Among the diagnosed speech dysfunctions, which are caused by various neurologic (often neurodegenerative) disorders and manifest themselves in the disturbance of sound reproduction, specialists distinguish pseudobulbar dysarthria.
Epidemiology of pseudobulbar dysarthria: in 85% of cases this type of speech disorder occurs as a result of cerebral ischemic stroke in patients older than 50 years; in young people, the main cause is traumatic brain injury. Among patients with pseudobulbar palsy, 65-90% of women aged 50 to 80 years.
Causes of the pseudobulbar dysarthria
The key causes of pseudobulbar dysarthria are bilateral lesion of nerve fibers of the corticobulbar tract, which conducts signals from motoneurons of the cerebral cortex to the nuclei of the motor cranial nerves (glossopharyngeal, trigeminal, facial, sublingual) located in the bulbar section of the medulla oblongata.
Pseudobulbar dysarthria is a problem of innervation of the muscles of the articulatory apparatus, and its pathogenesis is associated with the slowing or even the arrest of the passage of nerve impulses to these muscles and their paresis (partial paralysis).
In turn, damage to nerve fibers occurs for several reasons - vascular (vascular) nature or related to demyelination of the nerve fiber membrane.
To the vascular reasons for the development of pseudobulbar dysarthria, neurologists include:
- bilateral cerebral infarction (type of ischemic stroke as a result of atherothrombotic or thromboembolic damage of cerebral blood vessels);
- cerebral autosomal dominant arteriopathy with subcortical leukoencephalopathies (CADASIL syndrome), which is recognized as the most common form of hereditary progressive degeneration of cells of smooth muscle fibers of the walls of blood vessels. The pathogenesis of this syndrome is associated with mutations of the Notch 3 gene on the chromosome 19.
The main risk factors for the development of pseudobulbar dysarthria on the background of cerebrovascular disorders, in particular embolic stroke, are high blood pressure, atherosclerosis, infective endocarditis, obesity, elderly age, and men using Sildenafil (Viagra).
Loss of protective envelopes of nerve fibers of myelin - demyelination - is the cause of pseudobulbar dysarthria in multiple sclerosis, X-chromosome of adrenoleukodystrophy, toxic effects of organophosphorus herbicides and insecticides, as well as some neuroleptic drugs.
Pseudobulbar dysarthria can develop due to inflammation (encephalitis, meningitis, neurosyphilis), tumors or brain traumas. This neurologic disorder also occurs with progressive supranuclear paralysis (Steele-Richardson-Olszewski syndrome), whose epidemiology among Europeans does not exceed six people per 100,000 population.
Three times less pseudobulbar dysarthria is manifested as a symptom of incurable motor neuron disorders: sporadic or hereditary amyotrophic lateral sclerosis (when neurons of the motor cortex gradually die due to gene mutations), as well as pseudobulbar paralysis (with degenerative damage to the upper motor neurons). In principle, pseudobulbar syndrome is a clinical condition that, in addition to dysarthria, is manifested by dysphagia (swallowing disorder), increased emetic reflex and lability (variability) of emotional responses.
Symptoms of the pseudobulbar dysarthria
As neurologists note, in many cases, patients with pseudobulbar dysarthria themselves do not notice the first signs of pathology, and their relatives pay attention to the changes in their speech when it becomes muffled.
The following clinical symptoms of pseudobulbar dysarthria are distinguished:
- the rate of speech is abnormally slow, speech is quiet and fuzzy (the spoken word sounds as if a person is trying to "squeeze out" words);
- vocalization nasal (pronounced nasal);
- the tongue is strained (spastic) and rotates poorly in the mouth (but its muscles are not atrophied);
- speech is monotonous, because the total spasticity of the muscles of the larynx does not allow you to vary the pitch;
- spasms of the vocal cords (dysphonia);
- difficulties in the simultaneous movement of the tongue and jaws cause difficulties with chewing and swallowing (dysphagia);
- increased mandibular (mandibular) and pharyngeal reflexes;
- To close the mouth, a certain effort is required, which causes drooling;
- reduced or there is no possibility to control facial muscles of the face (for example, a smile often looks like a grin);
- spontaneous manifestations of abnormal affective behavior, a syndrome of involuntary mourning and / or laughter.
In some cases, disruption of innervation can affect the pyramidal pathways of the passage of nerve impulses, which is manifested in increased tonus of other muscle groups (spastic paresis) or hyperreflexia.
Pseudobulbar dysarthria in children
Pseudobulbar dysarthria in children may be a consequence of idiopathic cerebral neuropathies caused by hereditary dysontogenesis; hereditary globoid-cellular or metachromatic leukodystrophy; leukoencephalitis of Van Bogart; acute encephalomyelitis; secondary post-vaccination encephalitis; caused by gene mutations of Tay-Sachs disease (GM2-gangliosidosis); brain tumors (medulloblastoma, astrocytoma, ependymoma); craniocerebral injuries (including trauma to the cervical spine obtained at birth); juvenile progressive pseudobulbar syndrome. He was included in the list of causes of this type of dysarthria in children and cerebral palsy, although in most cases cerebral cortical lesions, cerebellar lesions, etc., and not specifically nerve fibers of the corticobulbar pathway are observed in cerebral palsy.
The manifestation of pseudobulbar dysarthria can begin in a child with frequent choking and coughing, problems with chewing and swallowing, salivation, mimicry, and later - at the age when children begin to speak - problems with sound reproduction of different degrees of severity are revealed.
Speech therapists recommend that parents pay attention to how actively the children's mimic muscles "work", whether the child can stick out his tongue, tightly cover his lips or pull them out with a "tube", widen his mouth widely, etc. It should also be borne in mind that in children with pseudobulbar dysarthria speech is slowed and incomprehensible, and when a child tries to say something, it is tense and therefore most often silent.
Because of the stiffness of the muscles, the automaticity of articulation is not developed, and such a child speaks poorly even at the age of five or six. Moreover, pseudobulbar dysarthria in children leads not only to the lack of lexical stock sufficient for communication, but also makes it difficult to adequately perceive another's speech. The most severe degree of pseudobulbar dysarthria in childhood is anarthria, that is, complete dysfunction of articulatory muscles.
The intensity of the manifestation of symptoms directly depends on the degree of damage to the nerve fibers of the corticobulbar tract: mild (III), medium (II) or severe (I). If minor articulation disorders appear with a mild degree, then with the progression of the pathology, irreversible consequences and complications occur over time, related not only to the inability to pronounce articulate sounds, but to swallow food.
Domestic speech therapists distinguish such forms of pseudobulbar dysarthria as the spastic form of pseudobulbar dysarthria, paretic, mixed, and with malovyrazhennoy symptomatology determined erased pseudobulbarnaya dysarthria.
Whereas neurologists consider pseudobulbar dysarthria a spastic type of dysarthria, since the defeat of nerve fibers in this pathology is bilateral and leads to an increase in the muscle tone of the extremities and hyperreflexia.
Diagnostics of the pseudobulbar dysarthria
Diagnosis of pseudobulbar dysarthria is carried out during the examination of patients by a neurologist, and the possibilities of the articulatory apparatus (after diagnosis) are evaluated by a speech therapist.
Neurological examination includes examination and collection of anamnesis. There is a set of special tests (on the reflexes of oral automatism), with the help of which the functional usefulness of the motor neurons and the state of innervation of the articulatory musculature are determined. To cause the reflexes characteristic for this type of dysarthria, the doctor touches the lips, teeth, gums, the hard palate, nose, or chin of the patient. According to the patient's response, the expert can assume that dysarthria is pseudobulbarnaya, that is, to clarify the picture of pathology.
Assign general and biochemical blood tests, as well as the study of cerebrospinal fluid (for which an aspiration spinal puncture is performed). Genetic analysis may be appropriate for pseudobulbar dysarthria in children.
Be sure to use all the possibilities that instrumental diagnostics of neurological disorders gives. Electroencephalography (EEG) is used to assess the level of nerve conduction in individual brain structures; To determine the bioelectrical activity of muscle fibers and the level of their innervation, electromyography (EMG) allows.
Speed parameters of the passage of the pulse from motoneurons to the nuclei of motor nerves, and from them to specialists can be established by means of electroneuromyography (ENMG), and detection and visualization of the zones of lesion of conduction nerve fibers is carried out with craniocerebral MRI examination.
Treatment of the pseudobulbar dysarthria
The neurologist and the speech therapist need to be treated as early as possible, since it is possible to correct articulation at a mild to moderate degree of pseudobulbar dysarthria, and with this syndrome in children, to master speech skills with the help of targeted development of articulatory motility. Drug treatment of pseudobulbar dysarthria, which would restore neurons damaged due to gene mutations or autoimmune pathologies and would establish the innervation of the muscles of the articulatory apparatus, is not yet possible.
Correct the pseudobulbarnaya dysarthria in both children and adults (including those who have suffered a stroke) should a graduate doctor-speech therapist. The expert assesses the degree of speech dysfunction in each patient and, individually, in writing, compiles a working program for correcting the pseudobulbar dysarthria.
This is an exercise plan that includes special exercises (for normalizing the tone of the articulatory muscles, setting the breath); correcting the correct background; the development of the articulatory way of sound, etc. In working with children, special attention is paid to the development of vocabulary, the formation of grammatical skills, and the assimilation of norms of usage. This creates a foundation for the development of reading and writing with the start of schooling and preventing such complications as general underdevelopment of speech. Therefore, the active participation of parents in the home fixing of the skills received by the child in classes with a speech therapist is an indispensable condition in the fight against the manifestation of dysarthria.
Obviously, because it is impossible to prevent the cause of this disorder. And the cause depends on the prognosis, which, when the underlying disease progresses, may be disappointing ...
It should be borne in mind that the disability of group I B is given in the case of partially or completely lost speech (aphasia) after strokes, traumas and neoplastic diseases of the brain, as well as in certain mental illnesses. Official information (with a list of pathologies and conditions) is contained in the order of the Ministry of Health of Ukraine No. 561 (September 5, 2011) "On approval of the Instruction on the establishment of disability groups".