Christian Scheiwe

Use of Piezosurgery for removal of retrovertebral body osteophytes in anterior cervical discectomy.

BACKGROUND CONTEXTnThe relatively new technique of Piezosurgery is based on microvibrations, generated by the piezoelectrical effect, which results in selective bone cutting with preservation of adjacent soft tissue.nnnPURPOSEnTo study the applicability of Piezosurgery in anterior cervical discectomy with fusion (ACDF) surgery.nnnSTUDY DESIGN/SETTINGnProspective clinical study at the neurosurgical department of the University of Freiburg, Germany.nnnPATIENT SAMPLEnNine patients with cervical disc herniation and retrovertebral osteophytes who underwent ACDF surgery.nnnOUTCOME MEASURESnPiezosurgery was evaluated with respect to practicability, safety, preciseness of bone cutting, and preservation of adjacent neurovascular tissue. Pre- and postoperative clinical and radiological data were assessed.nnnMETHODSnPiezosurgery was supportively used in ACDF in nine patients with either radiculopathy or myelopathy from disc herniation or ventral osteophytes. After discectomy, osteophytes were removed with Piezosurgery to decompress the spinal canal and the foramina. Angled inserts were used, allowing for cutting even retrovertebral osteophytes.nnnRESULTSnIn all nine cases, Piezosurgery cut bone selectively with no damage to nerve roots, dura, or posterior longitudinal ligament. None of the patients experienced any new neurological deficit after the operation. The handling of the instrument was safe and the cut precise. Osteophytic spurs, even retrovertebral ones that generally only can be approached via corpectomies, could be safely removed because of the angled inserts through the disc space. Currently, a slightly prolonged operation time was observed for Piezosurgery. Furthermore, the design of the handpiece could be further improved to facilitate the intraoperative handling in ACDF.nnnCONCLUSIONSnPiezosurgery proved to be a useful and safe technique for selective bone cutting and removal of osteophytes with preservation of neuronal and soft tissue in ACDF. In particular, the angled inserts were effective in cutting bone spurs behind the adjacent vertebra which cannot be reached with conventional rotating burs.

Comparative Study of C-Arms for Intraoperative 3-Dimensional Imaging and Navigation in Minimally Invasive Spine Surgery Part II - Radiation Exposure.

Study Design: A radiation exposure study in vitro. Objective: This study aimed to compare the radiation exposure of 2 different 3-dimensional (3D) C-arm devices on an anthropomorphic phantom. Summary of Background Data: Minimally invasive pedicle screw placement requires intraoperative imaging techniques for visualization of the unexposed spine. Mobile 3D C-arms compose a 3D image data set out of multiple successive fluoroscopic images. Methods: We compared the 3D C-arm devices Siremobil Iso-C 3D (Siemens Sector Healthcare, Erlangen, Germany) and Vision FD Vario 3D (Ziehm Imaging, Nuremberg, Germany) regarding their radiation exposure. For this purpose, dosimeters were attached on an anthropomorphic phantom at various sites (eye lenses, thyroid gland, female, and male gonads). With each C-arm, 10 automated 3D scans as well as 400 fluoroscopic images were performed on the cervical and lumbar spine, respectively. Results: The Vision FD Vario 3D generally causes higher radiation exposures than the Siremobil Iso-C 3D. Significantly higher radiation exposures were assessed at the eye lenses performing cervical (294.1 vs. 84.6 &mgr;Sv) and lumbar 3D scans (22.5 vs. 11.2 &mgr;Sv) as well as at the thyroid gland performing cervical 3D scans (4405.2 vs. 2761.9 &mgr;Sv). Moreover, the Vision FD Vario 3D caused significantly higher radiation exposure at the eye lenses for standard cervical fluoroscopic images (3.2 vs. 0.4 &mgr;Sv). Conclusions: 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.

PEEK Cages versus PMMA Spacers in Anterior Cervical Discectomy: Comparison of Fusion, Subsidence, Sagittal Alignment, and Clinical Outcome with a Minimum 1-Year Follow-Up

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 2.3–2.6u2009mm 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.

Comparative Study of C-Arms for Intraoperative 3-Dimensional Imaging and Navigation in Minimally Invasive Spine Surgery Part I - Applicability and Image Quality.

Study Design: This was a retrospective analysis. Objective: This study compares 2 different 3-dimensional (3D) C-arm devices for intraoperative imaging and navigation with regard to clinical applicability and image quality. Summary of Background Data: Minimally invasive spine surgery requires intraoperative imaging techniques to adequately visualize the unexposed spine. For this purpose, mobile 3D C-arms became available along with the evolution of intraoperative navigation techniques. Methods: The C-arm devices Siremobil Iso-C 3D (Siemens) and Vision FD Vario 3D (Ziehm) perform an automated orbital rotation around the patient acquiring a 3D image set out of multiple successive fluoroscopic images. We report on technical specifications of the C-arms and our daily experience regarding clinical applicability. Furthermore, 5 spine surgeons evaluated blinded triplanar planes of 40 cervical, thoracic, and lumbar 3D scans that were obtained during routine surgery regarding usability for navigation. We assessed the delineation of cortical bone, artifacts, and overall image quality using a 0–10 numeric rating scale. Results: The Siremobil Iso-C 3D requires 128 seconds for its 190-degree scanning arc with equidistant isocenter. The Vision FD Vario 3D performs an elliptical scanning arc and completes its 135-degree scan in 64 seconds; furthermore, it features a flat panel detector and fully digital imaging. The smaller dimensions of the Vision FD Vario 3D made it easier to maneuver in the operating room compared with the more bulky Siremobil Iso-C 3D. With respect to image quality in cervical 3D scans, the Siremobil Iso-C 3D reached significantly higher scores in all categories. The Vision FD Vario 3D revealed less artifacts in lumbar 3D scans. Conclusions: The Siremobil Iso-C 3D provides high-quality 3D scans in slender spine regions (eg, cervical spine), whereas the Vision FD Vario 3D appears to have advantages in the lumbar spine. Further evolution and novel devices are needed to optimize image quality and handling.

Minimally Invasive Technique for PMMA Augmentation of Fenestrated Screws.

Purpose. To describe the minimally invasive technique for cement augmentation of cannulated and fenestrated screws using an injection cannula as well as to report its safety and efficacy. Methods. A total of 157 cannulated and fenestrated pedicle screws had been cement-augmented during minimally invasive posterior screw-rod spondylodesis in 35 patients from January to December 2012. Retrospective evaluation of cement extravasation and screw loosening was carried out in postoperative plain radiographs and thin-sliced triplanar computed tomography scans. Results. Twenty-seven, largely prevertebral cement extravasations were detected in 157 screws (17.2%). None of the cement extravasations was causing a clinical sequela like a new neurological deficit. One screw loosening was noted (0.6%) after a mean follow-up of 12.8 months. We observed no cementation-associated complication like pulmonary embolism or hemodynamic insufficiency. Conclusions. The presented minimally invasive cement augmentation technique using an injection cannula facilitates convenient and safe cement delivery through polyaxial cannulated and fenestrated screws during minimally invasive screw-rod spondylodesis. Nevertheless, the optimal injection technique and design of fenestrated screws have yet to be identified. This trial is registered with German Clinical Trials DRKS00006726.

Clinical relevance of anterior cerebral artery asymmetry in aneurysmal subarachnoid hemorrhage

OBJECTIVE An asymmetry of the A1 segments (A1SA) of the anterior cerebral arteries (ACAs) is an assumed risk factor for the development of anterior communicating artery aneurysms (ACoAAs). It is unknown whether A1SA is also clinically relevant after aneurysm rupture. The authors of this study investigated the impact of A1SA on the clinical course and outcome of patients with aneurysmal subarachnoid hemorrhage (SAH). METHODS The authors retrospectively analyzed data on consecutive SAH patients treated at their institution between January 2005 and December 2012. The occurrence and severity of cerebral infarctions in the ACA territories were evaluated on follow-up CT scans up to 6 weeks after SAH. Moreover, the risk for an unfavorable outcome (defined as > 3 points on the modified Rankin Scale) at 6 months after SAH was assessed. RESULTS A total of 594 patients were included in the final analysis. An A1SA was identified on digital subtraction angiography studies from 127 patients (21.4%) and was strongly associated with ACoAA (p < 0.0001, OR 13.7). An A1SA independently correlated with the occurrence of ACA infarction in patients with ACoAA (p = 0.047) and in those without an ACoAA (p = 0.015). Among patients undergoing ACoAA coiling, A1SA was independently associated with the severity of ACA infarction (p = 0.023) and unfavorable functional outcome (p = 0.045, OR = 2.4). CONCLUSIONS An A1SA is a common anatomical variation in SAH patients and is strongly associated with ACoAA. Moreover, the presence of A1SA independently increases the likelihood of ACA infarction. In SAH patients undergoing ACoAA coiling, A1SA carries the risk for severe ACA infarction and thus an unfavorable outcome. Clinical trial registration no.: DRKS00005486 ( http://www.drks.de/ ).

Atypical meningioma: progression-free survival in 161 cases treated at our institution with surgery versus surgery and radiotherapy

Although atypical meningioma recurs frequently in spite of total resection and/or radiotherapy, no consensus on optimal adjuvant management was found. However, several retrospective studies analysed the additional effect of adjuvant radiotherapy in atypical meningioma with inconsistent results. Therefrom, the purpose of this study was to evaluate prognostic factors influencing the recurrence/progression and progression-free survival (PFS) rates of atypical meningioma, particularly focused on the role of postoperative adjuvant radiotherapy. Between February 2001 and March 2015, 161 atypical meningioma resections were performed in our Department of Neurosurgery, of which, 128 cases underwent surgical treatment alone and 33 cases underwent surgery and radiotherapy. Kaplan–Meier analysis was used to provide median point estimates and PFS rates. The Cox-regression model was used in the univariate and multivariate analysis to identify significant factors associated with treatment. The extent of resection (Simpson grade I and II) significantly influenced the risk of recurrence (hazard ratiou2009=u20091.8, CI (95%) 1.3–2.6, p-valueu2009=u20090.0004). There was no significant benefit for progression-free survival after adjuvant radiotherapy (hazard ratiou2009=u20091.48, CI (95%) 0.76–2.86, p-valueu2009=u20090.22). Additionally, meningioma located at the anterior and posterior fossa showed a significantly longer PFS compared to other locations (p-valueu2009=u20090.03). Adjuvant postoperative radiotherapy had no significant impact on recurrence/progression rate or PFS. The extent of resection according to Simpson grade remains the most important prognostic factor associated with lower recurrence/progression rates and longer PFS in patients with atypical meningioma. The location of the tumours at the anterior or posterior fossa was an independent factor associated with improved PFS.

Stereotactic Catheter Ventriculocisternostomy for Clearance of Subarachnoid Hemorrhage: A Matched Cohort Study

Background and Purpose— Delayed cerebral infarction (DCI) is a major source of morbidity and mortality after aneurysmal subarachnoid hemorrhage. We report a novel intervention—stereotactic catheter ventriculocisternostomy (STX-VCS) and fibrinolytic/spasmolytic lavage therapy—for DCI prevention. Outcomes of 20 consecutive patients are compared with 60 matched controls. Methods— On the basis of individual treatment decisions, STX-VCS was performed in 20 high-risk aneurysmal subarachnoid hemorrhage patients admitted to our department between September 2015 and October 2016. Three controls matched for age, sex, aneurysm treatment method, and admission Hunt and Hess grade were assigned to each case treated by STX-VCS. DCI was the primary outcome. Mortality and mRS at rehabilitation discharge were secondary outcome parameters. The association between STX-VCS and DCI, mortality, and mRS was assessed by conditional logistic regression. Results— Stereotactic procedures were performed without surgical complications. Continuous cisternal lavage was feasible in 17 of 20 patients (85%). One adverse event because of cisternal lavage was without sequelae. DCI occurred in 25 of 60 (42%) controls and 3 of 20 (15%) patients with STX-VCS (odds ratio, 0.15; 95% confidence interval, 0.04–0.64). Mortality occurred in 20 of 60 (33%) controls and 1 of 20 (5%) patients with STX-VCS, respectively (odds ratio, 0.08; 95% confidence interval, 0.01 – 0.66). Favorable outcome (mRS⩽3) at rehabilitation discharge was observed in 12 of 20 patients with STX-VCS (60%) versus 21 of 60 (35%) matched controls (odds ratio, 0.26; 95% confidence interval, 0.8–0.86). Conclusions— STX-VCS was feasible and safe in patients with severe aneurysmal subarachnoid hemorrhage. Initial results indicate that DCI and mortality can be reduced, and neurological outcome may be improved with this method.

Surgeon, staff, and patient radiation exposure in minimally invasive transforaminal lumbar interbody fusion: impact of 3D fluoroscopy-based navigation partially replacing conventional fluoroscopy: study protocol for a randomized controlled trial

BackgroundSome symptomatic degenerative conditions of the lumbar spine may be treated with spinal fusion if conservative treatment has failed. The minimally invasive technique of transforaminal lumbar interbody fusion (MIS TLIF) is increasingly used but has been found to generate increased radiation exposure to the patient and staff. Modern three-dimensional (3D) C-arm devices are capable of providing conventional two-dimensional fluoroscopic images (x-rays) as well as 3D image sets for intraoperative navigation. This study was designed to compare the radiation exposure between these two intraoperative imaging techniques in MIS TLIF procedures.MethodsThis study is a randomized controlled trial. Forty participants scheduled to undergo monosegmental MIS TLIF will be recruited and randomly allocated to one of two groups with respect to the applied intraoperative imaging technique: conventional fluoroscopy (FLUORO group) and 3D fluoroscopy-based navigation combined with conventional fluoroscopy (NAV group). Furthermore, patients scheduled to undergo bisegmental MIS TLIF during the recruitment period for monosegmental MIS TLIF will be assessed for eligibility and will be randomly assigned separately. The primary endpoint is the radiation exposure to the surgeon and is measured by dosimeter readings. Secondary endpoints are the radiation exposure to the assistant surgeon, scrub nurse, anesthetist, patient, and C-arm as well as radiation exposure in relation to the body mass index of the patient.DiscussionResults of this randomized study will help to compare the radiation exposure to the operating staff and patient during MIS TLIF procedures using conventional fluoroscopy versus 3D fluoroscopy-based navigation combined with conventional fluoroscopy. Furthermore, recommendations regarding the appropriate use of the investigated intraoperative imaging techniques will be made to improve radiation protection and to reduce radiation exposure.Trial registrationRegistration number of the German Clinical Trials Register: DRKS00004514. Registration date: 11 August 2012.

Differential Expression Profile of Class I and Class III Metabotropic Glutamate Receptors during Postnatal Development of Rat Hippocampus

The expression profile of neurotransmitter receptors changes significantly during brain development. In particular, the postnatal regulation of glutamate receptor expression may play a critical role in synaptogenesis, formation of neuronal circuitries and neuronal vulnerability. In this study, we have analyzed the mRNA expression profile of excitatory class I metabotropic glutamate receptors (mGluR) mGluR1 and mGluR5 as well as the inhibitory class III receptors mGluR4 and mGluR7 during postnatal hippocampal development in the rat using a competitive RT-PCR assay. A transient upregulation was observed for mGluR1 with a peak expression at postnatal day 30. The expression for mGluR4 and mGluR5 continuously declined during postnatal maturation (postnatal days 4–90). In contrast, the decline of mGluR7 expression was less substantial in this period. This divergent pattern of mGluR gene expression during postnatal development of the hippocampus may correspond to neuronal pattern formation and plasticity, but may also provide a molecular basis for altered seizure susceptibility and neuronal vulnerability in the developing rat hippocampus.