18F FDG-PET correlates of motor neuron disease motor variants.

While 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) is an established biomarker in amyotrophic lateral sclerosis (ALS), the metabolic correlates of motor neuron disease (MND) motor variants remain poorly defined. This is why we investigated patterns of cerebral glucose metabolism across the spectrum of MNDs, including progressive muscular atrophy (PMA), primary lateral sclerosis (PLS), and ALS. We retrospectively included 18 PMA, 25 PLS, and 43 matched non-hereditary ALS patients according to most recent diagnostic criteria. FDG-PET imaging revealed similar widespread hypometabolism in PMA, as in ALS, whereas PLS showed a more focal motor cortical pattern of hypometabolism. Despite clinical differences between MND subtypes, PMA and ALS showed similar FDG-PET metabolic patterns, whereas PLS exhibited a more restricted cortical signature in this retrospective study.