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CHAPTER 10
Chapter Overview
Mixed dysarthria is a motor speech disorder that can occur when neurological damage
extends to two or more parts of the nervous system, and is characterized by a
combination of the traits found in single (or pure) dysarthrias. Neurological damage that
crosses anatomical boundaries and affects various components of the motor system
simultaneously causes mixed dysarthria. Consequently, an individual with mixed
dysarthria will demonstrate at least some of the speech characteristics of two or more of
the pure dysarthrias. Nearly any combination of the pure dysarthrias can appear in a
mixed dysarthria. Mixed dysarthrias are quite common. The relative prominence of each
dysarthria type within a mixed dysarthria can vary significantly from individual to
individual. The prominence of one dysarthric characteristic over another is usually
dependent upon the severity and extent of the neurological damage. The prominence of
one dysarthric component over another can change over time. Mixed dysarthria is
caused by various disorders, including single or multiple strokes, brain tumors, traumatic
head injuries, degenerative disease, and infectious diseases. Multiple sclerosis (MS), a
progressive demyelinating disease, can occur in the brainstem, cerebellum, cerebral
hemispheres, and spinal cord. Ataxic-spastic dysarthria is the most common mixed
dysarthria associated with MS. Multisystems atrophy is a collective term for a
progressive group of degenerative disorders that can cause mixed dysarthria. Shy-
Treating mixed dysarthria can be a challenge because so many speech errors exist that
the clinician may not know where to begin. The general rule in treating mixed dysarthria
is to first treat the component that is most severely affecting speech production. When
the elements of a mixed dysarthria are affecting speech production equally, Dworkin
(1991) suggested that treatment be sequenced according to which of the components of
speech production are being most affected by the dysarthria. He recommended treating
in the following sequence: respiration, resonation, phonation, articulation, and finally,
prosody. His rationale is that the different components of speech support each other.
Motor Speech Disorders, Second Edition
ii
7. Describe the four areas of the motor system that can be affected by
amyotrophic lateral sclerosis.
8. What type of mixed dysarthria is most associated with the latter stages of
amyotrophic lateral sclerosis?
9. What is the cause of Wilson’s disease?
10. What treatment sequence does Dworkin recommend when all components
of a mixed dysarthria are contributing equally to a patient’s speech
production errors?
