Factors affecting the extent of resection and neurological outcomes following transopercular resection of insular gliomas.

BACKGROUND: Surgical resection of insular gliomas is a challenge. TO resection is considered more versatile and has lower risk of vascular damage. In this study, we aimed to understand the factors that affect resection rates, ischemic changes and neurological outcomes and studied the utility of IONM in patients who underwent TO resection for IGs. METHODS: Retrospective analysis of 66 patients with IG who underwent TO resection was performed. RESULTS: Radical resection was possible in 39% patients. Involvement of zone II and the absence of contrast enhancement predicted lower resection rate. Persistent deficit rate was 10.9%. Although dominant lobe tumors increased immediate deficit and fronto-orbital operculum involvement reduced prolonged deficit rate, no tumor related factor showed significant association with persistent deficits. 45% of patients developed a postoperative infarct, 53% of whom developed deficits. Most affected vascular territory was lenticulostriate (39%). MEP changes were observed in 9/57 patients. 67% of stable TcMEPs and 74.5% of stable strip MEPs did not develop any postoperative motor deficits. Long-term deficits were seen in 3 and 6% patients with stable TcMEP and strip MEPs respectively. In contrast, 25% and 50% of patients with reversible strip MEP and Tc MEP changes respectively had persistent motor deficits. DWI changes were clinically more relevant when accompanied by MEP changes intraoperatively, with persistent deficit rates three times greater when MEP changes occurred than when MEPs were stable. CONCLUSION: Radical resection can be achieved in large, multizone IGs, with reasonable outcomes using TO approach and multimodal intraoperative strategy with IONM.

AB004. Transsylvian approach for radical resection of insular gliomas: emphasizing the importance of the transsylvian approach for elderly patients with Zone II and III insular gliomas.

BACKGROUND: Insular gliomas present significant challenges due to their deep-seated location and proximity to critical structures, including sylvian veins, middle cerebral arteries (MCAs), lenticulostriate arteries, long insular arteries, and functional cortices and white matter tracts. The Berger-Sanai classification categorizes them into four zones (I-IV), providing a framework for understanding insular gliomas. The key factors for successful insular glioma removal are achieving the greatest insular exposure and surgical freedom. There are two main types of approach methods, such as transsylvian approach with meticulous wider dissection of the sylvian fissure and transcorticosubcortical approach with intraoperative functional brain mapping under awake surgery to remove the functionally silent cortices and white matter tracts. Because splitting the distal sylvian fissure is more challenging, a transcortical approach through the parietorolandic operculum in awake patients has been reported to be more effective access to the posterior insular gliomas (Zone II and III) in the dominant hemisphere. The object of this study emphasize the importance of the transsylvian approach for radical resection of insular gliomas. METHODS: We retrospectively analyzed our experiences with radically resected insulo-opercular gliomas. Basically, we pursue the transsylvian approach for resecting insular gliomas without removal of any normal brain. RESULTS: Motor pathways running beneath the parietorolandic operculum can be damaged by ischemia caused by sacrificing the medullary arteries (MAs) arising from the pial arteries of the M3 and M4 portions of the MCA. Motor deficit after resection of this area was significantly found in the elderly patients. This phenomenon might be described by the age-associated decreasing the vascular reserve capacity. Autopsy brains showed that the sclerotic rate of the MAs increased with age and hypertension. Even with the intraoperative functional brain mapping, we cannot avoid the ischemic complication caused by sacrificing the MAs during stepwise removal of the functionally silent cortices and white matter tracts. CONCLUSIONS: We make a suggestion not to remove the parietorolandic operculum in elderly patients with insular gliomas located at Zone II and III. Distal transsylvian approach should be applied.

Transsylvian Insular Glioma Surgery.

Currently, there is a unanimous opinion that the first line of the treatment of insular gliomas is microsurgical removal.1-3 At the same time, surgery of insular glial tumors remains a challenge because of the complex anatomy of the insular region. Among the most crucial anatomical structures are branches of the middle cerebral artery (MCA), lenticulostriate arteries (LSAs), and corticospinal tract.4 Surgery of the insular glioma becomes much more complicated in cases when the tumor extends to the anterior perforated substance, which, according to our data, occurs in 29,1% of cases.5 We present a 33-year-old woman with a history of generalized seizures (Video1). Magnetic resonance imaging scan revealed a left insular lobe tumor with tumor expansion to the anterior perforated substance and mesial temporal lobe. Given the large size of the tumor and the patient's symptoms, the decision was made in favor of surgery. The video demonstrates the technique of a Sylvian fissure dissection, manipulations with MCA branches and LSA, removal of the tumor from the region of the anterior perforated substance, and a discussion of surgical nuances and safety aspects. The most challenging part of the operation was to identify and protect the LSAs.6 Advanced microsurgical techniques, and the correct patient selection for surgical treatment, are cornerstones for a successful outcome and provide an acceptable frequency of postoperative neurologic deficits in patients who undergo surgery of insular gliomas through the transsylvian approach.

Laser interstitial thermal therapy for first-line treatment of insular glioma.

OBJECTIVE: Insular gliomas pose a significant surgical challenge due to the complex surrounding functional and vascular anatomy. The authors report their experience using a novel framework for the treatment of insular gliomas with laser interstitial thermal therapy (LITT) and provide representative case examples emphasizing indications, rationale, and technical pearls. METHODS: A prospectively gathered institutional database was used to identify patients with newly diagnosed insular gliomas who underwent LITT between 2015 and 2023. The proposed framework of insular glioma management is guided by tumor size and extent of extra-insular tumor involvement. Patients with tumors localized to the insula (insula-only) were treated with single-session or staged LITT. Patients with insular tumors with frontotemporal involvement (insular+) were treated with insular LITT and standard frontotemporal resection of extra-insular tumor. Clinical and volumetric lesional characteristics were analyzed, with particular emphasis on extent of cytoreductive treatment and safety. RESULTS: Of the 261 patients treated at the authors' institution with LITT between 2015 and 2023, 33 LITT procedures were identified involving 22 unique patients with treatment-naive insular gliomas. Of the 22 patients, 12 had insular-only tumors and were treated with LITT alone, while 10 patients had insular+ lesions and were treated with LITT and resection. The median tumor volume for insular-only tumors was 13.4 cm3 (IQR 10.6, 26.3 cm3), with a median extent of treatment of 100% (IQR 92.1%, 100%). Insular+ lesions were significantly larger, with a median volume of 81.2 cm3 (IQR 51.9, 97 cm3) and median extent of treatment of 96.6% (IQR 93.7%, 100%). All patients with insular-only tumors were discharged the day after ablation, while insular+ patients had significantly longer hospital stays, with 50% staying more than 3 days. Overall, 8% of insular-only patients had permanent neurological deficits compared with 33% of insular+ patients. Two patients' tumors progressed during follow-up: one patient with WHO grade 4 astrocytoma and the other with diffuse glioma not otherwise specified. Patients with grade 4 tumors had the highest rate of permanent neurological deficit (43%) and a larger decline in postoperative Karnofsky Performance Status score (p = 0.046). CONCLUSIONS: The authors present their experience using a novel insular glioma treatment paradigm that incorporates LITT into the broader framework of insular glioma surgery. Their findings suggest that insular LITT is feasible and may allow for high rates of cytoreduction while potentially ameliorating the risks of conventional insular glioma surgery.

Safety of an operculoinsulectomy in the language-dominant hemisphere for refractory epilepsy.

BACKGROUND: Operculoinsular cortectomy is increasingly recognized as a therapeutic avenue for perisylvian refractory epilepsy. However, most neurosurgeons are reluctant to perform this type of procedure because of feared neurological complications, especially in the language-dominant hemisphere, as the insula is involved in speech and language processes. The goal of this retrospective study is to quantify the incidence and types of speech and language deficits associated with operculoinsulectomies in the dominant hemisphere for language, and to identify factors associated with these complications. METHODS: Clinical, imaging, and surgical data of all patients who had an operculoinsulectomy for refractory epilepsy at our center between 1998 and 2018 were reviewed. Language lateralization was determined by functional magnetic resonance imaging (fMRI) and/or Wada test. Speech and language assessments were carried out by neurosurgeons, neurologists, neuropsychologists and/or speech language pathologists, before surgery, during the first week after surgery, and at least 6 months after surgery. RESULTS: Amongst 44 operculoinsulectomies, 13 were performed in the language-dominant hemisphere. 46% of these patients presented with transient aphasia post-surgery. However, a few months later, the patients' performances on language assessments were not statistically different from before surgery, thus suggesting a complete recovery of speech and language functions. CONCLUSION: Temporary aphasias after operculoinsulectomy for refractory epilepsy in the language-dominant hemisphere are frequent, but eventually subside. Potential mechanisms underlying this recovery are discussed.

Seizure Outcome After Surgery for Insular High-Grade Glioma.

BACKGROUND: The insular cortex is an eloquent island of mesocortex surrounded by vital structures making this region relatively challenging to neurosurgeons. Historically, lesions in this region were considered too high risk to approach given the strong chance of poor surgical outcome. Advances in recent decades have meant that surgeons can more safely access this eloquent region. Seizure outcome after excision of insular low-grade gliomas is well reported, but little is known about seizure outcomes after excision of insular high-grade gliomas. METHODS: A retrospective analysis was performed of all patients presenting with new-onset seizures during 2015-2019 who underwent excision of an insular high-grade glioma at 3 regional neurosurgical centers in the United Kingdom. RESULTS: We identified 38 patients with a mean (SD) age of 45.7 (15.3) years with median follow-up of 21 months. At long-term follow-up, of 38 patients, 23 were seizure-free (Engel class I), 2 had improved seizures (Engel class II), 6 had poor seizure control (Engel class III/IV), and 7 died. CONCLUSIONS: Excision of insular high-grade gliomas is safe and results in excellent postoperative seizure control.