Cerebellar hypermetria: reduction in the early component of the antagonist electromyogram.

Several articles have described the electromyographic (EMG) patterns underlying cerebellar hypermetria. However, the description of the EMG associated with hypermetria is not consistent between studies. It is hypothesized that the reason for this concerns the criteria used to define and describe the antagonist latency. Several studies on neurologically normal individuals have shown that there are two components to the antagonist EMG: an early component and a late component. However, many studies have identified only one component and have not defined whether it was the early or late component. A reanalysis of one published data set that had previously identified only one antagonist component was performed. The reanalysis suggests that hypermetria can be caused by an absence of an early antagonist EMG component, a delayed late component, or both. In addition, a new measure is suggested that allows this hypothesis to be further evaluated.