Faculty Bibliography

OBJECTIVE The objective of this study was to determine the effects of a quality improvement initiative in which daily antibiotics and daily sampling of cerebrospinal fluid (CSF) were discontinued for patients with lumbar drains. METHODS The frequency of surgical site infections (SSIs), antibiotic-related complications (development of Clostridium difficile infection [CDI] and growth of resistant bacteria), and cost for patients with lumbar drains were compared during 3 periods: 1) prolonged prophylactic systemic antibiotics (PPSA) until the time of drain removal and daily CSF sampling (September 2013-2014), 2) PPSA and CSF sampling once after placement then as needed (January 2015-2016), and 3) antibiotics only during placement of the lumbar drain and CSF sampling once after placement then as needed (April 2016-2017). RESULTS Thirty-nine patients were identified in period 1, 53 patients in period 2, and 39 patients in period 3. There was no change in the frequency of SSI after discontinuation of routine CSF testing or PPSA (0% in period 1, 2% in period 2, and 0% in period 3). In periods 1 and 2, 3 patients developed infections due to resistant organisms and 2 patients had CDI. In period 3, 1 patient had an infection due to a resistant organism. The median cost of CSF tests per patient was $100.68 (interquartile range [IQR] $100.68-$134.24) for patients in period 1 and $33.56 (IQR $33.56-$33.56) in periods 2 and 3 (p < 0.001). The median cost of antibiotics per patient was $26.32 (IQR $26.32-$30.65) in periods 1 and 2 and $3.29 ($3.29-$3.29) in period 3 (p < 0.001). The cost associated with growth of resistant bacteria and CDI was $91,291 in periods 1 and 2 and $25,573 in period 3. CONCLUSIONS After discontinuing daily antibiotics and daily CSF sampling for patients with lumbar drains, the frequency of SSI was unchanged and the frequency of antibiotic-related complications decreased.

Background/UNASSIGNED:Numerous medical society guidelines recommend discontinuation of antibiotics at a maximum of 24 hours after noninstrumented spinal surgery, even when a drain is left in place. As a result of these recommendations, our institution's Neurosurgery Quality Improvement Committee decided to stop administering prolonged prophylactic systemic antibiotics (PPSAs) to patients with drains after noninstrumented spinal surgery. Methods/UNASSIGNED:We retrospectively reviewed data for patients who had noninstrumented spinal surgery performed by a neurosurgeon at our institution between December 2012 and July 2014 (PPSA period) and December 2014 and July 2016 (non-PPSA period) and had a drain left in place postoperatively. In the PPSA period, patients received antibiotics until drain removal. In the non-PPSA period, patients received antibiotics for a maximum of 24 hours. Results/UNASSIGNED:= .24). Conclusion/UNASSIGNED:After discontinuing PPSAs for patients with noninstrumented spinal procedures, as is recommended for quality improvement, we saw a nonsignificant increase in our rate of SSIs. Further monitoring of this population is warranted.

INTRODUCTION: Postoperative antibiotics (PA) are often administered to patients after instrumented spinal surgery until all drains are removed to prevent surgical site infections (SSI). This practice is discouraged by numerous medical society guidelines, so our institutional Neurosurgery Quality Improvement Committee decided to discontinue use of PA for this population. METHODS: We retrospectively reviewed data for patients who had instrumented spinal surgery at our institution for seven months before and after this policy change and compared the frequency of SSI and development of antibiotic related complications in patients who received PA to those who did not (non-PA). RESULTS: We identified 188 PA patients and 158 non-PA patients. Discontinuation of PA did not result in an increase in frequency of SSI (2% of PA patients vs. 0.6% of non-PA patients, p = .4). Growth of resistant bacteria was not significantly reduced in the non-PA period in comparison to the PA period (2% in the PA period and 1% in the non-PA period). The cost of antibiotics for PA patients was $5,499.62, whereas the cost of antibiotics for the non-PA patients was $0. On a per patient basis, the cost associated with antibiotics and resistant infections was significantly greater for patients who received PA than for those who did not (median of $26.32 with IQR $9.87-$46.06 vs. median of $0 with IQR $0-$0; p < .0001). CONCLUSION: After discontinuing PA for patients who had instrumented spinal procedures, we did not observe an increase in the frequency of SSI. We did, however, note that there was a non-significant decrease in the frequency of growth of resistant organisms. These findings suggest that patients in this population do not need PA, and complications can be reduced if PA are withheld.

Background: Assessment of preoperative imaging is important for operative planning of meningioma resection. A hyperintense rim on T2-weighted (T2W) MRI is frequently thought to represent a CSF cleft between the tumor and the brain, suggesting a clean arachnoid plane. However, brain invasion (loss of arachnoid plane) is often encountered instead. We sought to further characterize this radiographic finding and identify correlates with intraoperative brain invasion and pathology in patients undergoing meningioma resection. Methods: Retrospective review of 42 patients (mean age: 54.2 years, SD: 13.0, 76% female) who underwent meningioma resection between 2013 and 2016 at a single institution. Demographic variables and pathology results were recorded. Radiographic variables on preoperative MRI included presence and size of a hyperintense rim on T2W MRI, a contrast-enhancing rim on fluid-attenuated inversion recovery (FLAIR), and adjacent edema. Operative reports were reviewed for identification of loss of arachnoid plane (brain invasion) noted during surgery. Radiographic findings were then correlated with brain invasion using nonparametric statistics. Results: Of 42 meningiomas resected, there were 29 (69%) WHO Grade I, 12 (29%) WHO Grade II, and 1 (2%) WHO Grade III. Twenty-three tumors (55%) were located at the skull base. On preoperative T2WI, 36 (86%) of meningiomas demonstrated a hyperintense cleft with a mean width of 2.86 mm (SD: 1.66) and 16 had adjacent edema. Twenty-six meningiomas demonstrated a contrast-enhancing rim on FLAIR with a mean width of 2.85 mm (SD: 1.06) and 28 meningiomas exhibited a rim that was both T2 hyperintense and enhancing on FLAIR. Intraoperatively, 24 (57%) of meningiomas were found to have partial or complete loss of an arachnoid plane between the tumor and adjacent brain parenchyma. Both a hyperintense T2 cleft and enhancing FLAIR rim were associated with loss of arachnoid plane (p=0.004 for T2, <0.001 for FLAIR, <0.001 for combined). Conclusion: Preoperative MRI of meningiomas often identifies a T2 hyperintense rim frequently thought to represent a CSF cleft. A correlation with enhancement on FLAIR and intraoperative loss of arachnoid plane suggests this may be a useful marker of brain invasion and could aid in operative planning and risk assessment

OBJECTIVE: Because the d-2-hydroxyglutarate (D2HG) product of mutant isocitrate dehydrogenase 1 (IDH1mut) is released by tumor cells into the microenvironment and is structurally similar to the excitatory neurotransmitter glutamate, we sought to determine whether IDH1mut increases the risk of seizures in patients with glioma, and whether D2HG increases the electrical activity of neurons. METHODS: Three WHO grade II-IV glioma cohorts from separate institutions (total N = 712) were retrospectively assessed for the presence of preoperative seizures and tumor location, WHO grade, 1p/19q codeletion, and IDH1mut status. Rat cortical neurons were grown on microelectrode arrays, and their electrical activity was measured before and after treatment with exogenous D2HG, in the presence or absence of the selective NMDA antagonist, AP5. RESULTS: Preoperative seizures were observed in 18%-34% of IDH1 wild-type (IDH1wt) patients and in 59%-74% of IDH1mut patients (p < 0.001). Multivariable analysis, including WHO grade, 1p/19q codeletion, and temporal lobe location, showed that IDH1mut was an independent correlate with seizures (odds ratio 2.5, 95% confidence interval 1.6-3.9, p < 0.001). Exogenous D2HG increased the firing rate of cultured rat cortical neurons 4- to 6-fold, but was completely blocked by AP5. CONCLUSIONS: The D2HG product of IDH1mut may increase neuronal activity by mimicking the activity of glutamate on the NMDA receptor, and IDH1mut gliomas are more likely to cause seizures in patients. This has rapid translational implications for the personalized management of tumor-associated epilepsy, as targeted IDH1mut inhibitors may improve antiepileptic therapy in patients with IDH1mut gliomas.