1. 47-year-old with progressive upper limb weakness Teaching NeuroImages Neurology Resident and Fellow Section © 2014 American Academy of Neurology

2. Vignette 47-year-old developed progressive upper limb weakness and generalised hyperreflexia over four years Normal lower limb examination Normal EMG, nerve conduction studies and MRI of brain and spinal cord FDG-PET demonstrated severe bilateral hypometabolism in the primary motor cortex (Figures A and B). Cosgrove et al. © 2014 American Academy of Neurology

3. Imaging BA Cosgrove et al. © 2014 American Academy of Neurology

4. Hypometabolism of the primary motor cortex in primary lateral sclerosis – the stripe sign In the correct clinical context this ‘stripe’ of hypometabolism supports a diagnosis of primary lateral sclerosis (PLS) 1 PLS is a rare motor neuron disease characterised by degeneration of upper motor neurons only. This pattern of hypometabolism can also occur in amyotrophic lateral sclerosis (ALS) 2 - therefore FDG-PET cannot be used to differentiate between ALS and PLS. Cosgrove et al. © 2014 American Academy of Neurology