“Advanced ET” Is a More Appropriate Term Than “ET‐Plus”

Dear Editor,

Despite a remarkably high disease incidence and prevalence, there are surprisingly few prospective, longitudinal natural history studies of patients with essential tremor (ET). At a point when disease classification and nomenclature are under active discussion, such studies would provide the necessary data to effectively inform and guide such efforts. Angelini et al. [1] should be congratulated for undertaking a prospective natural history study and for providing high resolution phenotypic data derived from careful evaluations over three time points.

The data they present offer valuable insights into the dynamics of the ET phenotype. In presenting these data, they allow us to revisit current classification constructs. One important point that can be taken from their data is that the myriad of clinical features of ET evolve over time. Although this is not surprising, their study also underscores the point that the layering in of additional features in ET, above and beyond the core clinical feature, kinetic tremor, likely occurs as a function both of the aging process as well as disease duration (a proxy for the evolution of the underlying disease‐associated pathophysiology). Furthermore, as a corollary, what has been termed “ET‐plus” is likely no more than a disease stage rather than a distinct, stable, separable clinical‐pathological entity. Other data firmly support this view [2, 3].

As a field we need to do two things. First, we need to stop using the term “ET‐plus” and rather replace it with the term “advanced ET.” This preferable term captures the concepts of disease heterogeneity, the dynamic layering in of disease features over time, the concept of a continuum of features, and the concept that the addition of these features does not herald a new diagnosis, but rather simply a more advanced disease stage. Second, we need to move further along in the process of establishing a staging scheme for this common disease to order the procession of clinical features [4] as well as the growing catalog of postmortem cerebellar degenerative changes [5]. The only way to do this, and to produce a valid result, is to base such efforts on data derived from longitudinal data. The authors of this report should be commended for moving us closer to this goal.

Author Contributions

Elan D. Louis: conceptualization, writing – original draft.

Conflicts of Interest

The author declares no conflicts of interest.

Data Availability Statement

Data sharing not applicable to this article as no datasets were generated or analyzed during this current study.