BACKGROUND AND PURPOSE:New deep brain stimulation leads with electrode contacts that are split along their circumference allow steering of the electrical field in a predefined direction. However, imaging-assisted directional stimulation requires detailed knowledge of the exact orientation of the electrode array. The purpose of this study was to evaluate whether this information can be obtained by rotational 3D fluoroscopy.

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Purpose. To compare radiographic and clinical outcomes after anterior cervical discectomy in patients with cervical degenerative disc disease using PEEK cages or PMMA spacers with a minimum 1-year follow-up. Methods. Anterior cervical discectomy was performed in 107 patients in one or two levels using empty PEEK cages (51 levels), Sulcem PMMA spacers (49 levels) or Palacos PMMA spacers (41 levels) between January, 2005 and February, 2009. Bony fusion, subsidence, and sagittal alignment were retrospectively assessed in CT scans and radiographs at follow-up. Clinical outcome was measured using the VAS, NDI, and SF-36. Results. Bony fusion was assessed in 65% (PEEK cage), 57% (Sulcem), and 46% (Palacos) after a mean follow-up of 2.5 years. Mean subsidence was 2.3–2.6 mm without significant differences between the groups. The most pronounced loss of lordosis was found in PEEK cages (−4.1°). VAS was 3.1 (PEEK cage), 3.6 (Sulcem), and 2.7 (Palacos) without significant differences. Functional outcome in the PEEK cage and Palacos group was superior to the Sulcem group. Conclusions. The substitute groups showed differing fusion rates. Clinical outcome, however, appears to be generally not correlated with fusion status or subsidence. We could not specify a superior disc substitute for anterior cervical discectomy. This trial is registered with DRKS00003591.

Sympathetic preganglionic neurons (SPNs) are located in the intermediolateral column (IMLC) of the spinal cord. This specific localization results from primary and secondary migratory processes during spinal cord development. Thus, following neurogenesis in the neuroepithelium, SPNs migrate first in a ventrolateral direction and then, in a secondary step, dorsolaterally to reach the IMLC. These migratory processes are controlled, at least in part, by the glycoprotein Reelin, which is known to be important for the development of laminated brain structures. In reeler mutants deficient in Reelin, SPNs initially migrate ventrolaterally as normal. However, most of them then migrate medially to become eventually located near the central canal. Here, we provide evidence that in wild-type animals this aberrant medial migration towards the central canal is prevented by Reelin-induced cytoskeletal stabilization, brought about by phosphorylation of cofilin. Cofilin plays an important role in actin depolymerization, a process required for the changes in cell shape during migration. Phosphorylation of cofilin renders it unable to depolymerize F-actin, thereby stabilizing the cytoskeleton. Using immunostaining for phosphorylated cofilin (p-cofilin), we demonstrate that SPNs in wild-type animals, but not in reeler mutants and other mutants of the Reelin signalling cascade, are immunoreactive for p-cofilin. These findings suggest that Reelin near the central canal induces cofilin phosphorylation in SPNs, thereby preventing them from aberrant migration towards the central canal. The results extend our previous studies on cortical neurons in which Reelin in the marginal zone was found to stabilize the leading processes of migrating neurons and terminate the migration process.

3D C-arms facilitate minimally invasive and accurate pedicle screw placement by providing 3D image datasets for intraoperative 3D imaging and navigation. However, the hereby potentially increased radiation exposure has to be considered. In particular, the Vision FD Vario 3D appears to generally evoke higher radiation exposures than the Siremobil Iso-C 3D. Well-indicated application of ionizing radiation and compliance with radiation protection principles remain mandatory to keep radiation exposure to patient and staff as low as reasonably achievable.

Objective: To compare the radiation exposure with the scrub nurse, assistant surgeon, and anesthetist during minimally invasive transforaminal lumbar interbody fusion using conventional 2-dimensional (2D) fluoroscopy or 3D fluoroscopy-based navigation.Summary of Background Data: Minimally invasive spinal fusion techniques are related to higher radiation exposures compared with open techniques. Especially the routinely exposed surgical staff faces the risks of increased radiation exposure.Methods: In total, 41 patients with planned monosegmental minimally invasive transforaminal lumbar interbody fusion were randomized into the intraoperative imaging techniques 2D fluoroscopy or 3D navigation. Eye lens and film dosemeters were attached to defined locations of the scrub nurse, assistant surgeon, and anesthetist. Mann-Whitney U and Wilcoxon-matched pairs signed-rank test were used to compare dosemeter readings. This study was registered with the German Clinical Trials Register (DRKS00004514). Results:The radiation exposure per surgery was low for the scrub nurse, assistant surgeon, and anesthetist in both the 2D fluoroscopy and 3D navigation groups. The maximum average value of 0.057 ± 0.031 mSv was measured on the unprotected chest of the assistant surgeon and was thus slightly above the lower detection limit of the dosemeters (0.044 mSv). The annual occupational dose limit would be exceeded at the earliest after 571 operations for the unprotected eye lens of the assistant surgeon.Conclusions: Minimally invasive lumbar fusion surgery is possible with comparatively low radiation exposure to the assisting operating room personnel without exceeding the annual maximum occupational radiation exposure. However, there is no definite dose value below which ionizing radiation poses no risk. Consequently, radiation sparing work routines should be strictly followed.

Neurogenic polyglobulia occurs in a subset of patients with hemangioblastomas. This phenomenon is mostly observed in VHL mutation carriers, but also occurs in patients with sporadic hemangioblastomas. Removal of the tumor results in the permanent cure of polyglobulia. Our observations suggest that polyglobulia is an effect by the tumor itself, either due to paraneoplasia or extramedullary hematopoiesis.