Cerebellar Pathways, Function, and Dysfunction

Question 1

For the paravermis region of the spinocerebellum, name the: Inputs, deep nuclei, outputs, and functions.

Answer 1

Inputs: Spinal afferents
Deep nuclei: Interposed nuclei
Outputs: Lateral descending system
Function: Smoothing/correction of limb movement

Question 2

For the vermis region of the spinocerebellum, name the: Inputs, deep nuclei, outputs, and functions

Answer 2

Inputs: Spinal afferents, and facial/visual/auditory/vestibular inputs
Deep nuclei: Fastigial nuclei.
Outputs: Medial descending systems
Function: Smoothing/correction of axial movements

Question 3

What are the inputs to the corticopontine cerebellum (aka cerebrocerebellum)? Deep nuclei? Outputs?

Answer 3

Cortical afferents (Frontal pontine and POTpontine).
Dentate nuclei.
Sends info to motor and premotor cortex

Question 4

What are the outputs of the vestibulocerebellum? Functions

Answer 4

Vestibulospinal, MLF (for eye movements)

Posture, balance, and coordination of head and eye movements.

Question 5

Where do the two inputs to the cerebrocerebellum first synapse?
Where do their axons cross the midline?
Through which peduncle do they enter the cerebellum

Answer 5

Frontopontine and Parietal-Occipital-Temporal(POT)pontine fibers both synapse in the pontine nuclei.
They cross immediately in the crossing fibers of the pons.
They enter the cerebellum through the MCP.

Question 6

Does ataxia involve weakness or involuntary movement?

Answer 6

Nope.

Question 7

What will a midline cerebellar lesion lead to?

Answer 7

Truncal and proximal limb dysfunction.

Question 8

What is titubation?

Answer 8

Aka. truncal ataxia. When person trying to sit still, trunk shakes all over due to lots of overcorrections to maintain posture (it’s like oversteering a car)

Question 9

For our purposes dysmetria and intention tremor are the same… but what is the difference?

Answer 9

Dysmetria: Initiation of a complex movement is delayed, muscles at different joints are often desynchronized, pathy is erratic and jerky.
Intention tremor: oscillations from over-correcting for error when

Question 10

What is dysdiadochokinesis?

Answer 10

Problems with rapidly alternating movements.

Question 11

What is nystagmus?

Answer 11

Jerky eye movments,

Question 12

“Gaze-evoked” nystagmus vs. “occular dysmetria”?

Answer 12

“Gaze evoked” when moving eyes horizontally. Occular dysmetria occurs when trying to fixate on still object. Eyes overshoot, then oscillate until obtaining fixation.

Question 13

What is ataxic dysarthria? How do you test for it?

Answer 13

Disruption of metrical nature of speech. Can’t say “ka-ka-ka-ka-ka” etc. at constant rhythm or volume.

Question 14

How much cerebellum function must you lose before you start having signs/symptoms? Is recovery rapid or slow?

Answer 14

“A large volume,” obviously, depending on the area. Recovery can be rapid.

Question 15

Are isolated cerebellar symptoms common or uncommon? Why or why not?

Answer 15

Uncommon. Structures in brain stem are right nearby and share blood supply with the cerebellum.

Question 16

How does tone change in cerebellar damage? (note acute vs. chronic effects)

Answer 16

Acute: transient hypotonia
Chronic: normal or hypotonia

Question 17

If you have truncal or limb ataxia,. what part of the cerebellum might be damaged?

Answer 17

Midline cerebellar regions.

Question 18

What parts of the body are affected when there’s damage to a cerebellar hemisphere?

Answer 18

Ipsilateral limb dysfunction.

Question 19

Where is appendicular ataxia most evident?

Answer 19

Distal from the body, when the limb is fully extended away from the body.

Question 20

Cerebellar lesions: ipsilateral or contralateral deficits?

Answer 20

ipsilateral, ipsilateral, ipsilateral

Question 21

What kind of lesion might produce a contralateral ataxia?

Answer 21

Lesion in the pontine nuclei… theoretically, but since there are pretty much always crossing fibers there that have come over from the other side, that would more likely have bilateral effects.

Question 22

How can sensory ataxia be distinguished clinically from cerebellar ataxia?

Answer 22

Sensory ataxia will have a positive Romberg sign. Additionally, would expect mechanoreception (esp vibration) to be impaired.

Question 23

How can vestibular function be distinguished from cerebellar dysfunction?

Answer 23

Vertigo will occur in vestibular dysfunction… *I’m trying to resolve this contradiction with the previous lecture

Question 24

How can pseudoataxia from corticospinal (UMN) disease be distinguished from cerebellar dysfunction?

Answer 24

UMN lesions will have UMN signs, such as hyperreflexia.

Question 25

How can proximal muscle weakness (say in muscular dystrophy) be distinguished from cerebellar dysfunction?

Answer 25

Both will cause a wobbly gait, but cerebellum things don’t cause weakness.

Question 26

What might a big mass in the midline cerebellum cause? (3 things)

Answer 26

Truncal titubations
Unsteady gait
Inability to do tandem (heel-to-toe) gait

Question 27

A patient has lots of atrophy of the right cerebellar hemisphere. What might you expect to see? (3 things)

Answer 27

Abnormal rebound (when you push held out arm down)
Dysmetria of finger-to-nose
Dysdiadochokinesia
all on the right side

Question 28

What causes “dysarthria-clumsy hand” syndrome?

Answer 28

Infarct of right SCA superior cerebellar artery.
(can also occur with right pontine a. infarct)
(this is probably too much detail…)

Question 29

What structures in the cerebellum does the SCA supply? (5 things)

Answer 29

Superior areas… Fastigial, interposed, and (some of) dentate nuclei.
SCP, and MCP
(… this is definitely too much detail….)

Question 30

What areas of the cerebellum does the AICA supply? (3 things)

Answer 30

Lateral regions of inferior surface…

flocculus, some of MCP, some of dentate nucleus

Question 31

What areas of the cerebellum does the PICA supply? (1 structure…)

Answer 31

Medial inferior surface of cerebellum…

nodulus