Augmented Reality-Supported Rod Bending in Multilevel Spinal Fusion Using the ADVISE Software.

BACKGROUND: One of the most common reasons for poor patient outcomes and revision surgery in spinal fusion is hardware failure. Screw loosening or pullout occurs in up to one-quarter of all cases. It is known that even small screw-rod misalignments can cause significant mechanical overloads during rod fixation, which can result in hardware failure. To address this crucial surgical step, a novel augmented reality-assisted software was developed to generate custom rod templates that are precisely adapted to the individual patient. METHODS: The novel software, which runs on a tablet, is used in spinal fusion surgery and is based on the use of a specific pedicle screw system, in which the polyaxial screw heads are connected to detachable guides. These guides can be recognized by the tablet camera and a light detection and ranging scanner. This image information is processed to determine the spatial positions of the screw heads and to calculate an ideally fitting rod template. RESULTS: The calculated rod template is displayed in a 1-to-1 scale on the tablet screen. This template is used to cut and bend the rods of the pedicle screw system. Finally, the custom bent rod can be inserted into the screw heads without tension. CONCLUSIONS: The augmented reality-assisted software is intended to give surgeons access to patient-specific intraoperative real-time data, helping them in bending rods that are more precisely adapted to the individual patient compared with the freehand technique.

Prophylactic nimodipine treatment improves hearing outcome after vestibular schwannoma surgery in men: a subgroup analysis of a randomized multicenter phase III trial.

A 2016 published randomized multicenter phase III trial of prophylactic nimodipine treatment in vestibular schwannoma surgery showed only a tendency for higher hearing preservation rates in the treatment group. Gender was not included in statistical analysis at that time. A retrospective analysis of the trial considering gender, preoperative hearing, and nimodipine treatment was performed. The treatment group received parenteral nimodipine from the day before surgery until the seventh postoperative day. The control group was not treated prophylactically. Cochlear nerve function was determined by pure-tone audiometry with speech discrimination preoperatively, during in-patient care, and 1 year after surgery and classified according to the Gardner-Robertson grading scale (GR). Logistic regression analysis showed a statistically significant effect for higher hearing preservation rates (pre- and postoperative GR 1-4) in 40 men comparing the treatment (n = 21) and the control (n = 19) groups (p = 0.028), but not in 54 women comparing 27 women in both groups (p = 0.077). The results were also statistically significant for preservation of postoperative hearing with pre- and postoperative GR 1-3 (p = 0.024). There were no differences in tumor sizes between the treatment and the control groups in men, whereas statistically significant larger tumors were observed in the female treatment group compared with the female control group. Prophylactic nimodipine is safe, and an effect for hearing preservation in 40 men with preoperative hearing ability of GR 1-4 was shown in this retrospective investigation. The imbalance in tumor size with larger tumors in females of the treatment group may falsely suggest a gender-related effect. Further investigations are recommended to clarify whether gender has impact on nimodipine's efficacy.

The role of intraoperative microelectrode recording and stimulation in subthalamic lead placement for Parkinson's disease.

OBJECTIVE: Intraoperative microelectrode recording (MER) and test-stimulation are regarded as the gold standard for proper placement of subthalamic (STN) deep brain stimulation (DBS) electrodes in Parkinson's disease (PD), requiring the patient to be awake during the procedure. In accordance with good clinical practice, most attending neurologists will request the clinically most efficacious trajectory for definite lead placement. However, the necessity of microelectrode-test-stimulation is disputed, as it may limit the access to DBS therapy, excluding those not willing or incapable of undergoing awake surgery. METHODS: We retrospectively analyzed the MERs and microelectrode-test-stimulation results with regard to the decision on definite lead placement and clinical outcome in a cohort of 67 PD-patients with STN-DBS. All patients received bilateral quadripolar ring electrodes. To ascertain overall procedural efficacy, we calculated the surgical index (SI) by comparing preoperative motor improvement induced by levodopa to that induced by stimulation 7 to 18 months after surgery, measured as the relative difference between ON and OFF-states on the Unified Parkinson's Disease Rating Scale motor part (UPDRS-3). Additionally, a side-specific surgical index (SSSI) was calculated using the unilateral assessable items of the UPDRS-3. The SSSI where microelectrode-test-stimulation overruled MER were compared to those where the result of microelectrode-test-stimulation was congruent to MER results. RESULTS: A total of 134 electrodes were analyzed. For final lead placement, the central trajectory was chosen in 54% of patient hemispheres. The mean SI was 0.99 (± 0.24). SSSI averaged 1.04 (± 0.45). In 37 lead placements, microelectrode-test-stimulation overruled MER in the final trajectory selection, in 27 of these lead placements adverse effects during microelectrode-test-stimulation were decisive. Neither the number of test electrodes used nor the STN-signal length had an impact on the SSSI. The SSSI did not differ between lead placements with MER/microelectrode-test-stimulation congruency and those where the results of microelectrode-test-stimulation initiated lead placement in a trajectory with shorter STN signal. CONCLUSION: Intraoperative testing is mandatory to ensure an optimal motor outcome of STN DBS in PD-patients when using quadripolar ring electrodes. However, we also demonstrated that neither the length of the STN-signal on MER nor the number of test electrodes influenced the motor outcome.

Diagnostic yield of fluorescence-assisted frame-based stereotactic biopsies of intracerebral lesions in comparison with frozen-section analysis.

PURPOSE: Stereotactic biopsies are routinely used to establish a histological diagnosis of unclear cerebral pathologies. Intraoperatively, frozen-section analysis often confirms diagnostic tissue but also exhibits methodological pitfalls. Intraoperative five-aminolevulinic acid (5-ALA)-fluorescence has been described not only in gliomas but also in other cerebral pathologies. In this study, we assessed the 5-ALA contribution to the intraoperative confirmation of diagnostic tissue in frame-based stereotactic biopsies of unclear intracerebral lesions in direct comparison with frozen-section analysis. METHODS: Patients scheduled for stereotactic biopsies of unclear intracerebral pathologies received 5-ALA preoperatively. Obtained samples were intraoperatively analyzed for the presence of 5-ALA-fluorescence. One sample was used for frozen-section and a second one for permanent histopathological analysis. The diagnostic yield of frozen-section and intraoperative 5-ALA-fluorescence was calculated. The inclusion criteria for this retrospective analysis were unclear intracerebral lesions with inconclusive imaging findings and several differential diagnoses. RESULTS: A total of 39 patients with 122 obtained specimens were included. The overall diagnostic yield was 92.3%. 5-ALA-positive samples were obtained in 74.3% (29/39) of patients and all these samples contained diagnostic tissue. 5-ALA-fluorescence confirmed diagnostic tissue with a sensitivity of 100%, a specificity of 27%, a positive predictive value (PPV) of 78%, and a negative predictive value (NPV) of 100%. A clear diagnosis could be predicted by frozen section with a sensitivity of 80%, a specificity of 100%, a PPV of 100%, and NPV of 30%; Fisher's exact test p = 0.01. CONCLUSION: The 5-ALA-fluorescence in stereotactic biopsies of unclear intracerebral pathologies exhibits a high PPV/NPV for intraoperative confirmation of diagnostic tissue and might increase the diagnostic yield of the procedure by overcoming some of the limitations of frozen-section.

It is time for a change in the management of elderly severely injured patients! An analysis of 126,015 patients from the TraumaRegister DGU®.

BACKGROUND: The number of elderly patients among the severely injured has been increasing continuously. It has been suggested that an increased life expectancy and a higher level of activity and mobility in older ages could explain this observation. Elderly trauma patients have relevant higher mortality rates and poorer functional outcomes. The reasons remain unclear. The aim of this study was to look for differences in the management of severely injured elderly patients compared to younger age groups and to evaluate their potential impact on outcome. METHODS: The TraumaRegister DGU® is a multicenter database that documents de-identified data of severely injured patients since 1993. Trauma cases documented between 2009 and 2016 with an ISS ≥ 9 were divided in four age groups. The groups were compared with respect to mechanism of injury, pattern of injury, severity of injury, management and outcome. RESULTS: The analysis of 126,015 severely injured patients showed that 37.5% of the population were elderly patients (≥ 60 years). Their rate actually increased every year by 1.7%. The elderly trauma patients experience different mechanisms of injury (more low energy trauma) and different pattern of injuries (more brain trauma, less abdominal and extremity injuries). Evaluating the management of patients showed that elderly patients have lower intubation rates and less volume replacement in the prehospital setting. Diagnostic interventions like CT scans in the emergency room were performed more restrictively. Elderly trauma patients also received fewer surgical interventions for brain injuries, pelvic fractures and femur fractures. Their hospital mortality rates were higher. CONCLUSIONS: Severely injured elderly patients are treated with a more "wait and see approach" resulting in higher mortality rates. We suggest that this population needs a more "aggressive management" to improve their outcome, if the wish to perform complete treatment including surgical procedures and intensive care medicine has not been excluded by the patients or their legal guardian.

A critical comparison between the semisitting and the supine positioning in vestibular schwannoma surgery: subgroup analysis of a randomized, multicenter trial.

OBJECTIVE: Patient positioning in vestibular schwannoma (VS) surgery is a matter of ongoing discussion. Factors to consider include preservation of cranial nerve functions, extent of tumor resection, and complications. The objective of this study was to determine the optimal patient positioning in VS surgery. METHODS: A subgroup analysis of a randomized, multicenter trial that investigated the efficacy of prophylactic nimodipine in VS surgery was performed to investigate the impact of positioning (semisitting or supine) on extent of resection, functional outcomes, and complications. The data of 97 patients were collected prospectively. All procedures were performed via a retrosigmoid approach. The semisitting position was chosen in 56 patients, whereas 41 patients were treated while supine. RESULTS: Complete resection was obtained at a higher percentage in the semisitting as compared to the supine position (93% vs 73%, p = 0.002). Logistic regression analysis revealed significantly better facial nerve function in the early postoperative course in the semisitting group (p = 0.004), particularly concerning severe facial nerve paresis (House-Brackmann grade IV or worse; p = 0.002). One year after surgery, facial nerve function recovered. However, there was still a tendency for better facial nerve function in the semisitting group (p = 0.091). There were no significant differences between groups regarding hearing preservation rates. Venous air embolism with the necessity to terminate surgery occurred in 2 patients in the semisitting position (3.6%). Supplementary analysis with a 2-tailed permutation randomization with 10,000 permutations of treatment choice and a propensity score matching showed either a tendency or significant results for better facial nerve outcomes in the early postoperative course and extent of resection in the semisitting group. CONCLUSIONS: Although the results of the various statistical analyses are not uniform, the data indicate better results concerning both a higher rate of complete removal (according to the intraoperative impression of the surgeon) and facial nerve function after a semisitting as compared to the supine position. These advantages may justify the potential higher risk for severe complications of the semisitting position in VS surgery. The choice of positioning has to consider all individual patient parameters and risks carefully.

Development of evidence-based quality indicators for deep brain stimulation in patients with Parkinson's disease and first year experience of implementation of a nation-wide registry.

INTRODUCTION: Deep Brain Stimulation (DBS) is a complex, invasive and cost-intensive therapy that requires a high level of expertise. To date, data on quality of DBS in clinical routine in the German health care system are lacking. METHODS: The development of evidence-based QIs for DBS in PD patients was performed following a standardized process by a multidisciplinary board between 2014 and 2016. The process was initiated by the German Parkinson Society and followed international recommendations for developing QIs including: a systematic literature search; an appraisal of the published evidence; a consensus-based selection of the QI set; and a pilot study to assess the feasibility in implementing the QIs in clinical routine. RESULTS: A set of 28 QIs for determining the quality of DBS in PD was established by the board covering different dimensions of health care quality (structure, process, and outcome) in different treatment phases of DBS care (pre-operative, peri-operative, and post-operative). Implementation in clinical practice was tested in a pilot study comprising three hospitals delivering DBS care. The feasibility of the QI set was evaluated positively by the participating physicians and hospitals. Mean time to document one patient was 25 min. The German-wide implementation of the defined indicator set within a dedicated quality registry (QualiPa) started in June 2016. CONCLUSION: QIs are a necessary requirement to monitor hospital performance in DBS care. The evidence-based approach to develop the proposed indicator set is expected to assure transparency, acceptance and long-term applicability of the QI set in Germany.

Predictors of ventricular tension pneumocephalus after posterior fossa surgery in the sitting position.

BACKGROUND: Ventricular pneumocephalus is a rare but potentially life-threatening complication of cranial surgery in the sitting position. OBJECTIVE: The objective of the study is to assess the incidence and risk factors of postoperative ventricular pneumocephalus. METHODS: We performed a retrospective chart review of 307 consecutive patients (147 men, 160 women) treated at our institution by intracranial surgery in the sitting position from January 2010 to October 2014. Ventricular air entrapment with lack of arousal or neurologic deterioration requiring external ventriculostomy (EVD) was defined as ventricular tension pneumocephalus (VTP). Demographic variables were recorded along with radiological and clinical data. The occurrence of pneumocephalus was correlated with patient-related and surgical variables. RESULTS: VTP was observed in 12 cases (3.9%). These patients had higher intraventricular air volumes (48.5 cm3 (CI 95% [29.06-67.86])) compared to asymptomatic patients (7.4 cm3 (CI 95% [5.43-9.48])). Opening of the fourth ventricle was the most potent predictor of VTP (OR = 34.7, CI 95% [4.4-273.5], p = 0.001). In patients undergoing no additional treatment for pneumocephalus, ventricular air volume declined to an average of 41.7% of the initial postoperative volume on postoperative day 3. CONCLUSIONS: Entrapment of intracranial and particularly ventricular air requiring emergent EVD occurred in 3.9% cases of intracranial surgery in the sitting position. Especially the opening of the fourth ventricle was associated with the development of VTP, which should warrant particularly diligent postoperative observation of these patients. In cases without neurological symptoms, the rate of spontaneous air resorption is sufficiently high to warrant expectant management.

Robot guidance for percutaneous minimally invasive placement of pedicle screws for pyogenic spondylodiscitis is associated with lower rates of wound breakdown compared to conventional fluoroscopy-guided instrumentation.

Postoperative wound healing can pose a problem in patients undergoing instrumented surgery for pyogenic spondylodiscitis. Robotic guidance allows the minimally invasive placement of pedicle screws in the thoracolumbar spine. We assessed whether using this technique to perform minimally invasive surgery had an impact on wound healing in patients with pyogenic spondylodiscitis when compared to conventional open fluoroscopy-guided surgery. We reviewed charts of 206 consecutive patients who underwent instrumentation for pyogenic spondylodiscitis. The need for wound revision was the primary outcome measure. Patient variables and comorbidities as well as surgical technique (robotic versus fluoroscopy-guided) were analyzed. We also compared fluoroscopy times between the two groups. Multivariate regression analysis was performed to identify predictors of wound breakdown. A total of 206 patients underwent surgery for spondylodiscitis. Robotic surgical assistance was used for percutaneous instrumentation in 47.6% of cases (n = 98). Wound healing problems requiring revision occurred in 30 out of 206 patients (14.6%). Univariate analysis revealed a potential association of wound breakdown with (1) robotic technique, (2) age > 70 years, and (3) the presence of methicillin-resistant Staphylococcus aureus. After multivariate correction however, only robotic technique retained significance with an odds ratio of 0.39 (CI 95% 0.16-0.94; p = 0.035). Wound revision was required in eight out of 98 patients (8.1%) in the robot group and 22/108 (20%) in the conventional surgery group. Fluoroscopy times were significantly lower in the robot group with a mean of 123 ± 86 s in comparison with a mean of 157 ± 99 s in the conventional group (p = 0.014). While initially designed to improve the accuracy of pedicle screw placement, robot-assisted minimally invasive technique had a tangible effect on both radiation exposure and the rate of wound breakdown in patients with pyogenic spondylodiscitis in our large single-center study.

Rescue Implantation of Expandable Cages for Severe Osteolysis and Cage Dislocation in the Lumbosacral Junction.

BACKGROUND: Osteolysis and implant loosening are commonly encountered problems after spinal instrumentation. CASE DESCRIPTION: In a patient who had previously undergone a posterior lumbar interbody fusion procedure, fusion did not occur, and a secondary cage dislocation led to an impingement of the L5 nerve root with severe radiculopathy. Revision surgery was performed. Intraoperatively, osteolysis was found to be so severe that conventional cages did not fill the void to allow for sufficient anterior column support. We used expandable transforaminal lumbar interbody fusion cages and implanted them bilaterally to replace the dislodged posterior lumbar interbody fusion cages. Clinical follow-up was uneventful. Imaging performed at 1 year showed satisfactory cage position and fusion. CONCLUSIONS: We propose the use of cages with the ability of ventral distraction in similar rescue interventions with cage dislocation and bone resorption. This may prevent a second surgery via a ventral approach.

Robotic versus fluoroscopy-guided pedicle screw insertion for metastatic spinal disease: a matched-cohort comparison.

OBJECTIVE Robot-guided pedicle screw placement is an established technique for the placement of pedicle screws. However, most studies have focused on degenerative disease. In this paper, the authors focus on metastatic spinal disease, which is associated with osteolysis. The associated lack of dense bone may potentially affect the automatic recognition accuracy of radiography-based surgical assistance systems. The aim of the present study is to compare the accuracy of the SpineAssist robot system with conventional fluoroscopy-guided pedicle screw placement for thoracolumbar metastatic spinal disease. METHODS Seventy patients with metastatic spinal disease who required instrumentation were included in this retrospective matched-cohort study. All 70 patients underwent surgery performed by the same team of experienced surgeons. The decision to use robot-assisted or fluoroscopy-guided pedicle screw placement was based the availability of the robot system. In patients who underwent surgery with robot guidance, pedicle screws were inserted after preoperative planning and intraoperative fluoroscopic matching. In the "conventional" group, anatomical landmarks and anteroposterior and lateral fluoroscopy guided placement of the pedicle screws. The primary outcome measure was the accuracy of screw placement on the Gertzbein-Robbins scale. Grades A and B (< 2-mm pedicle breach) were considered clinically acceptable, and all other grades indicated misplacement. Secondary outcome measures included an intergroup comparison of direction of screw misplacement, surgical site infection, and radiation exposure. RESULTS A total of 406 screws were placed at 206 levels. Sixty-one (29.6%) surgically treated levels were in the upper thoracic spine (T1-6), 74 (35.9%) were in the lower thoracic spine, and the remaining 71 (34.4%) were in the lumbosacral region. In the robot-assisted group (Group I; n = 35, 192 screws), trajectories were Grade A or B in 162 (84.4%) of screws. The misplacement rate was 15.6% (30 of 192 screws). In the conventional group (Group II; n = 35, 214 screws), 83.6% (179 of 214) of screw trajectories were acceptable, with a misplacement rate of 16.4% (35 of 214). There was no difference in screw accuracy between the groups (chi-square, 2-tailed Fisher's exact, p = 0.89). One screw misplacement in the fluoroscopy group required a second surgery (0.5%), but no revisions were required in the robot group. There was no difference in surgical site infections between the 2 groups (Group I, 5 patients [14.3%]; Group II, 8 patients [22.9%]) or in the duration of surgery between the 2 groups (Group I, 226.1 ± 78.8 minutes; Group II, 264.1 ± 124.3 minutes; p = 0.13). There was also no difference in radiation time between the groups (Group I, 138.2 ± 73.0 seconds; Group II, 126.5 ± 95.6 seconds; p = 0.61), but the radiation intensity was higher in the robot group (Group I, 2.8 ± 0.2 mAs; Group II, 2.0 ± 0.6 mAs; p < 0.01). CONCLUSIONS Pedicle screw placement for metastatic disease in the thoracolumbar spine can be performed effectively and safely using robot-guided assistance. Based on this retrospective analysis, accuracy, radiation time, and postoperative infection rates are comparable to those of the conventional technique.

Prophylactic nimodipine treatment and improvement in hearing outcome after vestibular schwannoma surgery: a combined analysis of a randomized, multicenter, Phase III trial and its pilot study.

OBJECTIVE In clinical routines, neuroprotective strategies in neurosurgical interventions are still missing. A pilot study (n = 30) and an analogously performed Phase III trial (n = 112) pointed to a beneficial effect of prophylactic nimodipine and hydroxyethyl starch (HES) in vestibular schwannoma (VS) surgery. Considering the small sample size, the data from both studies were pooled. METHODS The patients in both investigator-initiated studies were assigned to 2 groups. The treatment group (n = 70) received parenteral nimodipine (1-2 mg/hour) and HES (hematocrit 30%-35%) from the day before surgery until the 7th postoperative day. The control group (n = 72) was not treated prophylactically. Facial and cochlear nerve functions were documented preoperatively, during the inpatient care, and 1 year after surgery. RESULTS Pooled raw data were analyzed retrospectively. Intent-to-treat analysis revealed a significantly lower risk for hearing loss (Class D) 12 months after surgery in the treatment group compared with the control group (OR 0.46, 95% CI 0.22-0.97; p = 0.04). After exclusion of patients with preoperative Class D hearing, this effect was more pronounced (OR 0.38, 95% CI 0.17-0.83; p = 0.016). Logistic regression analysis adjusted for tumor size showed a 4 times lower risk for hearing loss in the treatment group compared with the control group (OR 0.25, 95% CI 0.09-0.63; p = 0.003). Facial nerve function was not significantly improved with treatment. Apart from dose-dependent hypotension (p < 0.001), the study medication was well tolerated. CONCLUSIONS Prophylactic nimodipine is safe and may be recommended in VS surgery to preserve hearing. Prophylactic neuroprotective treatment in surgeries in which nerves are at risk seems to be a novel and promising concept. Clinical trial registration no.: DRKS 00000328 ( https://drks-neu.uniklinik-freiburg.de/drks_web/ ).

Interobserver variability of the House-Brackmann facial nerve grading system for the analysis of a randomized multi-center phase III trial.

BACKGROUND: Evidence of a high interobserver variability of the subjective House-Brackmann facial nerve grading system (HBGS) would justify cost- and time-consuming technological enhancements of objective classifications for facial nerve paresis. METHOD: A total of 112 patients were recruited for a randomized multi-center trial to investigate the efficacy of prophylactic nimodipine treatment in vestibular schwannoma (VS) surgery. For the present investigation both treatment groups were pooled for the assessment of facial nerve function preoperatively, in the early postoperative course and 1 year after the surgery. Facial nerve function was documented photographically at rest and in motion and classified according to the HBGS by three independent observers (neurosurgeon, neurologist, ENT) and by the investigator of each center. RESULTS: Interobserver variability was considerably different with respect to the three time points depending upon the severity of facial nerve paresis. Preoperative facial nerve function was normal or only mildly impaired (HB grade I or II) and was assessed consistently in 97%. Facial nerve function deteriorated during the early postoperative course and was subsequently documented without dissent in only 36%, with one grade difference in 45%, two grade difference in 17% and three grade difference in 2%. One year after surgery, facial nerve function predominantly improved resulting in a consistent assessment in 66%. Differing ratings were observed in 34% with one grade deviation in 88% and of two grades in 12%. Patients with differing ratings of two or more grades exhibited considerably worse facial nerve function (p < 0.001). CONCLUSIONS: The HBGS produced comparable results between different observers in patients with normal or only mildly impaired facial nerve function. Interobserver variability increased depending on the severity of facial nerve paresis. The results suggest that the HBGS does not promote uniformity of reporting and comparison of outcomes in patients with moderate or severe facial nerve paresis.

Contrast-enhanced shunt series ("shuntography") compare favorably to other shunt imaging modalities in detecting shunt occlusion.

BACKGROUND: Obstruction is a common cause of ventriculo-peritoneal shunt failure. Head computed tomography and plain x-ray examinations of shunt tubing ("shunt series") are routinely used in patients readmitted for reemerging symptoms but are of limited value. The validity of shunt series can be improved by applying contrast agent into the system (contrast-enhanced shunt series, a.k.a. a "shuntogram" or "shuntography"). We hypothesized that contrast-enhanced shunt series have a high predictive value for shunt revision surgeries. METHODS: We retrospectively re-evaluated 107 contrast-enhanced shunt series and reviewed the patient histories. We defined outcome parameters for calculating the utility of a pathological contrast-enhanced shunt series in predicting revision surgery. RESULTS: Of 107 contrast-enhanced shunt series, 41 examinations were positive for obstruction, mainly of the ventricular (36.5 %) and the peritoneal catheter (48.8 %). Within 30 days, 35 successful revision surgeries and 3 revision surgeries without resolution of symptoms were performed. In two cases the shunt tubing was found to be patent. Sixty-six negative examinations resulted in two revision surgeries, in addition to ten surgeries not attempting to restore patency. After 30 days, the specificity of contrast-enhanced shunt series for shunt failure identification was calculated at 92.8 %, the sensitivity at 94.7 %, the positive predictive value at 87.8 %, and the negative predictive value at 97.0 %. CONCLUSIONS: The contrast-enhanced shunt series method is a highly specific examination with a negative predictive value exceeding that of head computed tomography and plain shunt series. Compared to radionuclide marker studies, contrast-enhanced shunt series demonstrate better spatiotemporal resolution, enabling focused local surgical repair.

Enlightening the Cerebellopontine Angle: Intraoperative Indocyanine Green Angiography in Microvascular Decompression for Trigeminal Neuralgia.

Background and Study Aims In microvascular decompression of the trigeminal nerve for trigeminal neuralgia (TN), the site of conflict is occasionally difficult to identify. Endoscopy has been described to better evaluate the anatomical conflict in such situations. We hypothesized that indocyanine green (ICG) angiography could allow for better visualization of the compressing artery and its anatomical relation to the nerve. Material and Methods ICG angiography was performed in 17 TN patients undergoing microvascular decompression. We focused on whether ICG angiography is helpful in determining the site of conflict, particularly when not directly visible via the microscope, and whether fluorescence is strong enough to shine through the nerve obliterating the direct view of the compressing vessel. Results In four patients, the site of conflict was immediately apparent after opening the cerebellopontine cistern, and ICG angiography did not provide the neurosurgeon with additional information. In another two patients, imaging quality and fluorescence were too poor. Of the remaining 11 patients with a hidden site of nerve-vessel conflict, ICG angiography was found to be helpful in anticipating the site of compression and the course of the artery in 7 patients, particularly in regard to the so-called shining-through effect through fiber bundles of the thinned nerve. Of all the patients, 88% reported at least improvement or cessation of their symptoms, including all of the patients with a shine-through effect. Conclusion ICG angiography could be a helpful adjunct in decompressing the trigeminal nerve and can guide the surgeon to the nerve-vessel conflict. Intensity of the fluorescence is powerful enough to shine through thinned and splayed trigeminal nerve fiber bundles.

Asphyxia due to laryngeal spasm as a severe complication of awake deep brain stimulation for Parkinson's disease: a case report.

BACKGROUND: In accordance with German neurosurgical and neurological consensus recommendations, lead placements for deep brain stimulation (DBS) in patients with Parkinson's disease (PD) are usually performed with the patient awake and in "medication off" state. This allows for optimal lead position adjustment according to the clinical response to intraoperative test stimulation. However, exacerbation of Parkinsonian symptoms after withdrawal of dopaminergic medication may endanger the patient by inducing severe "off" state motor phenomena. In particular, this can be a problem in awake craniotomies utilizing intraoperative airway management and resuscitation. CASE PRESENTATION: We report the case of a PD patient with progressive orofacial and neck muscle dystonia resulting in laryngeal spasm during DBS lead placement. This led to upper airway compromise and asphyxia, requiring resuscitation. CONCLUSIONS: Laryngeal spasms may occur as a rare "off" state motor complication in patients with PD. Other potential causes of intraoperative difficulties breathing include bilateral vocal cord palsy, positional asphyxia, and silent aspiration. In our practice, we have adjusted our medication regimen and now allow patients to receive their standard dopaminergic medication until the morning of surgery. Neurologists and neurosurgeons performing lead placement procedures for PD should be aware of this rare but unsafe condition to most optimized treatment.

Stability of hearing preservation and regeneration capacity of the cochlear nerve following vestibular schwannoma surgery via a retrosigmoid approach.

OBJECTIVE The purpose of this research was to examine the stability of long-term hearing preservation and the regeneration capacity of the cochlear nerve following vestibular schwannoma (VS) surgery in a prospective study. METHODS A total of 112 patients were recruited for a randomized multicenter trial between January 2010 and April 2012 to investigate the efficacy of prophylactic nimodipine treatment versus no prophylactic nimodipine treatment in VS surgery. For the present investigation, both groups were pooled to compare hearing abilities in the early postoperative course and 1 year after the surgery. Hearing was examined using pure-tone audiometry with speech discrimination, which was performed preoperatively, in the early postoperative course, and 12 months after surgery and was subsequently classified by an independent otorhinolaryngologist using the Gardner-Robertson classification system. RESULTS Hearing abilities at 2 time points were compared by evaluation in the early postoperative course and 1 year after surgery in 102 patients. The chi-square test showed a very strong association between the 2 measurements in all 102 patients (p < 0.001) and in the subgroup of 66 patients with a preserved cochlear nerve (p < 0.001). CONCLUSIONS There is no significant change in cochlear nerve function between the early postoperative course and 1 year after VS surgery. The result of hearing performance, as evaluated by early postoperative audiometry after VS surgery, seems to be a reliable prognosticator for future hearing ability. Clinical trial registration nos.: 2009-012088-32 ( clinicaltrialsregister.eu ) and DRKS 00000328 ("AkNiPro," drks-neu.uniklinik-freiburg.de/drks_web/ ).

Prophylactic nimodipine treatment for cochlear and facial nerve preservation after vestibular schwannoma surgery: a randomized multicenter Phase III trial.

OBJECTIVE: A pilot study of prophylactic nimodipine and hydroxyethyl starch treatment showed a beneficial effect on facial and cochlear nerve preservation following vestibular schwannoma (VS) surgery. A prospective Phase III trial was undertaken to confirm these results. METHODS: An open-label, 2-arm, randomized parallel group and multicenter Phase III trial with blinded expert review was performed and included 112 patients who underwent VS surgery between January 2010 and February 2013 at 7 departments of neurosurgery to investigate the efficacy and safety of the prophylaxis. The surgery was performed after the patients were randomly assigned to one of 2 groups using online randomization. The treatment group (n = 56) received parenteral nimodipine (1-2 mg/hr) and hydroxyethyl starch (hematocrit 30%-35%) from the day before surgery until the 7th postoperative day. The control group (n = 56) was not treated prophylactically. RESULTS: Intent-to-treat analysis showed no statistically significant effects of the treatment on either preservation of facial nerve function (35 [67.3%] of 52 [treatment group] compared with 34 [72.3%] of 47 [control group]) (p = 0.745) or hearing preservation (11 [23.4%] of 47 [treatment group] compared with 15 [31.2%] of 48 [control group]) (p = 0.530) 12 months after surgery. Since tumor sizes were significantly larger in the treatment group than in the control group, logistic regression analysis was required. The risk for deterioration of facial nerve function was adjusted nearly the same in both groups (OR 1.07 [95% CI 0.34-3.43], p = 0.91). In contrast, the risk for postoperative hearing loss was adjusted 2 times lower in the treatment group compared with the control group (OR 0.49 [95% CI 0.18-1.30], p = 0.15). Apart from dose-dependent hypotension (p < 0.001), no clinically relevant adverse reactions were observed. CONCLUSIONS: There were no statistically significant effects of the treatment. Despite the width of the confidence intervals, the odds ratios may suggest but do not prove a clinically relevant effect of the safe study medication on the preservation of cochlear nerve function after VS surgery. Further study is needed before prophylactic nimodipine can be recommended in VS surgery.

Use of closed suction devices and other drains in spinal surgery: results of an online, Germany-wide questionnaire.

PURPOSE: The risks of drains in spine surgery (e.g., increasing venous plexus bleeding, maintaining CSF leakage, and infections) must be balanced with their benefits (e.g., reduced rate of postoperative hematoma and seroma formation). Little is known about factors that influence surgeons' decision to employ a drain. METHODS: We conducted a survey among German spine surgeons regarding their use of drains. Neurosurgical and orthopedic departments along with privately practicing neurosurgeons were invited to complete an online questionnaire featuring general and case-specific questions with regard to drain placement. RESULTS: We received 163 questionnaires (private practice and small-volume centers 36.1%, medium- and large-volume centers 43.6%, university centers 20.2%). Factors influencing the decision to use a drain include size of wound, type of procedure, hemostasis at the end of the procedure, and coagulopathies; factors found to be less important include overall blood loss, body mass index, and implants. 31% of surgeons will use drains for microdiskectomies. For other pathologies, percentages are as follows: anterior cervical diskectomy and fusion, 58%; cervical laminoplasty, 62%; hemilaminectomy for bisegmental lumbar stenosis, 69%; transpedicular instrumentation, 88%; vertebral body replacement for metastasis, 94%. Over half of those who usually employ a drain will not use a drain in cases of unintentional durotomy. CONCLUSION: In terms of indication, duration, and safety measures, use of drains in spinal surgery is heterogeneous. The majority of surgeons prefer drains to suction in most cases, except for microdiskectomies, for which only 31% will use a drain. Nearly all colleagues discontinue drains by day 4.

Unskilled unawareness and the learning curve in robotic spine surgery.

BACKGROUND: Robotic assistance for the placement of pedicle screws has been established as a safe technique. Nonetheless rare instances of screw misplacement have been reported.The aim of the present retrospective study is to assess whether experience and time affect the accuracy of screws placed with the help of the SpineAssist™ robot system. METHODS: Postoperative computed tomography (CT) scans of 258 patients requiring thoracolumbar pedicle screw instrumentation from 2008 to 2013 were reviewed. Overall, 13 surgeons performed the surgeries. A pedicle breach of >3 mm was graded as a misplacement. Surgeons were dichotomised into an early and experienced period in increments of five surgeries. RESULTS: In 258 surgeries, 1,265 pedicle screws were placed with the aid of the robot system. Overall, 1,217 screws (96.2 %) were graded as acceptable. When displayed by surgeon, the development of percent misplacement rates peaked between 5 and 25 surgeries in 12 of 13 surgeons. The overall misplacement rate in the first five surgeries was 2.4 % (6/245). The misplacement rate rose to 6.3 % between 11 and 15 surgeries (10/158; p = 0.20), and reached a significant peak between 16 and 20 surgeries with a rate of 7.1 % (8/112; p = 0.03). Afterwards, misplacement rates declined. CONCLUSIONS: A major peak in screw inaccuracies occurred between cases 10 and 20, and a second, smaller one at about 40 surgeries. One potential explanation could be a transition from decreased supervision (unskilled but aware) to increased confidence of a surgeon (unskilled but unaware) who adopts this new technique prior to mastering it (skilled). We therefore advocate ensuring competent supervision for new surgeons at least during the first 25 procedures of robotic spine surgery to optimise the accuracy of robot-assisted pedicle screws.