Hypertrophic olivary degeneration secondary to traumatic brain injury: a unique form of trans-synaptic degeneration

A 33-year-old man with a history of traumatic brain injury (TBI) from a few years prior, secondary to a high-speed motor vehicle accident, presented with worsening right-sided motor function. Brain MRI showed diffuse axonal injury, punctuate microbleedings, asymmetric Wallerian degeneration along the left corticospinal tract in the brainstem and haemorrhagic left superior cerebellar peduncle, all consistent with his prior TBI. Moreover, the right inferior olivary nucleus was enlarged, which is exemplified in unilateral right hypertrophic olivary degeneration (HOD), likely secondary to the haemorrhagic lesion within …