This is a current physiological classification of myoclonus:

Cortical

Cortical reflex myoclonus

Cortical myoclonus without reflex activation

Asterixis

Epilepsia partialis continua

Cortico-thalamic myoclonus

Idiopathic generalized epilepsy

Myoclonic epilepsy

Myoclonic astatic seizures

Juvenile myoclonic epilepsy

Sub-cortical (basal-ganglia or brainstem origin)

Reticular reflex myoclonus (typically combined with cortical myoclonus)

Myoclonus dystonia

Opsoclonus myoclonus syndrome

Palatal myoclonus

Subcortical periodic myoclonus (SSPE, CJD)

Myoclonus related to focal lesions in basal ganglia

Spinal

Segmental myoclonus

Propriospinal myoclonus

Peripheral myoclonus