Youmans Neurological Surgery

1. Chapter 121
Low-Grade Gliomas :
Astrocytoma, Oligodendroglioma, and Mixed Glioma
• Youmans,Neurological Surgery • Greenberg,Handbook of Neurosurgery

3. Epidemiology
• 15% of all brain tumors in adults
• Classified,WHO grade II
– diffuse infiltrating astro­cytoma : fibrillary, protoplasmic, and
gemistocytic variants
– oligodendroglial
– ependymal, or mixed cellular histology
• Youmans,Neurological Surgery

4. Spatial definition
• Type 1:
– solid tumor only without infiltration of brain parenchyma
– Most amenable to surgical resection. Most favorable
prognosis
– Includes gangliogliomas, pilocytic astrocytomas,
pleomorphic xanthoastrocytomas, and some protoplasmic
astrocytomas (no oligodendrogliomas are in this group)

5. Spatial definition
• Type 2 :
– solid tumor associated with surrounding tumor-infiltrated
brain parenchyma
– Surgical resection may be possible, depending on tumor
location
– Often low-grade astrocytomas
• Type 3:
– infiltrative tumor cells without solid tumor tissue
– Risk of neurologic deficit may preclude surgical resection.
– Usually oligodendroglioma
• Greenberg,Handbook of Neurosurgery

6. Clinical presentation
• Typically arise in the frontal lobes, followed by temporal
and parietal lobe lesion
• Presentation
– seizures with most remaining otherwise neurologically intact
– increase intracranial pressure (head-ache, nausea, vomiting,
lethargy, papilledema)
– focal neurological deficits (weakness, sensory disturbance or
neglect, visual neglect, agnosia, aphasia)
– impaired executive function (altered per-sonality, disinhibition,
apathy)
• Youmans,Neurological Surgery

7. Neuroradiology
• CT
– one of an either discrete or diffuse hypodense to isodense
mass lesion
– minimal or no enhancement with intravenous contrast
administration
– calcification : oligodendrogliomas or mixed oligoastrocyro­mas
• MRI
– T1 : hypointense to isointense
– T2 : hyperintense
– most LGGs do not show gadolinium enhancement on MRl
– display a tendency to reside within and extend along white
matter tracts (e.g., corpus callosum, subcortical white matter)
• Youmans,Neurological Surgery

8. Neuroradiology
• Positron emission tomography (PET) and single­photon
emis­sion computed tomography (SPECT)
– usually shows reduced uptake offluorodeoxyglucose compared
to the rest of the brain
– the characterization of tumor grade because LGGs are typically
hypometabolic compared with high­grade lesions
• Youmans,Neurological Surgery

9. Treatment

10. Treatment