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. [¹⁸F]FDG PET/CT of the brain showed unspecific pattern of regional cortical hypometabolism and, more pronounced, striatal hypometabolism. [¹²³I]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.