Tremor Syndromes: An Updated Review

Abstract

Tremor is the most commonly encountered movement disorder in clinical practice. A wide range of pathologies may manifest with tremor either as a presenting or predominant symptom. Considering the marked etiological and phenomenological heterogeneity, it would be desirable to develop a classification of tremors that reflects their underlying pathophysiology. The tremor task force of the International Parkinson Disease and Movement Disorders Society has worked toward this goal and proposed a new classification system. This system has remained a prime topic of scientific communications on tremor in recent times. The new classification is based on two axes: 1. based on the clinical features, history, and tremor characteristics and 2. based on the etiology of tremor. In this article, we discuss the key aspects of the new classification, review various tremor syndromes, highlight some of the controversies in the field of tremor, and share the potential future perspectives.

Keywords: action tremor; dystonic tremor; essential tremor plus; myorhythmia; neuropathic tremor; orthostatic tremor; rest tremor; tremor.

Figure 1

Categories of tremor based on the activation pattern.

Figure 2

Decision tree for clinical identification of the major tremor syndromes (Axis-2 etiologies should be explored for all the tremor syndromes). EVT, Essential vocal tremor; EHT, Essential Head tremor; EPT, Essential palatal tremor; SPT, Symptomatic palatal tremor; ET, Essential tremor; PD, Parkinson's disease; DT, Dystonic tremor; TAWD, Tremor associated with dystonia; MSA, Multiple system atrophy; FXTAS, Fragile-X-tremor ataxia syndrome; CMT, Charcot-Marie-Tooth disease; MGUS, Monoclonal gammopathy of uncertain significance; AIDP, Acute inflammatory demyelinating polyradiculoneuropathy; CIDP, Chronic inflammatory demyelinating polyradiculoneuropathy.