While most cases of dysarthria are lumped into one category many patients exhibit a variety of symptoms, leaving the possibility open for the existence of different subgroups within the broader diagnosis of ataxic dysarthria. For over ten years, Dr. Spencer and her team have conducted various studies examining subgroups of dysarthria. The most recent study began in 2022.

The study was conducted over Zoom with participants found on the CoRDs Ataxia Patient Registry. Over 400 people from across the US and Canada volunteered to be a part of the study. The initial volunteers were evaluated on several criteria including if the individuals had been diagnosed with ataxic dysarthria. This is because dysarthria caused by damage to the cerebellum, like ataxia, is different than dysarthria caused by damage to other parts of the brain. In the end, 25 participants were selected to participate. The participants recorded samples of their speech for analysis of subgroups.

After all the sample recordings had been collected, Dr. Spencer and 17 other Speech-Language Pathologists (SLPs) set to work analyzing the recordings. They found that there are two main subgroups of ataxic dysarthria. The first group called the “instability” subgroup tends to be highly variable in terms of voice pitch, volume, speech errors, and rhythm. The second group called the “inflexibility” subgroup, tends to sound more “robotic” and has unusually reduced variability in these same areas. Both subgroups were present in the recorded samples. However, the variable subgroup was more common. Only two participants were classified as having the inflexible subtype.