We characterized neurodegeneration in Wolfram syndrome by combining MR neuroimaging and proton MRS, and evaluated pathological accumulation of brain lactate as a. mitochondrial oxidative impairment marker. Cerebellar white matter loss was widespread, while grey matter loss was stronger within sensorimotor and cognitive cerebellar lobules. Infratentorial neurodegeneration was confirmed by biochemical signs of neuro-axonal degeneration in cerebellum and pons. The lack of abnormal ventricle lactate suggests an absence of dysfunction of mitochondrial metabolism. These morphological, microstructural and biochemical alterations were in line with neuropathological findings of loss of myelinated axons in the visual system, smaller brainstem and cerebellar white matter loss.