Surgery in high-grade insular tumors: Oncological and seizure outcomes from 41 consecutive patients

Abstract

Background: Insular high-grade gliomas are uncommon and constitute approximately 10% of all intracranial high-grade gliomas. Several publications in the recent years have thrown substantial light in the understanding of insular low-grade gliomas. However, there is a paucity of information concerning the spectrum of high-grade lesions affecting the insula, the mode of presentation vis-à-vis low-grade gliomas, and the survival rates to modern therapy. Aims and Objectives: We aim to highlight various clinical patterns, histo-pathological spectrum and the survival rates in patients with high-grade insular lesions. Also, we explore the factors that govern favourable outcomes. Materials and Methods: A retrospective study of 41 patients operated for high-grade insular tumors at our institute between March 2010 to December 2018 was done to evaluate the clinico-radiological features, surgical nuances, survival rates and seizure outcomes. Results: Raised intracranial pressure was the most frequent clinical presentation ( n =28/41, 68.3%). Nearly 60% of the patients ( n =25) had involvement of all four Berger-Sanai zones. The high-grade tumors encountered in our series were: glioblastoma ( n =15), gliosarcoma ( n =3), and embryonal tumor, not otherwise specified in 3 patients, while 21 patients had grade 3 astrocytoma. 33 out of 41 patients (80.5%) in our study showed excellent seizure control (ILAE grade 1A) at follow-up. Clinical presentation with seizures ( P = 0.01, HR=0.3), WHO grade IV histopathology ( P = 0.04, HR=3.7) and development of recurrence ( P = 0.05, HR=5.5) were found to be independent predictors of OS. Conclusion: Insular high-grade gliomas are commoner than thought and nearly half of these are grade IV tumors (51%). A presentation with seizures may indicate precursor low-grade gliomas and portend a better survival. A maximum “safe” surgical resection, keeping the postoperative quality of life in mind, should be the goal.

The dilemma of multifocality in insular tumors: Multicentricity versus metastasis

“…Therefore, insular multifocal glioma, like in any other site, is a fatal disease with poorer outcomes than unifocal tumors. [ 2 ] The poor prognosis has been corroborated in many previous studies.…”

“…The surgical approach was either trans-sylvian (patients #1, 4, and 5) or transcortical (patients #2 and 3), as per the tumor's extension. [ 2 8 9 ] The extent of excision is shown in Table 1 . In one patient (case #5), simultaneous excision (subtotal) of the second lesion was performed using the same craniotomy.…”

“…Our understanding of these tumors has improved immensely, both on a conceptual and technological front. [ 1 2 3 4 ] Multifocality and possible tumor metastasis from insular glioma are extremely rare and less explored. [ 5 ] Therefore, very little is known regarding the predictability of such growth patterns and their management implications.…”

Surgical treatment for insular gliomas. A systematic review and meta-analysis on behalf of the EANS neuro-oncology section

“…& LGG: 57% 5 yrs. Khatri et al (2020) 41 Epilepsy: 24 (58.5%), motor deficit: 17 (41.5%), dysphasia: 1 (2.4%), intracranial hypertension (papilledema): 19 (46.3%) GBM: 21 (51.2%), anapl. : 20 (48.8%), LGG: 0, WHO°I: 0, other: 0 3 (7.3%) 1 (2.4%) NA NA GBM: 24% 1 yr., anapl.…”

“… Sanai et al, 2010 ) 0 Electrostim. : 49 (45.0%), awake: 60 (55.0%) 33 (30.3%) Baran et al (2018) 22 18 (81.8%) NA TOP (22, 100%) 0 Neuronavigation: 22 (100%), awake: 11 (50.0%) 22 (100%) Rao et al (2018) 48 NA NA, LSA encased vs. pushed TS (48, 100%) 48 (100%) US, awake 5 (22.7%) Hameed et al (2019) 255 203 (79.6%) Berger-Sanai TOP (255, 100%) 0 Neuronavigation, DTI, iopM (MEPs): 255 (100%), fMRI, iopMRI, electrostim., awake 172 (67.5%) Khatri et al (2020) 41 40 (97.6%) Yasargil, Berger-Sanai TS (13, 31.7%), TOP (28, 68.3%) 13 (31.7%) Neuronavigation: 6 (14.6%), US: 4 (9.8%), iopM (MEPs), electrostim. : 5 (12.2%), awake: 2 (4.9%) 23 (56.1%) Li et al (2020) 253 NA Berger-Sanai TOP (253, 100%) 0 fMRI, iopM, electrostim.…”