Table 1

Typical characteristics of tremor types seen in writing and drawing tasks

Essential tremorDystonic tremorParkinson’s diseaseFunctional tremor
 SizeNormal or largeNormalUsually smallVariable
 Tremor featuresRegular amplitude and frequencyIrregular jerky amplitude and frequencyRegular amplitude and frequencyVariable; often no tremor in writing
 Tremor intrusion in letter sectionsVertical letter strokes; unidirectional axisAll sections of letters; multidirectional axisVertical letter strokes; unidirectional axisVariable
 Progressive deteriorationNoYes—shape of letters worsens due to posturingSometimes—size of letters may decrementNot usually
 Pen pressureNormalHard pressureNormalNormal
 Spacing of turnsNormal (maybe wider)Normal (maybe tighter)TighterVariable
 Tremor axisUnidirectionalMultidirectionalUnidirectionalVariable
 Tremor frequencyRegularIrregular/jerkyRegularVariable
 Progressive deteriorationNoSometimes—more tremor and pressureNoVariable tremor frequency, axis and amplitude
Straight lines
 Tremor axisUnidirectional
Right: 8–2 o’clock Left: 10–4 o’clock
Right: 8–2 o’clock Left: 10–4 o’clock
 Tremor frequencyRegularIrregularUsually regularVariable
 Tremor amplitudeSmall, regularSmall, irregularSmall, regularLarge, irregular
 Other featuresWriting may be worse than drawing tasksLonger duration to compete task (bradykinesia)Straight lines usually most impaired task