Introduction: To determine whether abnormal Central Motor Conduction Times (CMCT) and Somatosensory Evoked Potentials (SEP) in dystonic children are associated with specific [¹⁸F]FDG uptake patterns on PET/CT imaging.

Methods: Data from 122 children with dystonia were analysed retrospectively. [¹⁸F]FDG PET/CT scans were obtained over 15 min-30 min p.i. CMCT and SEP were recorded using standard methods. Patients were divided into groups based on their neurophysiology results, as follows: both tests normal (NN; 72), both abnormal (AA; 15), normal CMCT/abnormal SSEP (NA; 24), abnormal CMCT/normal SSEP (AN;11). All scans were normalized to a template, smoothed and quantitatively analysed with Statistical Parametric Mapping (SPM12), using age at time of scan and global uptake as covariates. A visualization threshold of p=0.001 was applied.

Results: The NA group showed hypoactivity in the posterior thalami bilaterally and mild hyperactivity in the left post-central sulcus compared to NN. The AA group had relative hypometabolism along the frontal lobe’s wall when compared to all other groups.

Discussion: Neurophysiological evidence of motor or sensory pathway dysfunction is mainly associated with specific hypometabolic patterns: abnormal SEP correlated with thalamic hypometabolism, while having both tests abnormal is related to reduced frontal lobe uptake. These novel findings demonstrate an important link between imaging and neurophysiology and provide further insight on the pathophysiology of dystonia.