Motor speech disorders are a class of
speech disorders that disturb the body's natural ability to
speak due to neurologic impairments. These neurologic impairments make it difficult for individuals with motor speech disorders to plan, program, control, coordinate, and execute speech productions.
[Duffy, J. R. (2013). Motor speech disorders (3rd ed.)St. Louis, MO: Elsevier Mosby.] Disturbances to the individual's natural ability to speak vary in their
etiology
Etiology (pronounced ; alternatively: aetiology or ætiology) is the study of causation or origination. The word is derived from the Greek (''aitiología'') "giving a reason for" (, ''aitía'', "cause"); and ('' -logía''). More completely, e ...
based on the integrity and integration of cognitive, neuromuscular, and
musculoskeletal activities. Speaking is an act dependent on thought and timed execution of airflow and oral motor / oral placement of the
lips,
tongue, and
jaw that can be disrupted by weakness in oral musculature (
dysarthria) or an inability to execute the motor movements needed for specific speech sound production (
apraxia of speech or
developmental verbal dyspraxia). Such deficits can be related to pathology of the nervous system (central and /or peripheral systems involved in
motor planning In psychology and neuroscience, motor planning is a set of processes related to the preparation of a movement that occurs during the reaction time (the time between the presentation of a stimulus to a person and that person's initiation of a motor r ...
) that affect the timing of respiration, phonation, prosody, and articulation in isolation or in conjunction.
Dysarthria
Dysarthria is the reduced ability to motor plan
volitional movements needed for speech production as the result of weakness/paresis and/or paralysis of the musculature of the oral mechanism needed for
respiration,
phonation
The term phonation has slightly different meanings depending on the subfield of phonetics. Among some phoneticians, ''phonation'' is the process by which the vocal folds produce certain sounds through quasi-periodic vibration. This is the defini ...
,
resonance,
articulation, and/or
prosody.
Apraxia
There are two types of Apraxia. Developmental (or Childhood Apraxia of speech) or acquired Apraxia. Childhood apraxia of speech (CAS) is a neurological childhood speech sound disorder that involves impaired precision and consistency of movements required for speech production without any neuromuscular deficits (ASHA, 2007a, Definitions of CAS section, para. 1). Both are the inability to plan volitional motor movements for speech production in the absence of muscular weakness. Apraxia is not a result of sensory problems, or physical issues with the articulatory structures themselves, simply the way the brain plans to move them.
Developmental verbal dyspraxia
Developmental verbal dyspraxia is a developmental inability to motor plan volitional movement for the production of speech in the absence of muscular weakness. Research has suggested links to the
FOXP2 gene.
See also
*
KE family
References
{{citation, last=Duffy , first=Joseph , date=2013 , title=Motor speech disorders , edition=3rd , publisher=St. Louis, MO: Elsevier Mosby
Neurological disorders
Communication disorders
Symptoms and signs: Speech and voice