Motor Speech Disorders: Anatomy, Signs, and Treatment Strategies

Primary motor cortex

Precentral gyrus — Betz cells

Lower motor neurons (LMNs) for cranial nerves

Brainstem cranial nerve nuclei

Spinal cord anterior horn cells

Classic hallmark sign of an LMN lesion affecting speech muscles

Atrophy and fasciculations in the affected muscles

Characteristic sign of an UMN lesion

Spasticity, hyperreflexia, and Babinski sign

Extrapyramidal (indirect activation) system contribution

Regulation of tone, posture, and reflexive adjustments that support movement

Lower facial weakness affecting the entire ipsilateral face

Ipsilateral LMN lesion (facial nerve nucleus or peripheral nerve)

Contralateral weakness only of the lower quadrant of the face

Contralateral UMN (supranuclear) lesion affecting corticobulbar fibers

• basal ganglia damage

• associated with Parkinson's disease

Hypokinetic dysarthria

Patient presentation with slow, effortful, strained voice

Reduced pitch variability, hypernasality, and slow rate

Spastic dysarthria

Which dysarthria type is most likely?

Respiration, phonation, resonance, articulation, and prosody

Which subsystem(s) of speech are evaluated in a comprehensive motor speech examination?

Isolated reading of a single word list with no connected speech sample or nonspeech tasks

Which of the following is LEAST useful for differential diagnosis of dysarthria?

Hypokinetic dysarthria (Parkinson disease)

Lee Silverman Voice Treatment (LSVT LOUD) is an evidence-based treatment most often used for which motor speech disorder?

Activity and participation

Which ICF domain addresses how a speech impairment affects daily life activities and social roles?

Nonmaleficence

In motor speech counseling, which of the following ethical principles requires that clinicians do no harm and avoid interventions likely to cause damage?

Irregular articulatory breakdowns and prosodic excess (scanning speech)

A hallmark sign of ataxic dysarthria is:

Developmental norms, family involvement, and neuroplasticity considerations

When evaluating a pediatric client with suspected motor speech disorder, clinicians must first consider:

Intention tremor and ataxic gait

A lesion of the cerebellum is most likely to produce which non-speech motor sign?

Bilateral UMN (pyramidal) lesions or bilateral cortical involvement

Pseudobulbar affect (involuntary laughing/crying) is most commonly associated with:

Nasal emission on consonants and hypernasality on vowels

Which clinical measure is most specific for identifying velopharyngeal incompetence during speech?

Assessing language and literacy, family roles, beliefs about disability, and adapting interventions accordingly

Cultural competence in motor speech practice should include:

Muscle atrophy in affected muscles; Breathiness and reduced voice loudness; Fasciculations

Features commonly seen with flaccid dysarthria (select all that apply)

Oral mechanism exam including cranial nerve assessment; Perceptual speech tasks (AMR/SMR, connected speech, reading); Review of medical history and neuroimaging (if available)

Components of a thorough motor speech evaluation include (select all that apply)

Bradykinesia and reduced amplitude of movement; Resting tremor and rigidity; Chorea or dyskinesias

Clinical signs that point toward a basal ganglia (extrapyramidal) disorder include (select all that apply)

Rate control strategies and pacing boards for ataxic dysarthria; LSVT LOUD for hypokinetic dysarthria; Use of AAC when severity prevents functional communication

Evidence-based interventions for motor speech disorders can include (select all that apply)

Forehead involvement spared (suggests UMN); Presence of fasciculations in facial muscles (suggests LMN); Weakness affects both upper and lower face on same side (suggests LMN)

When making a differential diagnosis between UMN and LMN facial weakness, useful clues include (select all that apply)

Obtaining informed consent; Balancing patient autonomy with clinician recommendations; Discussing realistic goals and prognosis with families

Important ethical considerations when working with clients with motor speech disorders include (select all that apply)

Respiration; Phonation; Resonance

The five speech subsystems where signs of dysarthria are observed include (select all that apply)

Stage of grief; Health literacy and cultural beliefs; Providing resources, AAC options, and referrals

Factors that should be considered in counseling families of individuals with motor speech disorders include (select all that apply)

Ipsilateral cranial/spinal nerve motor neuron cell bodies and peripheral nerves terminating in muscle

Final common pathway

Corticospinal / corticobulbar fibers originating in motor cortex for skilled voluntary movement

Direct activation pathway (pyramidal tract) — primary clinical function

Regulation of movement, muscle tone, and involuntary movements (basal ganglia influence)

Indirect activation pathway (extrapyramidal system) — primary clinical function

Brainstem or peripheral nerve nucleus/axon lesion (e.g., CN VII nucleus or nerve) — weakness, atrophy, fasciculations

Flaccid dysarthria — typical lesion location

Bilateral UMN (corticobulbar) lesions — spasticity, slow strained voice, hypernasality

Spastic dysarthria — typical lesion location

Cerebellum (coordination) — irregular articulation, prosodic disturbances

Ataxic dysarthria — typical lesion location

Reduced loudness and monopitch; masked facies (e.g., Parkinsonism)

Hypokinetic dysarthria — common coexisting non-speech sign

Involuntary movements (e.g., chorea, dystonia) and variable articulatory breakdowns

Hyperkinetic dysarthria — common perceptual speech sign

Measurement of respiratory-phonatory support and breath control for speech

Maximum phonation time (MPT) — what it primarily assesses

Family support, communication partner training, or workplace adaptation

An important ICF environmental factor for motor speech treatment

Bilateral corticobulbar damage producing pseudobulbar signs (e.g., severe dysphagia, emotional lability)

A clinical sign suggesting bilateral UMN involvement rather than unilateral UMN

Device/strategies to support participation when natural speech is insufficient

AAC (augmentative and alternative communication) — role in motor speech management