Spastic dysarthria often results from bilateral supranuclear lesions, rendering the muscles that govern articulation both weak and spastic. Phonation is typically strained-strangled, and articulation is slow. The tongue is protruded and moved from side to side with difficulty. Mouth opening may seem restricted and speech seems to come from the back of the mouth. The jaw jerk, gag reflex and facial reflexes often become exaggerated. ALS may cause dysarthria with both spastic and flaccid features.(4)
The video shows two patients with spastic dysarthria due to ALS, courtesy of Dr. Rick Barohn. Contrast this with the video of flaccid dysarthria (see http://neurosigns.org/wiki/Flaccid_dysarthria). Here the patients can pronounce the individual palatals and linguals better but articulation is slow and the voice sounds strained or strangled.
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.