Spastic Dysarthria

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Speech: the motor act of verbal expression

The Five Subsystems of Speech:

1. Respiration

2. Phonation

3. Resonance

4. Articulation

5. Prosody

Dysarthria - Defining Characteristics

It is a group of speech disorders caused by disturbances of neuromuscular control of the speech production systems

A disruption to the execution of speech movements

It can result from underlying neuromuscular disturbances to muscle tone, reflexes and kinematic aspects of movement, such as speed, range, accuracy and steadiness

Generally more consistent in its errors and amount of intelligibility compared to apraxic speech

Seven Types of Dysarthria

Spastic Dysarthria

Flaccid Dysarthria

Hypokinetic Dysarthria

Hyperkinetic Dysarthria

Ataxic Dysarthria

Unilateral UMN Dysarthria

Mixed Dysarthrias

Assessment Methods

Perceptual: listening; audio visual and tactile

Acoustic: measurement of speech

Physiologic: measurement of physiological processes (electrical measurement)

SPASTIC DYSARTHRIA

Quick Overview:

associated with bilateral damage that affects the UMN - direct and indirect activation pathways of the CNS

this means the PYRAMIDAL and EXTRAPYRAMIDAL motor pathways

Px has increased muscle tone (spasticity)

Weakness

Reduced speed and range and force of movements

Hyperreflexes

Can be a result of bilateral lesions in the motor cortex and its pathway to the LMN that are responsible for muscle contraction

Pyramidal Descending Motor Pathway

Motor impulses at the cortical level

Corticospinal and corticobulbar tract

Controls speech movements, which are discrete and skilled movements

Works at a conscious level - voluntary movements

Direct Pathway - this is because its axons descend without synapsing from the pyramidal neurones to the spinal cord

Large neurons with long axons that project into the spinal cord

Control the precise or skilled voluntary movements of our skeletal muscles

If damaged:

Leads to weakness and slowness of movements

Further info:

the pyramidal cells that control foot movements are in one place and those that control hand movements are in another

Extrapyramidal Descending Motor Pathway

Motor impulses in the cerebral cortex

Rubrospinal, reticulospinal, vestibulospinal and tectospinal tract

These pathways are involved in:

Maintaining posture

Regulation of reflexes

Monitoring muscle tone

More unconscious and therefore involuntary motor control

Indirect Pathway - this is because they project to influence the activity of most extrapyramidal nuclei

Involved in:

maintaining balance and posture

controlling coarse limb movement

head, neck and eye movements that follow objects in the visual field

If damaged:

Weakness of movements

Spasticity

Abnormal reflex movements

Presentation

May affect one or a combination of:

Respiration

Phonation

Resonance

Articulation

Prosody

Diagnosis of spastic dysarthria = bilateral damage to UMN

Unilateral UMN damage = Upper Motor Neuron Dysarthria - generally less severe due to bilateral CN innervation

THEREFORE:

Result of combined effects of:

Bilateral damage to pyramidal motor tracts

Bilateral damage to extrapyramidal motor tracts

THIS THEN LEADS TO:

Weakness

Slowness

Spasticity

Abnormal reflexes

AETIOLOGIES

Those conditions that can impede the function of UMN of DESCENDING pathways BILATERALLY

These include:

Degenerative conditions (MND, MSA etc)

Degenerative causes make up the largest group

Spastic dysarthria may be evident if degeneration begins in the UMN

Vascular (CVA, anoxia)

CVA need to be at brainstem to cause bilateral damage, multiple CVA in both hemispheres or one CVA in one hemisphere plus pre-existing condition in other hemisphere

Vascular dementia can also cause spastic dysarthria

Idiopathic causes

Congential

Traumatic (TBI)

Demyelinating Conditions (MS)

CLINICAL CHARACTERISTICS

The weakness and spasticity we can see in the Px speech may also present elsewhere in the body

Keep in mind their gag reflex might be hypersensitive, but this is generally a redundant procedure

Babinski Reflex - this may reappear even though previously diminished. Px toes may curl up if bilateral damage

Jaw Jerk Reflex - this is only carried out on Px suspected of having neurological damage and is an indicator of spastic dysarthria

DYSPHAGIA

may be present

Px may be able to swallow food, but chewing may take a long time

Due to reduced swallowing frequency and control over saliva secretion, there may be drooling

LABILITY

Px may be emotionally labile

Excessive and uncontrollable laughter or crying

CLONUS

Shivering or rapid tremor-like appearance

ORO-MOTOR

Slow movements

Symmetrical appearance of structures

IMPACT ON SPEECH

According to Duffy, spastic dysarthria will most likely impact all speech systems, as it is associated with impaired patterns of movement that use muscle groups and not just individual muscles

DAB - MOST COMMON CHARACTERISTICS

Imprecise consonants

Monopitch

Reduced stress

Harsh voice quality

Monoloudness

Low pitch

Slow rate

Hypernasality

Strained-strangled voice quality

Short phrases

Distorted vowels

Pitch breaks

Breathy voice

Excess and equal stress

REMEMBER: You can't rely on the presence of one of these features to make a differential diagnosis; look for clusters or patterns of features

CLUSTERS

CLUSTER ONE: PROSODIC EXCESS

Result of slowness of repetitive movements that are associated with speech

Evident when there is:

Excess and equal stress

Slow rate of speech

CLUSTER TWO: ARTICULATORY-RESONATORY INCOMPETENCE

Result of the decreased range and force of movement by the articulators

Evident when there is:

Imprecise consonants

Distorted vowels

Hypernasality

CLUSTER THREE: PROSODIC INSUFFICIENCY

It is the reduced ability to vary the patterns of movement (in speech)

This is apparent through:

Monopitch

Monoloudness

Reduced stress

Short phrases

CLUSTER FOUR: PHONATORY STENOSIS

When there is over-adduction of the vocal chords as as result of spasticity

This is apparent due to:

low pitch

harshness

strained-strangled voice

pitch breaks

short phrases

slow rate

IMPACT ON THE SPEAKER

PERSONAL IDENTITY

Somebody who has had a bilateral stroke may also have cognitive deficits, therefore they may be unaware of their limitations

WHAT THE PATIENT MIGHT TELL YOU ABOUT THEIR SPEECH

Speech might be slow or effortful

Speaking against resistance

Speech will deteriorate when patient becomes fatigued

May need to speak slower

Speech may be nasalised

Swallowing difficulties and drooling

Emotional lability

INTRO

SPASTIC DYSARTHRIA

SPASTIC DYSARTHRIA - CHARACTERISTICS