Tremor or myoclonus? A practical clinical approach to distinguishing two common hyperkinetic movement disorders.

Abstract

Tremor and myoclonus are among the most common hyperkinetic movement disorders encountered in neurological practice, with tremor being considerably more common than myoclonus in everyday clinical practice, yet distinguishing between them remains a frequent diagnostic challenge. Although their definitions are conceptually distinct, several disorders - including cortical tremor, dystonic tremor, and generalized polymyoclonus - can mimic one another, leading to diagnostic uncertainty and inappropriate management. This practical review provides clinicians with a structured approach to recognizing and differentiating these movement disorders. The initial assessment relies on careful bedside examination, focusing on rhythmicity, movement duration, oscillatory versus jerky phenomenology, stimulus sensitivity, and the identification of negative myoclonus (asterixis). When clinical uncertainty persists, surface electromyography is the key complementary investigation, reliably distinguishing rhythmic tremor from irregular myoclonic bursts while providing valuable clues regarding the underlying generator. Beyond phenomenological diagnosis, this review outlines a practical framework for etiological orientation based on activation conditions, anatomical distribution, temporal evolution, associated neurological signs, and medication history. Common tremor syndromes and the major categories of myoclonus are discussed, with particular emphasis on identifying reversible causes such as metabolic disturbances and drug-induced disorders. Finally, uncommon but important entities - including orthostatic tremor, palatal tremor, geniospasm, Holmes tremor, functional tremor, and myorhythmia - are reviewed with practical bedside clues to facilitate their recognition. By integrating clinical examination with targeted electrophysiological testing, this guide aims to improve diagnostic accuracy, avoid common pitfalls, and promote timely identification of treatable causes in everyday neurological practice.