To summarize, hypotonia is generally associated with flaccid dysarthria and damage to the LMN pathway, whereas hypertonia occurs with spastic, hypokinetic (when consistent), and hyperkinetic (when fluctuating) disorders, and is associated with damage to the indirect UMN pathway and/or the basal ganglia control circuit [3,12-13].
005), wherein individuals with flaccid dysarthria had significantly lower severity scores than either of these groups.
Only one participant in the study had ratings of abnormal muscle tone for more than one task: an 18 yr-old female with mild flaccid dysarthria due to myotonic dystrophy received 4 out of 5 abnormally low tone ratings, all bilaterally.
Tissue stiffness values tended to be higher in individuals with flaccid dysarthria than in those with spastic or hypokinetic dysarthria.
Stiffness values from Myoton-3 testing fell within ~25 percent of the mean for the flaccid dysarthria group for all measures except the superior surface of the tongue, which was 2.
Instead, the data from study 1 suggested the opposite; individuals with spastic and hypokinetic dysarthria, typically considered to have abnormally high tone, had lower orofacial stiffness values on average than did individuals with flaccid dysarthria, which is characterized by abnormally low tone.
Flaccid dysarthria is linked to LMN damage, which can lead to abnormally low resting muscle tension ("floppiness") and eventually muscle atrophy; therefore, those in the flaccid dysarthria group may have thinner tissue than the other cohorts  and thus stiffness measures may be artificially inflated at some thin muscle sites.