Dysarthria (violation of articulation): causes, symptoms, diagnosis

In dysarthria, in contrast to aphasia, the "technique" of speech suffers, and not its higher (praxic) functions. In dysarthria, despite defects in pronunciation, the patient understands what he has heard and written, and logically expresses his thoughts.

Thus, dysarthria is a violation of the articulation process, the causes of which can be the following disorders of the verbal musculature:

1. Paresis (peripheral or / and central);
2. Spasm or increased tone (tetany, rigidity, spasticity, stiffness);
3. Hyperkinesis;
4. Ataxia;
5. Hypokinesia (akinesia);
6. Combination of several of the above reasons;
7. Pseudoparesis.

In this regard, the following syndromal forms of dysarthria are distinguished: bulbar and pseudobulbarnaya, extrapyramidal (hypokinetic and hyperkinetic), cerebellar, cortical and dysarthria, associated with pathology at the muscular level. There is also a psychogenic dysarthria.

There are diseases in which several of the above reasons can lie at the heart of the dysarthria (for example, olive-ponto-cerebellar atrophy, multiple sclerosis and other diseases).

"Paretic" dysarthria develops with the defeat of the lower motor neuron and is observed in the picture of bulbar paralysis. This dysarthria is caused by damage to the motor neurons of the medulla oblongata and the lower parts of the variolium bridge, as well as their intracerebral and peripheral axons. A characteristic "blurring" of speech develops ("porridge in the mouth"), the pronunciation of the vibrating sound "P", as well as lingual and labial sounds, is disrupted. With the bilateral weakness of the soft palate, a nasal hue of the voice appears. The voice can also suffer due to the paresis of the vocal cords.

Diplegia of facial nerves with certain polyneuropathies leads to weakness of labile muscles and disruption of pronunciation of labial sounds ("B", "M", "P").

Neurological status reveals atrophy and fasciculations in the tongue, weakness of the palatine curtain and facial muscles.

The main causes of dysarthria (violation of articulation): polyneuropathy (diphtheria, PVDP, hyperthyroidism, porphyria, paraneoplastic polyneuropathy), amyotrophic lateral sclerosis, syringobulbia. In the same group can be attributed dysarthria in other diseases of the motor neuron, myasthenia, rare forms of myopathy. Transient dysarthria of this type is possible in the picture of transient ischemic attacks or as an early symptom of cerebral ischemia in the stenosis of the basilar or vertebral arteries. All these diseases are accompanied by another neurologic symptomatology, which facilitates diagnosis.

"Spastic" dysarthria develops when the upper motor neuron is affected and enters the picture of pseudobulbar paralysis (with bilateral damage to corticobulbar tracts). The most common cause: bilateral cerebral infarction, a high form of amyotrophic lateral syndrome.

"Atactic" dysarthria can be observed in acute and chronic diseases of the nervous system accompanied by cerebellar involvement (multiple sclerosis, craniocerebral trauma and others) or its connections (spinocerebellar degenerations).

"Hypokinetic" dysarthria is characteristic for parkinsonism and, first of all, for Parkinson's disease, as its most frequent form.

"Hyperkinetic" dysarthria is typical for diseases manifested by hyperkinesis (especially in the presence of choreic or dystonic syndromes, rarely - tremor and other dyskinesias).

The "mixed" type of dysarthria develops when several pathological processes involved in the regulation of motor (speech) functions are involved: multiple sclerosis, Wilson-Konovalov's disease, ALS and other diseases.

The above is a purely clinical classification of dysarthria, based on the identification of the leading neurological syndrome underlying dysarthria. Below is another classification of the same variants of dysarthria, based on the delineation of all dysarthria on "peripheral" and "central" forms.

Dysarthria - as a symptom of the defeat of different levels of the nervous system

I. Peripheral dysarthria

1. "Diffuse": polyneuropathy, myopathy, myasthenia gravis
2. "Focal" (with isolated lesions of separate caudal cranial nerves)

II. Central Dysarthria

A. Associated with damage to individual brain systems

1. Spastic (Pseudobulbar syndrome)
2. Atactic (Damage to the cerebellar system)
3. Hypokinetic (Parkinsonism Syndrome)
4. Hyperkinetic (chorea, dystonia, tremor, myoclonus)

B. Associated with a combined lesion of several brain systems

1. Spastico-Paretic (ALS)
2. Spastic-atactic (multiple sclerosis)
3. Other combinations

III. Psychogenic dysarthria. This form is more often manifested in the form of pseudo-copying and is accompanied by other psychogenic motor, sensory and psycho-vegetative disorders.

Dysarthria - as an early symptom of neurological diseases

• Ischemia of the brainstem with stenosis of the basilar or vertebral artery
• Amyotrophic lateral sclerosis
• Multiple sclerosis
• Myasthenia gravis
• Spino-cerebellar degeneration
• Syringobulbia
• Progressive paralysis
• Wilson-Konovalov's disease.

Dysarthria as a side effect of drugs (iatrogenic):

• androgens, anabolics
• antipsychotics
• barbiturates
• lithium
• L-dopa
• diphenine
• hexamidine
• cytarabine (a drug for the treatment of cancer)
• cerulean
• kanamycin (antibacterial agent)

Recognition of the cause of dysarthria is mainly carried out taking into account its clinical features and on the basis of the analysis of concomitant subjective (patient complaint) and objective neurological symptoms ("syndromic environment"). Apply tests for the detection of myasthenia gravis, hypokinesia, dystonia; use according to indications EMG, VP, neuroimaging and other methods.

Paroxysmal dysarthria can sometimes be observed with multiple sclerosis.

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