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
The human musculoskeletal system (also known as the human locomotor system, and previously the activity system) is an organ system that gives humans the ability to move using their muscular and skeletal systems. The musculoskeletal system provi ...
activities. Speaking is an act dependent on thought and timed execution of airflow and oral motor / oral placement of the
lips,
tongue
The tongue is a muscular organ in the mouth of a typical tetrapod. It manipulates food for mastication and swallowing as part of the digestive process, and is the primary organ of taste. The tongue's upper surface (dorsum) is covered by taste b ...
, and
jaw that can be disrupted by weakness in oral musculature (
dysarthria
Dysarthria is a speech sound disorder resulting from neurological injury of the motor component of the motor–speech system and is characterized by poor articulation of phonemes. In other words, it is a condition in which problems effective ...
) or an inability to execute the motor movements needed for specific speech sound production (
apraxia of speech or
developmental verbal dyspraxia
Development of the human body is the process of growth to maturity. The process begins with fertilization, where an egg released from the ovary of a female is penetrated by a sperm cell from a male. The resulting zygote develops through mit ...
). Such deficits can be related to pathology of the nervous system (central and /or peripheral systems involved in
motor planning) 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
Respiration may refer to:
Biology
* Cellular respiration, the process in which nutrients are converted into useful energy in a cell
** Anaerobic respiration, cellular respiration without oxygen
** Maintenance respiration, the amount of cellul ...
,
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 defi ...
,
resonance
Resonance describes the phenomenon of increased amplitude that occurs when the frequency of an applied periodic force (or a Fourier component of it) is equal or close to a natural frequency of the system on which it acts. When an oscilla ...
,
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
The KE family is a medical name designated for a British family, about half of whom exhibit a severe speech disorder called developmental verbal dyspraxia. It is the first family with speech disorder to be investigated using genetic analyses, by w ...
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