Does Essential Tremor Have Stages?

Essential tremor (ET) is the most common movement disorder, involving rhythmic trembling of the hands, head, or voice in over 90% of cases (other body parts can also be affected). When symptoms first appear, may patients fear that they have Parkinson’s disease, a serious degenerative disorder that moves through worsening stages as brain cells die off. However, in almost all cases of ET the source is dysfunctional motor neurons (signal transmitters) in the brain, not dying brain cells. Unlike Parkinson’s, ET patients are less sure if their tremors will progress through stages, and if so, what they are.

A small group of Spanish researchers addressed this issue and reported their findings in 2015. They pointed out that while ET symptoms seem to worsen over time, no one had undertaken a true lifetime study with an objective way to identify stages, record when they occurred, and measure the rate progression.

They developed an assessment tool based on a single question: “When you are seated at the table, how do you drink water from a glass in your dominant hand?” They call it the Glass Scale. It has four scores:

• Glass Scale I – When the patient first noticed tremor in the arms
• Glass Scale II – When the tremor increased, making it difficult to drink from the glass using one hand
• Glass Scale III – When the tremor provoked the need to use both hands to drink from the glass
• Glass Scale IV – When the patient needed to drink with a straw.

For the purposes of their study, from Jan. 2012 – Sep. 2014 they enrolled 50 consecutive patients with severe ET (Glass Scale III). They conducted extensive interviews with the patients and their relatives, using common life/developmental milestones (e.g. starting school, graduating, military service, marriage, birth of a child, etc.) to look back and identify during each patient’s life when each stage began. They also reviewed clinical records, in an effort to determine the rate of progression (change from one score to the next. Their findings confirm what has previously been observed in shorter term studies: ET does move through stages in most patients, but the earlier the age at onset, the slower the progression. Patients diagnosed at age 40 will tend to progress at a faster rate, and those diagnosed at age 60 have a much worse prognosis (future outlook). Perhaps what’s most useful is the Glass Scale itself, which is a very simple resource that could be used to record each patient’s journey with ET.

The Sperling Medical Group offers FDA-approved MR-guided Focused Ultrasound (MRgFUS) for the noninvasive, immediately effective treatment of severe hand tremors. This is good news for patients who experience unpleasant side effects from medication, for those whose medication is no longer effective, and even for patients who do not wish to use drugs at all. For more information, contact the Sperling Medical Group.