Metabolic patterns in brain 18F-fluorodeoxyglucose PET relate to aetiology in paediatric dystonia

Abstract

There is a lack of imaging markers revealing the functional characteristics of different brain regions in paediatric dystonia. In this observational study, we assessed the utility of [18F]2-fluoro-2-deoxy-D-glucose (FDG)-PET in understanding dystonia pathophysiology by revealing specific resting awake brain glucose metabolism patterns in different childhood dystonia subgroups. PET scans from 267 children with dystonia being evaluated for possible Deep Brain Stimulation (DBS) surgery between September 2007 and February 2018 at Evelina London Children’s Hospital (ELCH) United Kingdom were examined. Scans without gross anatomical abnormality (e.g. large cysts, significant ventriculomegaly; n = 240) were analysed with Statistical Parametric Mapping (SPM12). Glucose metabolism patterns were examined in the 144/240 (60%) cases with the ten commonest childhood–onset dystonias, focusing on nine anatomical regions. A group of thirty-nine adult controls was used for comparisons. The genetic dystonias were associated with the following genes: TOR1A, THAP1, SGCE, KMT2B, HPRT1 (Lesch Nyhan disease), PANK2 and GCDH (Glutaric Aciduria type 1). The acquired Cerebral Palsy (CP) cases were divided into those related to prematurity (CP-Preterm), neonatal jaundice/kernicterus (CP-Kernicterus) and hypoxic-ischaemic encephalopathy (CP-Term). Each dystonia subgroup had distinct patterns of altered FDG-PET uptake. Focal glucose hypometabolism of the pallidi, putamina, or both, was the commonest finding, except in PANK2, where basal ganglia metabolism appeared normal. HPRT1 uniquely showed glucose hypometabolism across all nine cerebral regions. Temporal lobe glucose hypometabolism was found in KMT2B, HPRT1 and CP-Kernicterus. Frontal lobe hypometabolism was found in SGCE, HPRT1, and PANK2. Thalamic and brainstem hypometabolism were seen only in HPRT1, CP-Preterm and CP-term dystonia cases. The combination of frontal and parietal lobe hypermetabolism was uniquely found in CP-term cases. PANK2 cases showed a distinct combination of parietal hypermetabolism with cerebellar hypometabolism but intact putaminal-pallidal glucose metabolism. HPRT1, PANK2, CP-kernicterus and CP-preterm cases had cerebellar and insula glucose hypometabolism as well as parietal glucose hypermetabolism. The study findings offer insights into the pathophysiology of dystonia and support the network theory for dystonia pathogenesis. “Signature” patterns for each dystonia subgroup could be a useful biomarker to guide differential diagnosis and inform personalised management strategies.

Cross-frequency cortex–muscle interactions are abnormal in young people with dystonia

“… 3 , 6 , 20 This concept is further supported by a recent fluorodeoxyglucose positron emission tomography study that revealed divergent patterns of abnormal brain glucose metabolism across different brain regions in 10 aetiologically distinct dystonia groups. For example, pallidal and/or putaminal hypometabolism were seen as common findings in most groups, parietal and frontal hypermetabolism were prominent in dystonic cerebral palsy, but PANK2 neurodegeneration with brain iron accumulation was characterized by parietal hypermetabolism, cerebellar hypometabolism and preserved putaminal–pallidal metabolism, 21 demonstrating how the network above may be disrupted differentially between dystonia aetiologies.…”