The Cerebellum and its various connection.ppt

anatomy of the cerebellum and its various connections

3. Cerebellum come from a latin word-means
little brain.
Weight -150 gm approx.
Shape-Ovoid in shape and constricted in
median part.
Parts-Consist of Two Cerebellerhemisphare
Joined by narrow median vermis.

4. Largest part of the hindbrain (pons, medulla,
cerebellum).
Lies in posterior cranial fossa.
Superiorly tentorium cerebelli, anteriorly fourth
ventricle, pons and medulla.
Three bundles of nerve fibers- superior
(midbrain), middle(pons) and inferior cerebellar
peduncle (medulla oblongata).

7. Three main lobes: Anterior, middle and
flocculonodular.
Fissures: Primary fissure, flocculonodular
fissures and horizontal fissure.
Structure of cerebellum: Outer cortex (grey
matter), inner white matter and
intracerebellar nuclei (grey matter).
Layers of cortex:1. external molecular layer
2.middle Purkinje cell layer 3.Internal
granular layer.

11. Phylogenetically divided into-
1. Vestibulocerebellum or archiecerebellum
2. Spinocerebellum or paleocerebellum
3. Cerebrocerebellum or pontocerebellum or
neocerebellum.

13. Functional areas of cerebellar cortex:
1. Cortex of vermis: influences movements of
the long axis of the body – neck, shoulders,
thorax, abdomen, hips.
2. Intermediate zone: (Just lateral to vermis)
controls distal parts of the limbs hands and
feet.
3. Lateral zone: planning of sequential
movements of entire body and conscious
assessment of movement errors.

14. Cerebellum is first noted at 5-6
th
wk as the
rhombic lips of cranial edge of the thinned roof
of the fourth ventricle of the hindbrain.

Growth causes the two rhombic lips to fuse in
midline to form the cerebellar plate which covers
the fourth ventricle caudal to metencephalon.

16. Intracerebellar nuclei:
4 masses of grey matter, from
lateral to medial-
1.Dentate
2.Emboliform
3.Globose
4.Fastigial

18. White matter: 3 groups of fibers-
1.Intrinsic fibers- do not leave
cerebellum & connects different regions.
2.Afferent fibers- enter through
middle and inferior cerebellar peduncles.
3.Efferent fibers- leave through
superior cerebellar peduncle except the fibers
of fastigial nucleus which leave through
inferior cerebellar peduncle.

19. Purkinje cells form the center of a functional
unit of cerebellar cortex.
Climbing fibers-terminal fibers of olivo-
cerebellar tract. Excitatory effect on Purkinje
cells.
Mossy fibers-terminal fibers of all other
cerebellar afferent tracts. Diffuse excitatory
effect on Purkinje cells.
Stellate, basket and Golgi cells- inhibitory
interneurons. Influence the degree of
Purkinje cell excitation by climbing and mossy
fibers.

22. Intracerebellar nucleus receives information
from-
1. Inhibitory axons from Purkinje cells
2. Excitatory axons of climbing and mossy
fibers.
Sensory input to cerebellum excitatory
impulse to nucleus short time later receives
inhibitory impulse from Purkinje cells
efferent impulse leaves cerebellum and
distributed to brain and spinal cord.
NT: glutamate, norepinephrine, serotonin.

23. FROM CORTEX:
1. Corticopontocerebellar pathway
2. Cerebro-olivocerebellar pathway
3. Cerebro-reticulocerebellar
pathway

25. FROM SPINAL CORD:
1. Anterior Spinocerebellar tract
2. Posterior Spinocerebellar tract
3.Cuneo-cerebellar tract.
FROM VESTIBULAR NUCLEI IN BRAINSTEM:
OTHER AFFERENT FIBERS

27. Globose-Emboliform-Rubral pathway
Dentothalamic pathway
Fastigial Vestibular pathway
Fastigial Reticular pathway

29. 1.Maintainence of equilibrium
2.Maintainence of co-ordination
3.Maintainance of tone
4.Helps in some cognitive function like
attention ,language, and involved in some
emotional function like fear ,pleasure.

30. Blood supply-
-Superior cerebellar artery
-Anterior inferior cerebellar artery
-Posterior inferior cerebellar artery
Venous drainage:
-great cerebral vein
-adjacent venous sinuses.

33. APPLIED PART OF CEREBELLUM

34. Depends on the following:
a) Developmental
b) Demyelinating
c)Degenerative/ Hereditary
d)Neoplastic
e)Paraneoplastic
f)Infection
g)Metabolic
h)Vascular
i) Drugs/ toxins

35. a)Developmental:
-Agenesis (aplasia, hypoplasia)
-Dandy Walker Syndrome
-Arnold Chiari malformation
-Von Hippel Lindau Syndrome
b)Demyelinating:
-Multiple sclerosis
-ADEM ( Acute Demyelinating
Encephalomyelitis)

36. c)Degenerative/ Hereditary:
- Spinocerebellar ataxia
-Cerebellar degeneration
-Multiple System Atrophy (MSA)
d)Neoplastic:
-Hemangioblastoma
-Medulloblastoma
-Astrocytoma - Metastasis

37. e) Paraneoplastic:
-Subacute cerebellar degeneration
f) Infection:
-Abscess
-Acute cerebellitis (viral)
-Crudtzfeldt Jacob disease
g)Metabolic:
-Hypothyroidism -Hypoxia
-Hyponatremia -Inborn error of
metabolism
-Hypoglycaemia -Alcohol

38. h) Vascular:
-Cerebellar hemorrhage
-Cerebellar Infarction
i)Drugs/ Toxins:
-Alcohol
-Phenytoin
-Carbamazepine other AED
-Benzodiazepine
-Chemotherapeutic- cytosine arabinoside

39. Nystagmus
Dysarthria
Intention tremor
Dysdiadochokinesia
Rebound phenomena
Pendular knee jerk
Hypotonia
Ataxia

40. VERMIS SYNDROME:
Medulloblastoma of vermis in children
Muscular incoordination in head and trunk and
not the limb.
Tendency to fall forward or backward.
Difficulty in holding the head in upright and
trunk in erect position.

41. CEREBELLAR HEMISPHERE SYNDROME:
Cause- tumor of cerebellum.
S/S: unilateral, affects arm and limbs, tendency
to fall towards the site of lesion, nystagmus,
dysarthria present.

42. Ataxia- 1. Symmetrical, 2. Focal.
According to duration of onset:
1.Acute: over hours or days
2.Subacute: over weeks and months
3.Chronic: months to years.

43. Gradually progressive bilateral and
symmetrical involvement – suggests
biochemical, metabolic, immune or toxic
etiology.
Focal unilateral symptoms with headache,
impaired level of consciousness with ipsilateral
cranial nerve palsies and contralateral limb
weakness indicates a space occupying lesion.

44. ACUTE AND REVERSIBLE ATAXIA:
1. Intoxication with
- Alcohol
-Phenytoin
-Lithium
-Barbiturate
-Cytotoxic drugs-paclitaxel,
fluorouracil.
2.Infectious:
-Acute viral cerebellitis(CSF
supportive)

45. Post infectious syndrome: after varicella.
Other rare infections are-
* Viral:Polio, coxsackie, EBV
*Bacterial: Legionella, Lyme disease
*Parasitic:Toxoplasma
 These produce ataxia and mild dysarthria.

46. 1. Combination of alcoholism and
malnutrition (deficiencies of vit B1 and B12)-
degeneration of cerebellar vermis.
2.Hyponatremia
3.Hypothyroidism (treatable and reversible
cause of ataxia so it must be remembered)
4.Paraneoplastic syndrome- breast, ovary,
small cell lung cancer, Hodgkin’s disease.

47. 5. Antigliadin antibody syndrome (coeliac
disease)
6.Anti-GAD antibody syndrome (Type1 DM).
CHRONIC ATAXIA:
1.Metabolic: Hypothyroidism
2.Infectious: Meningovascular syphilis, tabes
dorsalis.
3.Inherited ataxia: spinocerebellar ataxia.

48. ACUTE FOCAL ATAXIA:
Lesions produce-
*Ipsilateral cerebellar S/S
*Impaired consciousness- due to raised
ICP and brainstem compression.
*Ipsilateral pontine signs- 6
th
and 7
th

nerve palsy.
*Contralateral limb weakness.

49. 1.Ischemic Infarct
2.Cerebellar hemorrhage
3.Posterior fossa subdural hematoma
4.Cerebellar abscess
5.Primary or metastatic tumor.
Metastasis- from brochus, breast, thyroid,
kidney, prostate, ovary, stomach, melanoma.

50. Neurological emergencies- need acute surgical
decompression as sudden devastating
herniation through tentorium cerebelli or
foramen magnum leading to death.

51. SUBACUTE FOCAL ATAXIA:
1.Lymphoma
2.PML (Progressive Multifocal
Leucoencephalopathy) in AIDS patients
CHRONIC FOCAL ATAXIA:
1.Multiple sclerosis
2.Chiari malformation
3.Dandy-Walker syndrome (congenital cyst
of posterior fossa).

52. Cerebellar ischemia

58. These are – Autosomal dominant
- Autosomal recessive
-Mitochondrial inheritence
Clinical manifestation dominated by cerebellar
signs but there are changes in
-basal ganglia –spinal cord – Optic nerve- Retina
– Peripheral nerves
Rarely dementia is present.

59. Begins in adult life.
Occurs in each generation of pedigree.
SCA type 1 to SCA type 28, episodic ataxia type
1&2.
Triplet repeat expansion in different genes.
Clinical phenotypes overlaps
Genetic analysis is the gold standard for
diagnosis and classification.

60. Begins in childhood or early adulthood.
Parental consanguinity of marriage is more
likely but not essential.
Examples:
-Friedreich’s ataxia
-Ataxia Telangiectasia
-Ataxia with isolated Vit-E deficiency.

61. Mutation in maternal mitochondrial DNA
E.g.-
MERRF syndrome
MELAS
Kearans Sayre syndrome

62. Previously known as Olivopontocerebellar
atrophy (OPCA).
Presentation at early or mid adult life.
Presentation-
-Progressive ataxia
-Impairment of equilibrium and gait
-Dysarthria
-Dysphagia
-Occulo motor and facial palsy
-Extrapyramidal features may
accompany

63. Findings- reflexes normal but knee and ankles
are lost, planter bilateral extensor.
Mild dementia
Sphincter disturbance
Summary: Ataxia
Ophthalmoparesis
Pyramidal and extrapyramidal
features.

64. Genetics: Triplet repeatation (CAG) in
chromosome 6 and gene product is Ataxin-1
protein.
MRI findings:
-Atrophy of cerebellum
-Marked shrinkage of ventral half of
pons
-Disappearance of Olivary eminence of
medulla.

66. Most common hereditary ataxia
Presents before the age of 25yrs
Presentation: Progressive staggering gait,
frequent fall and titubation.
Lower extremity severely affected then the
upper extremity.
Initial signs: skeletal deformity- scoliosis, pes
cavus, neurological- nystagmus, optic atrophy,
deep tendon reflex absent, planter b/l extensor.

67. Others- cardiomyopathy, DM(20%cases).
Median age of death is 35yrs.
Prognosis is better in female than male.
Primary sites of pathology – Spinal cord,
dorsal root ganglia, peripheral nerve and
cerebellum.
In spinal cord- degeneration of spino
cerebellar tract, dorsal column, corticospinal
tract.

68. Genetics: Triplet repeat in chromosome 9
Point mutation in Frataxin gene.
Frataxin is a mitochondrial protein
involved in iron homeostasis.
Diagnosis:History
Clinical examination
Neuroimaging: Brain &spinal cord
Genetic analysis

71. METASTASIS:
In adults metastasis is the most common
tumor.
Primary sites:
-Bronchus - Breast -Thyroid
-Stomach -Kidney -Prostate
-Testes -Melanoma

72. A)Hemangioblastoma:
-Commonest tumor in adult
-More in male
-Benign tumor of vascular origin
-Association: Polycythemia
Von hippellindau syndrome

73. B) Medulloblastoma:
-Primitive neuroectodermal tumor
-Occurs in childhood
-Peak age of onset is 5yrs of age
-Highly malignant tumor
-Arise in vermis and extend into 4
th
ventricle
-Presentation- truncal ataxia, raised ICP, visual
loss.
- Treatment: Surgery, radiotherapy.

74. C)Cerebellar Astrocytoma:
-It is low grade in nature in contrast to
astrocytoma of cerebral hemisphere.
D) Ependymoma:
-Arises from ependymal cells
E) CP angle tumor:
- Acoustic neuroma - Meningioma

78. Rapidly progressive cerebellar syndrome.
Associated with-
- Ca. breast
-Ca. ovary
-Small cell lung ca of lung
-Lymphoma
MRI of brain shows cerebellar atrophy.

79. Tumor markers:
-Anti yo Ab – ovarian ca
-Anti Hu Ab – SCLC
-Anti ri Ab – Ca. breast

80. History and clinical features
-Age of onset
-Tempo of progression
-Associated neurological and systemic features
-Family history

81. Investigations:
-Neuroimaging (MRI of brain)
-Thyroid function test
-VDRL
-CSF study
-Vit B12, Vit E level
-Anti Gliadin Ab
-Anti GAD Ab
-Anti Yo Ab, Anti- Hu Ab, Anti-Ri Ab
-Genetic analysis