Subtle hypometabolism on [18F]FDG-PET, yet absent [123I]FP-CIT SPECT binding in a patient with spastic paraplegia type 7

Abstract Nuclear medicine neuroimaging is becoming increasingly important for the diagnosis and differential diagnosis of Parkinson’s disease, atypical parkinsonian syndromes and more rare neurological (movement) disorders. We report on a 46-year-old woman presented with frequent falls, a gradually progressive bipyramidal syndrome with gait ataxia, dysphagia, urinary urgency and -incontinence, low mood with disturbed emotional regulation and a mild asymmetric hypokinetic rigid syndrome. Additionally, she had a blurry vision, asymmetrical ptosis and abnormal vertical saccades. [ 18 F]FDG PET/CT of the brain showed unspecific pattern of regional cortical hypometabolism and, more pronounced, striatal hypometabolism. [ 123 I]FP-CIT SPECT showed a complete absence of on-target binding. Subsequent genetic testing revealed two variants in SPG7 . The patient showed a modest favourable response on levodopa. This case illustrates profound neurodegeneration of the presynaptic dopaminergic nigrostriatal neurons in SPG7.