Need to Know: What Is a Tremor?
Editor’s note: “Need to Know” is a series inspired by common forum questions and comments from readers. Have a comment or question about MS? Visit our forum. This week’s question is inspired by the forum topic “Tremors Caused by MS” from April 30, 2018.
If you have MS, your answer is likely to refer to at least one part of your body. Tremor describes an uncontrolled, rhythmic movement like shaking or twitching. It’s a symptom that as many as 75 percent of people with MS experience.
For some, tremor is a minor nuisance, but for others, it can be a major occurrence. Those with severe tremor (up to 6 percent of all people with MS) may need treatment to reduce its impact on daily living.
What causes tremor in MS?
MS causes misfiring of brain signals to different parts of the body.
In the case of the muscles, signals from the brain may become confused (thanks to demyelination) and result in repetitious relaxing and contracting of muscle groups that typically work opposite one another. This causes the rhythmic movements characteristic of tremors.
MS tremor: 4 types
There are four main types of MS tremor:
These occur following a smooth movement by the hand or foot. A person with an intention tremor may reach for a cup of coffee, only to find their hand beginning to shake when they grasp the cup’s handle.
When a person with postural tremor stands up or sits down, the weight-bearing motion in between leads to “antigravity” shaking.
You know this type of tremor as the one that seizes your eyelid and makes it twitch uncontrollably.
Simply put: This happens when your body is at rest. Resting tremor characterizes Parkinson’s disease, but it can also happen to people with MS.
New research on measuring tremor
It’s clinically important to measure tremor severity if doctors are to treat it. Yet, it’s difficult to do so. Clinical observation and self-reporting are often the only way to assess this symptom.
Simply witnessing tremors doesn’t provide measurable data. Patients may be asked to pour water from cups, draw spirals, or demonstrate tremor-affected handwriting, but this only proves it’s a symptom. None of these efforts accounts for objective severity.
Scaling the severity of tremor in people with MS can drive research into adequate therapies that can reduce, or potentially eliminate, this disabling symptom.
Currently, treatments for tremor are limited to a handful of off-label medications and the use of limb weights to counteract tremor movement. Experimental options include deep brain stimulation, alcohol, and THC.
Some measurement tools do exist, such as sensors that incorporate accelerometry. These sensors cull objective data on the amplitude, frequency, and occurrence of tremor activity. However, they’re hard to access, and most aren’t scientifically validated.
Another tool, the inertial sensor, can be wonky when it comes to trapping signal noise, which may or may not be a tremor, making data collected from these sensors difficult to interpret.
More of an issue with the current sensor options is that they are currently used to measure only the most common tremor found in Parkinson’s disease, resting tremor, and none have been tested against all forms of MS-related tremor.
Introducing electromagnetic motion tracking
Research published in the Journal of Neuroscience Methods in January highlights the possibility of an electromagnetic tracking sensor called TREMBAL that may be used to measure and rate tremor activity in people with MS.
This device, worn on the index finger, measures electromagnetic motion using four different kinds of sensors. To its advantage, it works without risking collection of random signal artifact.
With TREMBAL, the patient is hooked up to a sensor, then completes five 20-second exercises from which TREMBAL captures movement data.
If this sensor can adequately capture tremor, it can also adequately characterize it and inform treatment protocols for those with severe tremor activity. Stay tuned as the technology develops.
Do you experience tremor? How severe is it? Post your replies in the comments below or at the original “Tremors Caused by MS” forum entry.
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