Lecture 10: Cerebellar Disorders and Ataxia Flashcards
What are the main functions of the cerebellum?
- coordinates range, velocity and strength of muscle contractions to produce steady volitional movements and postures
- muscle tone regulation
- equilibrium in conjunction with vestibular system
What is a more cognitive function of cerebellum?
interconnections with pre frontal cortex for non motor functions of memory, cognition, attention and executive functions
Where do the cerebellar peduncles connect to?
dorsal aspect of pons, midbrain, and medulla
peduncles form 4th wall of ventricles
What are the 3 cerebellar peduncles?
- superior- connects to midbrain, carries efferent info from cerebellum
- middle- afferents from contra cerebellum via pontine nuclei
- inferior- connections with medulla, efferent to vestibular nuclei
What are the 3 cerebellar nuclei?
- spinocerebellum
- cerebro-cerebellum
- vestibulocerebellum
What are two functional zones in spinocerebellum?
- fastigal- medial descending systems
- interposed- lateral DS
responsible for motor execution
What is functional zone in cerebro- cerebellum?
denate- areas 4 and 6 (premotor and motor cortex)
for motor planning
What is functional zone for vestibulocerebellum?
vestibular nuclei
for balance and eye movements
What will result from a lesion in the vestibulocerebellum region?
ataxia with vertigo and nystagmus, inability to use vestibular system to control eye movements during head rotation
What portion of the spinocerebellum is the fastigal zone located?
medial zone / vermis
controls posture and muscle tone, upright stance, locomotion
What will happen if there is a lesion in the medial zone/vermis?
poor balance, ataxic gait, falls, hypotonia, ocular motor deficits
What portion of the spinocerebellum is the inter posed zone located?
intermediate zone
controls agonist-antagonist timing in gait and limb movements
What will happen if there is a lesion in the intermediate zone?
ataxic gait, intention tremor, dysdiachokinesia, dysmetria, dysarthria
What is the function of the cerebrocerebellum?
denate nuclei: associated with planning movements, timing of ag and antag, cooridnation of fine finger movements, planning of complex motor actions,
What will happen if there is a lesion in the denate nuclei?
limb dysmetria, decomposition of movement and dysdiacochokinesia
What are the 3 main arteries of the cerebellum?
- SCA- anterior lobe
- PICA- posterior lobe
- AICA- ventral anterior, and posterior lobes, flocculonodular lobe
all arise from vertebro-basilar artery
What branch of cerebellar arteries is an infarct most common?
PICA
What is clinical presentation of cerebellar infarcts?
N/V, vertigo, nystagmus, limb ataxia, unsteady gait, and HA
can cause swelling leading to hydrocephalus
What are some examples of hereditary cerebellar lesions?
spinocerebellar ataxia, Freidrich’s ataxia, episodic, mitochondrial disease, fragile x syndrome
What are examples of acquired cerebellar lesions?
CVA, tumor, arnold chiari, toxicity, MS, trauma/TBI, infection
What is the most common hereditary cerebellar lesion?
Freidrich’s which is the degeneration of spinal cord, peripheral nerves and cerebellum
leads to ataxic gait, then arms and trunk, sensory loss, hyporeflexia and dysarthria
What is age of onset for Friedrich’s?
5-15 years old, wheelchair bound in 10-20 years
may survive into 60-70’s
What side will effects be seen on for cerebellar lesion if lesion is unilateral ?
ipsilateral as they cross at superior peduncle and then cross back at corticospinal and rubrospinal tracts
When will a patient experience a poorer prognosis with cerebellar lesion?
if damage is to cerebellar output pathways are damaged, worse with SC artery, hemorrhagic, degenerative process, extracerebellar damage
What is prognosis for an acute onset lesion such as CVA or trauma?
more severe sx, recovery greatest in first 4 weeks, plateau by 6 months
What are sx of cerebellar ataxia?
dysmetria, dysdia, dyssynergia, tremor
What is sensory ataxia?
impaired motor responses due to absent or insufficient sensory input
What are two types of clinical tests and measures for cerebellar lesions?
non-equilibrium and equilibrium tests
What are some body structure and function areas to test?
dysdia, dysmetria, dyssynergia, intention tremors, postural tremors, hypotonia (due to less excitation of alpha and gamma motor neurons), asthenia (general weakness), dysarthria
What are activities that should be examined?
gait- ataxic gait most common finding in cerebellar lesions
balance, rolling, bed mobility, transfers, stairs
What are two common outcome assessment measures for cerebellar lesions?
ICARS and SARA
