Hand tremors can be caused by many things. Some are related to medication, drugs or toxins; some result from accidents or clinical conditions like Parkinson’s disease (PD) or multiple sclerosis (MS). In fact, hand tremors are frequently misdiagnosed as Parkinson’s disease, but when PD medications turn out to have no benefit for ET, the diagnosis needs to be corrected. If no cause for tremors can be determined, the uncontrollable shaking is then diagnosed as essential tremor (ET).

The word “essential” simply means the tremor is its own essence—that is, no known cause or connection was found. Sometimes, it is called familial ET, since roughly half of patients have one or more family members with the same movement disorder.

Smartphones and ET

These days, smartphones are increasingly the universal mobile phone of choice. These multipurpose devices that fit in pockets or purses are like mini-computers, and just as versatile. Want to get on the internet? Check email? Take photos and videos? Use a calculator or stopwatch? Play video games? Watch a movie? Your smartphone can do it all. Depending on which apps you use, it can do even more!

If a 2021 article in the journal BMC Bioinformatics is any indication, smartphones may soon be able to use machine learning (a branch of Artificial Intelligence) to diagnose ET! According to a multidisciplinary team from Belgium and The Netherlands, a smartphone with the right app, strapped to the wrist, can gather tremor data that “…is useful for the constructing of machine learning models that can be used to support the diagnosis and monitoring of patients who suffer from Essential Tremor.”^[i]

In practice, accurately measuring tremors is key to proper diagnosis. The severity (frequency and range of motion) of hand tremors must be assessed. Until fairly recently, doctors relied on subjective tools such as observation, paper and pencil tests, tremor diaries, and patient questionnaires.

Now, with the development of computer-driven technologies, “Using direct measurements from wearable sensors could provide more objectivity of the tremor severity assessment.” Current measurement devices include:

• Accelerometers that measure linear acceleration
• Gyroscopes that measure rotation speed and orientation
• Electromyograms that can distinguish between PD and ET by recording tremor activity using needs inserted in muscles, but are unpleasant and even painful for the patient
• Force sensors that evaluate torque and angular motion but are non-portable and expensive.

The problem is that patients don’t have access to them in daily life. Therefore, the team turned to the feasibility of wearable smartphone assessment, as is being clinically tested with PD patients.

For purposes of their study, they programmed an iPhone 5s with an app called the TREMOR12, which was developed by clinicians to help monitor treatment effects in ET patients. The app “offers low-cost tremor quantification for research purposes and algorithm development.” It enabled them to collect raw signal data using the phone’s accelerometer and gyroscope to record tremor acceleration and rotation speed. It Twenty ET patients who already had been treated with Deep Brain Stimulation (DBS) were recruited to build a data set on their relatively mild tremors using the smartphone’s app.

Each participant performed 5 tests, using right and left hand separately for each test. From the data thus gathered, the researchers developed a machine learning model that was correlated with existing tremor assessment tools and patient questionnaires.

Although the study participants did not have severe tremors (a separate study would have to be done for that), the possibilities for using smartphones are encouraging. According to the authors, “For example, they can be used to find the correct dosage for ET patients treated with medication or measure the effectiveness of magnetic resonance (MR) guided focused ultrasound.”

MR-guided focused ultrasound for ET (MRgFUS)

At Sperling Neurosurgery Associates, we agree it would be useful to use smartphones for objective measure of tremor improvement following MRgFUS treatment, especially for clinical case records and research purposes. On the other hand, witnessing the breathtaking responses of our own ET patients who receive our Neuravive MRgFUS is not something that can be measured by a smartphone. It is profoundly moving to witness a person be able to drink water from a cup without spilling, after decades of humiliating accidents and deep embarrassment leading to social isolation and anxiety.

In the words of author Antoine de Saint-Exupery, “It is only with the heart that one can see rightly; what is essential is invisible to the eye.” Or to the smartphone.

NOTE: This content is solely for purposes of information and does not substitute for diagnostic or medical advice. Talk to your doctor if you are experiencing pelvic pain, or have any other health concerns or questions of a personal medical nature.

[i] Fuchs C, Nobile MS, Zamora G, Degeneffe A et al. Tremor assessment using smartphone sensor data and fuzzy reasoning. BMC Bioinformatics. 2021 Apr 26;22(Suppl 2):57.