A Novel Cause of Inferior Olivary Hypertrophy

Inferior olivary hypertrophy (IOH) develops with lesions affecting the Guillain Mollaret triangle (GMT) otherwise known as the dento–rubro–olivary triangle. The triangle connects deep cerebellar nuclei, contralateral red nucleus, and inferior olive through the superior cerebellar peduncle, central tegmental tract, and inferior cerebellar peduncle, respectively.1 Lesions are typically caused by arteriovenous malformation (AVMs), hemorrhages, infarcts, demyelination, or tumors,2 and IOH occurs with a lack of GABAergic inhibition.3 Inferior olivary hypertrophy develops contralaterally with a cerebellar lesion and ipsilaterally with a brain stem lesion