Chapter 16
Cerebellum
LEARNING OBJECTIVES
▶ Identify cerebellar peduncles in gross anatomy
specimens. Describe the contents of the cerebellar
peduncles.
▶ Describe the internal circuitry of the cerebellum.
▶ Describe the etiopathogenesis and clinical features
for Arnold–Chiari malformation.
▶ Describe the blood supply of the cerebellum.
▶ Describe the effects of alcohol on the cerebellum.
▶ Describe the effects of lesions in the various
functional areas of cerebellum.
▶ Define the types of appendicular ataxias found in
cerebellar disorders.
▶ Describe various forms of input to the cerebellum.
▶ Describe the etiopathogenesis and clinical features
for Dandy–Walker syndrome.
▶ Describe the connections for the various functional
areas of cerebellum.
Das and Baugh, Medical Neuroscience Q&A (ISBN 978-1-62623-537-3),
copyright © 2019 Thieme Medical Publishers. All rights reserved. Usage subject to terms and conditions of license.
16
Cerebellum
16.1 Questions
Easy
Medium
Hard
3. Which of the following areas contains important communicating fibers from the cerebellum to
the thalamus?
A. Area A
Consider the following image for questions 1 to 3:
B. Area B
C. Area C
D. Area D
E. Area E
4. A 56-year-old woman presents with intention
tremor. Investigation reveals cerebellar hemorrhage
that has affected the immediate input pathway for
the deep cerebellar nuclei. Which of the following
neurons might have been affected?
A. Granule cells within the cerebellum
B. Golgi cells
C. Stellate cells
D. Basket cells
E. Purkinje cells
Consider the following case for questions 5 and 6:
A female newborn presented with flaccid paraplegia
of the lower limbs. Neuroimaging revealed Arnold–
Chiari (type II Chiari) malformation.
5. Which of the following features might have
helped the clinician to diagnose her case?
A. Herniation of cerebellar tonsils through foramen
magnum
B. Herniation of lower medulla through foramen
magnum
C. Enlarged posterior fossa
1. Which of the following areas contains important
inputs from the cerebral cortex to the cerebellum?
D. Atresia of foramen of Luschka
E. Agenesis of cerebellar vermis
A. Area A
C. Area C
6. Which of the following additional features is
most likely to be present in this case?
D. Area D
A. Syringomyelia
E. Area E
B. Myelomeningocele
B. Area B
C. Normal skull base
2. Which of the following areas contains climbing
fibers to the cerebellum?
A. Area A
D. Normal supratentorial structures
E. Hydrocephalus due to adhesions occluding the
fourth ventricle
B. Area B
C. Area C
D. Area D
E. Area E
142
Das and Baugh, Medical Neuroscience Q&A (ISBN 978-1-62623-537-3),
copyright © 2019 Thieme Medical Publishers. All rights reserved. Usage subject to terms and conditions of license.
16.1 Questions
Consider the following case for questions 7 and 8:
A 48-year-old woman presents with truncal and
limb ataxia, and nystagmus. CT scan reveals evidence
of hemorrhage in the left interposed and fastigial
nuclei.
7. Which of the following vessels is most likely
involved?
A. AICA
B. PICA
C. SCA
D. Pontine branches of basilar
E. Vertebral artery
11. A 60-year-old woman presents with an
unsteady wide-based stance and nystagmus. Which
of the following is the most likely location of a
lesion?
A. Superior cerebellar peduncle (SCP)
B. Cortex of the paravermal cerebellar area
C. Cortex of the posterior cerebellar lobe
D. Dentate nucleus
E. Flocculonodular lobe
Consider the following case for questions 12 and 13:
A 69-year-old man is unable to rapidly slap his hand
to his knee while alternating pronation and supination of his hand with each movement.
8. To control bleeding from the involved artery,
which of the following vessels should be clamped at
surgery?
12. Which of the following specifies this particular deficit?
A. Internal carotid artery
A. Asterixis
B. Vertebral artery
B. Dysrhythmia
C. Rostral part of the basilar artery proximal to its
bifurcation
C. Dysmetria
D. Caudal part of the basilar artery just distal to its
formation
E. Titubation
E. Subclavian artery
Consider the following case for questions 9 and 10:
A 62-year-old chronic alcoholic presents with truncal instability, uncoordinated gait, and moderate
ataxia of his arms. He has consumed alcohol for 40
years, averaging ~90 mL a day.
D. Dysdiadochokinesia
13. Which of the following structures is most
likely lesioned in this patient?
A. Dentate nucleus
B. Fastigial nucleus
C. Flocculonodular lobe of cerebellum
D. Vermal region of cerebellum
E. Ventral spinocerebellar tract
9. Which of the following regions might have
undergone significant degeneration?
B. Superior vermis
14. Which of the following pairs correctly indicates the exclusive source and nature of climbing
fibers to the cerebellar cortex?
C. Flocculus
A. Ipsilateral inferior olivary nuclei, inhibitory
D. Paravermal area
B. Contralateral inferior olivary nuclei, inhibitory
E. Posterior lobe
C. Ipsilateral inferior olivary nuclei, excitatory
A. Inferior vermis
D. Contralateral inferior olivary nuclei, excitatory
10. Which of the following cells will most notably
be affected?
E. Contralateral pontine nuclei, inhibitory
F. Contralateral reticular nuclei, excitatory
A. Granule cell
B. Golgi cell
Consider the following case for questions 15 and 16:
C. Stellate cells
A 10-year-old female presents with ataxia, mental
retardation, and seizures. Examination reveals an
enlarged posterior fossa with cystic dilatation of the
fourth ventricle. Atresia of foramens of Luschka and
Magendie was considered as the probable etiology
for her symptoms.
D. Basket cells
E. Purkinje cells
143
Das and Baugh, Medical Neuroscience Q&A (ISBN 978-1-62623-537-3),
copyright © 2019 Thieme Medical Publishers. All rights reserved. Usage subject to terms and conditions of license.
16
Cerebellum
15.
Which of the following is the likely diagnosis?
A. Type I Chiari malformation
19. Which of the following areas receives input
from the ankle joint?
B. Type II Chiari malformation
A. Area A
C. Dandy–Walker syndrome
B. Area B
D. Occipital encephalocele
C. Area C
E. Holoprosencephaly
D. Area D
16. Which of the following is a likely associated
finding?
20. Output from which of the following areas is
contained within the uncinate fasciculus?
A. Syringomyelia
A. Area A
B. Herniation of cerebellar tonsils through foramen
magnum
B. Area B
C. Herniation of cerebellar vermis through foramen
magnum
D. Area D
C. Area C
D. Agenesis of cerebellar vermis
E. Buckling (Z deformity) of the medulla
16.2 Answers and Explanations
Consider the following image for questions 17 to 20:
Easy
Medium
Hard
Refer to the following image key for answers 1 to 3:
A, SCP; B, inferior cerebellar peduncle; C, stria
medullaris of the fourth ventricle; D, MCP; E, superior medullary velum.
1.
Correct: Area D (D)
Pontocerebellar fibers contain sensory information
from the cerebral cortex (conveyed by corticopontine fibers to pontine nuclei) and travel to the contralateral cerebellum via the MCP (D).
2.
17. Which of the following areas is the primary
destination for fibers conveyed within the MCP?
A. Area A
B. Area B
C. Area C
D. Area D
18. Which of the following areas functions by
influencing the MLF?
A. Area A
B. Area B
C. Area C
D. Area D
Correct: Area B (B)
The inferior cerebellar peduncles (B) communicate
between the cerebellum and the medulla. These
carry climbing fibers (from the contralateral inferior
olivary nuclear complex) to the cerebellum. All other
input to the cerebellum are via mossy fibers.
3.
Correct: Area A (A)
The superior (A) cerebellar peduncles carry efferent
fibers from the cerebellum to the thalamus (dentatothalamic fibers), often via the red nucleus (dentatorubrothalamic tract).
The stria medullaris of the fourth ventricle (C)
consists of fibers travelling to the cerebellum from
the arcuate nuclei (within the medulla) via the inferior cerebellar peduncle.
The roof of the rhomboid fossa is formed by the
superior medullary velum (E). The trochlear nerve
decussates in the rostral aspect of the velum.
144
Das and Baugh, Medical Neuroscience Q&A (ISBN 978-1-62623-537-3),
copyright © 2019 Thieme Medical Publishers. All rights reserved. Usage subject to terms and conditions of license.
16.2 Answers and Explanations
4.
Correct: Purkinje cells (E)
The internal circuitry of the cerebellum is depicted
in the following flowchart:
In the cerebellar glomerulus, the mossy fiber
afferents synapse with granule cells (A). After this
first processing stage, the granule cells convey this
afferent information through the excitatory parallel
fibers to the Purkinje cells and the Golgi cells (B). The
Golgi cell exerts an inhibitory (feedback) influence on
the synapse between the mossy fibers and the granule cells, within the glomerulus. The Purkinje cells
also receive direct afferent information (excitatory)
through the climbing fibers. Further inhibitory synapses with the Purkinje cells are from stellate cells
(C) and basket cells (D). The Purkinje cells then send
its efferent projections (inhibitory) to the deep cerebellar or vestibular nuclei. These nuclei serve as
relay and processing stations for information coming from the cerebellar cortex to targets outside the
cerebellum.
Consider the following explanation for answers 5
and 6:
Chiari malformations are defined as cerebellar herniation through foramen magnum due to a normalsized cerebellum developing within an abnormally
small posterior fossa.
5. Correct: Herniation of lower medulla
through foramen magnum (B)
Chiari type II (Arnold–Chiari) malformation presents
in infancy and is characterized by herniation of cerebellar vermis and lower medulla through the foramen magnum.
Isolated herniation of the cerebellar tonsils (A)
occurs in type I Chiari malformation.
Enlarged posterior fossa (C), atresia of the foramens of Luschka and Magendie (D), and agenesis
of the cerebellar vermis (E) occur in Dandy–Walker
syndrome.
6.
Correct: Myelomeningocele (B)
Myelomeningocele is an inevitable association
with Arnold–Chiari malformation. Buckling of the
medulla, beaking of the tectum, colpocephaly, lacunar skull, and platybasia are associated signs.
Syringomyelia (A) in which a cavity forms within
the spinal cord can occur in type II Chiari malformations; however, it is much more frequent in type I.
Platybasia, or flattening of skull base (C), is a frequent finding in type II Chiari malformation.
145
Das and Baugh, Medical Neuroscience Q&A (ISBN 978-1-62623-537-3),
copyright © 2019 Thieme Medical Publishers. All rights reserved. Usage subject to terms and conditions of license.
16
Cerebellum
Supratentorial structures (D) are often involved in
type II Chiari malformation. Hypoplastic and irregular tentorium and falx (Chinese letter sign), enlarged
interthalamic adhesion, and agenesis of corpus callosum could occur.
Hydrocephalus, if present in Arnold–Chiari malformation, occurs from cerebral aqueduct stenosis. Hydrocephalus due to adhesions occluding the
fourth ventricle (E) is commonly seen in type I Chiari
malformation.
7. Correct: SCA (C)
The SCAs supply the upper part of the cerebellum,
which includes most of the deep cerebellar nuclei
(dentate, interposed [globose and emboliform], and
fastigial), rostral portion of the MCP, and SCP.
The AICA (A) supplies anterior portions of the
inferior cerebellum including the flocculus, caudal
part of the dentate nucleus, and most of the MCP.
The PICA (B) supplies majority of the inferior surface
including inferior vermis and ICP. Pontine branches
of the basilar artery (D) supply the pons. A pair of
vertebral arteries (E) joins to form the basilar artery.
8. Correct: Rostral part of the basilar artery
proximal to its bifurcation (C)
The SCAs arise bilaterally near the rostral end of the
basilar artery, proximal to its bifurcation. This region
will, therefore, need to be clamped to operate on the
bleeding SCA.
Clamping the basilar artery just distal to its formation (D) will occlude blood supply to vital brainstem and cerebellar structures and should not be
considered. The internal carotid (A), vertebral (B), or
subclavian (E) arteries are too far and unrelated to
the bleeding vessel.
Consider the following explanation for answers 9
and 10:
The most consistently reported structural damage
in the cerebellum of alcoholics is tissue volume loss
in the anterior superior vermis. Tissue volume loss in
this area is due especially to either shrinkage or atrophy of Purkinje cells. Cerebellar shrinkage is most
notable in older alcoholics with at least a 10-year
duration of alcoholism.
In contrast to alcohol, which exerts its greatest
effect on the anterior superior lobules, normal aging
primarily affects the posterior lobules.
9.
Correct: Superior vermis (B)
10. Correct: Purkinje cells (E)
11.
146
Correct: Flocculonodular lobe (E)
The flocculonodular lobe, via its bidirectional connections with the vestibular nuclei, influences the
medial longitudinal fasciculus (MLF) and plays an
important role in maintaining balance and vestibulo-ocular reflexes. Lesion to this part of the cerebellum leads to truncal ataxia, vertigo, and nystagmus.
Ventral and rostral spinocerebellar fibers traverse
the SCP (A) to project to the paravermal (B) area
within the cerebellum. These structures influence
distal limb coordination and their lesion might cause
appendicular ataxia, intention tremor, hypotonia,
etc.
Output fibers from the posterior cerebellar lobe
(C) and the dentate nucleus (D) form the dentatorubrothalamic tract and traverse the SCP (A). These
tracts are involved in motor planning for the extremities and their lesion might cause different forms of
appendicular ataxia (dysdiadochokinesia, dysmetria,
etc.).
12.
Correct: Dysdiadochokinesia (D)
The patient is suffering from dysdiadochokinesia,
which is a form of appendicular ataxia characterized
by abnormalities of rapid alternating movements.
Ataxic movements might have abnormal timing
(dysrhythmia, B) or abnormal trajectories (dysmetria, C).
Asterixis (A), or flapping tremor, is a form of brief
rapid movement that is often seen in metabolic
encephalopathies, particularly in hepatic failure.
Titubation (E) is a peculiar tremor of the head or
the trunk that occurs with midline cerebellar lesions.
13. Correct: Dentate nucleus (A)
Output from the neocerebellar cortex is primarily to
the dentate nucleus, which in turn projects to the red
nucleus (parvocellular part) and from there to the
VLC of the thalamus, making up the dentatorubrothalamic tract. From the thalamus, information projects back to motor (primary and association) areas of
the cortex. This circuit is involved in planning motor
programs for the extremities. Lesions to the involved
structures cause different forms of appendicular
ataxia (dysdiadochokinesia, dysmetria, etc.).
The flocculonodular lobe (C), via its bidirectional
connections with the vestibular nuclei, influences
the MLF and plays an important role in maintaining
balance and vestibulo-ocular reflexes. Lesion of this
part of the cerebellum leads to truncal ataxia, vertigo, and nystagmus.
Afferents from the vestibular nuclei also project
to the vermis (D). The midline vermis projects to
fastigial nuclei (B) and is important in the control of
proximal limb and trunk muscles. Lesions of these
structures will primarily cause truncal ataxia.
The ventral spinocerebellar tract (E) originates
from leg interneurons within the spinal cord and
projects to the intermediate or paravermal area
within the cerebellum. Lesion of this structure is
unlikely to cause upper limb ataxia.
Das and Baugh, Medical Neuroscience Q&A (ISBN 978-1-62623-537-3),
copyright © 2019 Thieme Medical Publishers. All rights reserved. Usage subject to terms and conditions of license.
16.2 Answers and Explanations
14. Correct: Contralateral inferior olivary
nuclei, excitatory (D)
Climbing fibers carry excitatory inputs from the
contralateral inferior olivary nucleus and synapse directly onto Purkinje cells. The inferior olivary nuclei are fed by several important structures
including cerebral cortex, red nucleus, brainstem,
and spinal cord.
15.
Correct: Dandy–Walker syndrome (C)
The patient has classical features of Dandy–Walker
syndrome, which presents with hydrocephalus,
ataxia, mental retardation, and/or seizures.
Type I Chiari malformation (A) presents in young
adults and is characterized by herniation of cerebellar tonsils. Type II Chiari malformation (B) presents
in infancy and is characterized by herniation of cerebellar vermis and lower medulla. Occipital encephalocele (D) is characterized by herniation of brain
tissue (enclosed in meninges) through a defect in the
occipital bone. Holoprosencephaly (E) occurs when
the prosencephalon fails to cleave down the midline such that the telencephalon contains a single
ventricle.
16. Correct: Agenesis of cerebellar vermis (D)
Components of Dandy–Walker syndrome include
enlarged posterior fossa, elevated tentorial attachment, agenesis of cerebellar vermis, and cystic dilation of the fourth ventricle.
Herniation of cerebellar tonsils (B) and syringomyelia (A) are features of Chiari type I malformation.
Herniation of cerebellar vermis (C) and buckling of
medulla (E) are seen in type II Chiari malformation.
Refer to the following image key 17 to 20:
A, intermediate/paravermal area; B, vermis; C, lateral
region; D, flocculus.
17.
Correct: Area C (C)
Broad areas of cerebral cortex project to the ipsilateral pontine nuclei (corticopontine fibers). From the
pontine nuclei, fibers cross the midline (pontocerebellar fibers) and, via the MCP, project to the lateral
areas of the cerebellar hemisphere.
18.
Correct: Area D (D)
The flocculonodular lobe, via its bidirectional connections with the vestibular nuclei, influences the
MLF and plays an important role in maintaining balance and vestibulo-ocular reflexes.
19.
Correct: Area A (A)
Unconscious proprioception from lower limb muscles and joints is relayed to Clarke’s nucleus in the
spinal cord. From there, the fibers travel as dorsal
spinocerebellar tract through the ICP to the paravermal or intermediate area of the cerebellum.
20.
Correct: Area B (B)
Afferents from the vestibular nuclei project to the
vermis. The midline vermis projects to fastigial
nuclei. Contralateral fibers from the fastigial nucleus
form the uncinate fasciculus and projects back to
vestibular nuclei.
147
Das and Baugh, Medical Neuroscience Q&A (ISBN 978-1-62623-537-3),
copyright © 2019 Thieme Medical Publishers. All rights reserved. Usage subject to terms and conditions of license.
Das and Baugh, Medical Neuroscience Q&A (ISBN 978-1-62623-537-3),
copyright © 2019 Thieme Medical Publishers. All rights reserved. Usage subject to terms and conditions of license.