Eloquent areas in the Sawaya study are the motor/sensory cortices, visual center, speech center, internal capsule, basal ganglia, hypothalamus/thalamus, brainstem, and dentate nucleus

Grade I lesions are located in noneloquent brain

Grade II lesions in near-eloquent brain

Grade III lesions in eloquent brain 1).

see Friedlein grading

see Sawaya grading

1)
Sawaya R, Hammoud M, Schoppa D, Hess KR, Wu SZ, Shi WM, et al. Neurosurgical outcomes in a modern series of 400 craniotomies for treatment of parenchymal tumors. Neurosurgery 1998;42:1044-56.