Where Gliomas Start — And Why Location Should Shape Surgery

Where gliomas start matters. This Warhol-inspired graphic highlights the insula and operculum—regions critical to speech, awareness, and emotional salience. Understanding their networks helps guide safe, precise brain tumor surgery. Created by Dr. Randy D’Amico, Lenox Hill Hospital, New York City.

Post 4: Insula & Operculum

About this series. Plain-English guides to where adult gliomas begin and which brain networks are at risk—so patients and families understand planning, mapping, and recovery.

Why the insula & operculum matter

The insula sits hidden beneath the frontal, temporal, and parietal opercula (the “lids” of cortex). Tumors here are challenging because:

• It’s packed near speech and salience hubs.

• It neighbors long language tracts and motor-speech pathways.

• It’s intertwined with M2 middle cerebral artery branches and small perforators which when injured can cause strokes. …So safe corridors matter.

Plain-English takeaway: This is the brain’s switchboard for “what matters now,” speech clarity, and body-state signals (taste, gut, heartbeat). Good planning keeps those online while removing tumor.

Insula networks in plain English

1) Salience network — the brain’s “this matters now” switch

• What it does: Helps you notice important events and switch focus quickly (anterior insula ↔ anterior cingulate).

• If affected: Slower to shift attention, flatter emotional reactivity, “I know it’s important, but it doesn’t feel urgent.”

2) Motor-speech / articulation hub — clarity and effort of speech

• Where: Inferior frontal/rolandic operculum and nearby SLF III connections.

• If affected: Words are there but harder to say clearly; effortful speech, orofacial apraxia (can’t coordinate lips/tongue on command).

3) Ventral language (semantics) nearby — linking words to meaning

• Where: IFOF / extreme capsule plus uncinate skirt the insula/operculum.

• If affected: Fluent but vague speech, trouble with uncommon words or proper names; comprehension feels “thin.”

4) Interoception & gustation — signals from inside the body

• Where: Mid-to-posterior insula.

• If affected: Odd visceral auras (nausea, heartbeat awareness), taste changes; some people describe blunted internal “gut sense.”

5) Auditory–speech coupling

• Where: Superior temporal operculum near Heschl’s gyrus.

• If affected: Trouble linking hearing to clear speech output; repetition becomes effortful.

Common signs you might notice

• Speech clarity/effort: “I know the word, but my mouth won’t cooperate.”

• Word meaning: Fluent but nonspecific wording; proper names slip.

• Auras/seizures: Rising stomach feeling, brief nausea, a rush of heartbeat awareness, or unusual taste/smell.

• Attention/drive: Harder to shift gears or feel urgency when you should.

• Swallowing/face control: Subtle orofacial clumsiness, occasional drooling, effort with complex words.

How teams plan surgery (Before • During • After)

Before surgery

• Map the roads: Tractography of IFOF/EC, uncinate, SLF III, plus proximity to arcuate/SLF II and corticobulbar fibers.

• Define corridors: Transopercular vs transsylvian routes based on venous/arterial anatomy (M2 branches, insular perforators) and functional anatomy.

• Tailored testing:

  • Articulation & orofacial praxis (repetition of multisyllabic words, non-words).

  • Semantic tasks (low-frequency words, proper names).

  • Auditory–verbal linkage (listen→repeat).

  • Interoceptive/gustatory history to benchmark unusual auras.

During surgery

• Awake mapping when helpful:

  • Articulation: clarity, diadochokinesia (pa-ta-ka), sentence repetition.

  • Semantics: low-frequency picture naming, famous-face naming (if anterior temporal proximity).

  • Phonology near dorsal stream; semantics near ventral stream.

• Subcortical stimulation: Guard IFOF/EC, uncinate, and SLF III when dissecting deep to the operculum.

• Vessel-aware technique: Identify and respect M2 trunks and perforators; pause if mapping triggers speech arrest or semantic/paraphasic errors.

After surgery

• Speech therapy matched to the deficit (articulation vs semantics).

• Swallow strategies if needed.

• Seizure care: tune meds; track auras.

• Energy/attention support: structured routines while salience systems settle.

Ask your surgeon (patient-facing)

• Which route will you use—transopercular or transsylvian—and why?

• How will you protect IFOF/EC/uncinate and SLF III if you encounter them?

• What speech tasks will you use during mapping (articulation vs meaning)?

• What arteries/veins are the “do-not-touch” structures in my case?

Bottom line

Insular and opercular gliomas live where speech clarity, meaning, salience, and vessels converge. When teams plan vessel-safe corridors, image the long tracts, and use targeted awake mapping, they can push resection safely and preserve what people feel and notice all day.

Fast FAQ

Do all insular tumors require awake surgery?
No. Awake mapping is used when language or articulation mapping is likely to change decisions; otherwise, asleep surgery may be appropriate.

Why is insular surgery considered “high-stakes”?
Because it sits beside M2 branches and perforators, and next to language and motor-speech pathways. Planning the corridor is as important as the resection itself.

If the ventral stream is near my tumor, will I lose word meaning?
Risk depends on proximity and subcortical mapping. Testing meaning, proper names, and comprehension during surgery helps avoid lasting deficits.