Growth Analysis of Untreated Meningiomas under Observation.

BACKGROUND: When meningiomas are small or asymptomatic, the decision to observe rather than treat requires balancing the growth potential of the lesion with the outcome and side effects of treatment. The aim of this study is to characterize the growth patterns of untreated meningiomas to better inform the clinical decision-making process. METHODS: Patients with meningiomas were identified from 2005 to 2015. Those without treatment who had been followed for 1.5 years, with three magnetic resonance imaging (MRI) scans, were identified. Scans were measured with orthogonal diameters, geometric mean diameters, and volumes using the ABC/2 method. Regression modeling determined what growth pattern these parameters best approximated. RESULTS: Two hundred and fifteen MRI scans for 34 female (82.9%) and 7 male (17%) patients with 43 tumors were evaluated. Initial tumor volumes ranged from 0.13 to 9.98 mL. The mean and median initial volumes were 2.44 and 1.52 mL, respectively. Follow-up times ranged from 21 to 144 months, with a median of 70 months. There were 12 tumors (28%) whose growth rates were significantly greater than zero. For all tumors, use of a linear regression model allowed accurate prediction of the future size using prior data. CONCLUSION: Three-quarters of presumptive meningiomas managed conservatively do not grow significantly. The remainder have significant growth over time, and the behavior could be approximated with linear regression models.

Comparison of ABC/2 estimation and a volumetric computerized method for measurement of meningiomas using magnetic resonance imaging.

INTRODUCTION: Measurement of tumor growth rates over time for patients with meningiomas has important prognostic and therapeutic implications. Our objective was to compare two methods of measuring meningioma volume: (1) the simplified ellipsoid (ABC/2) method; and (2) perimetric volume measurements using imaging software modules. METHODS: Patients with conservatively managed meningiomas for at least 1.5 years were retrospectively identified from the VCU Brain and Spine Tumor Registry over a 10-year period (2005-2015). Tumor volumes were independently measured using the simplified ellipsoid and computerized perimetric methods. Intra class correlations (CC) and Bland-Altman analyses were performed. RESULTS: A total of 26 patients representing 29 tumors were identified. Across 146 images, there were 24 (16%) images that were non-measurable using standard application commands with the computerized perimetric method. The mean volume obtained using the ABC/2 and computerized perimetric methods were 3.2 ± 3.4 cm3 and 3.4 ± 3.5 cm3, respectively. The mean volume difference was 0.2 cm3 (SE = 0.12; p = 0.10) across measurement methods. The concordance correlation coefficient (CCC) between methods was 0.95 (95% CI 0.91, 0.98). CONCLUSIONS: There is excellent correlation between the simplified ellipsoid and computerized perimetric methods of volumetric analysis for conservatively managed meningiomas. The simplified ellipsoid method remains an excellent method for meningioma volume assessment and had an advantage over the perimetric method which failed to allow measurement of roughly one in six tumors on imaging.

Outcomes after craniotomy for resection of craniopharyngiomas in adults: analysis of the National Surgical Quality Improvement Program (NSQIP).

PURPOSE: Craniopharyngiomas occur in suprasellar locations that pose challenges for surgical management. This study evaluates the incidence of complications following craniotomy for craniopharyngioma in adults and investigates risk factors for these complications. METHODS: Patients who underwent craniotomy for excision of craniopharyngioma were identified from the 2005-2016 American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP). Incidence of 30-day postoperative complications was determined. Multivariable logistic regression identified demographic, comorbid and perioperative characteristics associated with any complication and major (Clavien IV) complications.  RESULTS: There were 143 cases identified. Fifty-one (35.7%) had a complication, twenty (14.0%) experienced a major complication and there were four (2.8%) deaths. The most common complications were: unplanned readmission (13.3%), prolonged ventilation > 48 h (9.8%), and unplanned reoperation (9.3%). In multivariable analysis, variables significantly associated with any complication were: black race (OR 0.16; 95% CI 0.03-0.84; p = 0.03), hypertension (OR 5.04; 95% CI 1.79-14.17; p = 0.002) and longer duration of surgery (OR 1.27; 95% CI 1.01-1.58; p = 0.04). Hypertension (OR 9.33; 95% CI 1.61-54.21; p = 0.01) and longer duration of surgery (OR 1.51; 95% CI 1.05-2.17; p = 0.03) were also significant predictors for major complications. CONCLUSION: One-third of patients undergoing craniotomy for craniopharyngioma resection experienced a postoperative complication. While high, this contrasts previously reported rates of two-thirds. Prolonged operative time and hypertension are positive predictors of major complications. This information can assist in counseling patients and decision-making for management. We note that other treatment approaches, such as endoscopic surgical techniques, radiosurgery and radiation therapy likely have different profiles and predictors of complications.

Safety Outcomes Following Spine and Cranial Neurosurgery: Evidence From the National Surgical Quality Improvement Program.

BACKGROUND: The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) was used to establish predictors for 30-day postoperative complications following spine and cranial neurosurgery. MATERIALS AND METHODS: The ACS-NSQIP participant use files were queried for neurosurgical cases between 2005 and 2015. Prevalence of postoperative complications following neurosurgery was determined. Nested multivariable logistic regression analysis was used to identify demographic, comorbidity, and perioperative characteristics associated with any complication and mortality for spine and cranial surgery. RESULTS: There were 175,313 neurosurgical cases (137,029 spine, 38,284 cranial) identified. A total of 23,723 (13.5%) patients developed a complication and 2588 (1.5%) patients died. Compared with spine surgery, cranial surgery had higher likelihood of any complication (22.2% vs. 11.1%; P<0.001) and mortality (4.8% vs. 0.5%; P<0.001). In multivariable analysis, cranial surgery had 2.73 times higher likelihood for mortality compared with spine surgery (95% confidence interval, 2.46-3.03; P<0.001), but demonstrated lower odds of any complication (odds ratio, 0.93; 95% confidence interval, 0.90-0.97; P<0.001). There were 6 predictors (race, tobacco use, dyspnea, chronic obstructive pulmonary disease, chronic heart failure, and wound classification) significantly associated with any complication, but not mortality. Paradoxically, tobacco use had an unexplained protective effect on at least one complication or any complication. Similarly, increasing body mass index was protective for any complication and mortality, which suggests there may be a newly observed "obesity paradox" in neurosurgery. CONCLUSIONS: After controlling for demographic characteristics, preoperative comorbidities, and perioperative factors, cranial surgery had higher risk for mortality compared with spine surgery despite lower risk for other complications. These findings highlight a discrepancy in the risk for postoperative complications following neurosurgical procedures that requires emphasis within quality improvement initiatives.

Restricted feedback control in discrete-time dynamical systems with memory.

When an equilibrium state of a physical or biological system suffers a loss of stability (e.g., via a bifurcation), it may be both possible and desirable to stabilize the equilibrium via closed-loop feedback control. Significant effort has been devoted towards using such control to prevent oscillatory or chaotic behavior in dynamical systems, both continuous-time and discrete-time. Regarding control in discrete-time systems, most prior attempts to stabilize unstable equilibria require that the system be perturbed once during each time step. However, there are examples of systems for which this is neither feasible nor possible. In this paper, we analyze a restricted feedback control method for discrete-time systems (restricted in the sense that the controller's perturbations may be applied only in every other time step). We apply our theoretical analysis to a specific example from cardiac electrophysiology in which this sort of restricted feedback control is especially relevant. The example is a useful test case for the theory, and one for which an experimental setup is rather straightforward.