Neurologists have a problem in diagnosing essential tremor (ET), which is the most common movement disorder. The problem is not what ET is, but rather what it is not. In order to diagnose a shaking hand as ET, other conditions such as Parkinson’s disease or a side effect of medication must be ruled out.
What makes it difficult to establish an encompassing definition of ET is the variety of ways it shows up in individuals, with no known visible brain abnormality, biomarker, or single associated gene in familial cases. In other words, there is no test for ET, so a process of describing and eliminating other possibilities is used to conclude that a person’s tremors are definitely ET.
Deciding what an abnormal condition is NOT is a rather clunky way to arrive at a diagnosis. To illustrate the problem, let’s imagine that you are very knowledgeable about birds. It’s early spring, and a friend calls to say a bird they’ve never before seen landed briefly in their yard. Since it flew away before they could take a picture, they want to describe it so you can tell them what it was.
Here’s what they might say: “I know it wasn’t a pigeon or a parrot. Also, it wasn’t a robin because it didn’t have a red breast, or a blue jay because it wasn’t blue. It briefly landed on the water in my backyard fishpond and it didn’t sink. Its beak wasn’t short but it wasn’t exactly long, and I noticed it wasn’t pointy. It had a neck but not a long one. It was bigger than a pigeon but smaller than a goose. When it flew away, I watched it until it was out of sight past the next block over—it was quiet a flyer! What do you think it was?” You know it could be any number of things, but at least you’re sure it wasn’t a hawk (it could swim), a chicken (it flew strongly for quite a distance), or some type of crane (neck not long enough). Now that you know several things it’s NOT, you’re still at the disadvantage of not being sure of what it is. However, you at least form a hypothesis: it might be some type of migrating duck species headed north for the summer.
There is a high rate of misdiagnosis when it comes to ET, with estimates ranging from 37% to 50%.i It can be mistaken for Parkinson’s disease or a condition called parkinsonism, functional tremor, enhanced physiological tremor, dystonic tremor and others. Efforts to classify ET into identifiable subtypes have so far not met with widespread agreement, though most authorities today lean toward the theory that ET is a family of disorders rather than a single condition.
Lack of clear diagnosis makes treatment decisions somewhat hit-or-miss. Standard therapy is oral medication such as Primidone or propranolol. A neurologist will put a patient initially on a single medication, and the patient will report back on effectiveness and side effects. For many patients, this begins a trial-and-error process over months, even years, as combinations of drugs and varying dosages are put into play. Often, the person finds that either the drugs don’t help, or the side effects are unacceptable, or both. If that happens, many people simply reject taking medications and turn to other coping strategies such as assistive devices, physical therapy, dietary changes, etc.
Long term solution: Focused Ultrasound
ET is a progressive disorder with no known cure at this time. However, a new noninvasive, outpatient procedure gaining ground with patients and doctors because it puts an end to tremors without the use of medication. It is called the Neuravive procedure. It uses MRI-guided ultrasound beams to precisely destroy a tiny part of the brain’s tremor pathway. Tremor signals to the hand are immediately blocked, and what seems especially “miraculous” is that no incisions or holes drilled in the skull are needed. While there are minimal to no risks, if side effects like facial tingling or slight balance issues occur, they generally quickly resolve on their own. However, the affected hand is returned to normal use and motion, without tremors. The best part is, it seems effective with all varieties of ET, whether they responded to medication or not. For those who have experienced the treatment, life without ET is very good.
Want to learn more about focused ultrasound? Click here to find out how we use it to treat essential tremor.
iEspay AJ, Lang AE, Erro R, Merola A et al. Essential pitfalls in “essential” tremor. Mov Disord. 2017 Mar;32(3):325-331