CSDS 172- Final Exam (Section 7)

Site of Lesion for Unilateral Upper Motor Neuron Dysarthrias

Result from damage to either hemisphere.

Site of Lesion for Spastic Dysarthrias

bilateral damage to both the direct activation pathway (corticobulbar or corticospinal tract) as well as the indirect activation pathway (extrapyramidal pathways) from the cortex to brainstem and spinal cord

Site of Lesion for Flaccid Dysarthrias

lower motor neuron lesions of the bulbar muscles, neuromuscular junction, cranial nerves, and anterior horn cells of the brainstem nuclei

Site of Lesion for Hypokinetic Dysarthiras

Lesions in the basal ganglia produce dyskinetic movements

Site of Lesion for Hyperkinetic Dysarthrias

Lesions in the basal ganglia produce dyskinetic movements

Site of Lesion for Ataxic Dysarthrias

lesions on the cerebellum and cerebellar pathways

Site of Lesion for Mixed Dysarthrias

lesions can occur in combinations of of any other five types

Etiology and neurologic characteristics for Unilateral Upper Motor Neuron Dysarthrias

The primary etiology is a unilateral lesion, such as a stroke.

Trauma and tumors can cause injury confined to a single hemisphere

Etiology and neurologic characteristics for Spastic Dysarthrias

Bilateral upper motor neuron damage may result from stroke, head trauma, tumor, infection, degenerative disease, and inflammatory or toxic-metabolic diseases.

There is often bilateral damage to both the direct activation pathway (corticobulbar or corticospinal tract) as well as the indirect activation pathway (extrapyramidal pathways) from the cortex to brainstem and spinal cord.

Damage to the direct activation pathway results in the characteristic loss of skill movement, hypoflexia, a positive Babinski sign, and muscle weakness and loss of tone.

Damage to the indirect activation pathway causes increased muscle tone (spasticity) and hyperactive stretch reflexes.

This hypertonicity and hyperreflexia will dominate if both systems are damaged. Although there is increased tone, the muscles are weak, range of motion is limited, and rate of movement is slow due to the direct activation motor system damage.

Etiology and neurologic characteristics for Flaccid Dysarthrias

Any disease that affects part of the motor unit – the cell body, its axon, the myoneural junction, or the muscle fibers themselves – may cause lower motor neuron symptoms

The cause of the dysarthria may be from viral infections, tumors, trauma to the nerve itself, or a brainstem stroke with involvement of the nerve fibers.

Lower motor neuron damage impairs the final common pathway for muscle contraction. The muscles become hypotonic or flaccid, and reflexes are reduced.

Every type of muscle movement is affected (i.e., voluntary, automatic, and reflexive movement are all impaired).

Note: The involved muscles, especially the tongue muscles, will show fasciculations – tiny spontaneous muscle contractions of the motor unit or muscle fiber innervated by an axon.

The facilitations appear as spontaneous dimplings of the tongue, which may look as though there are tiny moving worms just beneath the surface.

Etiology and neurologic characteristics for Hypokinetic Dysarthrias

In Parkinson’s disease, there are degenerative changes in the substantia nigra (midbrain structures related to motor functions).

This results in a deficiency in a chemical neurotransmitter known as dopamine in the caudate nucleus and putamen.

A tremor may be present at rest that tends to subside on movement, and is absent during sleep.

Rigidity is another common characteristic, and is elicited by passive movement of the limb, which includes involuntary contractions in the muscle being stretched.

Hypokinesia, or reduced amplitude of movement, is a prime characteristic as well.

Dementia is a correlate of Parkinson’s disease, with an incidence between 15 and 40 percent.

Etiology and neurologic characteristics for Hyperkinetic Dysarthrias

huntington’s chorea, related to increase in movement.

The involuntary movement disorder of tremor, chorea, athetosis (involuntary slowing movements of the limbs), and dystonia can result from extrapyramidal damage

Etiology and neurologic characteristics for Ataxic Dysarthrias

Damage to the cerebellum causes a disorder called ataxia, and the motor speech symptoms yield an ataxic dysarthria.

Etiologies include degenerative diseases, stroke, trauma, tumors, alcohol toxicity, drug-induced neurotoxicity, encephalitis, lung cancer, and severe hypothyroidism.

a disruption in the smooth coordination of movements with failure to coordinate sensory data with motor performance.

Rapid alternating movements may be affected.

Equilibrium may be affected, and gait may be impaired.

Muscle tone is hypotonic.

Intention or kinetic tremor (tremor during purposeful movements) is also present.

Etiology and neurologic characteristics for Mixed Dysarthrias

can be a combination of any of the other five types

Speech Characteristics for Unilateral Upper Motor Neuron Dysarthrias

The most prominent deviant characteristic of speech is imprecise articulation.

Other characteristics include harshness, reduced loudness, and hypernasality.

The same speech characteristics pertain as to spastic dysarthria, only less severe.

Speech Characteristics for Spastic Dysarthrias

Speech is characterized by harsh, strain-and- strangle speech, with a slow speaking rate, low pitch (reduced range), and impressively articulated consonants.

Hypernasality is a frequent component of spastic dysarthria.

Speech Characteristics for Flaccid Dysarthrias

Speech is characterized by hypernasal breathy speech (bilaterally vocal fold involvement) with audible inspiration, and imprecisely articulated consonants (often weak lingual contacts).

Monotony of pitch and loudness is a distinctive pattern.

Speech Characteristics for Hypokinetic Dysarthrias

Speech is characterized as is displaying decreased and monotonous loudness and pitch, hypernasality, occasional rushes of syllables, and some imprecisely articulated consonants.

Speech Characteristics for Hyperkinetic Dysarthrias

Speech is characterized by variable rate, excessive variation in loudness and timing, and distorted vowels.

In dystonia, this form of dysarthria can also involve harsh strain-and-strangle speech with imprecisely articulated consonants.

Speech Characteristics for Ataxic Dysarthrias

Speech is characterized by irregular cadence or prosody of speech, with long pauses and sudden explosions of sound, abnormal and sometimes excessively equal stress on specific syllables, and imprecisely articulated consonants.

This pattern is sometimes called scanning speech.

Speech Characteristics for Mixed Dysarthrias

could include a combination of any of the other five types

Common examples of Mixed Dyarthrias

amyotrophic lateral sclerosis: the spastic and flaccid elements coexist

multiple sclerosis: spastic and ataxic characteristics predominate.