Classifications
of the
Dysarthrias;
Motor Speech Disorders



​Dysarthria is a term used for a group of speech disorders caused by weakness, paralysis, rigidity, spasticity, sensory loss, or incoordination of muscle groups responsible for speech. Dysarthrias are neurogenic speech disorders that can affect any of the following subsystems necessary to produce speech & language
  • Respiration
  • Phonation
  • Resonance
  • Articulation
  • Prosody
All of the following Speech Disorders are caused by a pathology affecting the nervous system. Most neurogenic speech disorders fit into one of the dysarthria types. Meaning that if this speech disorder is diagnosed, the brain is somehow involved, and it's most likely that we, an SLP, can easily figure out where the SOL (Site of Lesion) is occurring based on the symptoms. Site of Lesion can mean a few different things, so don't rush to judgement and automatically think cancer. It just means, refer to the neurologist first if they have not already been and you are suspecting dysarthria. There are seven (7) main types of Dysarthrias.

Flaccid Dysarthria
The patient shows weakness and is usually marked by a droop towards one side of the face (mouth open, drooling, etc).

All of the speech CN's are involved

  • Flaccid Dysarthria. (CN V)
  • Trigeminal, (CN VII)
  • Facial Nerve, (CN IX)
  • Glossopharyngeal ,(CN X)
  • Vagus Nerve and all three of it's branches; In the vagus nerve we worry about VF peresis or paralysis, and respiratory. -Pharyngeal Branch -Superior Laryngeal Nerve Branch -Reccurrent Laryngeal Nerve (RLN)
  • CN XII
  • C3 C4 & C5 of the Cranial Nerves

Neuropathology location: LMN
Speech characteristics: depends upon what CN, SN, muscles are involved (motor, sensory)


Hyperkinetic Dysarthria
  • HYPERkinetic Dysarthria is marked by involuntary movements
  • Orofacial stable at rest and involuntary movements, involuntary jerk single or repetitive movements, jerky movements of the velum, tics, chorea, slower movements and slower involuntary movements as well as Spasmodic Dysphonia.
  • Neuropathology location: extrapyramidal system
  • Speech characteristics: dependent upon site of dyskinesias
  • In terms of voice disorder, we worry about dyskinesias at the level of the vocal folds

Spasmodic dysphonia
Dyskinesias affect the nerves innervating laryngeal muscles causing forceful,inappropriate contractions of muscle groups - Adductor type
-Most severe form of vocal hyperfunction
-VFs are adducted involuntarily at intervals, resulting in hyperadduction (ventricular folds and a-e folds also approximated)
-Results in a harsh voice quality periodically
- Abductor type
-VFs are abducted involuntarily at intervals
-Results in a normal voice with periods of aphonia
- Much rarer
-Mixed
-Some abductor and adductor spasms
-With or without tremor

Essential tremor
- Often confused with Spasmodic Dysphonia, but it is very different.
-May or may not be associated with tremors elsewhere in the body (head, hand, lip, tongue, jaw, soft palate)
-Idiopathic, but aggravated by stress and reduced by alcohol
- Only produced during volitional movement
-Mid-late ages
-Steady fluctuation in pitch and loudness; voice sounds quavery
-More frequent cycle than SD; NOT present at rest
-May accompany SD or in isolation

Spastic Dysarthria
  • Spasticity causing harsh & strained voice.
  • Marked by slow speech as well.
  • Hypernasal


Ataxic Dysarthria
  • This is the drunk sounding dysarthria (slur)
  • Incoordination


Hypokinetic Dysarthria
  • HYPOkinetic Dysarthria is most associated with Parkinsons' Disease characterized by Rigidity, Masked Face, flat, diminished, monotone speech. Speech mirrors movements. Slow shuffled gait.
  • SOL is in the Basal Ganglia.


Apraxia of Speech
  • Automatic speech is fine, prompted speech is difficult - Demonstrates inconsistency
  • Marked by groping and increasing errors with complex language
  • Articulation & Prosody may be different.
  • AOS is often associated with Broca's Aphasia due to it's location in the brain.
  • There is evidence of AOS also diagnosed in a lot of children.