We aim to better characterize tremor in children from a clinical, neurophysiological and kinematic perspective.

Tremor is one of the most common movement disorders during childhood. Growing evidence outlines the importance to implement ancillary assessment methods that allow quantification of its basic kinematic features. Nevertheless, the majority of tremor research pertains exclusively to an adult population.

a cross sectional study was performed in a tertiary pediatric movement disorders clinic. Ten consecutive patients with essential tremor(ET) were assessed. Clinical evaluation was performed utilizing the Tremor Rating Scale (TRS). Subsequently, triaxial accelerometers were placed equidistantly at the dorsum of the hands and arms, the recording was done during 90 second intervals within  various tasks and different arm positions following the TRS protocol. Kinematic evaluation was performed with a validated reaching task protocol from the Kinarm exoskeleton.

Mean age was 13.4 SD 1.9 years, 77.8% were males.  Mean age at onset of tremor was 8.5 SD 5.05 years. Mean TRS score was 9.3 SD 7.1.  Principal component analysis of the accelerometers with a subsequent Fast Fourier Transform revealed mean median frequencies in the 0-30hz band power of 16.1 SD 3.7hz arms extended and 16.7 SD 3.4 hz within finger to nose maneuvers. Comparison of patients with tremor with a matched age and handedness control group in the Kinarm reaching task yielded significant differences in maximum speed(0.1498m/s±0.036m/s vs 0.1869m/s ±0.035m/s, respectively; p<0.05).

To the best of our knowledge this is the first study demonstrating kinematic differences in children with ET. It remains to be determined if these differences could be attributed to motor compensatory mechanisms or be part of the intrinsic components of ET.