Essential tremor plus rest tremor: current concepts and controversies

Area of Science:

• Neurology
• Movement Disorders
• Clinical Neuroscience

Background:

• Essential Tremor (ET) is a common neurological disorder.
• The presence of rest tremor in ET (ET-plus) is controversial and lacks clear definition.
• Existing tremor classifications propose ET-plus but its nature remains unclear.

Purpose of the Study:

• To systematically review existing literature on ET-plus with rest tremor.
• To clarify the heterogeneous nature of ET-plus rest tremor.
• To analyze clinical, electrophysiological, imaging, and anatomopathological data.

Main Methods:

• Systematic literature review of Medline-indexed studies.
• Inclusion of studies published before and after the new tremor classification.
• Analysis of 44 studies involving 4028 patients using descriptive statistics.

Main Results:

• ET-plus rest tremor represents a heterogeneous group of conditions.
• Possible underpinnings include late-stage ET, a distinct disorder, early Parkinson's disease, or misdiagnosis.
• Evidence supports the ET-plus construct as a syndrome with varied causes.

Conclusions:

• ET-plus rest tremor is not a single entity but a syndrome with diverse etiologies.
• The ET-plus classification is valuable for differentiating tremor subtypes.
• Future research should address methodological limitations in studying ET-plus.