Dysarthria . This term comes from the Greek words dis-disorder and arthron-articulation and is essentially an alteration in the process of articulation of sounds, it is the speech disorder, characterized by difficulties in the mobility of the articulatory organs that affect the pronunciation of the verbal sounds and that depending on their severity may be accompanied by other alterations, general motor, respiratory, voice, rhythm and speed, intonation and the grammatical lexicon aspect; whose etiopathogenic basis is neurological.
Summary
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- 1 Mechanism of alteration
- 2 Etiology
- 3 Classification of Dysarthria
- 1 Classification of dysarthria according to the prevailing clinical symptom
- 2 Classification of dysarthria according to the level affected
- 3 Classification of D. according to the severity of the clinical picture
- 4 Classification of dysarthria according to the location of the lesion
- 4 Characteristics of dysarthria according to the traditional classification
- 1 The signs of cerebellar alteration are:
- 2 Two forms of Cerebellar Dysarthria are observed:
- 5 Sources
Altering mechanism
Dysarthria is caused by failures in the motor link of the verbal functional system; specifically when the efferent motor pathways that guarantee the kinetic basis of speech are injured. In this way, the innervation and coordinated action of the systems that make up the peripheral language apparatus are affected , with articulatory movements being absent or inadequate.
Etiology
All those causes that can alter the Central Nervous System , being the most frequent:
- Traumatic craniocervical processes.
- Benign or malignant tumor of the brain, cerebellum, or brain stem.
- Brain vascular injury.
- Infectious diseases of the Central Nervous System .
- Metabolic diseases
- Toxic diseases
- Degenerative diseases
- Child brain paralysis.
Dysarthria classification
When specifying the mechanism of alteration of Dysarthria, it was stated that said logopathy is the consequence of injuries to different structures of the Nervous System , injuries that damage the motor conduction pathways and sometimes also the sensitive ones, which unite the conscious centers with the reflex centers.
These have different origins and depending on the path or structure affected, the type of dysarthria will be.
Dysarthria classification according to the prevailing clinical symptom
- Spastic: Bilateral damage to the corticobulbar pathways at the level of the brainstem, causing different degrees of muscle spasticity. Hyperproduction of the vocal folds, hypertonicity of the supraglottic musculature and articulation difficulties with hypernasality are observed.
- Hypokinetics: The substance Nigra and the striatum are injured. There is akinesia, hypotonia, and tremor.
- Hyperkinetics: Result of injury to the extrapyramidal pathway, mainly the striatum and the pale globe. Myoclonus, chorea and tics appear that prevent good articulation due to repeated vocal stops.
- Ataxic: There is diffuse bilateral injury to the cerebellum or cerebellar left hemisphere, changes in language coordination, characterized by gross joint failure.
- Flaccid: In Myasthenia gravis, myopathy, neuropathies, myelopathies and lesions of the IX and X cranial nerves. There is injury to the lower motor neuron, which prevents the flow of impulses from the upper pathways. The articulatory difficulty is due to the tone of the speech structures.
- Mixed: Sequence to injuries in multiple sites of the Central and Peripheral Nervous System (amyotrophic lateral sclerosis, plaque sclerosis, Wilson’s disease) combines the above.
Dysarthria classification according to the level affected
- Central
- Of conduction
- Peripheral
When talking about Cortical Central Dysarthria and Peripheral Dysarthria, it is the one that occurs due to the injury in the termination of the cortical spinal tract, specifically in the lesion of the anterior horns of the medulla as in the amyotrophic lateral sclerosis of Chaikover, in other diseases such as Myasthenia Grave and in those diseases of the Peripheral Nervous System that affect articular motor skills such as some types of neuritis.
Dysarthria in myasthenia is characterized by progressive tiredness and fatigue. The voice becomes whispered, the articulation is increasingly difficult, dragged and with a markedly nasal timbre due to the decrease in the mobility of the veil. The pronunciation of the / s / and / k / phones causes exhaustion, which occurs due to blockage at the neuromuscular junction. This difficulty affects the eye muscles, the chewing and swallowing muscles and the upper ones of the veil.
Classification of D. according to the severity of the clinical picture
- Discreet dysarthria
- Dysarthria as General Failure in Language Development.
Dysarthria classification according to the location of the lesion
- Cortical
- Bulbar
- pseudobulbar
- subcortical
- cerebellar
Characteristics of dysarthria according to the traditional classification
Dysarthria Bulbar . The bulb is a wider cylindroid formation at its top, located between the protuberance and the spinal cord. It constitutes the first level (unconditional segmental) in the integration of a series of complex visceral reflexes such as; cough, swallowing, vomiting , respiratory and sinocarotid and aortic (circulation).
Its main function is to serve as a relay station for the pyramidal routes that go down from the crust towards the periphery. In it is the nucleus of important cranial nerves for the verbal act: trigeminal V, facial VII, glossopharyngeal IX and vagus or pneumogastric x which are mixed nerves and the spinal motor XI and hypoglossal XII.
Bulbar dysarthria occurs due to injury to the motor nuclei of the cranial nerve pairs mentioned and which are part of the motor pathway at this level.
The fundamental symptom of this type of dysarthria is paralysis. As a consequence of velopharyngeal insufficiencies, a weak intraoral pressure is produced, which causes low vocal intensity and nasal air leakage, hypernasality being one of its most notable signs.
Associated signs are atrophy of the tongue, contraction of the wings of the nose and facial muscle contractions that appear to compensate for the aforementioned deficiencies.
The injury it produces causes severe respiratory and cardiac conditions that in many cases lead to death. This type of dysarthria is more frequent in adults and speech therapy is not recommended.
Pseudobulbar dysarthria . It is a consequence of the bilateral lesion of the conductive pathways that go from the cortex to the bulb, that is, the lesion is not located in the bulb, therefore it is falsely called bulbar.
It is characterized by impairments in the coordinated movements of the lips, insufficient closure of the maxilla and dysphagia, signs that cause sialorrhea and joint disorders.
Voice disorders are frequent, which is weak, hoarse, poorly modulated, sometimes nasal and without expressiveness. The verbal rhythm is slow, the movements of the tongue are clumsy and slow, it cannot be carried upwards or stay long in that position.
In mild cases of arteriosclerotic origin, there is only vocal tremor due to the uninterrupted rhythmic contraction of the respiratory and pharyngeal muscles. Later the monotonous, bradylalic, spastic voice appears and finally the pronunciation disorders. The fundamental symptom of this type of dysarthria is also paralysis, being necessary to differentiate it from bulbar paralysis.
Cerebellar dysarthria . Cerebellar dysarthria occurs by damaging the cerebellum and cerebellar pathways. The cerebellum occupies the posterior and inferior part of the cranial cavity. It is a single, medium and symmetrical organ and is the center of balance and coordination.
This structure does not provoke any sensation and rarely movements, “it watches and establishes corrective adjustments of the motor activities triggered by other parts of the brain”. Loss or injury to this area of the brain can affect each of these activities without causing paralysis.
The destruction of small portions of the cerebellar cortex does not cause major anomalies, since the remaining areas considerably compensate for the loss, provided that the movements are carried out slowly. To cause severe dysfunction, the injury must involve the deep cerebellar nuclei.
The signs of cerebellar alteration are :
Dysymmetry : Loss of the ability to predict the distance at which the movement must be carried out, therefore the movements usually go beyond the intended purpose. It produces ataxia.
Adiadochokinesia : It is the momentary loss of consciousness of the position taken by the limbs during fast motor actions, lacking progressiveness to movement.
Intentional tremor : Appears when making a voluntary movement, the muscles contract by jerking due to the lack of movement cushioning.
Hypotonia : Decreased muscle tone on the injury side.
Cerebellar nystagmus : Trembling of the eyeballs when wanting to fix the eyes on a scene next to it.
For speech, it is necessary to carry out a rapid and orderly succession of isolated muscle movements of the articulatory organs. The lack of coordination between them and the inability to predict the intensity and duration of sounds alters the progressivity of speech, this being the essential characteristic of dysarthria. Cerebellar.
In this way, some syllables are pronounced intense, others weak, some long, others short, making speech practically unintelligible. The words are choppy, slow, explosive, and confusing, not sharp. Originating a typical alteration in verbal fluency called scanned language.
In some cases, oscillatory-type gait disturbances are observed, which occur when the pathways that come from the semicircular canals are injured and take over in the cerebellum.
Two forms of Cerebellar Dysarthria are observed:
- Ataxic Cerebellar Dysarthria.
- Non-Ataxic Cerebellar Dysarthria: when the upper part of the left cerebral hemisphere is injured, being a discrete form of D.
Subcortical dysarthria . It appears when the extrapyramidal route and the subcortical nodules or basal ganglia (accumulations of gray matter that make up the subcortex) are injured. Composed of: striated body (caudate nucleus and putamen), globus pallidus, substance nigra, cloister and tonsillar body.
The globus pallidus is responsible for maintaining the basal muscle tone necessary for voluntary movements, instead of these being initiated by impulses from the cerebral cortex or striatum. It is responsible for semi-automatic and associated movements such as mov. in the dark of the arm and decreased muscle tone. Phylogenetically its fibers are older and make up the palliostriatum.
Hyperkinetic dysarthria . Constant joint errors are observed that do not appear in the isolated joint. Due to hyperkinesis, the tone, rhythm, modulation, and speed are also altered because language accelerates or retards. The voice in laughter and crying is normal.
The normal progression of movements cannot take place in the gait, which is called the dance of Saint Vitus. The movements follow the following course: normal movements, suddenly different movements, then another modality, etc.
