The Archimedes spiral is important because it captures the frequency, direction, and amplitude of a tremor. During this test, patients are required to draw an unbroken spiral, once with their left hand and once with their right hand. The resulting spiral can provide evidence for the type and severity of a tremor. This drawing task, alongside other clinical data and tests, can help inform diagnoses and treatments for tremor. It can also be repeated over time, to show the patient’s progress and whether or not he or she is responding to treatment. Because it’s a continuous movement, it’s much easier for doctors to observe any tremors that might be present. Although handwriting tests can also be helpful, the breaks in between writing separate words can “hide” subtle tremors. The spiral test helps to manifest any tremors, from more obvious to very subtle.
In this task, a user is asked to trace a spiral from the origin at the center to the spiral’s outer terminus with their dominant hand. They complete this five times, with no explicit time limit on task performance. Following the five traced spirals, they will be asked to reproduce the spirals as closely as they can from memory three times.