Study Design: A multicenter observational survey. Objective: To quantify and compare inter- and intraobserver reliability of the subaxial cervical spine injury classification (SLIC) and the cervical spine injury severity score (CSISS) in a multicentric survey of neurosurgeons with different experience levels. Methods: Data concerning 64 consecutive patients who had undergone cervical spine surgery between 2013 and 2017 was evaluated, and we surveyed 37 neurosurgeons from 7 different clinics. All raters were divided into 3 groups depending on their level of experience. Two assessment procedures were performed. Results: For the SLIC, we observed excellent agreement regarding management among experienced surgeons, whereas agreement among less experienced neurosurgeons was moderate and almost twice as unlikely. The sensitivity of SLIC relating to treatment tactics reached as high as 92.2%. For the CSISS, agreement regarding management ranged from medium to substantial, depending on a neurosurgeon’s experience. For less experienced neurosurgeons, the level of agreement concerning surgical management was the same as for the SLIC in not exceeding a moderate level. However, this scale had insufficient sensitivity (slightly exceeding 50%). The reproducibility of both scales was excellent among all raters regardless of their experience level. Conclusions: Our study demonstrated better management reliability, sensitivity, and reproducibility for the SLIC, which provided moderate interrater agreement with moderate to excellent intraclass correlation coefficient indicators for all raters. The CSISS demonstrated high reproducibility; however, large variability in answers prevented raters from reaching a moderate level of agreement. Magnetic resonance imaging integration may increase sensitivity of CSISS in relation to fracture management.

This study is devoted to the accuracy of the optic navigation system “Neuroplan”. To assess the complex error of the system, a plastic model of the skull with 8 radiocontrast target points was developed. Twelve neurosurgeons with different levels of training participated in the study. The design of the study provided for each doctor performance of registration in the “Neuroplan” system at various positions of the model with subsequent hit at the target points. To select the optimal method of registration for different patient positions on the operating table, the registration table for anatomical landmarks (from 3 to 7) and on the surface was used. The analysis of the obtained results showed a high accuracy of the optic navigation system “Neuroplan”: in the side position of the scull model the target error averaged 1.57 [1.11; 2.13] mm, in the face down position – 1.69 [1.26; 2.19] mm, which is comparable with the declared accuracy of foreign analogues. When the experiment was repeated, it was shown that the system has high retest reliability.

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Multilateral drilling technology offers a highly effective method of enhanced oil recovery in fields characterized by complicated geological structure. This paper describes the analysis of sidetracks in an open hole by annular ledge formation with the use of a downhole motor in multilateral wells in Vostochno-Messoyakhskoye field. Since May 2018, more than 130 sidetracks have been drilled in Vostochno-Messoyakhskoye field with the use of bottomhole assembly (BHA) with a downhole motor in open hole by annular ledge formation. The fundamental difference between this method and conventional sidetracking with a downhole motor is that during sidetracking the entire drill string constantly rotates, rather than just bit rotation produced by downhole motor operation. In the process of technology introduction a comparison was made on how different downhole and geological conditions influence the time and performance results. The technology introduction resulted in the sidetracking time reduction from 9 hours to just 3 to 4 hours. A number of additional advantages of sidetracking with annular ledge formation were confirmed in the process of operations: The constant rotation of the drill string enables smooth weight transfer to the bit smooth, without failures. This contributes to effective and uniform ledge formation. Such sidetracking can be carried out at an extended length of open hole when it is difficult to ensure a free movement of the BHA which is necessary of conventional sidetracking. Constant rotation mitigates the risk of differential sticking. More favorable conditions are created for BHA movement in an interval of the holes diversion and subsequently for liner running in. It is possible to sidetrack with the use of a stiff BHA including a complete set of logging tools. In case of conventional sidetracking, it is preferable to use a short and flexible BHA. The experience gained in Vostochno-Messoyakhskoye field can be extrapolate to other fields where multilateral wells are drilled with annular ledge formation.

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