The Hypertonia Assessment Tool is a 7-item instrument that discriminates spasticity, dystonia, and rigidity on 3 levels: item scores, subtype, and hypertonia diagnosis for each extremity. We quantified the inter- and intrarater reliability using Kappa statistics, Gwet's first-order agreement coefficient (both with 95% confidence interval), and percentage agreement for all levels. For validity, we compared the Hypertonia Assessment Tool subtype with the clinical diagnosis provided by the physicians. Two physiotherapists tested 45 children with neuromotor disorders. The interrater reliability (n = 45) of the Hypertonia Assessment Tool subtype was moderate to substantial whereas the intrarater reliability (n = 42) was almost perfect. The Hypertonia Assessment Tool showed good agreement in detecting spasticity. On the contrary, there was a higher presence of dystonia of 24% to 25% tested with the Hypertonia Assessment Tool compared to the clinical diagnosis. Even some individual items showed lower agreement between raters; the Hypertonia Assessment Tool subtypes and diagnosis were reliable. Validity of the Hypertonia Assessment Tool to test spasticity is confirmed, whereas, for dystonia and rigidity, further studies are needed.
Keywords: cerebral palsy; dystonia; measurement; psychometric properties; spasticity.