Dysarthria is a speech impairment disorder that may present with related symptoms. These possible additional symptoms, including respiratory or swallowing problems, are important factors in the assessment of dysarthria. Manifestation of core symptoms like vocalization impairments provide key information in assessment as well. Both causes and symptoms help create the categorization system for assessment of dysarthria. Since nervous system damage often lays the foundation for this condition, neurological testing should also be considered a primary factor.
Several forms of nervous system impairment may cause damage to the muscles that control speech, leading to dysarthria. An individual might have a congenital birth defect that damages the nerves. Other conditions arise during the critical development years of childhood, such as cerebral palsy. Degenerative disorders, on the other hand, usually occur at some point during adulthood, and constitute a progressive worsening of function. Traumatic injuries, infections, or sudden body deficits like stroke can also impair nerve functioning and cause different types of dysarthria.
The location of the nervous system damage will impact symptom presentation and degree of severity during the assessment of dysarthria. In general, damage to the motor neurons in the brain’s cerebral cortex can inflict the most abnormalities. For example, spastic dysarthria is diagnosed when these central nerve cells are impaired. Symptoms include the following: a strained voice; an inability to vocalize long phrases; consonant mix-ups; and a low-pitched, slow rate of speech. Damage to the lower motor nerve cells that connect to muscles characterizes flaccid dysarthria, which usually results in fewer symptoms.
Motor nerve cell damage may also occur in the brain’s cerebellum or basal ganglia, manifesting as ataxia dysarthria and hypokinetic or hyperkinetic dysarthria, respectively. Damage in either area may create some of the aforementioned symptoms or additional symptoms like incorrect vowel use, unusual tones, or prolonged pauses in speech. While individuals may sustain damage to one area, mixed dysarthrias that impact different areas of the brain and nervous system are perhaps more commonplace in the assessment of dysarthria. Depending on the origin and severity of the damage, individuals may experience occasional speech difficulties or may suffer from long-term, chronic speech abnormalities.
Since the impacted areas of the brain control more actions than speech, other associated conditions may develop alongside the speech difficulties. Afflicted individuals, for example, offer have a nasal quality to the voice. This effect is largely due to impaired respiration. Further, symptoms like a strained voice are often the result of impairment to primary nerves that control swallowing. On a psychological level, depression due to the speech difficulties may present another wrinkle in assessment.
Testing procedures such as the Frenchay Dysarthria Assessment that focus on speech patterns help physicians in the assessment of dysarthria. The physician will gather a speech sample from the patient and closely examine what characteristics are present in the patient’s speech. For example, the physician might note abnormalities in the patient’s vocalizing of small sound units, or phonemes. In addition, a physical examination of the mouth and facial area will be taken, and any aberrations — particularly when the patient is talking — will be noted. Brain imaging tests and blood tests can help uncover the source of the problem.
Considering all of the above factors, physicians will use an assessment to determine what type of therapeutic approach will best suit the patient. A patient’s individual response to these conditions may dictate whether he or she will need long-term treatment and how well the treatment will work. For cases where symptoms are less severe, strengthening speech-related muscles via vocalization repetition therapy can often facilitate improvement. If symptoms are pervasive and damage is located across several areas of the nervous system, then assistive speech devices may be a better option for treating dysarthria.