Gliomas may spread by the following mechanisms (note: < 10% of recurrent gliomas recur away from the original site):
1. tracking through white matter
a) corpus callosum (CC)
● through genu or body of CC → bilateral frontal lobe involvement (“butterfly glioma”)
● through splenium of CC → bilateral parietal or occipital lobes
b) cerebral peduncles → midbrain involvement
c) internal capsule → encroachment of basal ganglion tumors into centrum semiovale
d) uncinate fasciculus → simultaneous frontal and temporal lobe tumors
e) interthalamic adhesion → bilateral thalamic gliomas
2. CSF pathways (subarachnoid seeding): 10–25% frequency of meningeal and ventricular seeding by high grade gliomas
3. rarely, gliomas may spread systemically