After a few weeks, our small Essential Tremor working group settled on the first two projects we would work on. We first identified the need to be able to accurately measure tremors before we started to explore any treatment options. The online scientific literature available to us seemed to indicate some shortcomings in the area of measurement of Essential Tremors.
There is a well established consensus that about 90% of people with ETs experience tremors in the hands and arms. Astonishingly, we could only find one paper that accurately measured tremors in all 7 DOF (degrees of freedom) of the shoulder-elbow-wrist. Most studies that measure tremors are limited to 1 or 2 measurements. Additionally almost all of these studies are limited to measuring positional tremors.
Now I don’t know about you, but I am not particularly concerned that if I hold my left arm in the “wing-beating” position, I can trigger a Pronation-Supination tremor in my forearm. What bothers me is putting toothpaste on the tooth brush. An Action Tremor. Or eating soup with a spoon which I now find impossible.
Action Tremors or Kinetic Tremors that affect the Activities of Daily Living (ADL) are the tremors that we should care about the most. In approximately 95% of cases these kinetic tremors are more severe than positional tremors.
Why then do most ET studies measure Positional Tremors? Why? Because it is easier to measure Positional Tremor. That is not entirely correct! It is much more difficult to measure Kinetic Tremors. We need a moon shot on measurement of Kinetic Essential Tremors.
So far we have one accelerometer/gyro combination sensor integrated into a data logging software package that records to an SD card. This first test rig was built using Commercial Off The Shelf (COTS) hardware, two Open Source Software packages and a tiny amount of custom written software. Our first test was to record about 35 seconds of my Pronation-Supination forearm Essential Tremor. The data was processed by Google Sheets to produce the following chart.
The sensor was mounted on the back of my hand with a Velcro strip holding it in place.
The Blue x-axis is parallel to my fingers when they are extended straight out.
The Red y-axis is in the plane of the hand and parallel to the wrist joint
The Yellow z-axis is vertical to the hand.
In other news, the global chip shortage is real! We have been waiting for several weeks to purchase some additional sensors. Twice they came into stock but were sold out before we could place an order. We now have secured an order of these sensors and will start to build our next prototype SensorGlove in the next week or so.
Let’s hope this doesn’t take a decade like it did to reach the moon.
