| Type | Distribution | Temporal profile | Activation | Clinical neurophysiology | Anatomic-physiologic classification | Clinical-etiologic classification | Specific etiology |
| Hypnic jerks (massive myoclonus of sleep) | Generalized | Usually single | Occur only during sleep or sleep transitions | Not studied | Presumed subcortical-nonsegmental | Physiologic | Normal phenomenon |
| Partial myoclonic jerks (of sleep) | Multifocal, distal muscles | Usually single | Occur only during sleep or sleep transitions | Not studied | Presumed subcortical-nonsegmental | Physiologic | Normal phenomenon |
| Myoclonus-dystonia | Neck, trunk, proximal arms | Irregular | Rest, action, and posture | EMG with 50 to 100 ms discharges; EEG and SEP normal | Subcortical-nonsegmental | Essential | Genetically heterogeneous; SGCE, DYT15 mutations |
| Juvenile myoclonic epilepsy | Usually generalized | Irregular | Occurs from rest | EEG with 4 to 6 hertz polyspike and wave discharge | Cortical-subcortical | Epileptic | Genetically heterogeneous; EFHC1 and GABRA1 mutations |
| Palatal tremor | Palate, larynx, face; usually bilateral | Rhythmic | Persistent, continues during sleep | EMG with >100 ms rhythmic discharges | Segmental | Symptomatic (secondary) palatal tremor | Brainstem pathology in the region of the Guillain-Mollaret triangle |
| Essential palatal tremor | Idiopathic | ||||||
| Posthypoxic myoclonus | Multifocal and/or generalized | Irregular, less often rhythmic | Action and reflex | EMG discharges <50 ms; cortical EEG correlate grossly time-locked with EEG back-averaging | Cortical | Symptomatic (secondary) | Hypoxic brain injury |
| Progressive myoclonus epilepsy (PME) and progressive myoclonus ataxia (PMA) | Multifocal and/or generalized | Irregular | Action and reflex | EMG discharges <50 ms; cortical EEG correlate grossly time-locked with EEG back-averaging | Cortical | Symptomatic (secondary) | Unverricht-Lundborg disease, Lafora body disease, neuronal ceroid lipofuscinosis, myoclonic epilepsy with ragged red fibers (MERRF), sialidosis |
| Toxic-metabolic myoclonus | Multifocal, sometimes generalized | Irregular | Rest and action | Variable; positive or negative myoclonus; EMG discharges or silence lasting 50 to 200 ms; cortical correlate possible | Cortical most common | Symptomatic (secondary) | Drugs, toxins, organ failure |
| Neurodegenerative disease | Multifocal and worse distally; sometimes generalized | Irregular | Action most common, then rest and reflex | EMG discharges <50 ms; cortical EEG correlate grossly time-locked with EEG back-averaging | Cortical | Symptomatic | Alzheimer disease, dementia with Lewy bodies, Parkinson disease, Huntington disease |
| Creutzfeldt-Jakob disease | Focal, multifocal, or generalized | Single, irregular, or rhythmic | Rest, action, and/or reflex in response to somatosensory stimuli, particularly loud noise (startle) | EEG with periodic synchronous biphasic or triphasic sharp wave complexes; EMG discharge <50 ms | Cortical | Symptomatic (secondary) | Prion disease |
