Insular Glioma Classification

Safety and Efficacy in the Transcortical and Transsylvian Approach in Insular High-Grade Gliomas: A Comparative Series of 58 Patients
Feasibility, Safety, and Impact of Awake Resection for Recurrent Insular Diffuse Gliomas in Adults
Predicting Extent of Resection and Neurological Outcome for Insular Gliomas: An Analysis of Two Available Classifications
Anatomical and subcortical invasiveness in diffuse low-grade astrocytomas differ between IDH status and provide prognostic information
The Transtemporal Isthmus Approach for Insular Glioma Surgery
Surgical treatment for insular gliomas. A systematic review and meta-analysis on behalf of the EANS neuro-oncology section
Survival outcome and predictors of WHO grade 2 and 3 insular gliomas: A classification based on the tumor spread
The transfrontal isthmus approach for insular glioma surgery

Insular gliomas can be classified based on anatomical location, topographic extension, or involvement of subcortical white matter tracts. The following are the most referenced classification systems:

Insular gliomas are surgically complex due to their location near eloquent brain regions and deep vascular structures. Multiple classification systems help guide surgical planning and risk assessment.

This page includes the Berger–Sanai, Yaşargil, Mandonnet–Duffau, and Kawaguchi classification systems.

see Berger–Sanai Classification

Divides the insula into four quadrants using:

Horizontal axis → Sylvian fissure
Vertical axis → Foramen of Monro

Zone I: Anterior–superior
Zone II: Posterior–superior
Zone III: Posterior–inferior
Zone IV: Anterior–inferior

✔ Simple and reproducible ✔ Used in preoperative MRI ✔ Zone II = ↑ risk (lenticulostriate arteries)

Yasargil Classification of Insular Glioma

Anatomical classification based on topographic extension.

Type 3A: Confined to insular cortex
Type 3B: Involving perisylvian opercula
Type 5A: Extends to paralimbic areas
Type 5B: Includes hippocampus, frontal and temporopolar regions

Used to understand structural spread beyond the insula.

Functional classification based on white matter tract infiltration.

Focuses on:

Uncinate fasciculus (UF)
Inferior fronto-occipital fasciculus (IFOF)
Corticospinal tract (CST)
Arcuate fasciculus

Primarily used in awake craniotomy and tractography-based resection.

Grading system based on surgical complexity and depth of tumor invasion:

Grade I: Confined to insula
Grade II: Extends to opercula
Grade III: Involves putamen/internal capsule
Grade IV: Opercula + deep structures

✔ Helps estimate risk of morbidity ✔ Useful for predicting resectability

🧾 Classification Summary Table

Classification	Basis	Primary Use
Berger–Sanai	Quadrant anatomy	Vascular risk, surgical corridor
Yaşargil	Topographic extension	Spread to limbic/paralimbic structures
Mandonnet–Duffau	White matter tract infiltration	Functional preservation, awake surgery
Kawaguchi	Depth and complexity	Surgical risk and difficulty grading

Berger MS, Sanai N. *Neurosurgery* (2010)
Yaşargil MG. *Microneurosurgery Vol IVB* (1996)
Mandonnet E, Duffau H. *Neurochirurgie* (2008)
Kawaguchi T et al. *Neurosurgery* (2011)

Dominant insular tumor

Nondominant insular tumor

Despite the described Berger Sanai Classification of insular gliomas, other based on anatomical localization (Yasargil) or on extension within white matter tracts (Mandonnet and Duffau) are in use

The study findings of Wang et al., suggest that the putamen classification is an independent predictor of survival outcome in patients with insular low-grade gliomas. This newly proposed classification allows preoperative survival prediction for patients with insular gliomas ¹⁾.