Flaccid dysarthria often results from weakness of the soft palate, larynx, and tongue due to such conditions as ALS or MG.(4) The speech is “thick,” as though the mouth were filled with soft food. In advanced cases, speech is reduced to unintelligible laryngeal noises. In MG, the dysarthria becomes more severe with prolonged talking and may reach the point of anarthria. Thomas Willis, who provided one of the first descriptions of MG in 1672, wrote of a woman who, when she tried to talk for a prolonged period, “temporarily lost her power of speech and became mute as a fish.”
The video shows a woman with severe flaccid dysarthria due to bulbar ALS. She can pronounce the labials in baby but not the palatal k sounds in cupcake or the lingual t sounds in ate or train.
For a discussion of spastic dysarthria see http://neurosigns.org/wiki/Spastic_dysarthria.
1. Campbell WW. Barohn RJ. DeJong's the neurologic examination, 8th ed. Philadelphia: Wolters Kluwer, 2020.
2. Campbell WW. Clinical signs in neurology: a compendium. Philadelphia: Wolters Kluwer Health, 2016.
3. Enderby, P. Disorders of communication: dysarthria. Handb Clin Neurol. 2013; 110:273-81.
4. Tomik B, Guiloff RJ. Dysarthria in amyotrophic lateral sclerosis: A review. Amyotroph Lateral Scler. 2010;11:4-15.