- Action Tremor: Occurs During Voluntary Muscle Movement
- This is the classic sign of cerebellar dysfunction. The cerebellum is crucial for error correction and coordinating the timing and force of movements. Damage disrupts this feed-forward control, causing overshooting and corrective “jerks” that manifest as a tremor, which amplifies as the movement requires more precision near the target.
- Cerebellar Disease (e.g., spinocerebellar ataxia, Vitamin E deficiency, stroke, multiple sclerosis, Wilson disease)
- Resting Tremor: Occurs at Rest
- Primarily due to dysfunction in the basal ganglia, specifically the substantia nigra, leading to disturbances in the neural circuits that control movement initiation. This is often related to dopamine depletion.
- Parkinson Disease
- Midbrain Tremor
- Wilson Disease
- Progressive supranuclear palsy
- Multiple System Atrophy
- Drug-Induced Parkinsonism
- Postural Tremor: Occurs While Held Motionless Against Gravity
- Often linked to dysfunction in the cerebello-thalamo-cortical network. The cerebellum helps coordinate and smoothen motor commands, and dysfunction can lead to oscillations when maintaining a steady posture. It can also be an exaggeration of normal physiologic tremor.
- Enhanced Physiologic Change
- Essential tremor
- Dystonia
- Metabolic Etiology (Thyroid, Liver, Kidney)
- Drugs (Lithium, Amiodarone, Valproate)