Introduction
The insula is considered the fifth lobe and is a complex structure both anatomically and functionally. Functionally, the insula is thought to play critical roles in memory, executive function, taste, olfaction, memory, motor integration, and motor planning, among others. Gliomas, namely low-grade gliomas (LGGs), are the most common lesions within this region, in which they account for almost 30% of the lesions that involve the insula. Surgery in this region is challenging because of its complex anatomic location, in which morbidity rates are as high as 60%, and subtotal resection rates range from 62% to 100% in several series. Therefore surgery in this region can be associated with significant morbidity with little efficacy. The case in this chapter is a nondominant insular LGG.
Example case
Chief complaint: headaches
History of present illness
A 19-year-old, right-handed man with rheumatoid arthritis who presented with worsening headaches. He was in his usual state of health until he had an acute exacerbation of joint pain from his rheumatoid arthritis and concomitant headaches. These headaches were more severe and prolonged than usual, but not associated with vision changes, nausea, and/or vomiting. Imaging was done that showed a brain lesion, and he was referred for evaluation and management ( Fig. 7.1 ).
Medications : Prednisone, methotrexate.
Allergies : No known drug allergies.
Past medical and surgical history : Rheumatoid arthritis.
Family history : No history of intracranial malignancies.
Social history: Engineering student and avid hunter. No smoking or alcohol.
Physical examination : Awake, alert, oriented to person, place, and time; Language: intact naming and repetition; Cranial nerves II to XII intact; No drift, moves all extremities with full strength.
Preoperative magnetic resonance imaging. (A) T2 axial fluid attenuation inversion recovery image; (B) T1 axial image with gadolinium contrast; (C) T1 coronal image with gadolinium contrast; (D) diffusion tensor magnetic resonance imaging scan demonstrating a nonenhancing lesion involving the right insular region.
| Steven Brem, MD, University of Pennsylvania, Philadelphia, PA, United States | Hugues Duffau, MD, PhD, University Hospital of Montpellier, Montpellier, France | Frederick F. Lang, MD, MD Anderson Cancer Center, Houston, TX, United States | Manabu Natsumeda, MD, PhD, Niigata University, Niigata, Japan | |
|---|---|---|---|---|
| Preoperative | ||||
| Additional tests requested | DTI fMRI MRS Perfusion MRI Neuropsychological assessment | Repeat MRI for growth rate DTI (research) fMRI (research) Neuropsychological assessment | MRA/MRV fMRI DTI Neuropsychological assessment | Angiography MRA DTI MRS Neuropsychological assessment |
| Surgical approach selected | Right awake fronto-temporal craniotomy | Right fronto-temporal-parietal craniotomy with awake cortical/subcortical mapping | Right fronto-temporal craniotomy with awake cortical/subcortical mapping | Right frontal-temporal-parietal craniotomy with trans-Sylvian approach |
| Anatomic corridor | Right trans-Sylvian | Right frontal operculum | Right trans-Sylvian | Right trans-Sylvian |
| Goal of surgery | Maximal safe resection (>80%) | Extensive resection (GTR or NTR) with preservation of neurologic and cognitive functions | Complete removal of FLAIR abnormality | Complete removal of FLAIR abnormality |
| Perioperative | ||||
| Positioning | Right supine with 45-degree left rotation | Lateral | Right supine 45-degree rotation | Right supine 45-degree rotation |
| Surgical equipment | Surgical navigation Surgical microscope Ultrasonic aspirator | Brain stimulator Dedicated team (anesthesia, neuropsychological, speech pathology) No neuronavigation, intraoperative MRI, microscope, or functional neuroimaging | Surgical navigation Brain stimulator Ultrasonic aspirator | Surgical navigation Intraoperative monitoring (MEP/SSEP) Intraoperative CT/MRI Ultrasonic aspirator |
| Medications | Steroids Antiepileptics | Steroids Antiepileptics | Steroids Antiepileptics Milrinone for vasospasm | Mannitol Steroids Antiepileptics |
| Anatomic considerations | MCA branches laterally, CST medially | IFOF (temporal stem), negative motor network, CST, sensory thalamocortical tract | Sylvian fissure veins, M1 and M2 branches, lenticulostriates, IFOF, UF, AF | Insular cortex, long insular artery, MCA M1–3, LSA, insular sulci |
| Complications feared with approach chosen | Motor deficit | Motor deficit, movement control, executive function, semantic processing, and mentalizing | Injury to lenticulostriate and M2 branches | Motor deficit, cognitive dysfunction |
| Intraoperative | ||||
| Anesthesia | Asleep-awake-asleep | Asleep-awake-asleep | Asleep-awake-asleep | General |
| Skin incision | Pterional | Question mark | Question mark | Question mark |
| Bone opening | Right fronto-temporal | Right frontal-temporal | Right frontal-temporal-parietal | Right frontal-temporal-parietal-temporal |
| Brain exposure | Right fronto-temporal | Right frontal-temporal | Right frontal-temporal-parietal | Right frontal-temporal-parietal-temporal |
| Method of resection | Keyhole (∼3 cm) craniotomy centered over Sylvian fissure, curvilinear dural opening. Sylvian fissure opening under microscopic visualization, awaken patient, cortical stimulation, cortical entry on negative mapping sites with preference to anterior entry sites (pars orbitalis as opposed to pars opercularis), subpial dissection, maximal safe resection (80%–95%), avoid lateral lenticulostriate arteries, functional observation, map posterior aspect for CST, put patient asleep for closure | Bone flap to include IFG and perirolandic area for positive mapping, patient awoken prior to dural opening, cortical mapping at low intensity (1.5–3 mA) with counting/left upper extremity movement/naming /semantic association tasks/mentalizing tasks, cortical resection in right frontal operculum to access insula, subpial dissection concurrent with mapping and functional testing, resection up to functional boundaries of IFOF for semantics/mentalizing/negative motor network/sensorimotor pathways, avoidance of coagulation, general anesthesia for closure | Location of tumor identified, Sylvian fissure opened, inferior followed by superior and anterior insular sulcus dissected, MCA vessels dissected from tumor and small perforators to the tumor are cut, tumor internally debulked, dissection continues until medial edge of circular sulci reached, follow M2 perforators branches to define deep part of the tumor, tumor removed from front to back, patient awakened at most posterior part of tumor to stimulate for motor areas and IFOF/AF, ultrasound and navigation used to dictate location | Two layered skin flap, right craniotomy, SSEP/MEP analysis, Sylvian fissure opening from distal to carotid cistern, identify M1/M2 junction with M2 branches and insular cortex, dissection of superior periinsular sulcus, dissection along M1 to most lateral LSA, corticectomy in insular cortex, subpial removal of tumor, most lateral LSA defines medial boundary, insertion subgaleal drain, intraoperative CT, additional removal if necessary |
| Complication avoidance | Awake mapping, trans-Sylvian opening, subpial dissection, lateral lenticulostriate arteries as medial boundary, 80%–95% goal resection | Cortical and subcortical mapping with counting, left upper extremity movement, naming, semantic association task, and mentalizing, avoidance of coagulation, subpial dissection, resection up to functional boundaries | Trans-Sylvian opening, identify insular sulci to guide deep part of resection, awake subcortical mapping at posterior aspect of tumor in close proximity to CST | Trans-Sylvian opening, identification of M1/M2, insular cortex, dissection of periinsular sulci, resection to lateral most LSA, intraoperative CT |
| Postoperative | ||||
| Admission | ICU | ICU | ICU | ICU |
| Postoperative complications feared | Motor deficit, seizures | Motor deficit, executive function, semantic processing, theory of mind | Stroke, weakness, seizures | Motor deficit, cognitive dysfunction |
| Follow-up testing | MRI within 24 hours after surgery Next-generation sequencing | MRI within 24 hours after surgeryNeuropsychological assessment 48 hours after surgery | MRI within 24 hours after surgery | CT immediately after surgery MRI within 24 hours after surgery Neuropsychological assessment 1 week postoperative |
| Follow-up visits | 1 month after surgery | Cognitive rehabilitation, MRI 3 months and then every 3–6 months throughout lifetime | 10 days after surgery | 2 weeks after surgery |
| Adjuvant therapies recommended | ||||
| Diffuse astrocytoma (IDH mutant, retain 1p19q) | GTR–radiation +/– temozolomide STR–radiation +/– temozolomide | STR–observation for growth rate GTR–observation for growth rate | STR–radiation followed by temozolomide GTR–observation | STR–radiation/temozolomide GTR–observation |
| Oligodendroglioma (IDH mutant, 1p19q LOH) | Pending positive TERT status, GTR–PCV or temozolomide STR–PCV or temozolomide | STR–observation for growth rate GTR–observation for growth rate | STR–radiation followed by PCV GTR–observation | STR–radiation/PAV or temozolomide GTR–observation |
| Anaplastic astrocytoma (IDH wildtype) | GTR–radiation/temozolomide STR–radiation/temozolomide | Homogenous AA–temozolomide AA foci removal and GTR of FLAIR abnormality–treatment as for diffuse astrocytoma | STR–radiation/temozolomide GTR–radiation/temozolomide | STR–radiation/temozolomide GTR–radiation/temozolomide |
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