Cerebellar Dysarthria

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Cerebellar Dysarthria is a distinct speech disorder that specifically involves muscle weakness. Speech may be slow, slurred, and require more effort. Dysarthria differs from aphasia because dysarthria is a motor disorder and aphasia is a language disorder. It is possible to be affected by a combination of types (Flaccid & Ataxic) so Superficial Siderosis patients should consult with a speech and language specialist.

There are five identified types.

  • Flaccid dysarthria is caused by the dysfunction of cranial nerves and areas in the brain stem and midbrain.
  • Ataxic dysarthria comes from damaged pathways connecting the cerebellum to other areas in the brain.
  • Hypo-kinetic dysarthria is Parkinson’s disease,related
  • Hyper-kinetic from damage of the basal ganglia.
  • Spastic dysarthria from damage of motor regions in the cortex.

Flaccid Dysarthria

Difficulty in the pronunciation of words is attributed to the neurologic dysfunction of the nerves that control the facial muscles, tongue, lips, and throat. It presents as a slurring of words or speaking slowly. If nerve palsies are also involved you may also have trouble controlling the muscles in your mouth and face. Patients who exhibit flaccid dysarthria will have difficulties pronouncing consonants. The dysfunction of your peripheral nervous system is disrupting the flow between the cranial nerves and brain stem.

  • Trigeminal nerve (fifth cranial) supplies nerve function to the chewing muscles
  • Facial nerve (seventh cranial) control facial muscles
  • Hypoglossal nerve (twelfth cranial) controls the tongue
cranial nerves dysarthria

Ataxic Dysarthria

Ataxic dysarthria is a sensorimotor speech disorder occurring when the areas of the cerebellum which controls movement and receives sensory input becomes damaged. The role of the cerebellum  in feed-forward processing has been linked to speech motor control.1
Neuroimaging studies led researchers Kristie Spencer and Dana Slocomb, Department of Speech and Hearing Sciences, University of Washington, Seattle, established two cerebellar cortical regions are responsible for the feedforward motor commands for speech: the anterior paravermal and superior lateral areas. Previously ataxic dysarthria had been classified as a disorder of motor execution, focusing on uncoordinated and hypotonic muscles.²
Motor nerve difficulties clearly contribute to ataxic dysarthria but this doesn’t address the processing abnormalities controlled by the cerebellum that take place during the planning phase of speech.

 

 

 

Updated: November 5, 2020
Sources: Superficial siderosis is a rare neurologic disease characterized by progressive sensorineural hearing loss, cerebellar ataxia, pyramidal signs, and neuroimaging findings revealing hemosiderin deposits in the spinal and cranial leptomeninges and subpial layer. The disease progresses slowly, and patients may present with mild cognitive impairment, nystagmus, dysmetria, spasticity, dysdiadochokinesia, dysarthria, hyperreflexia, and Babinski signs. Additional features reported include dementia, urinary incontinence, anosmia, ageusia, and anisocoria. Superficial siderosis MedGen UID: 831707 •Concept ID: CN226971 •Finding Orphanet: ORPHA247245
¹Spencer, K.A. & Slocomb, D.L. Cerebellum (2007) 6: 58. https://doi.org/10.1080/14734220601145459
²Yorkston KM, Beukelman DR, Strand EA, Bell KA. Management of motor speech disorders in children and adults. 2nd ed. Austin: PRO-ED, Inc.; 1999.
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