Trigeminal Neuralgia Secondary to Intracranial Lesions: A Prospective Series of 17 Consecutive Cases

Object: The purpose of the study was to assess the role of Gamma Knife surgery (GKS) in secondary trigeminal neuralgia (TN) caused by space-occupying lesions. Methods: From July 2010 till January 2015, 17 patients had GKS for secondary TN caused by intracranial lesions. The primary outcome was tumor control. The secondary outcomes were the alleviation of pain and the eventual secondary effects. Covariates were the age, duration of symptoms, duration till alleviation etc. Results: The mean age in this series was 63.3 years (range 39-79). The mean follow-up period was 1.85 years (range 0.5-3). Nine (52.9%) were meningiomas, five (29.4%) trigeminal schwannomas, two (11.8%) brain metastases and one (5.9%) arteriovenous malformation (AVM). Eight were located on the right side and nine on the left side. The mean duration of TN was 13.5 months (range 0.5-160). Follow-up was available for 16 patients (94.1%). Pain alleviation appeared after a mean time of 4.6 months (1-11) in 15 patients (88.2%). Five (29.4%) patients completely stopped medication in a mean time of 7 months (range 1-13) and three (17.6%) decreased it at half of the initial doses. No patient developed new hypoesthesia or other cranial nerve complication. The marginal doses for meningiomas and trigeminal schwannomas were 12 Gy (12-14), for metastasis 20 (20-20) and for AVM 24 Gy. The mean target volume was 1.84 cc (range 0.12-8.10). The mean prescription isodose volume was 2.65 cc (0.19-11.90). The mean maximal diameter was 19.9 (range 9-36). The mean number of isocenters was 14.2 (4-27). The mean duration was 76.9 minutes (range 25-172). The mean conformity, selectivity, Paddick and gradient index were: 0.99 (range 0.955-1), 0.701 (range 0.525-0.885), 0.694 (range 0.525-0.885) and 2.904 (range 2.654-3.371). At last follow-up, tumor decreased in 10 (58.8%) patients, was stable in 6 (35.3%) and increased in one (5.9%), the latest at 6 months. Conclusions: Gamma Knife surgery is safe and effective in treating intracranial lesions presenting with secondary TN. The initial pain freedom response was close to 90%, while having no secondary effect. Pain alleviation is achieved even in the absence of a volume variation of the lesions.

Image guided critical screw placement precision in the cervical spine : important or incidental? : results of a series of 91 consecutive cases using OVEM

Study design: A retrospective study of image guided cervical implant placement precision. Objective: To describe a simple and precise classification of cervical critical screw placement. Summary of Background Data: "Critical" screw placement is defined as implant insertion into a bone corridor which is surrounded circumferentially by neurovascular structures. While the use of image guidance has improved accuracy, there is currently no classification which provides sufficient precision to assess the navigation success of critical cervical screw placement. Methods: Based on postoperative clinical evaluation and CT imaging, the orthogonal view evaluation method (OVEM) is used to classify screw accuracy into grade I (no cortical breach), grade la (screw thread cortical breach), grade II (internal diameter cortical breach) and grade III (major cortical breach causing neural or vascular injury). Grades II and III are considered to be navigation failures, after accounting for bone corridor / screw mismatch (minimal diameter of targeted bone corridor being smaller than an outer screw diameter). Results: A total of 276 screws from 91 patients were classified into grade I (64.9%), grade la (18.1%), and grade II (17.0%). No grade III screw was observed. The overall rate of navigation failure was 13%. Multiple logistic regression indicated that navigational failure was significantly associated with the level of instrumentation and the navigation system used. Navigational failure was rare (1.6%) when the margin around the screw in the bone corridor was larger than 1.5 mm. Conclusions: OVEM evaluation appears to be a useful tool to assess the precision of critical screw placement in the cervical spine. The OVEM validity and reliability need to be addressed. Further correlation with clinical outcomes will be addressed in future studies.

Change points detection in crime-related time series: an on-line fuzzy approach based on a shape space representation

The extension of traditional data mining methods to time series has been effectively applied to a wide range of domains such as finance, econometrics, biology, security, and medicine. Many existing mining methods deal with the task of change points detection, but very few provide a flexible approach. Querying specific change points with linguistic variables is particularly useful in crime analysis, where intuitive, understandable, and appropriate detection of changes can significantly improve the allocation of resources for timely and concise operations. In this paper, we propose an on-line method for detecting and querying change points in crime-related time series with the use of a meaningful representation and a fuzzy inference system. Change points detection is based on a shape space representation, and linguistic terms describing geometric properties of the change points are used to express queries, offering the advantage of intuitiveness and flexibility. An empirical evaluation is first conducted on a crime data set to confirm the validity of the proposed method and then on a financial data set to test its general applicability. A comparison to a similar change-point detection algorithm and a sensitivity analysis are also conducted. Results show that the method is able to accurately detect change points at very low computational costs. More broadly, the detection of specific change points within time series of virtually any domain is made more intuitive and more understandable, even for experts not related to data mining.