantly decreased (mean −22.18%, p = 0.014). Statistically significant improvements of the SF-36v2 quality of life survey (mean +48.16%, p = 0.012) and EQ-5D (+45.16%, p = 0.012) were observed. At 2 years after radiosurgery, the VAS pain score remained significantly reduced to a mean value of 5.5 (p = 0.027). Statistically significant improvements were also observed for the MPQ (mean −16.05%, p = 0.034); the EQ-5D (mean +35.48%, p = 0.028); and the SF-36v2 (mean +35.84%, p = 0.043). At the last follow-up visits, pain had recurred in 2 patients, who were suffering from central poststroke neuropathic pain and brachial plexus injury, respectively.CONCLUSIONSSafe, nonpharmacological therapies are imperative for the management of refectory chronic pain conditions. The present series demonstrates that Gamma Knife central lateral thalamotomy is safe and potentially effective in the long term for relieving chronic neuropathic pain refractory to pharmacotherapy and for restoring quality of life.

Object. The authors studied the efficacy of gamma knife radiosurgery (GKS) in the prevention of regrowth of nonfunctioning pituitary adenomas (NPA). Methods. One hundred nineteen patients were included in this study and were divided into two groups. All patients had undergone surgery in our department and recurrent or residual adenoma was demonstrated on postoperative MR imaging. Group A consisted of 68 patients who were followed without additional treatment. Group B was composed of 51 patients who received GKS within 1 year after microsurgery. There was no significant demographic difference between the two groups. In Group B the mean margin dose was 16.5 ± 0.3 Gy (range 13–21 Gy). Fifty one and one tenth percent of patients in Group A were recurrence free at 5 years and 89.8% in Group B (p < 0.001). In Group B patients, tumor volume decreased from a baseline value of 2.4 ± 0.2 cm3 to 1.6 ± 0.2 cm3 at last follow up (p < 0.001). Conclusions. The results of this study suggest that GKS is effective in controlling growth of residual NPA for at least 5 years following initial maximal surgical debulking compared with no radiation therapy. Thus, GKS is recommended after microsurgery when visible tumor can be detected on imaging studies.

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.

These preliminary results suggest that C-11 choline may better image meningiomas in comparison with F-18 FDG. Clinical applications of C-11 choline PET/CT for grading and follow-up of meningiomas need to be assessed in further studies.

BACKGROUND Patients with renal cell carcinoma (RCC) brain metastases are frequently treated with immune checkpoint inhibitors (ICIs) and stereotactic radiosurgery (SRS). However, data reporting on the risk of developing radiation necrosis (RN) are limited. METHODS RN rates were compared for concurrent therapy (ICI/SRS administration within 4 weeks of one another) and nonconcurrent therapy with the χ2 test. Univariable logistic regression was used to identify factors associated with developing RN. RESULTS Fifty patients (23 concurrent and 27 nonconcurrent) with 395 brain metastases were analyzed. The median follow‐up was 12.1 months; the median age was 65 years. The median margin dose was 20 Gy, and 4% underwent prior whole‐brain radiation therapy (WBRT). The median treated tumor volume was 3.32 cm3 (range, 0.06‐42.38 cm3); the median volume of normal brain tissue receiving a dose of 12 Gy or higher (V12 Gy) was 8.42 cm3 (range, 0.27‐111.22 cm3). Any‐grade RN occurred in 17.4% and 22.2% in the concurrent and nonconcurrent groups, respectively (P = .67). Symptomatic RN occurred in 4.3% and 14.8% in the concurrent and nonconcurrent groups, respectively (P = .23). Increased tumor volume during SRS (odds ratio [OR], 1.08; 95% confidence interval [CI], 1.01‐1.19; P = .04) was associated with developing RN, although V12 Gy (OR, 1.03; 95% CI, 0.99‐1.06; P = .06), concurrent therapy (OR, 0.74; 95% CI, 0.17‐2.30; P = .76), prior WBRT, and ICI agents were not statistically significant. CONCLUSIONS Symptomatic RN occurs in a minority of patients with RCC brain metastases treated with ICI/SRS. The majority of events were grade 1 to 3 and were managed medically. Concurrent ICI/SRS does not appear to increase this risk. Attempts to improve dose conformality (reduce V12) may be the most successful mitigation strategy in single‐fraction SRS.

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