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During deep brain stimulation of the sub-thalamic nucleus (STN-DBS), frequently adjusting the position of the cannula may lead to changes in tissue viscoelasticity. To investigate the mechanical properties of tissue on implant path at repeated loads, three cyclic tension and relaxation tests were carried out at 10 % and 20 % strains. Results indicated that white matter was about 25 %–140 % stiffer than gray matter. Within 20 % strain, the natural viscoelasticity of tissue was not affected by the repeated tension. Whereas at 20 % strain, irreversible internal structure rearrangements occurred at the first relaxation due to the persistent strain action, and almost 60 % of the attenuation modulus generated in the initial 5 s of the process, which leads to a softer transformation of the tissue. Further simulated puncture experiments revealed that an irreversible depression occurred when the cerebral hemisphere was subjected to a constant pressure of cannula for 5 s. [ABSTRACT FROM AUTHOR]

Purpose: To review the evidence on the relative prognostic performance of the available prognostic scores for survival in spinal metastatic surgery in order to provide a recommendation for use in clinical practice. Methods: A systematic review of comparative external validation studies assessing the performance of prognostic scores for survival in independent cohorts was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines. Eligible studies were identified through Medline and Embase until May 2021. Studies were included when they compared at least four survival scoring systems in surgical or mixed cohorts across all primary tumor types. Predictive performance was assessed based on discrimination and calibration for 3-month, 1-year and overall survival, and generalizability was assessed based on the characteristics of the development cohort and external validation cohorts. Risk of bias and concern regarding applicability were assessed based on the 'Prediction model study Risk Of Bias Assessment Tool' (PROBAST). Results: Twelve studies fulfilled the inclusion criteria and covered 17 scoring systems across 5.130 patients. Several scores suffer from suboptimal development and validation. The SORG Nomogram, developed in a large surgical cohort, showed good discrimination on 3-month and 1-year survival, good calibration and was superior in direct comparison with low risk of bias and low concern regarding applicability. Machine learning algorithms are promising as they perform equally well in direct comparison. Tokuhashi, Tomita and other traditional risk scores showed suboptimal performance. Conclusion: The SORG Nomogram and machine learning algorithms outline superior performance in survival prediction for surgery in spinal metastases. Further improvement by comparative validation in large multicenter, prospective cohorts can still be obtained. Given the heterogeneity of spinal metastases, superior methodology of development and validation is key in improving future machine learning systems. [ABSTRACT FROM AUTHOR]

Purpose: The core outcome measures index (COMI) is a validated multidimensional instrument for assessing patient-reported outcome in patients with back problems. The aim of the present study is to translate the COMI into Dutch and validate it for use in native Dutch speakers with low back pain.Methods: The COMI was translated into Dutch following established guidelines and avoiding region-specific terminology. A total of 89 Dutch-speaking patients with low back pain were recruited from 8 centers, located in the Dutch-speaking part of Belgium. Patients completed a questionnaire booklet including the validated Dutch version of the Roland Morris disability questionnaire, EQ-5D, the WHOQoL-Bref, the Numeric Rating Scale (NRS) for pain, and the Dutch translation of the COMI. Two weeks later, patients completed the Dutch COMI translation again, with a transition scale assessing changes in their condition.Results: The patterns of correlations between the individual COMI items and the validated reference questionnaires were comparable to those reported for other validated language versions of the COMI. The intraclass correlation for the COMI summary score was 0.90 (95% CI 0.84-0.94). It was 0.75 and 0.70 for the back and leg pain score, respectively. The minimum detectable change for the COMI summary score was 1.74. No significant differences were observed between repeated scores of individual COMI items or for the summary score.Conclusion: The reproducibility of the Dutch translation of the COMI is comparable to that of other validated spine outcome measures. The COMI items correlate well with the established item-specific scores. The Dutch translation of the COMI, validated by this work, is a reliable and valuable tool for spine centers treating Dutch-speaking patients and can be used in registries and outcome studies. [ABSTRACT FROM AUTHOR]

Helmet manufacturers recommend replacing a bicycle helmet after an impact or after anywhere from 2 to 10 years of use. The goal of this study was to quantify the effect of helmet age on peak headform acceleration during impact attenuation testing of field-used bicycle helmets. Helmets were acquired by donation from consumers and retail stores, and were included in the study if they were free of impact-related damage, had a legible manufacture date label, and were certified to at least one helmet standard. Helmets ( n = 770) spanning 0-26 years old were drop tested to measure peak linear headform acceleration during impacts to the right and left front regions of the helmets at two impact speeds (3.0 and 6.2 m/s). General linear mixed models were used to assess the effect of age and three covariates (helmet style, size and certification impact speed) on peak acceleration. Overall, age was related to either no difference or a statistically significant but small increase (≤0.76 g/year of helmet age) in peak headform acceleration. Extrapolated across 20 years, age-related differences were less than both style- (traditional vs. BMX) and size-related differences. The age-related differences were also less than the variability observed between different helmets after accounting for style, size and certification effects. These findings mean that bicycle helmets (up to 26-year-old traditional helmets and 13-year-old BMX helmets) do not lose their ability to attenuate impacts with age; however, other helmet features that may change with age were not evaluated in this study. [ABSTRACT FROM AUTHOR]

In ice hockey, concussions can occur as a result of many different types of impact events, however hockey helmets are certified using a single injury scenario, involving drop tests to a rigid surface. The purpose of this study is to measure the protective capacity of ice hockey helmets for different impact events in ice hockey. A helmeted and unhelmeted Hybrid III headform were impacted simulating falls, elbow, shoulder and puck impacts in ice hockey. Linear and rotational acceleration and maximum principal strain (MPS) were measured. A comparison of helmeted and unhelmeted impacts found significant differences existed in most conditions ( p < 0.05), however some shoulder and puck impacts showed no significant difference ( p > 0.05). Impacts to the ice hockey helmet tested resulted in acceleration levels below reported ranges of concussion and TBI for falls up to 5 m/s, elbow collisions, and low velocity puck impacts but not for shoulder collisions or high velocity puck impacts and falls. The helmet tested reduced MPS below reported ranges of concussion and TBI for falls up to 5 m/s but not for the other impact events across all velocities and locations. This suggests that the ice hockey helmet tested is unable to reduce engineering parameters below reported ranges of concussion and TBI for impact conditions which do not represent a drop against a rigid surface. [ABSTRACT FROM AUTHOR]

Several abstracts are presented which includes one on pain relief in lumbar spine surgery, the other on lumbar arthrodes and the third on vertebral vector.

Background: Cerebral autoregulation is increasingly recognized as a factor that requires evaluation when managing poor grade aneurysmal subarachnoidal hemorrhage (aSAH) patients. In this single center pilot study, we investigated whether intraventricular intracranial pressure (ICP) derived when extraventricular drain (EVD) is open can be used to calculate dynamic autoregulation estimates in ICU aSAH patients.Methods: Ten patients with the diagnosis of aSAH as confirmed by computed tomography (CT) and CT-angiography were enrolled. ICP was monitored via a transducer connected to the most proximal side exit of the EVD catheter. From at least 30 min periods of brain monitoring before, during, and after temporarily EVD closure, commonly used indexes of dynamic cerebral autoregulation were calculated.Results: Preserved pulsatile ICP signals were seen with open EVD. There were no significant changes in parameters describing cerebral autoregulation between EVD open and closed conditions. Power spectra of ABP and ICP showed no significant changes for the selected frequency ranges. There was a small significant increase in absolute ICP [2.4 (3.8) mmHg, p < 0.001] upon short-term EVD closure. Cerebral spinal reserve capacity (RAP index) worsened significantly by short-term EVD closure.Conclusions: Due to preserved slow fluctuations in the ICP signal, an open EVD system can be used to calculate dynamic autoregulation indices in aSAH patients requiring intensive care monitoring with the pressure measurement from the most proximal part of drain. If these results are confirmed in larger study, this technique can open the way for investigating the role of autoregulation disturbance in aSAH patients. [ABSTRACT FROM AUTHOR]

Purpose: To assess the impact of the duration and intensity of episodes of increased intracranial pressure on 6-month neurological outcome in adult and paediatric traumatic brain injury. Methods: Analysis of prospectively collected minute-by-minute intracranial pressure and mean arterial blood pressure data of 261 adult and 99 paediatric traumatic brain injury patients from multiple European centres. The relationship of episodes of elevated intracranial pressure (defined as a pressure above a certain threshold during a certain time) with 6-month Glasgow Outcome Scale was visualized in a colour-coded plot. Results: The colour-coded plot illustrates the intuitive concept that episodes of higher intracranial pressure can only be tolerated for shorter durations: the curve that delineates the duration and intensity of those intracranial pressure episodes associated with worse outcome is an approximately exponential decay curve. In children, the curve resembles that of adults, but the delineation between episodes associated with worse outcome occurs at lower intracranial pressure thresholds. Intracranial pressures above 20 mmHg lasting longer than 37 min in adults, and longer than 8 min in children, are associated with worse outcomes. In a multivariate model, together with known baseline risk factors for outcome in severe traumatic brain injury, the cumulative intracranial pressure-time burden is independently associated with mortality. When cerebrovascular autoregulation, assessed with the low-frequency autoregulation index, is impaired, the ability to tolerate elevated intracranial pressures is reduced. When the cerebral perfusion pressure is below 50 mmHg, all intracranial pressure insults, regardless of duration, are associated with worse outcome. Conclusions: The intracranial pressure-time burden associated with worse outcome is visualised in a colour-coded plot. In children, secondary injury occurs at lower intracranial pressure thresholds as compared to adults. Impaired cerebrovascular autoregulation reduces the ability to tolerate intracranial pressure insults. Thus, 50 mmHg might be the lower acceptable threshold for cerebral perfusion pressure. [ABSTRACT FROM AUTHOR]

The article presents abstracts on intensive care medicine including the impact of mechanical ventilation (MV) in patients with acute respiratory distress syndrome (ARDS), the risk of cardiovascular disease in patients with acute kidney injury (AKI) and recovery from AKI in intensive care patients.

The article presents abstracts on papers related to pediatric neurosurgery including "Pregnancy of patients with myelomeningocele," "Long-term follow-up in open spina bifida: transition from childhood to adulthood," and "Operated Closed Spinal Dysraphism (CSD): Transition to adulthood," which were presented at the 41st Annual Meeting of the International Society for Pediatric Neurosurgery in Mainz, Germany from September 29 to October 3, 2013.

A correction to the article "Qualitative and quantitative assessment of degeneration of cervical intervertebral discs and facet joints" in the January 27, 2009 issue is presented.

Incidental durotomy in spinal surgery has been reported with incidences varying between 1 and over 16%, depending on the type of surgery and the region of the spine. When a dural tear occurs, immediate and meticulous repair is advised in order to minimize the risk of complications secondary to persistent leakage of cerebrospinal fluid (CSF). These complications include intracranial hypotension, pseudomeningocele formation and the development of a CSF fistula with secondary wound infection and meningitis. Most dural tears are caused during biting actions by Kerrison rongeurs, and dural adhesions, dural redundancy and thinned dura are known risk factors. Accurate visualization and thorough preparation of the surgical field are key steps in dural tear repair. Those tears that are amenable to it should be carefully sutured. Large defects may require a patch of dural substitute to be sewed in. Autologous fat has proven to be useful as onlay or plugin graft. The use of fibrin glue has become a widespread practice and its effectiveness as an adjunct to primary suturing and graft constructions has been well demonstrated. Hydrogel sealants and collagen matrix onlay grafts have become available to the surgeon as additional tools in dural tear repair. However, primary suturing - if possible - is still considered to be the most effective way of reducing the chance of persistent CSF leakage. Tight closure of the fascial layer is imperative. After lumbar durotomy repair, bed rest is advised. Postoperative lumbar or ventricular CSF drainage can also help as an additional protective measure. While numerous measures and tools are available, the key message is that the surgeon confronted with a dural tear should take his time and apply all intraoperative and postoperative means required to secure watertight closure. [ABSTRACT FROM AUTHOR]

Service data does not exist for the strength of enclosures for subdermally implanted biotelemetry devices intended for young wild animals. Developing adequate tests especially for implants intended for endangered species is difficult due to the very limited availability of live animals and cadaverous tissue, ethical concerns about using them, and high enclosure costs. In this research, these limitations were overcome by taking a conservative approach to design and testing. Reliability tests were developed and performed to establish the likelihood that a thin subdermally and cranially implanted alumina enclosure would fail due to typical external forces related to diving, fights, and falls over the expected 30-year life time of sea lions. Cyclic fatigue tests indicative of deep dives performed out of tissue and at the 90% reliability level indicated no failure after 70,000 stress cycles at stresses of approximately 15 MPa; dynamic fatigue tests indicated a 5% probability of failure at 250 MPa; and puncture tests indicative of fight bites showed a 5% probability of failure at 1500 N. These values were far outside of what the animals might expect to encounter in real life. On the other hand, the response of the enclosure to impact outside of the tissue was failure at a mean energy level of 6.7 J. Modeling results predict that head impacts due to trampling by fighting sea lion males and falls over 1 m onto a rocky ledge typical of haul out environments would likely fracture an infant's head as well as the implant. The device can be implanted under an impact absorbing 1 cm blubber layer for extra protection. More service data for enclosures can be made more available despite limited availability of test animals if a conservative approach to testing is taken. [ABSTRACT FROM AUTHOR]

Oesophageal perforation related to anterior cervical surgery is an uncommon but well recognised and potentially life-threatening complication with an incidence of 0–3.4%. Our experience with this complication and a review of the literature are presented. We retrospectively reviewed our clinical experience over 10 years and found four patients in whom an oesophageal perforation was recognised after anterior surgery for cervical spine trauma. In three patients the perforation was noticed in the early post-operative period and the other had a delayed presentation. In all patients, the hardware was removed, long-term intravenous antibiotics were administered and parenteral nutrition was instituted. In two patients a primary suture of the perforation was performed and in one of these an additional sternocleidomastoid myoplasty was carried out as well. One patient had conservative treatment and one died before closure of the perforation could be performed. The two patients, in whom surgical repair of the perforation was performed, recovered well with residual neurological deficits as expected due to the cervical trauma. In the patient in whom conservative treatment was instituted, healing of the perforation occurred. One patient died due to systemic complications, indirectly related to the perforation. Although not very frequent and sometimes difficult to diagnose, oesophageal perforations after anterior cervical surgery constitute a potentially life-threatening complication. Diagnosis is made by imaging or endoscopic studies, but clinical suspicion is most important. Basic treatment consists of surgery with removal of hardware, drainage of abscesses, primary closure of the perforation if possible, parenteral nutrition and antibiotic therapy. Residual instability should be recognised in time and may be anticipated in patients in whom there has been little time for solid bony fusion. Successful management depends on early diagnosis and immediate institution of treatment. [ABSTRACT FROM AUTHOR]

Summary ¶Background. Non-traumatic acute subdural haematomas enable study of the morbidity and mortality due to the haematoma without the effect of trauma. Whereas it is known that coagulation disorders worsen the outcome of spontaneous intracerebral haematomas, this has not been studied in non-traumatic acute subdural haematomas. Methods. In a series of 13 non-traumatic acute subdural haematomas admitted to our department between January 1995 and March 2002, we had 9 coagulopathy associated haematomas and 3 haematomas corresponding to the syndrome of ‘spontaneous acute subdural haematoma of arterial origin’. Both groups were compared. Findings. Age and gender distribution were comparable. The bleeding source was a cortical artery in 2 of the 2 non-coagulopathy related haematomas operated on, but also in 2 of the 4 coagulopathy associated haematomas that underwent surgery. The average haematoma thickness was higher in the coagulopathy related haematomas. The mean Glasgow Coma Score on admission was 7,7 and the mortality rate was 55,6% in the coagulopathy related group. In the non-coagulopathy related haematomas the mean Glasgow Coma Score was 12,0 and the mortality rate 33,3%. The latter mortality rate corresponds well to that of a historical group of ‘spontaneous acute subdural haematomas of arterial origin’ collected from the literature. Interpretation. The outcome was worse in the non-traumatic acute subdural haematomas that were associated with a coagulation deficiency. While in all non-traumatic acute subdural haematomas the interval to surgery should be minimized, early recognition and urgent correction of coagulation deficiencies is certainly indicated. [ABSTRACT FROM AUTHOR]

Impairment of cerebrovascular autoregulation (CAR) is common after brain injury, although the pathophysiology remains elusive. The mechanisms of vascular dysregulation, their impact on brain function, and potential therapeutic implications are still incompletely understood. Clinical assessment of CAR remains challenging. Observational studies suggest that CAR impairment is associated with worse outcomes, and that optimization of cerebral blood flow (CBF) by individual arterial blood pressure (ABP) targets could potentially improve outcome. We present a porcine closed cranial window model that measures the hemodynamic response of pial arterioles, the main site of CBF control, based on changes in their diameter and red blood cell velocity. This quantitative direct CAR assessment is compared to laser Doppler flow (LDF). CAR breakpoints are determined by segmented regression analysis and validated using LDF and brain tissue oxygen pressure. Using a standardized cortical impact, CAR impairment in traumatic brain injury can be studied using our method of combining pial arteriolar diameter and RBC velocity to quantify RBC flux in a large animal model. The model has numerous potential applications to investigate CAR physiology and pathophysiology of CAR impairment after brain injury, the impact of therapeutic interventions, drugs, and other confounders, or to develop personalized ABP management strategies. [ABSTRACT FROM AUTHOR]