Object: The discovery of incidental low-grade gliomas (LGGs) on MR imaging is rare, and currently there is no existing protocol for management of these lesions. Various studies have approached the dilemma of managing patients with incidental LGGs. While some advocate surgery and radiotherapy, others reserve surgery until there is radiological evidence of growth. For neurosurgeons and radiologists, determining the course of action after routine brain imaging poses not only a medical but also an ethical dilemma. The authors conducted a systematic review of case reports and case series in hopes of enhancing the current understanding of the management options for these rare lesions.
Methods: A PubMed search was performed to include all relevant MR imaging studies in which management of suspected incidental LGG was reported. Comparisons were made between the surgical treatment arm and the active surveillance arm in terms of outcome, mode of discovery, reasons for treatment, and histology.
Results: Nine studies with 72 patients were included in this study (56 in the surgical arm and 16 in the active surveillance arm). Within the surgical arm, 49% remained deficit free after treatment, 25% showed evidence of tumor progression, 13% underwent a second treatment, and 7% died. The active surveillance group resulted in no unanticipated adverse events, with serial imaging revealing no tumor growth in all cases. Lesion regression was reported in 31% of this group. The surgical arm's mortality rate was 7% compared with 0% in the active surveillance arm.
Conclusions: Treatment decisions for incidental LGG should be individualized based on presenting symptoms and radiological evidence of growth. The asymptomatic patient may be monitored safely with serial MR imaging and occasionally PET scanning before treatment is initiated. In patients presenting with nonspecific symptoms or concurrent symptomatic lesions, treatment may be initiated earlier to reduce potential morbidity. All treatment decisions must be tempered by patient factors and expectations of anticipated benefit.