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Dysarthria is a
speech sound disorder A speech sound disorder (SSD) is a speech disorder in which some speech sounds (called phoneme In phonology and linguistics, a phoneme is a unit of sound that distinguishes one word from another in a particular language. For example, in mos ...
resulting from neurological injury of the motor component of the motor–speech system and is characterized by poor articulation of
phoneme In phonology and linguistics, a phoneme is a unit of sound that distinguishes one word from another in a particular language. For example, in most List of dialects of English, dialects of English, with the notable exception of the West Midlan ...
. In other words, it is a condition in which problems effectively occur with the muscles that help produce speech, often making it very difficult to pronounce words. It is unrelated to problems with understanding language (that is,
dysphasia or aphasia
dysphasia or aphasia
), although a person can have both. Any of the speech subsystems (
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 cellular ...

respiration
,
phonation The term phonation has slightly different meanings depending on the subfield of phonetics Phonetics is a branch of that studies how humans produce and perceive sounds, or in the case of s, the equivalent aspects of sign. Phoneticians—lingu ...
,
resonance Resonance describes the phenomenon of increased amplitude The amplitude of a Periodic function, periodic Variable (mathematics), variable is a measure of its change in a single Period (mathematics), period (such as frequency, time or Wavelen ...

resonance
,
prosody Prosody may refer to: * Sanskrit prosody, Prosody (Sanskrit), the study of poetic meters and verse in Sanskrit and one of the six Vedangas, or limbs of Vedic studies * Prosody (Greek), the theory and practice of Greek versification * Prosody (Lati ...
, and
articulation
articulation
) can be affected, leading to impairments in intelligibility, audibility, naturalness, and efficiency of vocal communication. Dysarthria that has progressed to a total loss of speech is referred to as anarthria. The term ''dysarthria'' is from
New Latin New Latin (also called Neo-Latin or modern Latin) is the revival of Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally spoken in the area around Rome, know ...
, ''dys-'' "dysfunctional, impaired" and ''arthr-'' "joint, vocal articulation". Neurological injury due to damage in the
central Central is an adjective usually referring to being in the center (disambiguation), center of some place or (mathematical) object. Central may also refer to: Directions and generalised locations * Central Africa, a region in the centre of Africa ...

central
or
peripheral nervous system The peripheral nervous system (PNS) is one of two components that make up the nervous system In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, ...
may result in weakness, paralysis, or a lack of coordination of the motor–speech system, producing dysarthria. These effects in turn hinder control over the tongue, throat, lips or lungs; for example, swallowing problems (
dysphagia Dysphagia is difficulty in swallowing Swallowing, sometimes called deglutition in scientific contexts, is the process in the human or animal body that allows for a substance to pass from the mouth, to the pharynx, and into the esophagus, while ...
) are also often present in those with dysarthria.
Cranial nerves Cranial nerves are the nerve A nerve is an enclosed, cable-like bundle of fibers (called axon An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see American and British English spelling differences#-re, -er, ...
that control the muscles relevant to dysarthria include the
trigeminal nerve The trigeminal nerve (the fifth cranial nerve, or simply CN V) is a nerve responsible for sensation in the face and motor functions such as biting and chewing; it is the most complex of the cranial nerves Cranial nerves are the nerve A ner ...

trigeminal nerve
's motor branch (V), the
facial nerve The facial nerve (the labyrinthine segment) is the seventh Cranial nerves, cranial nerve, or simply CN VII. It emerges from the pons of the brainstem, controls the muscles of facial expression, and functions in the conveyance of taste sensation ...

facial nerve
(VII), the
glossopharyngeal nerve The glossopharyngeal nerve (), known as the ninth cranial nerve Cranial nerves are the nerve A nerve is an enclosed, cable-like bundle of nerve fibers called axon An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerv ...
(IX), the
vagus nerve The vagus nerve, historically cited as the pneumogastric nerve, is the tenth cranial nerve Cranial nerves are the nerve A nerve is an enclosed, cable-like bundle of nerve fibers called axon An axon (from Greek ἄξων ''áxōn'', axi ...
(X), and the
hypoglossal nerve The hypoglossal nerve is the twelfth cranial nerve Cranial nerves are the nerve A nerve is an enclosed, cable-like bundle of nerve fibers called axon An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see ...
(XII). Dysarthria does not include speech disorders from structural abnormalities, such as
cleft palate A cleft lip contains an opening in the upper lip Lips are a visible body part at the mouth of many animals, including humans. Lips are soft, movable, and serve as the opening for food intake and in the articulation of sound and speech. Hu ...
and must not be confused with
apraxia of speech Apraxia of speech (AOS) is an acquired oral motor speech disorder affecting an individual's ability to translate conscious speech plans into motor plans, which results in limited and difficult speech ability. By the definition of apraxia Apraxia ...
, which refers to problems in the planning and programming aspect of the motor–speech system. Just as the term "articulation" can mean either "speech" or "joint movement", so is the
combining form Combining may refer to: * Combine harvester use in agriculture * Combining capacity, in chemistry * Combining character, in digital typography * Combining form, in linguistics * Combining grapheme joiner, Unicode character that has no visible glyph ...
of '' arthr-'' the same in the terms "dysarthria", "dysarthrosis", and "
arthropathy An arthropathy is a disease A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not due to any immediate external injury. Diseases are often known to b ...
"; the term "dysarthria" is conventionally reserved for the speech problem and is not used to refer to arthropathy, whereas "dysarthrosis" has both
senses Sense relates to any of the systems and corresponding organs involved in sensation, i.e. the physical process of responding to Stimulus (physiology), stimuli and providing data for perception. During sensation, sense organs collect stimuli for Tran ...
but usually refers to arthropathy.


Causes

There are many potential causes of dysarthria. They include toxic, metabolic, degenerative diseases, traumatic brain injury, or thrombotic or embolic
stroke A stroke is a medical condition A disease is a particular abnormal condition that negatively affects the structure or function (biology), function of all or part of an organism, and that is not due to any immediate external injury. Di ...

stroke
. Degenerative diseases include
parkinsonism Parkinsonism is a clinical syndrome characterized by tremor A tremor is an involuntary, somewhat rhythmic, muscle contraction and relaxation involving oscillations or twitching movements of one or more body parts. It is the most common of all ...
,
amyotrophic lateral sclerosis Amyotrophic lateral sclerosis (ALS; also known as Lou Gehrig's disease in Canada Canada is a country in the northern part of North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the A ...
(ALS),
multiple sclerosis Multiple sclerosis (MS), also known as encephalomyelitis disseminata, is the most common demyelinating disease A demyelinating disease is any disease of the nervous system in which the myelin sheath of neurons is damaged. This damage impa ...
,
Huntington's disease Huntington's disease (HD), also known as Huntington's chorea, is a neurodegenerative disease that is mostly Genetic disorder#Autosomal dominant, inherited. The earliest symptoms are often subtle problems with mood or mental abilities. A gener ...
, Niemann-Pick disease, and
Friedreich's ataxia Friedreich's ataxia (FRDA or FA) is an autosomal-recessive genetic disease that causes difficulty walking, a loss of sensation in the arms and legs, and impaired speech that worsens over time. Symptoms generally start between 5 and 20 years ...
. Toxic and metabolic conditions include:
Wilson's disease Wilson's disease is a in which excess builds up in the body. Symptoms are typically related to the and . Liver-related symptoms include , weakness, , , and . Brain-related symptoms include s, muscle stiffness, trouble speaking, personality c ...
, hypoxic encephalopathy such as in
drowning Drowning is a type of suffocation Asphyxia or asphyxiation is a condition of deficient supply of oxygen Oxygen is the chemical element with the chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen Grou ...

drowning
, and
central pontine myelinolysis Central pontine myelinolysis (CPM) is a neurological condition involving severe damage to the myelin sheath of nerve cells in the ''pons The pons (Latin for "bridge") is part of the brainstem that in human Humans (''Homo sapiens'') are th ...
. These result in lesions to key areas of the brain involved in planning, executing, or regulating motor operations in
skeletal muscles Skeletal muscles (commonly referred to as muscles) are Organ (biology), organs of the vertebrate muscular system that are mostly attached by tendons to bones of the skeleton. The muscle cells of skeletal muscles are much longer than in the other ...

skeletal muscles
(i.e. muscles of the limbs), including muscles of the head and neck (dysfunction of which characterises dysarthria). These can result in dysfunction, or failure of: the motor or
somatosensory cortex The somatosensory system is a part of the sensory nervous system that is associated with the sense of touch, but includes parallel receptors and nerve pathways for the sensations of temperature, body position and movement, and pain. This complex s ...
of the brain, corticobulbar pathways, the cerebellum, (consisting of the
putamen The putamen (; from Latin, meaning "nutshell") is a round structure located at the base of the forebrain (telencephalon). The putamen and caudate nucleus together form the dorsal striatum. It is also one of the structures that compose the basal nu ...

putamen
,
globus pallidus The globus pallidus (GP), also known as paleostriatum or dorsal pallidum, is a subcortical The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue Nervous tissue, also called neural tissue, is the main tiss ...

globus pallidus
,
caudate nucleus The caudate nucleus is one of the structures that make up the corpus striatum, which is a component of the basal ganglia. While the caudate nucleus has long been associated with motor processes due to its role in Parkinson's disease, it plays im ...

caudate nucleus
,
substantia nigra The substantia nigra (SN) is a basal ganglia structure located in the midbrain that plays an important role in reward system, reward and Motor system, movement. ''Substantia nigra'' is Latin for "black substance", reflecting the fact that parts ...

substantia nigra
etc.),
brainstem The brainstem (or brain stem) is the posterior stalk-like part of the brain A brain is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and anim ...

brainstem
(from which the
cranial nerves Cranial nerves are the nerve A nerve is an enclosed, cable-like bundle of fibers (called axon An axon (from Greek ἄξων ''áxōn'', axis), or nerve fiber (or nerve fibre: see American and British English spelling differences#-re, -er, ...
originate), or the
neuromuscular junction A neuromuscular junction (or myoneural junction) is a chemical synapse Chemical synapses are biological junctions through which neuron A neuron or nerve cell is an electrically excitable cell that communicates with other cells via spe ...

neuromuscular junction
(in diseases such as
myasthenia gravis Myasthenia gravis (MG) is a long-term neuromuscular disease A neuromuscular junction (or myoneural junction) is a chemical synapse between a motor neuron A motor neuron (or motoneuron) is a neuron A neuron or nerve cell is an electric ...
) which block the
nervous system In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mecha ...

nervous system
's ability to activate motor units and effect correct range and strength of movements. Causes: *
Brain tumor A brain tumor occurs when abnormal cells form within the brain A brain is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on ...
*
Cerebral palsy Cerebral palsy (CP) is a group of movement disorders Movement disorder refers to any clinical syndrome with either an excess of movement or a paucity of voluntary and involuntary movements, unrelated to weakness or spasticity Spasticity () is ...

Cerebral palsy
*
Guillain–Barré syndrome Guillain–Barré syndrome (GBS) is a rapid-onset muscle weakness Muscle weakness is a lack of muscle Skeletal muscles (commonly referred to as muscles) are organs An organ is a group of tissues with similar functions. Plant life and ...
*
Hypothermia Hypothermia is defined as a body core temperature Core or cores may refer to: Science and technology * Core (anatomy), everything except the appendages * Core (manufacturing), used in casting and molding * Core (optical fiber), the signal ...
*
Idiopathic intracranial hypertension Idiopathic intracranial hypertension (IIH), previously known as pseudotumor cerebri and benign intracranial hypertension, is a condition characterized by increased intracranial pressure Intracranial pressure (ICP) is the pressure exerted by fluid ...
(formerly known as ''pseudotumor cerebri'') *
Lyme disease Lyme disease, also known as Lyme borreliosis, is a vector-borne disease caused by the ''Borrelia ''Borrelia'' is a genus Genus (plural genera) is a taxonomic rank Taxonomy (general) is the practice and science of classification of thing ...
*
Stroke A stroke is a medical condition A disease is a particular abnormal condition that negatively affects the structure or function (biology), function of all or part of an organism, and that is not due to any immediate external injury. Di ...

Stroke
*
Tay–Sachs disease Tay–Sachs disease is a genetic disorder A genetic disorder is a health problem caused by one or more abnormalities in the genome. It can be caused by a mutation in a single gene In biology, a gene (from ''genos'' "...Wilhelm Johannse ...
, and late-onset Tay–Sachs disease (LOTS) *
Transient ischemic attack A transient ischemic attack (TIA), commonly known as a mini-stroke, is a brief episode of neurological dysfunction caused by loss of blood flow (ischemia Ischemia or ischaemia is a restriction in blood Blood is a body fluid in humans and ...
, a 'mini stroke'


Diagnosis


Classification

Dysarthrias are classified in multiple ways based on the presentation of symptoms. Specific dysarthrias include
spastic In medicine Medicine is the Art (skill), art, science, and Praxis (process) , practice of caring for a patient and managing the diagnosis, prognosis, Preventive medicine, prevention, therapy, treatment or Palliative care , palliation of their in ...
(resulting from bilateral damage to the
upper motor neuron Upper motor neurons (UMNs) is a term introduced by William Gowers in 1886. They are found in the cerebral cortex The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans ...
), flaccid (resulting from bilateral or unilateral damage to the
lower motor neuron Lower motor neurons (LMNs) are motor neuron A motor neuron (or motoneuron or efferent neuron) is a neuron whose cell body is located in the motor cortex, brainstem or the spinal cord, and whose axon (fiber) projects to the spinal cord or outside o ...
), ataxic (resulting from damage to cerebellum), unilateral upper motor neuron (presenting milder symptoms than bilateral UMN damage), hyperkinetic and hypokinetic (resulting from damage to parts of the
basal ganglia #REDIRECT Basal ganglia The basal ganglia (or basal nuclei) are a group of subcortical The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue Nervous tissue, also called neural tissue, is the main tissue ...

basal ganglia
, such as in Huntington's disease or
Parkinsonism Parkinsonism is a clinical syndrome characterized by tremor A tremor is an involuntary, somewhat rhythmic, muscle contraction and relaxation involving oscillations or twitching movements of one or more body parts. It is the most common of all ...
), and the mixed dysarthrias (where symptoms of more than one type of dysarthria are present). The majority of dysarthric patients are diagnosed as having 'mixed' dysarthria, as neural damage resulting in dysarthria is rarely contained to one part of the nervous system — for example, multiple strokes,
traumatic brain injury A traumatic brain injury (TBI), also known as an intracranial injury, is an injury to the brain caused by an external force. TBI can be classified based on severity (ranging from mild traumatic brain injury TBI/concussionto severe traumatic ...
, and some kinds of degenerative illnesses (such as
amyotrophic lateral sclerosis Amyotrophic lateral sclerosis (ALS; also known as Lou Gehrig's disease in Canada Canada is a country in the northern part of North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the A ...
) usually damage many different sectors of the nervous system. Ataxic dysarthria is an acquired neurological and sensorimotor speech deficit. It is a common diagnosis among the clinical spectrum of ataxic disorders. Since regulation of skilled movements is a primary function of the
cerebellum The cerebellum (Latin for "little brain") is a major feature of the hindbrain The hindbrain or rhombencephalon is a developmental Development of the human body is the process of growth to maturity. The process begins with fertilization ...

cerebellum
, damage to the superior cerebellum and the
superior cerebellar peduncle In the human brain The human brain is the central organ (anatomy), organ of the human nervous system, and with the spinal cord makes up the central nervous system. The brain consists of the cerebrum, the brainstem and the cerebellum. It control ...
is believed to produce this form of dysarthria in ataxic patients. Growing evidence supports the likelihood of cerebellar involvement specifically affecting speech motor programming and execution pathways, producing the characteristic features associated with ataxic dysarthria. This link to speech motor control can explain the abnormalities in articulation and
prosody Prosody may refer to: * Sanskrit prosody, Prosody (Sanskrit), the study of poetic meters and verse in Sanskrit and one of the six Vedangas, or limbs of Vedic studies * Prosody (Greek), the theory and practice of Greek versification * Prosody (Lati ...
, which are hallmarks of this disorder. Some of the most consistent abnormalities observed in patients with ataxia dysarthria are alterations of the normal timing pattern, with prolongation of certain segments and a tendency to equalize the duration of syllables when speaking. As the severity of the dysarthria increases, the patient may also lengthen more segments as well as increase the degree of lengthening of each individual segment. Common clinical features of ataxic dysarthria include abnormalities in speech modulation, rate of speech, explosive or scanning speech, slurred speech, irregular stress patterns, and vocalic and consonantal misarticulations. Ataxic dysarthria is associated with damage to the left cerebellar hemisphere in right-handed patients. Dysarthria may affect a single system; however, it is more commonly reflected in multiple motor–speech systems. The etiology, degree of neuropathy, existence of co-morbidities, and the individual's response all play a role in the effect the disorder has on the individual's quality of life. Severity ranges from occasional articulation difficulties to verbal speech that is completely unintelligible. Individuals with dysarthria may experience challenges in the following: * Timing * Vocal quality * Pitch * Volume * Breath control * Speed * Strength * Steadiness * Range * Tone Examples of specific observations include a continuous breathy voice, irregular breakdown of articulation, monopitch, distorted vowels, word flow without pauses, and hypernasality.


Treatment

Articulation problems resulting from dysarthria are treated by speech language pathologists, using a variety of techniques. Techniques used depend on the effect the dysarthria has on control of the articulators. Traditional treatments target the correction of deficits in rate (of articulation), prosody (appropriate emphasis and inflection, affected e.g. by
apraxia of speech Apraxia of speech (AOS) is an acquired oral motor speech disorder affecting an individual's ability to translate conscious speech plans into motor plans, which results in limited and difficult speech ability. By the definition of apraxia Apraxia ...
, right hemisphere brain damage, etc.), intensity (loudness of the voice, affected e.g. in hypokinetic dysarthrias such as in Parkinson's), resonance (ability to alter the vocal tract and resonating spaces for correct speech sounds) and phonation (control of the vocal folds for appropriate voice quality and valving of the airway). These treatments have usually involved exercises to increase strength and control over articulator muscles (which may be flaccid and weak, or overly tight and difficult to move), and using alternate speaking techniques to increase speaker intelligibility (how well someone's speech is understood by peers). With the speech–language pathologist, there are several skills that are important to learn; safe chewing and swallowing techniques, avoiding conversations when feeling tired, repeat words and syllables over and over in order to learn the proper mouth movements, and techniques to deal with the frustration while speaking. Depending on the severity of the dysarthria, another possibility includes learning how to use a computer or flip cards in order to communicate more effectively. More recent techniques based on the principles of motor learning (PML), such as LSVT (
Lee Silverman voice treatment#REDIRECT Lee Silverman voice treatment The Lee Silverman Voice Treatment – LOUD (LSVT LOUD) is a treatment for speech disorders associated with Parkinson's disease Parkinson's disease (PD), or simply Parkinson's, is a chronic condition, long- ...
) speech therapy and specifically LSVT may improve voice and speech function in PD. For Parkinson's, aim to retrain speech skills through building new generalised motor programs, and attach great importance to regular practice, through peer/partner support and self-management. Regularity of practice, and when to practice, are the main issues in PML treatments, as they may determine the likelihood of generalization of new motor skills, and therefore how effective a treatment is.
Augmentative and alternative communication Augmentative and alternative communication (AAC) encompasses the communication methods used to supplement or replace speech or writing for those with impairments in the production or comprehension of spoken or written language. AAC is used by t ...
(AAC) devices that make coping with a dysarthria easier include
speech synthesis Speech synthesis is the artificial production of human speech. A computer system used for this purpose is called a speech computer or speech synthesizer, and can be implemented in software or Computer hardware, hardware products. A text-to-speech ...
and text-based telephones. These allow people who are unintelligible, or may be in the later stages of a progressive illness, to continue to be able to communicate without the need for fully intelligible speech.


See also

*
Lists of language disorders Bibliography

* {{DEFAULTSORT:Language disorders Language disorders, Lists of diseases Communication-related lists ...


References


Further reading

* *Gatokowska, Izbela. Diagnosing Dysarthria in Adults: A New Speech Assessment Method for Polish, English, and Spanish. AE Academic Publishing, 2020. * * * *


External links

{{Wiktionary, dysarthria
Online Speech and Voice Disorder Support (VoiceMatters.net)

American Speech-Language-Hearing Association


Symptoms and signs: Nervous system Communication disorders Symptoms and signs: Speech and voice