The main clinical forms of dysarthria: a comparative characteristic

Depending on the types of violations of the musculature movement of the articulatory apparatus providing the pronunciation of sounds, various forms of dysarthria, neurogenic speech disorder, are determined.

This neurologic condition occurs when the innervation of the speech apparatus is insufficient due to organic lesions of the premotor cortex, cerebellum or limbic-reticular brain structures, as well as in diseases of the central nervous system and peripheral nervous system of cerebrovascular or neurodegenerative etiology.

Characteristics of forms of dysarthria

Each type of dysarthria - bulbar, pseudobulbar, cerebellar, cortical, extrapyramidal (subcortical) - leads to different forms of violation of the muscular mechanism of speech and negatively affects the articulation of consonant sounds, making speech inarticulate. And the severe form of dysarthria is also manifested in the distortion of the pronunciation of vowels. In this case, the intelligibility of speech varies greatly depending on the degree of damage to the nervous system.

Regardless of the pathogenesis of speech neuromotor disorders, the characteristic of the forms of dysarthria takes into account the anthropophonic features of speech, that is, the integration and coordination of the main physiological subsystems of sound reproduction. This is the conjugation of the musculature movements of parts of the articulatory apparatus (tongue, lips, soft palate, jaws), that is, articulatory motor skills or articulatory patterns of sound reproduction; character of speech breathing; voice formation (sound part of speech or phonation), which depends on the innervation of the muscles of the larynx and vibrations of the vocal folds.

Necessarily estimated prosody (tempo, rhythm, intonation and loudness of speech), as well as resonance - the passage of an air jet through the resonant cavities (mouth, nose and pharyngeal). For most clinical forms of dysarthria, nasal and hypernasal speech (nasal) is characteristic, which is associated with a violation of the lowering / lifting of the palatine curtain - the velum palatinum and the redirection of a part of the air flow through the nasal cavity.

In the domestic neurological practice, on the basis of key symptoms, such forms of dysarthria as:

• spastic form of dysarthria,
• spastico-paretic form of dysarthria (spastic-hyperkinetic),
• spastic-rigid form of dysarthria,
• Atactic form of dysarthria (or spastico-atactic),
• mixed form of dysarthria,
• erased form of dysarthria.

Western specialists in the diagnosis of speech disorders of motor character distinguish spastic, flaccid, atactic, hyperkinetic and hypokinetic forms of dysarthria.

For a better understanding of the terminology, it is worth recalling that under spasticity is meant

Increased muscle tone with their involuntary contraction; with muscle rigidity, muscles are clamped and inactive; paresis is a partial paralysis, that is, a significant decrease in muscle strength due to pathologies of nerve impulse transmission; the lack of coordination of movements of different muscles is called ataxia. If, for no apparent reason, a person has unintentional movements, then we are talking about hyperkinesis, and hypokinesia is characterized by a decrease in the speed of movements and their amplitude.

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Basic disorders in various forms of dysarthria

Since speech impairment is a part of the symptom complex of many neurogenic pathologies, the most important role is played by the differential characteristics of the clinical forms of dysarthria, including the most complete assessment of such factors as the severity of the decrease in muscle tone and the degree of general and local manifestations

Let us consider what are the main violations with different forms of dysarthria allocated

Neurologists and speech therapists during the diagnosis.

[2], [3]

Spastic form of dysarthria

The spastic form of dysarthria arising due to bilateral damage of the upper motor neurons, as well as the defeat of corticobulbar pathways of nerve impulse transmission, is manifested:

• weakness of the facial muscles and a decrease in the range of motion of the articulatory apparatus;
• spasticity and increased tonus of facial muscles;
• protrusion (loss) of the tongue;
• hyperactive emetic reflex;
• slowing down the pace of speech;
• the voice tension with increasing or decreasing its loudness with the general monotony of speech;
• intermittent breathing during conversation;
• hypernasal pronunciation.

People with a spastic form of dysarthria pronounce the sounds "smeared" and are usually expressed in short phrases; often they have difficulty swallowing (dysphagia).

The most common causes of spastic dysarthria are spastic paralysis, multiple sclerosis, amyotrophic lateral sclerosis (Charcot or Lou Gehrig's disease), as well as closed craniocerebral trauma.

Spastic-rigid form of dysarthria

In case of damage to the basal ganglia, a spastic-rigid form of dysarthria develops, usually associated with Parkinson's disease.

Problems with speech in this form of dysarthria arise from tremors and lack of consistency of the verbal musculature and include:

• violation of voice formation (hoarseness, decrease in loudness);
• resonating in the nose (nasal);
• Variable rate of speech (then slow, then accelerated);
• violation of voice modulation and monotony of speech (dysprosium);
• stretching syllables, compulsive repetition of syllables and words (palalalia) or repeated sounds or words (echolalia);
• long pauses and difficulties at the beginning of the conversation.

In general, experts call the inaccuracy of pronunciation of sounds with this form of dysarthria "articulatory undernutrition".

Spastic-paretic form of dysarthria

With the weakness of some muscles of the speech apparatus associated with a violation of the conduction of nerve impulses from the basal nuclei of the extrapyramidal system and the paresis of the muscle fibers, the spastic-paretic form of the dysarthria (and the identical hyperkinetic form) is characterized by a general elevated muscle tone, which is often accompanied by involuntary muscle movements number of mimic.

The main disorders in this form of dysarthria are:

• tension, intermittency and vibration of the voice;
• dyskinesia at the level of the vocal cords and convulsive dysphonia (compressed voice due to incomplete closure of ligaments);
• frequent and noisy breathing;
• spasticity of the tongue ("tongue does not turn in the mouth");
• difficulty in closing the lips, causing the mouth to remain open (with the expiration of saliva);
• change in tempo and rhythmic features of speech (significant slowdown);
• pronounced nasal;
• absence of changes in tone of speech (due to increased stress of the pharyngeal larynx muscles).

Atactic form of dysarthria (spastico-atactic)

The pathogenesis of atactic dysarthria is associated with damage to the cerebellum or its connection to the cortex and / or brainstem. Among the differential characteristics of this form of dysarthria, violations of prosody and articulation are particularly noted.

Thus, the loudness of speech is sometimes described as explosive, despite its slow pace, stretching syllables and individual sounds, and pauses after almost every word. Patients with atactic dysarthria - with inaccuracies in the range, strength and direction of articulatory movements, even when playing vowel sounds - speak especially vaguely.

Given the unstable position of the head and the general inconsistency of the movements of the person suffering from ataxia can easily be mistaken for a drunk.

[4], [5]

Mixed form of dysarthria

In cases of paresis or paralysis of the muscles of the articulatory apparatus due to the simultaneous damage of two or more motor neurons of the central nervous system, as is the case with scattered and lateral amyotrophic sclerosis or severe brain injuries, a mixed form of dysarthria is diagnosed. In fact, it is a combination of various symptoms of an erased form of spastic dysarthria and atactic.

The characteristics of the speech pathology will vary depending on which motor neurons are affected less - the upper ones (localized in the lower quarter of the premotor cortex of the cerebral hemispheres) or the lower ones (the site of their dislocation - the anterior horns of the spinal cord). For example, if the upper motor neurons are most damaged, the disturbance in the voice formation is expressed in a decrease in the timbre, and when the lower motor neurons are affected more severely, the voice will be hoarse with stridor during breathing.

Shabby form of dysarthria

A weak or worn out form of dysarthria or sluggish is due to the degree of damage to the trigeminal, facial, wandering and sublingual cranial nerves (V, VII, X and XII, respectively), since they are responsible for the innervation of the muscles of the tongue, lips, palate, lower jaw, larynx, vocal cords and folds. If the local lesion affects only the cranial nerve VII, then the circular muscle of the mouth will loosen, and if, in addition, the V pair of nerves is damaged, the muscle that lifts the upper lip paralyzes.

Forms of dysarthria in cerebral palsy

Violation of speech function in children occurs with a sufficiently large number of congenital anomalies of the brain and neurocognitive inferiority of various genesis. And infantile cerebral palsy is the most frequent cause of speech disorders, characterized by lack of stability, coordination and accuracy of movements of the muscles of the speech apparatus with varying degrees of narrowing of their range.

There are the following main forms of dysarthria in cerebral palsy: spastic and its variants - spastic-paretic and spastic-rigid, as well as a mixed form of dysarthria (which, along with spastic, happens more often).

Disturbance of swallowing (dysphagia) is a direct indication of a violation of trigeminal nerve signals, which is also manifested by a decrease in muscle tone of the entire face and lips with characteristic signs: open mouth and drooling. And because of the paralysis of the sublingual nerve in cerebral palsy, the deviation of the tongue (deviation of its tip) occurs on the side of the body opposite to the cerebral lesion.

Spastic form of dysarthria in cerebral palsy with spastic hemiplegia (unilateral paralysis) is associated with partial dysfunction of the sublingual cranial nerve, which is expressed in a decrease in the tone of the facial (chewing and facial) muscles. In such cases, an erased form of spasticy-paretic dysarthria is diagnosed with an increased range of motion of the lower jaw, a lower lip retraction, a tongue tremor, a flaccidity of the vocal cords, and weakness of the palate and pharynx. Together, this causes a persistent violation of the articulatory patterns of most consonant sounds and inarticulate speech. And with left-sided hemiplegia, a lighter form of dysarthria is noted, than with right-sided.

Most patients with cerebral palsy are characterized by monotony and nasal speech with stridor. Respiratory muscles may be affected, which leads to limited respiratory support of speech and fade disorders. Because of the weakness of the muscles of the chest in the athetoid variant of cerebral palsy, the diaphragm is forcedly reduced, so it is difficult for the patient to regulate the strength and loudness of the voice, and often all voiced consonant sounds are stunned.

Articulatory dysfunctions of this form of dysarthria in cerebral palsy, as spastic-rigid, are determined by the strained state of all the facial muscles, sensory deficiency of the chin and lips, and a significant limitation of the mobility of the tongue and vocal folds.

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