Left insular low-grade glioma

Introduction

As with other low-grade gliomas (LGGs), the ideal management of these lesions involves extensive resection while avoiding iatrogenic deficits. More extensive resection is associated with longer overall survival, delayed progression-free survival, and delayed malignant transformation. This association for only insular gliomas, however, is limited. ^, In previous series, extensive resection (>90%) is only achieved 16% to 87% of the time, in which subtotal resection rates range from 62% to 100%. Although the goal is extensive resection, there is a tremendous concern of iatrogenic deficits. Immediate and permanent neurologic deficits (not taking into account neuropsychological evaluations) range from 14% to 59% and 0% to 20%, respectively. ^, The permanent deficits included hemiparesis, facial palsy, dysphasia, and dysarthria, and were a result of direct injury to the eloquent tissue and vascular compromise of the middle cerebral artery and its branches. ^, Because of concern of iatrogenic injury in this location, others have pursued use of less invasive treatment options, including needle biopsy followed by various forms of radiotherapy and chemotherapy. ^, Despite the low postoperative neurologic morbidity in these cases, 26% of patients experienced radiotherapy-related complications, which were more prevalent in larger tumors. ^, The case in this chapter is a dominant-hemisphere, left-sided insular LGG.

Example case

Chief complaint: seizures

History of present illness

A 36-year-old, right-handed man with no significant past medical history who presented with new-onset seizures. He was involved in an altercation in which he was struck on the head and had an acute onset of loss of consciousness with diffuse body shaking and bowel and bladder incontinence. He was taken to the emergency room where imaging revealed a brain lesion ( Fig. 8.1 ).

Medications : None.
Allergies : No known drug allergies.
Past medical and surgical history : None.
Family history : No history of intracranial malignancies.
Social history : Self-employed. No smoking and occasional 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.

	Santiago Gil-Robles, MD, PhD, Universidad Europea de Madrid, Madrid, Spain	Zvi Ram, MD, Tel Aviv Medical Center, Tel Aviv, Israel	Nader Sanai, MD, Barrow Neurological Institute, Phoenix, AZ, United States	Andrew E. Sloan, MD, University Hospital, Case Western Reserve, Cleveland, OH, United States
Preoperative
Additional tests requested	DTI fMRI Neuropsychological assessment	DTI fMRI (research purposes) Neuropsychological assessment	DTI fMRI	DTI fMRI MR angiography Neuropsychological assessment
Surgical approach selected	Left pterional craniotomy with awake language and motor mapping	Left frontal-temporal craniotomy with awake motor mapping	Left frontal craniotomy with awake language and motor mapping	Left frontal-temporal craniotomy with awake language mapping
Anatomic corridor	Left frontal/temporal transopercular	Left frontal/temporal transopercular	Left frontal/temporal transopercular	Left frontal/temporal transopercular
Goal of surgery	Extensive resection with functional preservation	GTR	GTR	Maximal safe resection
Perioperative
Positioning	Left lateral	Left lateral	Left supine	Left supine
Surgical equipment	Brain stimulator Ultrasonic aspirator Surgical navigation Speech therapist	5-ALA IOM (MEP) Brain stimulator Ultrasonic aspirator Surgical microscope Neuropsychologist	Brain stimulator Surgical navigation Surgical microscope	Stereotactic navigation Surgical microscope IOM (after-discharge) Brain stimulator
Medications	Steroids Antiepileptics	Steroids	Steroids Mannitol	Antiepileptics
Anatomic considerations	M1-M2, ventral premotor, primary motor, IFOF, SLF III, CST	Sylvian vessels CST and SLF	Frontal and temporal opercula Sylvian fissure Internal capsule	M2 vessels, lateral lenticulostriates, internal capsule
Complications feared with approach chosen	Stroke, aphasia, dysarthria, motor deficit, phonological disorders	Language deficit, motor deficit, vascular injury	Language deficit, motor deficit	M2/lateral lenticulostriate injury, retraction injury, venous obstruction
Intraoperative
Anesthesia	Asleep-awake-asleep	Awake	Asleep-awake-asleep	Asleep-awake-asleep
Skin incision	Pterional	Pterional	Pterional	Pterional
Bone opening	Frontal-temporal-parietal craniotomy	Frontal-temporal craniotomy	Frontal-temporal craniotomy	Frontal-temporal craniotomy
Brain exposure	Frontal-temporal-parietal	Frontal-temporal	Frontal-temporal	Frontal-temporal
Method of resection	Subfascial temporal muscle dissection, fronto-temporal craniotomy with posterior extension, intradural and muscle local anesthesia, dural opening, awaken patient, speech therapist for examinations, detection of anatomic tumor limits based on navigation, calibration of stimulation parameters (1.5–3 mA) based on anarthria over ventral premotor cortex, cortical mapping with naming and verb generation task, subpial dissection of both frontal and temporal operculi according to negative mapping until superior insular sulci, subcortical stimulation over SLF III anteriorly and CST posteriorly and IFOF with semantic paraphasias caudal to inferior insular sulcus, patient put back asleep once boundaries reached, debulking of tumor with ultrasonic aspirator keeping vessels over insular surface, intraoperative scan to determine if additional nonfunctional tissue can be resected	Standard craniotomy, dural opening, cortical mapping, insertion of strip electrode for MEP and after discharge, temporal opercular corticectomy, removal of temporal portion up to Sylvian fissure, followed by frontal opercular corticectomy, removal of insular portion with continuous motor monitoring, irrigate vessels with papaverine if exposed, sedation without LMA once language and cognitive monitoring is not needed	Craniotomy to encompass lesion, awaken patient prior to dural opening, language cortical mapping to identify frontal and/or temporal opercular corridors based on negative mapping, subpial dissection, motor mapping at posterior aspect of lesion	Sedate heavily, craniotomy to include 10-mm margin, open dura, confirm location of tumor based on navigation, indicate margin of tumor using suture, awaken patient, language mapping (2–10 mA) in cortical and subcortical regions, mark areas with speech arrest/dysarthria/word finding errors with tags, bring in surgical microscope to create cortical windows over negative mapping sites sparing sulcal vessels, debulk tumor with continuous language mapping and until internal capsule identified, biopsy if eloquence makes resection unsafe
Complication avoidance	Cortical and subcortical mapping of ventral premotor, SLF III anteriorly, CST posteriorly, IFOF inferiorly	Continuous motor monitoring with MEP; papaverine of Sylvian vessels	Cortical and subcortical language and motor mapping	Cortical and subcortical language and motor mapping, spare sulcal vessels
Postoperative
Admission	ICU	ICU	ICU	ICU
Postoperative complications feared	Language deficit, motor deficit	Stroke, motor deficit, aphasia	Ischemic deficit	Seizures, stroke, aphasia
Follow-up testing	MRI within 24 hours after surgery Neuropsychological assessment Physical/cognitive therapy	CTA if deficits MRI within 48 hours after surgery	MRI within 24 hours after surgery	MRI within 48 hours after surgery
Follow-up visits	7–10 days after surgery	14 days after surgery	7–10 days after surgery	10–14 days after surgery
Adjuvant therapies recommended
Diffuse astrocytoma (IDH mutant, retain 1p19q)	>10 cc – reresection + temozolomide, or radiation/temozolomide if cannot be resected GTR–observation	STR–radiation/temozolomide GTR–observation	STR–possible reresection GTR–observation	STR–radiation/temozolomide or PCV GTR–radiation/temozolomide or PCV
Oligodendroglioma (IDH mutant, 1p19q LOH)	STR–PCV vs. reresection GTR–observation	STR–observation GTR–observation	STR–possible reresection GTR–observation	STR–radiation/temozolomide GTR–observation vs. radiation/temozolomide
Anaplastic astrocytoma (IDH wild type)	STR–radiation/temozolomide GTR–radiation/temozolomide	STR–radiation/temozolomide GTR–radiation/temozolomide	STR–radiation/temozolomide GTR–radiation/temozolomide	STR–radiation/temozolomide GTR–radiation/temozolomide