Ependymal fluorescence in fluorescence-guided resection of malignant glioma: a systematic review

Acta Neurochirurgica (2020) 162:365–372

Fluorescence in the ventricular wall or the ependyma during fluorescence-guided resection (FGR) of malignant glioma is commonly observed when malignant gliomas infiltrate the ventricles. However, the underlying pathophysiology and clinical importance are largely unknown but may play a role in deciding whether to continue resection into the ventricles or not. Here, we systematically review available data regarding ependymal fluorescence in FGR using five aminolevulinic acid (5-ALA) and sodium fluorescein (SF).

Methods A literature search on MEDLINE, EMBASE, and WEB OF SCIENCE was performed using the following headings and search operators: ependy* fluorescence AND (5-ALA OR five aminolevulinic acid), ventric* wall fluorescence AND (5- ALA OR five aminolevulinic acid), ependy* fluorescence AND fluorescein, and ventric* wall fluorescence AND fluorescein. Both authors analyzed abstracts independently. Included articles were further reviewed for prevalence of ependymal fluorescence, patterns of fluorescence, and histopathological characteristics of sampled tissues as well as radiological signs of ependymal fluorescence. Results are reported according to the PRISMA statement.

Results Of 202 records identified, 6 studies were included compiling a total number of 198 patients treated with FGR using 5- ALA. No study on ependymal fluorescence after administration of SF was found. Overall prevalence of ependymal fluorescence was 61.4%. A total of 54.5% of cases were found to be positive for tumor cells. A total of 25.5% of patients with ependymal fluorescence were related to contrast enhancement in ventricular walls.

Conclusions The phenomenon of ventricular wall fluorescence in 5-ALA-derived fluorescence-guided resection of malignant glioma is poorly understood and not always may fluorescence represent tumor infiltration. A larger scale prospective sampling study with molecular analyses is currently ongoing and will hopefully provide further insight into pathophysiology and clinical implications of ependymal fluorescence.

Brain Ventricular Size in Healthy Elderly:Comparison Between Evans Index and Volume Measurement

Neurosurgery 67:94-99, 2010 DOI: 10.1227/01.NEU.0000370939.30003.D1

A precise definition of ventricular enlargement is important in the diagnosis of hydrocephalus as well as in assessing central atrophy. The Evans index (EI), a linear ratio between the maximal frontal horn width and the cranium diameter, has been extensively used as an indirect marker of ventricular volume (VV). With modern imaging techniques, brain volume can be directly measured.

OBJECTIVE: To determine reference values of intracranial volumes in healthy elderly individuals and to correlate volumes with the EI.

METHODS:Magnetic resonance imaging (3 T) was performed in 46 healthy white elderly subjects (mean age ± standard deviation, 71 ± 6 years) and in 20 patients (74 ± 7 years) with large ventricles according to visual inspection. VV, relative VV (RVV), and EI were assessed. Ventricular dilation was defined using VV and EI by a value above the 95th percentile range for healthy elderly individuals.

RESULTS: In healthy elderly subjects, we found VV = 37 ± 18 mL, RVV = 2.47 ± 1.17%, and EI = 0.281 ± 0.027. Including the patients, there was a strong correlation between EI and VV (R = 0.94) as well as between EI and RVV (R = 0.95). However, because of a wide 95% prediction interval (VV: ±45 mL; RVV: ± 2.54%), EI did not give a sufficiently good estimate of VV and RVV.

CONCLUSION: VV (or RVV) and the EI reflect different properties. The exclusive use of EI in clinical studies as a marker of enlarged ventricles should be questioned. We suggest that the definition of dilated ventricles in white elderly individuals be defined as VV >77 mL or RVV >4.96 %. Future studies should compare intracranial volumes with clinical characteristics and prognosis.