Resection extent and BRAF V600E mutation status determine postoperative tumor growth velocity in pediatric low-grade glioma: results from a single-center cohort analysis.

PURPOSE: Despite excellent long-term overall survival rates, pediatric low-grade gliomas (pLGG) show high variety of clinical behavior regarding progress or senescence post incomplete resection (IR). This study retrospectively analyzes tumor growth velocity (TGV) of pLGG before surgery and after IR to investigate the impact of surgical extent, tumor location and molecular BRAF status on postoperative residual tumor growth behavior. METHODS: Of a total of 172 patients with pLGG receiving surgical treatment, 107 underwent IR (66%). Fifty-three vs 94 patients could be included in the pre- and post-operative cohort, respectively, and were observed over a mean follow-up time of 40.2 vs 60.1 months. Sequential three-dimensional MRI-based tumor volumetry of a total of 407 MRI scans was performed to calculate pre- and postoperative TGV. RESULTS: Mean preoperative TGV of 0.264 cm3/month showed significant deceleration of tumor growth to 0.085 cm3/month, 0.024 cm3/month and -0.016 cm3/month after 1st, 2nd, and 3rd IR, respectively (p < 0.001). Results remained significant after excluding patients undergoing (neo)adjuvant treatment. Resection extent showed correlation with postoperative reduction of TGV (R = 0.97, p < 0.001). ROC analysis identified a residual cut-off tumor volume > 2.03 cm3 associated with a higher risk of progress post IR (sensitivity 78,6%, specificity 76.3%, AUC 0.88). Postoperative TGV of BRAF V600E-mutant LGG was significantly higher than of BRAF wild-type LGG (0.123 cm3/month vs. 0.016 cm3/month, p = 0.047). CONCLUSION: This data suggests that extensive surgical resection may impact pediatric LGG growth kinetics post incomplete resection by inducing a significant deceleration of tumor growth. BRAF-V600E mutation may be a risk factor for higher postoperative TGV.

Lack of correlation of overnight monitoring data and lumbar infusion data in iNPH patients.

OBJECTIVE: Hydrodynamic theories of idiopathic normal pressure hydrocephalus (iNPH) favor a decrease in compliance as an important underlying principle of the disease's immanent pathophysiology. ICP overnight monitoring (ONM) and lumbar infusion study (LIS) are both established methods that aid as supplemental tests in the selection of shunt-responsive patients. Pulse wave amplitude (AMP) and RAP index are measures derived from ONM and are related to intracranial compliance. Elastance (E) and pressure volume index (PVI), parameters derived from LIS, also describe the compliance of the system. We investigated whether the parameters of the two methods correlat with each other. METHODS: Thirty-three patients with probable/possible NPH underwent ICP overnight monitoring and a lumbar infusion study in supine position with ICP recorded from the intracranial compartment. RESULTS: E and PVI from the lumbar infusion study did not correlate at all with RAP or AMP from ICP monitoring. A qualitative change of the RAP and E pointing towards the same direction of either increased or decreased compliance, however, was found in 60.6% of our patients. CONCLUSION: Although data from the infusion test and from overnight monitoring of ICP describe the underlying pathophysiology in at least 60% of patients qualitatively in the same way; there is no direct correlation of parameters. This indicates that the underlying mechanisms of RAP are different from those in principle or in reaction time that are responsible for E.