Dysarthria - Etiologies  

-        Due to one or more sensorimotor problems

-        E.g. weakness or paralysis; incoordination; involuntary movements; or excessive, reduced, or variable muscle tone

 

-        Many neurologic illnesses, diseases, and disorders; both acquired and congenital; can cause dysarthria. 

o   Speech gets affected due to effect on:

§  Tone of muscles

§  Range of movement

§  Strength of muscles

 

Congenital (Developmental)	Cerebral palsy, Chiari malformation, congenital suprabulbar palsy, syringomyelia, syringobulbia
	v.s. acquired (e.g. tumor, injury, PD, stroke)
Degenerative diseases	Amyotrophic lateral sclerosis, Parkinson's disease, progressive supranuclear palsy, cerebellar degeneration, corticobasal degeneration, multiple system atrophy, Friedreich's ataxia,Huntington's disease, olivopontocerebellar atrophy, spinocerebellar ataxia, ataxia telangiectasia
Demyelinating and inflammatory diseases	Multiple sclerosis, encephalitis, Guillain-Barré and associated autoimmune syndromes, meningitis, multifocal leukoencephalopathy
Infectious diseases	acquired immune deficiency syndrome (AIDS), Creutzfeldt-Jakob disease, herpes zoster, infectious encephalopathy, central nervous system tuberculosis, poliomyelitis
Neoplastic diseases	CNS tumors; cerebral, cerebellar, or brainstem tumors; paraneoplastic cerebellar degeneration
Other neurologic conditions	Hydrocephalus, Meige syndrome, myoclonic epilepsy, neuroacanthocytosis, radiation necrosis, sarcoidosis, seizure disorder, Tourette's syndrome, Chorea gravidarum
Toxic/metabolic diseases	Alcohol, botulism, carbon monoxide poisoning, central pontine myelinolysis, heavy metal or chemical toxicity, hepatocerebral degeneration, hypothyroidism, hypoxic encephalopathy, lithium toxicity, Wilson's disease
Trauma	traumatic brain injury (TBI), chronic traumatic encephalopathy, neck trauma, neurosurgical/postoperative trauma, skull fracture
Vascular Diseases	Stroke (hemorrhagic or nonhemorrhagic), Moyamoya disease, anoxic or hypoxic encephalopathy, arteriovenous malformations

 

Further Classification of etiologies 

Localization
1.   Focal	Single circumscribed area or contiguous group of structures
2.   Multifocal	More than one area or more than one group of contiguous structures
3.   Diffuse	Roughly symmetric portions of the nervous system bilaterally
Development of symptoms can be…
1.   Acute	Within minutes
2.   Subacute	Within days
3.   Chronic	Within months
Course (evolution after symptoms have developed)
1.     Transient	Symptoms resolve completely after onset
2.     Improving	Severity is reduced but symptoms are not resolved
	e.g. during spontaneous recovery from a stroke or closed head injury
3.     Progressive	Symptoms continue to progress or new symptoms appear
4.     Exacerbating-remitting	Symptoms develop, then resolve or improve, then recur and worsen, and so on
5.     Stationary/ Chronic	Symptoms remain unchanged for an extended period of time
	e.g. cerebral palsy in adults; patients who have reached a plateau after a stroke

 

Non-Progressive
Stroke		Concomitant language and cognitive impairments
		Type and severity related to site and size of lesion
TBI		Concomitant language and cognitive impairments
		Type and severity related to site and size of lesion
		Typically mixed dysarthria
Progressive
Parkinsonism
		Classification: -        Primary (Parkinson’s disease) -        Secondary – (identifiable causal agent) o    E.g. Toxins, drugs, infection, repeated trauma or strokes
		90% shows hypokinetic dysarthria
Hereditary Disease	Wilson’s Disease	Copper builds up, particularly affects brain and liver
		Mixed dysarthria
	Friedreich’s ataxia	Spinocerebellar
		Associated with ataxic dysarthria
	Hungtington’s Disease	Striatum (subcortical, forms major input to basal gangli)
		Associated with hyperkinetic dysarthria, chorea
Dystonias (due to basal ganglia disorder)		involuntary muscle contractions that cause slow repetitive movements or abnormal postures
		Hyperkinetic dysarthria
Motor Neuron Disease	Amyotrophic Lateral Sclerosis	Mixed spastic-flaccid dysarthria
	Progressive bulbar palsy	Flaccid dysarthria
Demyelinating Disease	Multiple Sclerosis	Plaques (lesion) predominately in white matter of CNS
		Optic nerves, brainstem, cerebellum, spinal cord
		Mixed dysarthria
	Guillain Barre	Autoimmune disease attacking PNS
		weakness tingling ... paralysis
		Flaccid dysarthria

References:

Duffy, J. R. (2020). Motor speech disorders: Substrates, differential diagnosis, and management (4^th ed.). St. Louis, MO: Elsevier Mosby.