Cortical dysarthria

There are quite specific speech disorders that are defined as dysarthria in clinical neurology. One of the varieties of this neurological disorder is the so-called cortical dysarthria. This is not a separate disease, but a speech disorder that manifests itself in organic damage to certain areas of the cerebral cortex. According to ICD-10, cortical dysarthria has the code R47.1, that is, it is classified as class R - symptoms, signs and deviations from the norm not associated with any specific diagnosis.

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Causes cortical dysarthria

The causes of cortical dysarthria (or cortical dysarthria) are pathological disorders of the areas of the cerebral cortex involved in regulating the process of reproducing speech sounds.

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Risk factors

Traumatic brain injury, neoplasia (tumors) of the brain, and infectious diseases such as meningitis, encephalitis, tick-borne borreliosis (Lyme disease), and echinococcosis of the brain can provoke damage to the premotor cortex of the frontal gyrus and cause cortical dysarthria.

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Pathogenesis

The pathogenesis of articulation disorders in this type of dysarthria is associated with a partial loss of neurotransmitter functions in the affected areas of the cortex, which are localized in the inferior frontal lobe of the brain - in the primary motor (premotor) cortex of the inferior frontal gyrus (gyrus frontalis inferior).

These areas, consisting of pyramidal neurons, receive signals from sensory systems and in response to them generate response signals and transmit them via subcortical nerve fibers to the motor neurons of the spinal cord, which ensures the movement of the hands and fingers, as well as all the muscles that provide articulation (sound formation). These muscles include the styloglossus, sublingual, stylohyoid, glossopharyngeal, glossopalatine, genioglossus, mylohyoid, etc.

When the above-mentioned areas of the cerebral cortex are damaged, the innervation of these muscles is disrupted and the mobility of the tongue and lips is limited, making pronunciation of sounds extremely difficult.

Cortical dysarthria is one of the symptoms of acute cerebrovascular accident (ischemic stroke), cerebral hemorrhage (hemorrhagic stroke), Charcot's disease (Lou Gehrig's disease) or amyotrophic lateral sclerosis, Huntington's syndrome (disease), multiple sclerosis, cerebral palsy in children (CP).

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Symptoms cortical dysarthria

The key symptoms of cortical dysarthria are manifested in the pronunciation disorders of most sounds, primarily consonants (labial, lingual, dental, occlusive, fricative, etc.), for the articulation of which the normal functioning of the main mobile articulators - the tongue and lips - is especially important. Frequent omissions or substitutions of sounds occur. As a result, speech becomes difficult to understand for others.

Tempo-rhythmic speech disorders (lack of fluency) are also noted, although its obvious slowing down is evident due to the longer pronunciation (stretching) of some sounds, syllables and whole words. From the outside it seems that the speaker has difficulty moving his tongue and lips, and this is true. The fact is that when the innervation of the muscles involved in the reproduction of sounds is disrupted, their articulatory structure (the correct sequence of movements of the articulation organs) does not have the necessary level of automatism. After all, in the absence of pathologies, this automatism is developed naturally in childhood.

By the way, the first signs of cortical dysarthria are expressed in a slowdown in the rate of speech, the replacement or omission of sounds (upper-tongue, fricative, explosive, hissing), the pronunciation of which requires maximum mobility of the articulatory muscles. And also in a decrease in the level of phonation, which is why the volume of sound decreases and a muffled pronunciation "through the nose" (nasality) appears.

Since disorders in the frontal cortex of the brain affect the functions of neurons responsible for the work of other muscle groups (in particular, the proximal parts of the upper limbs), the speech symptoms of cortical dysarthria are often accompanied by such CNS disorders as paresthesia, spasticity and rigidity of various muscles, and limited mobility. For example, in cerebral palsy in small children (under 1.5-2 years of age) who are not yet speaking, the signs of cortical dysarthria (like any other) are manifested in very low vocal activity. This, of course, complicates the normal development of speech.

For more information on the specific symptoms of cerebral palsy, read - Cerebral Palsy

The consequences of cortical dysarthria affect the general condition of the central nervous system of child patients and cause complications such as significant limitation of vocabulary, decreased attention and ability to remember, impaired writing and reading, motor and psycho-emotional disorders.

In adults, the consequences are often expressed in a depressive state due to problems with communication and a significant decrease in verbal communication.

Diagnostics cortical dysarthria

According to neurologists, diagnosing cortical dysarthria is associated with certain difficulties, and a thorough examination is required to identify the true cause of speech disorders.

In addition to the anamnesis and recording of articulation features (which is carried out with the involvement of a speech therapist), it may be necessary to:

• electroencephalogram (EEG) – to determine the level of nerve conduction and measure the strength and speed of electrical signals from the brain;
• CT or MRI of the brain, head and neck – to identify areas of damage to brain structures and nerve fibers;
• blood and urine tests (they can determine the presence of infection and inflammation);
• spinal puncture (by examining a sample of cerebrospinal fluid, serious infections, diseases of the central nervous system, as well as cancers of the brain or spinal cord can be identified);
• neuropsychological testing (helps to determine the level of cognitive abilities and speech comprehension, as well as reading and writing skills).

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Differential diagnosis

Without all of the above, differential diagnosis of this neurological disorder is impossible.

In children with cerebral palsy (both spastic and hemiparetic forms), it is especially difficult to diagnose cortical dysarthria, since it practically does not occur in its pure form in this disease: in most cases, in addition to pathological changes in the cortex of the frontal lobe of the brain, the cerebellum, structures of the medulla oblongata, fibers of the extrapyramidal system, etc. are insufficiently developed or damaged.

Treatment cortical dysarthria

Organic lesions of the cerebral cortex are in most cases not amenable to treatment, and if they are congenital, then therapeutic methods are completely powerless. In such a situation, the only way is the correction of cortical dysarthria, which is done by a speech therapist.

The main task of speech therapy is to develop the articulatory apparatus. Special exercises for the articulatory muscles and classes on setting the articulatory structure of sounds help to reduce the severity of speech disorders and improve speech skills in mild and moderate cortical dysarthria.

Read also – Speech and language development disorders in children and Post-stroke condition

Forecast

If the clinical picture of a disease includes such a neurological disorder as cortical dysarthria, then, according to experts, the prognosis is not so easy to make: the cerebral cortex is too “serious” an area for unfounded assumptions. Although it is comforting that this type of speech disorder is not fatal, although it is very uncomfortable in terms of adaptation in society.