Motor Speech Disorders (Dysarthria/Apraxia)

Motor Speech Disorders are?

A collection of speech production deficits caused by abnormal functioning of the motor system.

The motor system is part of the nervous system that controls

voluntary movement.

Type of motor disorder dependent on

location and extent of damage to motor system.

Damage to upper motor neurons results in

spasticity (increased muscle tone/stiffness)

Damage to the lower motor neurons (found in cranial and spinal nerves) results in

muscle paralysis or paresis (flaccidity.) 

Dysarthria and Apraxia are not

A language disorder, cognitive disorder, or a result of abnormal anatomical structures, sensory loss, or psychological disturbance.

What is Dysarthria?

Impaired speech production due to disturbances in muscular control of speech mechanism. Any basic process involved in speech can be affected (Including: respiration phonation resonance articulation prosody.)

What are some causes of Dysarthria?

S troke, TBI, Tumor, Bell’s Palsy (CN7), Multiple sclerosis, parkinsons, huntingtons, neuromuscular disease (amyotrophic lateral sclerosis)

Flaccid Dysarthria is often due to

damage to the cranial nerves, spinal nerves, or neuromuscular junction (LMNs)

Flaccid Dysarthria results in

muscle weakness that leads to imprecise consonants, breathy phonation, hypernasality, shallow breath support, and abnormal prosody.

Spastic dysarthria is often due to

Bilateral damage to the UMNs of the pyramidal and extra-pyramidal systems; often caused by brain stem strokes.

Spastic dysarthria can result in

Spasticity and weakness in the speech musculature that results in harsh or strained-strangled phonation, imprecise consonants, hypernasality, and abnormal prosody

Unilateral UMN dysarthria is due to

unilateral damage to UMNs

Unilateral UMN dysarthria results in

Imprecise consonants are the most common characteristic; there may be irregular articulatory breakdowns or harsh vocal quality in some patients

Ataxic dysarthria is due to

Damage to the cerebellum or the neural tracts that connect the cerebellum to the rest of the CNS

Ataxic dysarthria results in

Problems controlling the timing and force of speech movements, resulting in speech that often has a "drunken" quality; imprecise consonants, distorted vowels, irregular articulatory breakdowns, etc.

Hypokinetic dysarthria is due to

A reduction of dopamine in part of the basal ganglia; Parkinsonism is the most common cause of this dysarthria.

Hypokinetic dysarthria results in

A reduction in the range and speed Of speech movements; harsh or breathy phonation imprecise consonants, and abnormal prosody (in some patients, there is increased rate of speech)

Hyperkinetic dysarthria is

Often associated with damage to the basal ganglia but in some conditions the cause is unknown

Hyperkinetic dysarthria results in

Involuntary movements that interfere with normal speech production; unexpected inhalations and exhalations, irregular articulatory breakdown, and abnormal prosody

Mixed dysarthria is due to

Neurological damage that extends to more than one portion of the motor system

Mixed dysarthria results in

Any combination of the characteristics in the six pure dysarthrias

Apraxia of speech is a

Deficit in the ability to plan or smoothly sequence the speech-producing movements of the tongue, lips, jaw and other parts of the speech mechanism

Apraxia of speech may be caused by

any process that damages dominant hemisphere (usually the left), stroke, tumors, surgical trauma, head injury, degenerative disease,

Apraxia of speech affects

Affects articulation and prosody

Apraxia of speech often co-occurs with

aphasias (especially Broca’s)

Apraxia of speech is characterized by

Substitutions and distortions of phonemes. Increased difficulty with harder sounds and sound combinations. Altered rate and prosody. Visible groping. False starts, restarts, trouble initiating, and pauses.

People with Apraxia are often

aware of errors and try to correct.

What aspects of speech may be HARDER for people with apraxia.

Posterior sounds are harder. Sequencing sounds/syllables together are much harder. Unusual or irregular speech tasks (like counting 11-20.)

What aspects of speech may be EASIER for people with apraxia.

Single syllables, Words with repeating sounds, stops, nasals, and glides (the earliest learned sounds), automatic speech.

What is the main differences between Apraxia and Dysarthria?

Apraxia: Difficulty with voluntary programming of movements needed to produce speech (motor sequencing/planning)

Dysarthria: Collection of speech disorders resulting from mechanical or muscular control.

With apraxia, you often see

• Automatic > Volitional speech

• Substitution errors

• Difficulty with initiation groping

• Inconsistent errors

With dysarthria, you often see

• Automatic speech = volitional speech

• Consistent errors