Reliability of a new scale for essential tremor

Abstract Background: The objective of this study was to determine the reliability of a new scale for the clinical assessment of essential tremor. The Essential Tremor Rating Assessment Scale contains 9 performance items that rate action tremor in the head, face, voice, limbs, and trunk from 0 to 4 in half‐point intervals. Head and limb tremor ratings are defined by specific amplitude ranges in centimeters. Methods: Videos of 44 patients and 6 controls were rated by 10 specialists on 2 occasions 1–2 months apart. Inter‐ and intrarater reliability was assessed with a 2‐way random‐effects intraclass correlation, using an absolute agreement definition. Results: Inter‐ and intrarater intraclass correlations for head and upper‐limb tremor ranged from 0.86 to 0.96, and intraclass correlations for total score were 0.94 and 0.96. The intraclass correlations for voice, face, trunk, and leg were less robust. Conclusions: This scale is an exceptionally reliable tool for the clinical assessment of essential tremor. © 2012 Movement Disorder Society