LogoSpiral Analysis

Spiral Analysis Information

What is Spiral Analysis?

Spiral Analysis is a non-invasive system of quantifying motor function based on kinematic and physiologic features derived from handwritten spirals. Spiral Analysis uses a digitizing tablet and writing pen to record position, force and time measurements.

Spiral Analysis is based on “unraveling” the two-dimensional drawn spiral picture into a data series that captures its original kinematic information and allows for further computational manipulations and clinical correlations. Spiral data are collected in the X, Y and pressure axes providing virtual “tri-axial” recordings. This effectively extends spiral drawing - a standard clinical test - into an objective and accurate measure of motor control. Mathematical formulations are used to create into indices that quantify the kinematic parameters, and assess many spiral features including overall degree of severity, shape, drawing speed, tightness of loops, irregularity and tremor. Over 70 indices are created, and multiple spirals can be averaged.

Spiral Analysis provides greater accuracy and objectivity than the clinical exam alone. It has already been used to study the details of normal motor control, to quantify normal and abnormal motor development and analyze movement disorders such as Parkinson’s disease, tremors, dystonia, ataxia and functional movements. Because of its precision and reproducibility, Spiral Analysis is also useful in quantifying changes before and after medical or surgical treatments.

Why Use Spiral Analysis?

  • - Non-invasive and easy to administer
  • - Provides real-time feedback
  • - Tracks motor function over time
  • - Highly sensitive to neuromotor changes
  • - Useful for research and clinical assessments

How to Use This Tool

  • Draw at least 3-4 complete revolutions.
  • Draw a spiral on the provided canvas using your mouse or touchscreen.
  • Try to make the spiral as round and evenly spaced as possible.
  • Try to maintain a consistent drawing speed and pressure.
  • For best results, try to draw in a single, continuous motion.
  • Click Save to proceed on to the next drawing.
  • Click the "Finish Analysis" button to process your spiral.
  • Review the results and graphs provided for insights into your upper limb motor control.
  • Compare your results over time to track changes in your motor function!

Key Metrics in Spiral Analysis

  • DOS (Degree of Severity): A comprehensive measure of overall spiral drawing performance. It is a unitless, continuous measure correlating with a five-point rating scale (0 to 4) where 0 to 0.99 is normal, 1 to 1.99 mild, 2 to 2.99 moderate, and 3.0 to 4.0 severely abnormal.
  • Smoothness: A unitless measure of spiral continuity and variation from the ideal spiral shape. Normal is less than -4.
  • Tightness: Measures how closely the spiral loops are drawn to each other, normalized to 5 loops in a 10 x 10 cm drawing box. Normal is about 1.
  • Pressure: Analyzes the forces applied to the pen while drawing. It can reveal otherwise hidden tremors.
  • Speed: Measures the drawing speed (cm/sec) of the spiral. It is calculated as the distance between consecutive x, y points, averaged over the length of the spiral, divided by the sampling time. Normal is 15 - 25 cm/sec.
  • Tremor: The detectable tremor in the x, y, or pressure axes above the noise baseline greater than 1 Hz. Normal is less than 2.
  • Frequency Analysis: Examines the rhythmic components and axes of tremor of the spiral drawing. It can help identify specific types of tremor.
  • Width Variabiity: This measures unsteadiness and clumsiness of drawing. It is a unitless correlate of drawing irregularity and computed as the loop-to-loop variability sampled every 5°. Normal is less than 0.250.

⚠ Note: This tool is for educational purposes only. For medical concerns, always consult with a healthcare professional.