Most common movement disorder. Defined as an involuntary rhythmic alternating oscillatory movement. Essential tremor is a single symptom occurring in a sporadic or familial form. Tremors can be sole manifestation or part of a syndrome/movement disorder in the absence of an identifiable cause (eg Parkinson’s disease; drugs).
Differential diagnosis of essential tremor:
• Rest tremors – characteristically the “pill rolling” tremor; usually present asymmetrically; relieved by rest; eg Parkinson’s disease, parkinsonism, severe essential tremor, drug induced
• Postural tremors – at worse when limb held extended against gravity; eg physiologic tremor, essential tremor, neuropathic tremor, cerebellar head tremor, dystonic tremor, drug induced
• Action tremor – at worse during movement of limb eg cerebellar tremor (multiple sclerosis), primary writing tremor
• Mixed tremor – eg Wilson’s disease, psychogenic tremor
Tremor of hands and arms on action; if severe, occurs at rest