The Jigsaw Puzzle of Diagnosing Essential Tremor

Essential tremor (ET) is a movement disorder most often affecting upper limbs on both sides of the body with involuntary trembling or shaking during voluntary actions. It can also affect the head, voice and lower limbs, and some people report feeling like there is trembling inside their bodies even when not visible externally. As one expert puts it, “Essential tremor is often present for years or decades before presentation and it progresses insidiously.”[i] This means that for many people with ET, by the time it’s diagnosed, it may have been with them long before they even realized it.

A diagnostic puzzle

ET is frequently first diagnosed as Parkinson’s disease (PD) even though it’s far more prevalent than PD. This can be frightening for patients because PD ultimately leads to greater and more complex debilitation. However, ET does not respond to PD treatment, so usually PD can be ruled out fairly soon after misdiagnosis. This leads to a mystery: if it’s not PD, what is it?

Pinning down a correct ET diagnosis amount to solving a jigsaw puzzle without having a clue of what the final picture looks like. Some of the puzzle pieces are like riddles:

  • Since no gene has been identified, how can we account for ET that seems to run in some families?
  • How can ET be confidently distinguished from other tremor syndromes that share similar characteristics?
  • Why does ET apparently affect people differently, and progress in different ways among those who have it?
  • ET is thought to originate in the brain’s cerebellum, but why are imaging studies inconsistent in identifying structural abnormalities or dysfunctional activity patterns?

A good example of how many pieces this jigsaw puzzle has is a phenomenon we frequently see happening among members in our Sperling Neuro online Facebook forum, Essential Tremor Awareness and Support. Many member posts begin with the question, “Have any of you ______?” and go on to describe that member’s experience, which is like a single small piece of the giant puzzle. As other members respond, it quickly becomes clear that some share the problem, while others have their own puzzle pieces. It can come as a great relief to find that even one other member reports the same issue. It’s that thank-goodness-I’m-not-crazy feeling that so many people with ET crave, especially if they have felt unheard or discounted by the physician who’s treating them. Instead, people with ET who participate in peer support groups or forums are trying to make their own sense of the ET picture puzzle.

A more comprehensive diagnostic model

Identifying ET is not as simple and straightforward as, say, diagnosing a heart attack or chicken pox. There is too much overlap with other tremor conditions, and too much variety among those who appear to have it. Therefore, current thinking favors the notion that ET is a group of disorders. If this is correct, then using traditional approaches to diagnosis will prove unsatisfying. Instead, a multinational team of researchers suggest a different, more descriptive method of classifying, rather than “diagnosing”, an individual’s ET. Their proposed system takes the emphasis off of ET as a single diagnostic entity. Instead, it “…facilitates the understanding of the underlying disorders in order to develop biologically tailored diagnostic and therapeutic strategies.”[ii]

The key elements of their system include:

  1. The person’s history with ET, including any family members, age at onset, details on how it has changed or progressed, etc.
  2. How ET is manifesting in terms of which body parts are affected, the range and rate of tremors when they occur, what triggers tremors, response to medication or alcohol, etc.
  3. Imaging-based evaluation for abnormal structures or activity in the brain.

This proposal helps overcome lumping tremors that aren’t attributable to another disease or condition into a single basket called Essential Tremor. Until genetic or other causes are discovered, it makes good sense to classify each person’s tremors in line with features in common with other recognized tremor subgroups, and customize management and treatment practices accordingly. Of course, this means that doctors who specialize in movement disorders must take time to stay on top of the latest research publications and attend professional conferences in order to be in touch with the latest information on common tremor features and subgroups, as well as to share with colleagues what they see in their own cases. In addition, it might be good to create opportunities for physician-patient dialogue to compare notes on the myriad ways that ET shows up.

One person trying to put together a thousand-piece puzzle without a finished picture to refer to will spend many long hours assembling it, whereas a collaborative team could slash the time significantly. A collective approach to solving ET diagnostic riddles needs the pooled contributions of all concerned in order to generate better ways to identify ET, understand where it falls on the spectrum of all types, and offer each patient management and therapies that work for them.

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] Reich SG. Essential Tremor. Med Clin North Am. 2019;103(2):351?356.
[ii] Espay AJ, Lang AE, Erro R, et al. Essential pitfalls in “essential” tremor. Mov Disord. 2017;32(3):325?331.

 

About Dr. Dan Sperling

Dan Sperling, MD, DABR, is a board certified radiologist who is globally recognized as a leader in multiparametric MRI for the detection and diagnosis of a range of disease conditions. As Medical Director of the Sperling Prostate Center, Sperling Medical Group and Sperling Neurosurgery Associates, he and his team are on the leading edge of significant change in medical practice. He is the co-author of the new patient book Redefining Prostate Cancer, and is a contributing author on over 25 published studies. For more information, contact the Sperling Neurosurgery Associates.

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