Cerebellar Anatomy and Disorders Flashcards
Cerebellar anatomy and disorders
T or F: Cerebellum contains more neurons than any other brain region
True! And it integrates info to performs complex computations
How can you damage the cerebellum
TBI Stroke Tumor Degenerative Disease Congenital malformation
Where is info transmitted to/from the cerebellum?
Via axons in the cerebellar peduncles (Superior, Middle, and Inferior)
What contributes to the large SA of the cerebellum?
The in-folding to create the gyri and sulci
What is the role of the Perkinje cell?
To take many inputs and consolidate it to one output to the deep nuclei
How many cell types are found in the cerebellum
8 cells constructed in a uniform manner
What are the lobes of the cerebellum (per cathy)
Anterior
Posterior
Flocculonodular Lobe
What are the deep nuclei of the cerebellum
Vestibular nuclei
Fastigial Nucleus
Interposed Nucleus
Dentate Nucleus
What region(s) of the cerebellum is the vestibulocerebellum associated with?
Flocculonodular lobe
What region(s) of the cerebellum is the spinocerebellum associated with?
Primarily the vermis and some intermediate (paravermal)
What region(s) of the cerebellum is the neocerebellum associated with?
Lateral zone//Outside (cerebellar hemisphere)
What is the function of the vestibulocerebellum
- Coord. of eye-head mvmts
- Equib and balance
- Axial mvmts & prox. joints for posture, equib. and balance
What are the inputs to the vestibulocerebellum
Vestibular apparatus –> Vestibular nuclei –> Flocculonodular lobe
What are the outputs from the vestibulocerebellum
Vestibular nuclei –> M&L Vestibulospinal tract (VST)
What are the inputs to the spinocerebellar vermal region
Dorsal spinocerebellar, cuneocerebellar and trigeminocerebellar tracts (from trunk and head)
Vestibular nuclei
Tectospinocerebellar tract (Vis and aud from superior and inferior colliculi)
What are the outputs from the spinocerebellar vermal region
GROSS MOTOR TRACTS!!!!!!!
a) CMRST (corticomedullary reticulospinal tract)
b) L & M Vestibulospinal tract
c) Anterior CST
What are the functions of the spinocerebellar vermal region
GROSS MOTOR MOVEMENTS
- coord of axial and girdle musc.
- CPG of Walking
- t of locomotor mvmt
- Interlimb coord during locomotion
What are the inputs to the spinocerebellar intermediate zone
Dorsal spinocerebellar and cuneocerebellar from the U/LEs
What are the outputs from the spinocerebellar intermediate zone
FINE MOTOR TRACTS!!
- Rubrospinal tract
- Lateral CST
- CPRST (Corticopontine reticulospinal tract)
What tracts are associated w/gross motor movements?
Vestibulospinal tract
Anterior CST
CMRST (Corticomedullary reticulospinal tract)
What tracts are associated w/fine motor movements?
Rubrospinal tract
Lateral CST
CPRST (Corticopontine reticulospinal tract)
What is the function of the spinocerebellar intermediate zone?
Coord of distal musc of the extremities (hands and feet)
What are the inputs to the neocerebellum
Cerebral cortex (motor, sensory, PMA) –> Pontine nuclei –> neo
What are the outputs from the neocerebellum
Dentate nucleus –> VL nuc Thal –> PMA and MI of cerebral cortex
What are the functions of the neocerebellum
- Planning and timing of IPSI vol mvmts
- Motor plan of sequential mvmts/progression
- Onset, duration, amplitude and rate of mm contraction
What part of the cerebellum is responsible for a triphasic EMG of a single joint movement
Neocerebellum
Overtime, what occurs with a triphasic movement
The AG2 disappears after practice
What occurs in a triphasic mvmt?
AG stimulated, followed by antagonistic correction, followed by second AG2 burst
What two parts of the cerebellum function as a comparator?
Spino and neocerebellum
What is a comparator?
It compares the ACTUAL outcomes of the motor program with the INTENDED motor program via simultaneous dispersal of info from cortex to cerebellum and mm and then CORRECTS the movement
How long does it take for a correction to occur for the comparators?
100-200 ms for the spino and neocerebellum to do the job
What two areas of the cerebellum are responsible for mm tone?
Vestibulo and spinocerebellum
How do the vestibulo and spinocerebellum influence mm tone
They excite the gamma motor neurons, so if they are damaged, it leads to hypotonicity
What does hypotonicity from the cerebellum present as
Reduced extensor tone making it difficult to remain upright against gravity; reduced firmness, reduced tone in PROM
What is asthenia
A cerebellar dysfunction characterized by generalized weakness or decreased activity and easily fatigued
What are intention tremors
A cerebellar dysfunction characterized by 3-5 Hz frequency tremors whose amplitude increase as the effector approaches the target
What sort of disturbances of posture and balance are seen w/cerebellar dysfunction
- Flexed posture w/wide BOS,
- Poor equib and bal esp proximally & during rapid changes in body position or direction of mvmt
What is dysmetria
A cerebellar dysfunction characterized by the impaired ability to properly scale movement distance in a 3D world
What is dysdiadochokinesia
A cerebellar dysfunction characterized by a deficit in coordination b/t agonist-antagonist mm during rapid alternating mvmts resulting in errors in Amplitude and timing
What is an ataxic gait
Disruption in rhythm of gait, W/ wide BOS, unsteady –> Fall bwkd and to side of lesion
What is movement decomposition
A cerebellar dysfunction characterized by disrupted sequences in a multi-step task (break down into series of mvmts)
What eye mvmts are present w/cerebellar dysfunction
- Gaze-evoked nystagmus
- Ocular dysmetria w/saccades
- disrupted smooth pursuit
- Poor coord of eye-head mvmts
What occurs w/speech and mm of speech w/cerebellar dysfunction
Dysathria
- Poor coordination
- Explosive, staccato speech
What happens w/the time-velocity rln as cerebellar dysfunction progresses
Mild: Short acceleration, long deceleration
More severe: Long acceleration, short deceleartion
What happens w/Forces and F production w/cerebellar dysfunction
Delays in production and in force maintenance, indicating the cerebellum plays a role in maintaining a constant force
List 12 dysfunctions seen in the cerebellum
1 - Hypotonicity 2 - Asthenia 3 - Intention tremors 4 - Disturbances of posture and balance 5 - Dysmetria 6 - Dysdiadochokinesia 7 - Ataxic gait 8 - Mvmt decomposition 9 - Poor coord. of speech mm 10 - Eye mvmts 11 - assym t-v profiles 12 - Force production
What are the 3 main neuropathologies of the cerebellum
Fredreich’s ataxia
Stroke
Tumors
What % of strokes occur in the cerebellar artery
<5%
What is the best predictor of recovery post-CVA of the cerebellum
If the deep nuclei are NOT involved - if involved = poorer outcome
Which portion of the population has tumors in the cerebellum most?
Is this the same as the portion of the population that has the better prognosis?
Children
Children have greater prognosis than adults
What is the etiology of Fredreich’s Ataxia
It is an autosomal recessive hereditary disease
What is impacted in Fredreich’s ataxia? (Lesion)
CEREBELLUM DRG Dorsal Column Spinocerebellar tracts (unconscious prop.) Some CST involv.
What is unconscious proprioception?
Proprioceptive information that does not go to the cortex
What is the onset of Freidreich’s Ataxia?
5-15 yo
What is the course and prognosis of Freidreich’s Ataxia?
Lose ability to walk and confined to WC 10-20 yr post onset w/survival into 60s & 70s (if no heart attack)
What are the S/S of Freidreich’s Ataxia
Main:
- *ATAXIA (gait first, arms, then trunk)
- *Heart disease
other:
- Clumsiness and intention tremor
- MM weakness and loss of sensation in extremities
- Decreased DTRs
- Easily Fatigued
What region of the cerebellum is associated w/the Fastigial nucleus?
The output from the spinocerebellar vermal region goes to the fastigial nucleus THEN to CMRST
What region of the cerebellum is associated w/the Interposed nuclei?
The output from the spinocerebellar intermediate region goes to the interposed nucleus then to the Rubrospinal tract
What areas of the cerebellum are associated w/the vestibular nuclei?
Vestibulocerebellum (input and output) and the Spinocerebellar vermal region (input and output)
