Myoclonus: Differential diagnosis and current management

Abstract

Myoclonus classically presents as a brief (10-50 ms duration), non-rhythmic jerk movement. The etiology could vary considerably ranging from self-limited to chronic or even progressive disorders, the latter falling into encephalopathic pictures that need a prompt diagnosis. Beyond the etiological classification, others evaluate myoclonus' body distribution (i.e., clinical classification) or the location of the generator (i.e., neurophysiological classification); particularly, knowing the anatomical source of myoclonus gives inputs on the observable clinical patterns, such as EMG bursts duration or EEG correlate, and guides the therapeutic choices. Among all the chronic disorders, myoclonus often presents itself as a manifestation of epilepsy. In this context, myoclonus has many facets. Myoclonus occurs as one, or the only, seizure manifestation while it can also present as a peculiar type of movement disorder; moreover, its electroclinical features within specific genetically determined epileptic syndromes have seldom been investigated. In this review, following a meeting of recognized experts, we provide an up-to-date overview of the neurophysiology and nosology surrounding myoclonus. Through the dedicated exploration of epileptic syndromes, coupled with pragmatic guidance, we aim to furnish clinicians and researchers alike with practical advice for heightened diagnostic management and refined treatment strategies. PLAIN LANGUAGE SUMMARY: In this work, we described myoclonus, a movement characterized by brief, shock-like jerks. Myoclonus could be present in different diseases and its correct diagnosis helps treatment.

Keywords: electroclinical features; epilepsy; myoclonus; neurophysiology; nosology.

FIGURE 1

Schematic representation of the neurophysiological classification‐driven treatment of myoclonus. CZP, clonazepam; DBS, deep brain stimulation; ESM, ethosuximide; GABA, gabapentin; 5‐HTP, 5‐hydroxytryptophan; IVIG, intravenous immunoglobuline; LEV, levetiracetam; LTG, lamotrigine; PB, phenobarbital; PIR, piracetam; PRM, primidone; RES, reserpine; SUM, sumatriptan; SZ, seizures; TBZ, tetrabenazine; TPE, therapeutic plasma exchange; Tx, treatment; VPA, valproic acid; ZNS, zonisamide. Note, that doses are reported *daily.