Action Tremor is Common in Patients with Parkinson`s Disease

The term action tremor describes a tremor that occurs during any type of movement of an affected body part. The pathophysiology of action tremor is not well understood, and it is commonly misdiagnosed as another movement disorder, such as essential tremor or dystonia. Action tremor presents in patients with Parkinson’s disease; however, there is a lack of data about the frequency of its presentation and on its relationship with other motor and non-motor symptoms of Parkinson’s.

In an article recently published in the European Journal of Neurology, a team of researchers from the department of basic medical sciences, neurosciences, and sensory organs, University of Bari Aldo Moro, Italy, presented the results of a cross-sectional study that included 237 patients with Parkinson’s disease (stage 1-2). Using the Unified Parkinson’s Disease Rating Scale (part III: clinician-scored monitored evaluation) and the Non-Motor Symptoms Scale, the researchers gathered data on the patients’ motor and non-motor symptoms, including action tremor. They identified action tremor in 46% of patients and found that it was associated with severity of rest tremor (adjusted odds ratio [AOR], 3.0; P<.001) and the severity of rigidity (AOR, 1.5; P=.004). Also, patients with action tremor were more likely to present with fewer non-motor symptoms than patients without tremor, on average (2.1±1.3 vs 2.4±1.3; P=.04). No significant associations were observed between action tremor and the severity of bradykinesia or axial symptoms.

Based on these findings, the investigators concluded that action tremor is a common motor symptom in patients with the early stages of Parkinson’s disease. They suggest that “non-dopaminergic mechanisms may contribute to action tremor pathophysiology” and that it may be associated with a lower burden of non-motor symptoms.