Anarthria

Speech disorders such as dysarthria and anarthria (ICD-10 code R47.1) are among the speech and voice symptoms and signs of certain diseases and pathological conditions. A speech disorder in which the ability to pronounce something (articulate speech sounds) is completely lost is defined as anarthria, and it is considered the most severe degree of dysarthria.

Epidemiology

According to some estimates, the number of cases of anarthria seen annually worldwide may range from 10,000 to 50,000.

Causes of the anarthria

Dysarthria (articulation disorder) is a motor speech disorder that occurs when there is a lack of coordination or control of the muscles that provide speech functions, so speech becomes slurred. And in the case of anarthria, patients are unable to say anything due to the almost complete loss of motor ability of the speech apparatus (the muscles used for speech). [1]

Causes of anarthria may be due to:

• head trauma;
• ischemic stroke (brain infarction) and associated lesions of the medulla oblongata and the development of Wallenberg-Zakharchenko syndrome - with paresis of the vocal cords and soft palate; [2]
• infectious inflammatory diseases of the brain (meningitis, encephalitis), the complication of which can be paralysis of facial muscles and even central paralysis;
• benign or malignant cerebral neoplasms;
• Lou Gehrig's disease - amyotrophic lateral sclerosis syndrome (type II, juvenile) associated with motor neuron disease (in this case, upper);
• Bilateral lesions of the nuclei of the V, VII, IX, X and XII cranial nerves with the development of bulbar syndrome; [3]
• peripheral paralysis of the facial nerve with bilateral lesions of its trunk - Bell's palsy;
• multiple sclerosis; [4]
• acute demyelinating polyneuropathy - Guillain-Barré syndrome; [5]
• affecting the brain genetic Huntington's disease (Huntington's); [6]
• autoimmune damage to the neuromuscular system in the form of myasthenia gravis (congenital muscle weakness);
• pseudocoma or ventral bridge syndrome - locked-in syndrome;
• Parkinson's disease; [7]
• neurodegeneration with iron accumulation in the brain (neuroferritinopathy, Kufor Rakeb syndrome).

Anarthria in children can be caused by neurological disorders present at birth such as infantile cerebral palsy, muscular dystrophy, ascending hereditary spastic paralysis (with progressive weakness and stiffness of the muscles of the limbs and face as the child grows).

In addition, pronounced phonetic disintegration of speech is seen in children with progressive bulbar paralysis of childhood - a rare hereditary Fazio-Londe disease (resembling myasthenia gravis); with congenital pseudobulbar palsy - Worster-Drowett syndrome or pseudobulbar syndrome. [8]

Risk factors

Numerous risk factors for the development of anarthria are associated with lesions of cranial nerves innervating the muscles of the structures of the speech apparatus, or focal alteration of certain brain regions, which underlie the etiology of the listed diseases and syndromes.

Pathogenesis

Explaining the pathogenesis of the impossibility of verbal communication in case of anarthria, first of all, experts note the presence of neuromuscular problems: impaired innervation of active structures of the speech apparatus (lingual muscles and vocal cords), i.e. Lack of nerve impulse transmission.

Thus, in stroke, as well as traumatic brain injury, brain tumors, multiple sclerosis, and locked man syndrome, anarthria is usually the result of damage to the descending corticobulbar tracts of the Varolian bridge (pons Varolii), a cluster of nerve fibers in the anterior part of the posterior cranial fossa that connects the brain and cerebellum, which are responsible for voluntary motor control of the muscles of the face, head, and neck. Disruption of the integrity of tissues or vessels of this section of the brainstem leads to disconnection of brain mechanisms of speech function, and a person hears, sees, understands everything, but cannot speak.

The mechanism of anarthria and spastic quadriparesis (or quadriplegia) in patients with ischemic stroke may be due to damage to the pyramidal junction (at the junction of the medulla oblongata and spinal cord). Repeated strokes affecting the pars opercularis of the lower frontal lobes of the brain can lead to Foy-Chavany-Marie syndrome with bilateral facial nerve palsy and anarthria.

The pathogenesis of this speech disorder may be related to atrophy of the basal ganglia and cerebellum (with lesions of its legs); focal lesions of the lentiform nucleus, located under the central or insular lobes of the anterior cerebral cortex and regulating the synaptic transmission of nerve impulses. A lesion of the left anterior insular lobe (lobus insularis), which mediates the coordination of muscles involved in articulation and phonation, cannot be ruled out.

Symptoms of the anarthria

The symptoms of anarthria, caused by the complete loss of neural interaction between the various structures of the speech apparatus, are reduced to restricted movements of the tongue, lips and jaw with loss of intelligible speech. Patients understand what is said to them, can read (to themselves), but are unable to voice what they read or verbally express their thoughts.

In many cases, patients have difficulty chewing and swallowing, hypersalivation (salivation), oromotor dyspraxia, involuntary contractions of facial muscles, hoarseness and loss of voice - aphonia with anarthria. In brain injury or stroke, there may be aphasia (problem understanding language) with anarthria.

Types of anarthria, like dysarthria in general, are defined according to the specific sites of brain damage and include flaccid (with damage to cranial nerves or areas of the brainstem and midbrain), spastic (with alteration of upper motor neurons), ataxic (damage to conductive pathways connecting the cerebellum to other cerebral regions), hypokinetic (associated with Parkinson's disease), hyperkinetic (due to damage to the basal ganglia), and mixed varieties.

Complications and consequences

The consequences associated with anarthria are the lack of full-fledged communication, which leads to social isolation of patients, emotional and psychological disorders and the development of deep depression.

Diagnostics of the anarthria

As a rule, the diagnosis of anarthria is made by a speech therapist and a neurologist: the speech therapist determines the type of this speech disorder, and the neurologist determines its underlying cause.

Blood tests are taken for infection, general urinalysis; a lumbar puncture is performed to analyze cerebrospinal fluid.

Instrumental diagnostics include:

• computerized or magnetic resonance imaging (MRI) of the brain;
• ultrasound echoencephalography;
• electroencephalography (EEG);
• Doppler cerebral vascular imaging;
• electromyography (EMG) of the facial muscles.

Differential diagnosis

Very important and, at the same time, difficult differential diagnosis is carried out with other symptomatically similar conditions, such as mutism (mute), motor subcortical aphasia, Landau-Kleffner syndrome, sudden loss of speech and others.

Treatment of the anarthria

As the last stage of dysarthria, anarthria is usually not rehabilitable and its treatment will depend on the type of speech disorder and the underlying disease. For example, treatment paralysis after stroke or surgery to remove a brain tumor.

Read more: Treatment of dysarthria

Along with speech therapy, physiotherapy (physical therapy), various apparatus procedures, medication is also used, and patients may be prescribed Cavinton - to activate cerebral blood circulation; Piracetam, Pantogam and other cerebroprotective drugs - so-called nootropics.

Prevention

In most cases - apart from preparing women for pregnancy or preventing infectious brain diseases - prevention of speech disorders in many diseases and pathological conditions is currently impossible.

Forecast

When speech motor ability is lost, the prognosis will depend on the cause, location and severity of the brain damage, as well as general health. Symptoms may improve, remain the same, or worsen, but many patients with anarthria cannot regain speech.