SLP 516_ Lecture 4

Lecture 4: Flaccid Dysarthria

Definition of Dysarthria

  • Dysarthria is a term for a group of speech disorders stemming from muscle control issues due to neural damage (central or peripheral).

Flaccid Dysarthria

  • A category of motor speech disorders resulting from impairment in cranial or spinal nerves.

  • Causes include problems in nuclei, axons, or neuromuscular junctions affecting the final common pathway (FCP).

  • Manifestations can occur in:

    • Respiratory

    • Phonatory

    • Resonatory

    • Articulatory components of speech.

  • Major characteristics include:

    • Muscle weakness

    • Reduced muscle tone

    • Impact on speed, range, and accuracy of speech.

Common Terminology

  • Neuropathy: Any nerve disease, usually non-inflammatory.

  • Neuritis: Inflammatory nerve disorder.

  • Peripheral Neuropathy: Disorders affecting PNS nerves (motor, sensory, autonomic).

  • Radiculopathy: Disorder involving spinal nerve roots.

  • Plexopathy: PNS involvement at spinal nerve plexuses.

  • Myopathy: Muscle disease, typically affecting proximal muscles.

  • Myelopathy: Pathological condition of the spinal cord.

Definition of Flaccid Dysarthria

  • Results from lower motor neuron impairments in cranial/spinal nerves leading to:

    • Paralysis

    • Weakness

    • Hypotonicity

    • Atrophy of speech-related muscles.

Clinical Features

  • Weakness impacts speech and respiratory musculature leading to:

    • Slow-labored articulation.

    • Hypernasal resonance.

    • Hoarse-breathy vocal quality.

Neurologic Basis

  • Flaccid dysarthria arises from lower motor neuron damage, part of PNS affecting the flow of neural impulses.

Cranial Nerves of Speech Production

  • Six pairs are crucial for speech:

    1. Trigeminal (V)

    2. Facial (VII)

    3. Glossopharyngeal (IX)

    4. Vagus (X)

    5. Accessory (XI)

    6. Hypoglossal (XII)

  • Damage to any of these nerves can lead to distinct speech characteristics.

Cause of Damage

  • Potential damage sources include:

    • Brainstem strokes

    • Tumors

    • Infections

    • Physical injuries

    • Surgical errors.

Specific Cranial Nerve Damage

  • Trigeminal Nerve (V): Critical for lower jaw movement, affects speech when damaged unilaterally or bilaterally.

  • Facial Nerve (VII): Weakness leads to facial drooping, affecting upper/lower face muscles.

  • Glossopharyngeal Nerve (IX): Influences phonation/resonance by affecting pharynx position.

  • Vagus Nerve (X): Damage affects resonance and phonation.

  • Accessory Nerve (XI): Works with vagus to innervate velum, pharynx, larynx.

  • Hypoglossal Nerve (XII): Provides tongue muscle innervation; damage leads to imprecise articulation.

Spinal Nerves

  • Important for motor speech production; the phrenic nerve is vital for respiration.

Causes of Flaccid Dysarthria

  • Conditions damaging lower motor neurons include:

    • Myasthenia gravis

    • Guillain-Barré syndrome

    • Polio.

Assessment Techniques

  • Evaluations for speech characteristics include:

    • Stress tests

    • Kinematic analysis of respiration.

Treatment Approaches

  • Resonance Deficits: Surgical interventions like pharyngeal flaps, prosthetics.

  • Phonation Deficits: Focused therapy on bringing vocal folds together; various exercises to improve phonation.

  • Prosodic Deficits: Exercises for pitch range, stress, and intonational modification.

  • Articulation Remedies: Techniques to enhance phoneme production.

  • Respiratory Weakness Treatments: Maximize respiratory support through proper posture and breath control exercises.