Upper Limb Function but Not Proprioception is Impaired in Essential Tremor: A Between-Groups Study and Causal...

Area of Science:

• Neuroscience
• Movement Disorders
• Biomedical Engineering

Background:

• Essential tremor (ET) involves abnormal muscle activity and cerebellar dysfunction.
• These factors can lead to proprioceptive deficits, particularly during active tasks.
• Understanding these deficits is crucial for addressing functional impairments in ET.

Purpose of the Study:

• To quantify proprioceptive deficits in individuals with essential tremor.
• To estimate the contribution of proprioceptive deficits to functional impairments in ET.
• To investigate the relationship between upper limb function, proprioception, and ET.

Main Methods:

• Assessed upper limb sensory, proprioceptive, and motor function in ET patients and healthy controls.
• Measured proprioception through object width and weight discrimination tasks.
• Employed causal mediation analysis to determine the role of proprioception in ET-related functional impairments.

Main Results:

• Individuals with ET exhibited impaired upper limb function and increased tremor.
• No significant differences in proprioceptive discrimination of object width or weight were found between groups.
• Causal mediation analysis indicated that proprioceptive ability did not mediate the effect of ET on upper limb function.

Conclusions:

• Upper limb function is impaired in ET, whereas proprioception remains largely unaffected.
• Proprioception does not mediate the motor functional deficits observed in essential tremor.
• The central nervous system in ET patients may accommodate mild to moderate tremor in active proprioceptive tasks.