Cerebellar Ataxia Flashcards
Ataxia: definition
“lesions affecting the cerebellum would result in a disorder of movement coordination”
Term used to describe a number of abnormal mvmts that may occur during the execution on voluntary mvmts including:
- Incoordination.
- Delay in mvmvts.
- Dysmetria: inaccuracy in achieving target.
- Dysdiadochokinesia: inability to perform mvmts of constant force and rhythm.
- Tremor.
Role of the cerebellum in adaptation and motor learning
> Initiation and control of voluntary mvmt.
Timing of mvmt/muscle action.
Moment-to-moment correction of errors.
Compensating for lesions of the cerebral cortex.
Motor learning and adaptive adjustments.
Aetiology
Lesions of the cerebellum may result from:
- Developmental abnormality: hydrocephalus or hypoxia at birth.
- Traumatic brain injury (most common causative factor)
- Stroke
- Tumour or other space occupying lesion
- Infection: encephalitis
- Demyelinating disease: multiple esclerosis
- Familiar or hereditary disease: Friedreich’s ataxia
- Degenerative disease
- Metabolic disease: myxoedema, Wilson’s disease
- Vascular disease: vertebrovasilar artery insufficiency
- Drug and alcohol intoxications
Clinical signs
> Dysmetria: inaccurate amplitude of mvmt and misplaced force and reflects the impairment in timing of muscle force typical of cerebellar ataxia.
> Dyssynergia: AKA decomposition of mvmt. Lack of coordination between agonist, antagonist and other synergic muscles resulting in an absence of the normally smooth, sequential performance of various components of an action. Heel-to-shin test.
> Dysdiadochokinesia: difficulty performing rapid alternating mvmts. The mvmts are performed clumsily and slowly. Test for rapid alternating mvmts (pronation/supination)
> Rebound phenomenon: dysfunction in the agonist-antagonist relationship, specifically the problem with breaking of mvmt.
> Tremor: oscillatory mvmt about a joint due to alternating contractions of agonists and antagonists. Finger-to-nose test.
> Hypotonia: diminished resistance to passive mvmt. Pendular test (unable to differentiate between normal and cerebellar affected patients).
> Dysarthria: disorder of speech in which mechanical aspects of speech are impaired. Speech is slurred and slow with prolonged syllables.
> Nystagmus: seesaw rhythmical mvmts of the eyes.
Specific objectives to be achieved within the context of individual actions
> To improve performance of fx mvmts and develop skill, specifically during actions such as standing up, sitting down, walking (including stairs and hills) and reaching to take an object.
> To set up a practice environment which enables the person to develop more control (accuracy) during practice by varying support conditions, timing constraints and/or environmental context.
