Nuance in Craniovertebral Junction Surgical Approach for Posterior C1-C2 Harms Stabilization: "Window Transposition" of the External Vertebral Venous Plexus for Bloodless C1 Lateral Mass Screw Insertion: Anatomical Aspects and Technical Notes.

Atlas and axis instrumentation may be necessary in cases of several craniocervical junction pathologies. According to the Harms technique, C1-C2 polyaxial screws are inserted respectively in the C1 lateral masses and in C2 pedicles. C1 lateral mass screw insertion requires the careful subperiosteal dissection of the posterior elements of C1, the identification of the screw entry point by the downward distraction of C2 nerve root, and the cautious sparing of the overlying posterior external vertebral venous plexus (peVVP), whose bleeding, obstructing the surgical field, is sometimes barely controlled by hemostatic agents and swabbing. The authors describe in detail the anatomical aspects of an alternative surgical technique developed for the microsurgical transposition of the C1-C2 interposed external vertebral venous plexus in the case of Harms C1-C2 screw stabilization. The longitudinal median incision of the atlantoaxial membrane, followed by bilateral subperiosteal dissection and microsurgical section respectively at the inferior borders of the C1 laminae and at the superior borders of the C2 laminae, allows, as a "window opening," the symmetrical mediolateral transposition of the peVVP. This procedure provides a faster and cleaner anatomical exposition of the posterior surface of the C1 lateral mass and the C2 isthmus, preventing troublesome intraoperative venous bleeding that hinders C1 lateral mass screw insertion.

Multidrug-resistant Gram-negative post-neurosurgical meningitis and the role of intraventricular colistin: a case series.

The aim of this study was to report the clinical experience of intraventricular colistin for the treatment of multi-resistant Gram-negative post-surgical meningitis in a tertiary hospital. Post-neurosurgical meningitis (PNM) is one of the life-threatening complications of neurosurgical procedures, and is frequently sustained by Acinetobacter baumannii and Klebsiella pneumoniae. Here we describe our experience of five cases of PNM caused by gram-negative multi-drug resistant (MDR) bacteria, treated with intraventricular (IVT) colistin, admitted to the Neurosurgery Unit of A.R.N.A.S. Civico of Palermo, Italy, from January 2016 to June 2020. In four patients the cerebrospinal fluid (CSF) culture was positive for A. baumannii, while in one patient it was positive for K. pneumoniae. IVT colistin therapy was administered for a median time of 18 days (range 7-29). The median time to CSF negativization was seven days (range 5-29). IVT colistin administration was associated with intravenous administration of meropenem and colistin in all patients. As regards clinical outcome, four patients were successfully treated and were subsequently discharged, while one patient died following respiratory complications and subsequent brain death. IVT colistin administration is an effective therapy for MDR post-neurosurgical meningitis and its administration is also prescribed by guidelines. However, IVT therapy for Gram-negative ventriculitis is mostly understudied. Our paper adds evidence for such treatment that can actually be considered life-saving.