Hypokinetic Dysarthria: Overview
Associated with BG control circuit pathology.
Can manifest in any/all levels of speech production, but is most evident in voice, articulation, and prosody.
Decreased ROM is a significant contributor
Reflects problems of motor control such as preparation, maintenance, and switching of motor problems.
Hypokinesia = reduced movement
Hypokinetic Dysarthria: Characteristics
Reflects the effects of:
- Rigidity
- Reduced force
- ROM
- Slow individual but sometimes fast repetitive movements of speech
Clinical Characteristics of BG Control Circuit Disorders Associated with Hypokinetic Dysarthria
- Parkinsonism
- Bradykinesia
- Rigidity characterized by slowness of movement and stiffness (apparent during passive stretch on muscles)
- Posture characterized by involuntary flexion of the head, trunk, arms.
- With hypokinesia: reduced ROM, reduced use of affected body part, reduction of habitual movements.
- Masked/expressionelss facial expression
- Arm swing when walking
- Sweating
- Micrographic writing
- Cognitive decline, anxiety, depression
Parkinsonism
Most common cause of hypokinetic dysarthria
Classic signs include:
- Tremor at rest (static or resting)
- Rigidity
- Bradykinesia
- Loss of postural reflexes
Tremor in parkinsonism tends to occur when the body part is relaxed and decreases during voluntary movement; most apparent in limbs.
Sweating
Bradykinesia
Prominent in BG disorders, it reflects problems with movement planning, initiation, and execution.
Etiologies
Any process that interferes with BG control circuit functions can cause hypokinetic dysarthria.
- Degenerative
- Vascular
- Traumatic
- Infectious
- Inflammatory
- Neoplastic
- Toxic-Metabolic Disease
Parkinson’s Disease
A degenerative disease that is the most common neurologic movement disorder
Late adulthood onset
Dysarthria appears several years after other symptoms, but presents in 90% of cases and precedes dysphagia (which occurs in 40%)
Parkinson’s Disease: Characteristics
- Affects speech and voice
- Hypokinetic dysarthria
- Decreased loudness
- Monotone
- Vocal tremor
- Hoarseness
- Rapid rate of speech
Vascular Conditions
The following can be associated with parkinsonism and hypokinetic dysarthria:
- Diffuse frontal lobe white matter lesions
- BG vascular lesions
- Midbrain and bilateral thalamic strokes (sometimes)
Cerebral Hyponoxia can also produce parkinsonian symptoms.
Toxic/Metabolic Conditions
The following can cause parkinsonism:
- Certain drugs that block dopamine receptors
- Heavy exposure to metals or chemicals
- Alcohol withdrawal (temporary Parkinsonism)
- Acquired metabolic disorders including liver failure can damage the BG.
- Wilson’s Disease
Trauma
TBI can cause bradykinesia, rigidity, tremor, etc.
Repeated head trauma can damage the substantia nigra, which over time can lead to parkinsonism-like motor abnormalities such as dementia and hypokinetic dysarthria.
Infectious Conditions
- Influenza
- Japanese Encephalitis B
- West Nile
Other Causes
Normal pressure hydrocephalus and obstructive hydrocephalus
Patient Perceptions and Complaints
- Others say their voice is weak or quiet
- Rate is too fast or indistinct productions
- Hard to initiate speech
- Drooling and swallowing complaints
Non-Speech Oral Mech
- Reduced blink frequency
- Unsmiling/masked face
- Tremor of jaw or lips
- Tremor of tongue at rest or on protrusion
- Tight or immobile lips
- Non-speech AMRs may be slowly initiated, rapid, and restricted in range.
- 40-80% presence of dysphagia
Speech
Conversation, reading, AMRs, and vowel prolongation are most useful tasks.
AMRs offer insight into ROM and rate abnormalities.
Vowel prolongation useful for isolating phonatory characteristics, especially those associated with loudness and quality.
Speech Characteristics
- Flat, attentuated, sometimes accelerated speech pattern.
- Monopitch
- Monoloudness
- Reduced contrastivity
- Reduced stress
- Short phrases
- Variable rate
- Imprecise articulation
- Reduced loudness
- Inappropriate silences
- Breathy dysphonia
- Short rushes of speech
