Right frontal low-grade glioma

Introduction

Low-grade gliomas (LGGs) represent a heterogenous group of intrinsic brain neoplasms that typically occur in younger, healthier individuals. In 2012, there were approximately 66,000 new primary central nervous system tumors that were diagnosed, in which 20,000 of these cases were gliomas. LGGs are typically diagnosed between the second and fourth decade of life, and seizures are seen in 80% of patients. Magnetic resonance imaging (MRI) scans typically reveal a nonenhancing lesion that is hyperintense on T2-weighted imaging, but approximately 33% have some enhancement. The majority of these lesions have frontal lobe involvement that ranges from 40% to 70% in several series. In recent years, it has been shown that aggressive surgical resection with avoidance of neurologic deficits is far superior to observation, biopsies, or lesser resections in prolonging survival, delaying recurrence, and delaying malignant degeneration. A common location for these lesions is the frontal lobe, in which presenting symptoms can include seizures, headaches, cognitive disabilities, incoordination, and personality changes, among others. Tumors located in the right frontal lobe are often erroneously considered as minimal risk surgeries because this region is devoid of language and motor function. However, with improvement in brain mapping, functional MRI, and tractography, surgery for lesions in this region can be as dangerous as lesions in the dominant hemisphere. In this chapter, we present a right frontal likely LGG.

Example case

Chief complaint: syncopal event

History of present illness

A 51-year-old, right-handed woman with a history of anemia who presented after a syncopal event. She was working when she had a sudden loss of consciousness for an unspecified amount of time. She was started on levetiracetam, and imaging revealed a brain tumor ( Fig. 1.1 ).

Medications : Levetiracetam.
Allergies : No known drug allergies.
Past medical and surgical history : Anemia.
Family history : No history of intracranial malignancies.
Social history : Cashier, no smoking history, occasional alcohol.

Physical examination : Awake, alert, oriented to person, place, and time; cranial nerves II-XII intact; no drift, moves all extremities with full strength.

	Sunit Das, MD, PhD, St. Michael’s Hospital, University of Toronto, Toronto, Canada	Hugues Duffau, MD, PhD, University Hospital of Montpellier, Montpellier, France	John S. Kuo, MD, PhD, University of Texas at Austin, Austin, TX, United States	Nader Sanai, MD, Barrow Neurological Institute, Phoenix, AZ, United States
Preoperative
Additional tests requested	Functional MRI (motor, speech laterality) DTI MRI perfusion Neuropsychological assessment (research)	Neuropsychological assessmentRepeat MRI for growth rate Functional MRI (research) DTI (research)	Functional MRI\| DTI	DTI
Surgical approach selected	Right frontal craniotomy with awake cortical/subcortical mapping	Right frontal and central craniotomy with awake cortical/subcortical mapping	Right frontal craniotomy	Right frontal craniotomy with asleep cortical/subcortical motor mapping
Anatomic corridor	Right frontal	Dorsolateral prefrontal cortex	Right frontal	Right frontal
Goal of surgery	Gross total resection of FLAIR	Extensive resection (GTR or NTR) with preservation of neurologic and cognitive functions	Diagnosis, maximal resection of FLAIR abnormality and adjacent gyrus	Gross total resection of FLAIR
Perioperative
Positioning	Right supine with slight rotation	Lateral	Right supine with left rotation	Right supine
Surgical equipment	Surgical navigation Brain stimulator Surgical microscope Ultrasonic aspirator UltrasoundEEG	Brain stimulator Dedicated team (anesthesia, neuropsychological, speech pathology) No neuronavigation, intraoperative MRI, microscope, or functional neuroimaging	Surgical navigation IOM (EEG, phase reversal) Surgical microscope	Surgical navigation Brain stimulator Surgical microscope
Medications	Steroids	Steroids Antiepileptic drugs	Steroids Mannitol, furosemide Antiepileptic drugs	Steroids Mannitol
Anatomic considerations	Motor cortex CST	SFS medially, PCS posteriorly, FST, SLF, IFOF, oculomotor tract, CST	Central sulcus, white matter tracts deep to tumor	CST
Complications feared with approach chosen	Motor deficit	Motor deficit, executive function, semantic process, theory of mind	Motor deficit, residual/resectable tumor	Motor deficit
Intraoperative
Anesthesia	Asleep-awake	Asleep-awake-asleep	General	General
Skin incision	Reverse question mark	Reverse question mark	Horseshoe or curvilinear	Linear
Bone opening	Right frontal and parietal	Right frontal and central	Right frontal	Right frontal
Brain exposure	Right frontal and precentral	Right frontal and central area	Right frontal	Right frontal
Method of resection	Craniotomy to encompass lesion, ultrasound to visualize lesion, dura opened, patient awakened for testing, motor cortex identified and used as posterior extent of resection, subpial dissection to mobilize tumor from adjacent structures, at depth use ultrasound and biopsy to determine if beyond area of tumor involvement, inspect cavity with microscope and ultrasound	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/ mentalizing tasks, subpial dissection concurrent with mapping and functional testing, resection up to functional boundaries of FST/SLF/IFOF/oculomotor tract/CST, avoidance of coagulation, general anesthesia for closure	Craniotomy based on surgical navigation, center dural opening over lesion, antibiotic-impregnated irrigation during dural opening, place EEG strip electrode to identify central sulcus based on phase reversal, removal of lesion en bloc based on navigation and location of central sulcus, watertight dural closure	Craniotomy to include lesion, stimulation of cortical and subcortical pathways monitoring for EMG firing in face and arm, resection of negatively mapped areas
Complication avoidance	Cortical and subcortical mapping with motor movement, subpial dissection, ultrasound, biopsies to determine if beyond tumor	Cortical and subcortical mapping with counting, left upper extremity movement, naming, semantic association task, and mentalizing	Identification of central sulcus, en bloc resection	Asleep cortical and subcortical mapping
Postoperative
Admission	Step-down unit	ICU	ICU	ICU
Postoperative complications feared	Motor deficit	Movement execution and control, executive function, semantic processing, theory of mind	Seizure, motor deficit	Motor deficit
Follow-up testing	MRI within 48 hours after surgery	MRI within 24 hours after surgeryNeuropsychological testing 2 days after surgery	MRI within 24 hours after surgery	MRI within 24 hours after surgery
Follow-up visits	1 month after surgery	Cognitive rehabilitation, MRI 3 months and then every 3–6 months throughout lifetime	2 weeks after surgery	7–10 days after surgery
Adjuvant therapies recommended
Diffuse astrocytoma (IDH mutant, retain 1p19q)	STR–radiation/temozolomide GTR–radiation/temozolomide	STR–growth rate observation GTR–growth rate observation	STR–second look surgery if resectable, neuro and radiation oncology evaluation if not resectable GTR–observation	STR–radiation/temozolomide GTR–radiation/temozolomide
Oligodendroglioma (IDH mutant, 1p19q LOH)	STR–radiation/PCV GTR–observation	STR–growth rate observation GTR–growth rate observation	STR–second look surgery if resectable, neuro and radiation oncology evaluation if not resectable GTR–observation	STR–radiation/temozolomide GTR–observation
Anaplastic astrocytoma (IDH-wild type)	STR–radiation/temozolomide GTR–radiation/temozolomide	Homogenous AA–temozolomide AA foci removal and GTR of FLAIR abnormality– treatment as for diffuse astrocytoma	STR–second look surgery if resectable, radiation/chemotherapy GTR–radiation/chemotherapy	STR–radiation/temozolomide GTR–radiation/temozolomide