The tremor is called an action tremor, becoming noticeable in the arms when they are being used.

Contralateral rhythmic, ataxic action tremor; rhythmic postural or "holding" tremor (rubral tremor): Dentatothalamic tract.

Spinocerebellar Ataxia type 15 has been classified as an ADCA Type 3 as it has been noted to have postural and action tremor in addition to cerebellar ataxia.

This resting tremor, which can occur as an isolated symptom or be seen in other disorders, is often a precursor to Parkinson's disease (more than 25 percent of patients with Parkinson's disease have an associated action tremor).

Essential tremor is commonly described as an action tremor (it intensifies when one tries to use the affected muscles) rather than a resting tremor; rigidity, such as is seen in Parkinson's, is usually not included among its symptoms.