Unilateral Upper Motor Neuron Dysarthria (UUMND) Lecture Vocabulary

A comprehensive set of vocabulary flashcards covering definitions of key anatomical structures, clinical signs, syndromes, speech characteristics, and treatment concepts related to Unilateral Upper Motor Neuron Dysarthria.

Unilateral Upper Motor Neuron Dysarthria (UUMND)

A motor speech disorder resulting from damage to UMN pathways on one side, producing weakness (with possible spasticity or incoordination) that mainly affects articulation, phonation, and prosody.

Upper Motor Neuron (UMN)

Motor pathways (direct and indirect) that originate in the cerebral cortex and synapse on cranial- or spinal-motor nuclei; lesions produce contralateral weakness, spasticity, and other UMN signs.

Lower Motor Neuron (LMN)

Final common pathway neurons (cranial and spinal nerves) that directly innervate muscles; not damaged in isolated UUMND.

Pyramidal (Direct) Activation Pathway

Corticobulbar and corticospinal tracts that transmit voluntary movement commands; unilateral lesions cause weakness and loss of fine, skilled movement.

Extrapyramidal (Indirect) Activation Pathway

Brain-stem pathways that modulate posture, tone, and reflexes; unilateral lesions can yield spasticity, hyperreflexia, and Babinski’s sign.

Contralateral Innervation

Pattern in which most corticobulbar fibers cross to supply cranial nerves on the opposite side, explaining unilateral facial and lingual weakness in UUMND.

Cranial Nerve VII (Facial)

Supplies facial muscles; its lower-face branch receives primarily contralateral UMN input, making it vulnerable to weakness after a unilateral cortical lesion.

Cranial Nerve XII (Hypoglossal)

Innervates tongue muscles; primarily contralaterally driven, so unilateral UMN damage leads to contralateral tongue weakness.

Central Facial Weakness

Unilateral weakness of the lower face caused by UMN (supranuclear) damage, sparing emotional facial movements.

Central Lingual Weakness

Unilateral tongue weakness resulting from UMN damage, distinguished from hypoglossal (LMN) lesions by absence of atrophy or fasciculations.

Articulatory Imprecision

Common UUMND speech symptom characterized by distorted or slurred consonants due to facial and tongue weakness.

Irregular Articulatory Breakdowns

Intermittent, unpredictable distortions during speech, reflecting unilateral weakness or incoordination.

Slow Alternating Motion Rates (AMRs)

Reduced speed in rapid syllable repetition, indicating UMN weakness or spasticity.

Hypernasality

Excessive nasal resonance; mild and infrequent in UUMND because of bilateral innervation to velar muscles.

Spasticity

Velocity-dependent muscle tightness and hypertonia associated with UMN lesions; may give speech a strained or harsh quality.

Incoordination

Ataxia-like timing or force errors sometimes present in UUMND when white-matter pathways are involved.

Stroke (CVA)

Most common etiology of UUMND, especially small unilateral infarcts in the internal capsule, corona radiata, or brain-stem.

Lacunar Infarct

Small, deep cerebral stroke leaving a cavity (lacuna); frequently causes isolated UUMND without cortical signs.

Pure Motor Hemiparesis

Lacunar syndrome with unilateral weakness of face, arm, and leg, often accompanied by dysarthria.

Dysarthria-Clumsy Hand Syndrome

Lacunar syndrome featuring facial weakness, dysarthria, dysphagia, and ipsilateral hand clumsiness.

Pure Dysarthria

Lacunar variant where sudden-onset dysarthria (± facial/lingual weakness) is the main deficit; recovery is usually rapid.

Hemiplegia/Hemiparesis

Paralysis/weakness of one side of the body due to pyramidal tract damage.

Hyporeflexia

Reduced reflex responses that can appear acutely after UMN injury before spasticity develops.

Babinski’s Sign

Pathologic extensor plantar response indicating UMN (pyramidal tract) damage.

Clonus

Rhythmic, involuntary muscular contractions following sudden stretch, linked to UMN lesions.

Decerebrate Posturing

Rigid extension of limbs due to severe brain-stem (extrapyramidal) damage.

Decorticate Posturing

Flexed arm posture with extended legs stemming from damage above the red nucleus.

Alternating Motion Rates (AMRs)

Rapid repetitions of a single syllable (e.g., /pʌ/); used to assess speed and regularity of articulation.

Speech Subsystems

Functional divisions—respiration, phonation, resonance, articulation, prosody—evaluated during dysarthria assessment.

Imprecise Consonants

Primary articulatory error in UUMND arising from unilateral lower-face and tongue weakness.

Reduced Loudness

Soft speech that may accompany UUMND when respiratory drive is decreased or vocal fold closure is weak.

Slow Rate

Overall reduced speech tempo, a prosodic feature that can improve intelligibility in UUMND.

SLOB Strategy

Compensatory cue—Speak Slowly, Speak Loudly, Over-articulate, Breathe—to enhance clarity in dysarthria.

Intelligibility Drills

Structured articulation exercises where the speaker produces words/phrases for listener identification to improve clarity.

Phonetic Placement

Therapy technique that teaches specific articulator positions to achieve accurate consonant production.

Minimal Contrast Drills

Practice pairs differing by one phoneme (e.g., “bat” vs. “pat”) to refine precise articulation.

Alternating-Motion Rate Testing

Oral mech task measuring rapid repetitive syllables to detect slowness or irregularity characteristic of UUMND.

Over-Diagnosis

Risk of labeling spastic or ataxic dysarthrias as UUMND; clinicians must integrate perceptual, physical, and imaging data.

Ataxic Variant of UUMND

Subtype where incoordination predominates despite a unilateral UMN lesion, often involving white-matter pathways.

Spastic Variant of UUMND

Subtype in which strained voice and slow AMRs suggest spasticity even though the lesion is unilateral.

Weakness Variant of UUMND

Common presentation marked mainly by unilateral facial/tongue weakness with mild speech disturbance.

Pseudobulbar Affect

Involuntary emotional expression (crying/laughter) sometimes accompanying bilateral or severe UMN lesions.

Apraxia of Speech (AOS)

Motor-planning disorder often co-occurring with left-hemisphere UUMND, characterized by inconsistent articulatory errors and groping.

Aphasia

Language impairment that may mask or overshadow dysarthria when a unilateral cortical stroke affects language areas.

Aprosodia

Impaired emotional prosody, typically from right-hemisphere damage; can co-occur with right-side UUMND.

Corona Radiata

Fan-shaped white-matter fiber system connecting cortex to internal capsule; common site for small strokes causing UUMND.

Internal Capsule

Compact white-matter tract where corticobulbar and corticospinal fibers converge; unilateral lesions often cause UUMND.

Corticobulbar Tract

UMN pathway from cortex to cranial-nerve nuclei; lesions here produce cranial muscle weakness indicated in UUMND.

Corticospinal Tract

UMN pathway from cortex to spinal motor neurons; unilateral damage yields contralateral limb weakness often accompanying UUMND.

Reticular Formation

Brain-stem network participating in the indirect activation pathway; contributes to tone and reflex control affected by UMN lesions.