1. A 30 year old man with sub-acute ataxia Teaching NeuroImages Neurology Resident and Fellow Section © 2014 American Academy of Neurology

2. Vignette A 30 year old man with sensorineural hearing loss presented with sub-acute somnolence, slurred speech and unsteady gait. Examination revealed scanning speech, horizontal nystagmus, gait ataxia and symmetric hyporeflexia with distal sensory loss. Arkadir et al © 2014 American Academy of Neurology

3. Abnormal findings on MR images Arkadir et al © 2014 American Academy of Neurology

4. Hypertrophic olivary degeneration in a young man with POLG gene mutation Brain MRI demonstrated symmetric hyperintense signal abnormality and enlarged inferior olives on (A) FLAIR and (B) T2 images, characteristic of bilateral hypertrophic olivary degeneration. Additional findings included hyperintense T2 signal changes in the thalami (not shown) and deep cerebellar nuclei, and mild cerebellar vermis atrophy bilateral. Whole exome sequencing identified a homozygous pathogenic POLG mutation. Differential diagnosis of bilateral HOD includes mutations in the nuclear genes crucial to mitochondrial function, POLG and SURF1. Arkadir et al © 2014 American Academy of Neurology