NEUROANATOMY OF

CEREBELLUM AND

DISORDERS

Dr.Prerna Khar

JR-1

TOPICS TO BE COVERED….

• NEUROANATOMY

• FUNCTIONS IN BRIEF

• CEREBELLAR DISORDERS

• BEDSIDE CEREBELLAR TESTS

• Latin for ‘little brain.’

• Largest part of hindbrain.

• Location: Posterior cranial

fossa, below tentoriumcerebelli.

• Lies behind pons & medulla

– forming roof of 4th ventricle

OVERVIEW

PARTS OF CEREBELLUM

FUNCTIONAL AND PHYLOGENETIC SUBDIVISION

Regulation of

muscle tone,

coordination of

skilled voluntary

Movement.Connected

to Spinal cord.

Planning of

voluntary activity.

Connected to cerebrum

Maintenance of

balance, control

of eye movements

Connected with vestibular nuclei.Vestibulocerebellum/Archicerebellum

Spinocerebellum/Paleocerebellum

Cerebrocerebelum/neocerebellum

Anterior Lobe

Posterior

Lobe

Flocculo-Nodular

Lobe (FN lobe)

Primary fissure

Post

lat

fissure

INTERNAL STRUCTURE

• Cortex, white matter, deep nuclei.

• Cortex=folds ( Folia)- converge-arbor vitae cerebelli (branching white matter covered by grey matter).

• Input-cortex

• Output-deep nuclei.

WHITE MATTER

• 3 types of Fibers.

FIBRE FUNCTION

Fibrae Propriae Association and

commissural fibers

Axons of Purkinje Fibers Efferent

Projection Fibers Connect Cerebellum with

rest of CNS – Peduncles

INTRACEREBELLAR NUCLEI

NUCLEI LOCATION SIGNIFICANCE

DENTATE

(neocerebellum)

Largest, lateral most Input-lateral hemisphere

Output-SCP

GLOBOSE

EMBOLIFORMIS

(Paleocerebellum)

Collectively called

Interposed Nuclei

Input-paravermian

Output- SCP

FASTIGIAL -OLDEST

(archicerebellum)

Medial most Input-vermis+

flocculonodular

Output-ICP

CEREBELLAR CORTEX

• Grey matter.

• Purkinje cells=functional unit.

• Affferents=Climbing fibres-Excitatory(infolivary nucleus) or Mossy fibres( Excitatory,from spinal cord & brain stem)

(reach purkinje cells)

• Efferents=axons of Purkinje cells.(Inhibitory)

LAYERS OF CORTEX

LAYER DESCRIPTION FUNCTION

Purkinje cell

(INHIBITORY)

Large,flask shaped.

Only axons to emerge

from cerbellar cortex to

enter white matter

All impulses converge

here.GABA released.

Basket cell

(INHIBITORY)

In molecular layer, near

body of purkinje cell

Branching dendrite and

axon(arborize body of 10

purkinje cells)

Granule cell

(EXCITATORY)

Packed chromatic nuclei Horizontal fibres of outer

molecular layer

Outer stellate cell

(INHIBITORY)

In molecular layer Synapse with purkinje

cell dendrites

CEREBELLAR PEDUNCLESPEDUNCLE ALTERNATE NAME FUNCTION

Superior Cerebellar

Peduncle

Brachium

conjuctivum

Output from

cerebellum

Midddle Cerebellar

Peduncle

Brachium pontis Input to Cerebellum

Inferior Cerebellar

Peduncle

Restiform Body Input to Cerebellum

CEREBELLAR INPUTSPEDUNCLE TRACT

SUPERIOR Ventral spinocerebellar

Midbrain tectum (colliculi)

Trigeminal

MIDDLE Cerbral cortex(M+S) via pontine nuclei

INFERIOR Dorsal spinocerebellar

Rostral Spinocerebellar

Cuneocerebellar

Reticulocerebellar

Olivocerebellar

Trigeminocerebellar

Vestibulocerebellar

AFFERENT TRACTS

TRANSMITS DESTINATION

Dorsal spinocerebellar Unconscious kinesthetic & cutaneous afferents from trunk & leg

Via IPC to spinocerebellum

Ventral Spinocerebellar Exteroceptive and proprioceptive fibresfrom body

Vermis and anterior lobe via ipsilateral SCP

Vestibulocerebellar tract Vestibular impulse from labyrinth direct and via vestibular nuclei

Flocculonodular lobe via ipsilateral IPC

Cuneocerebellar tract Proprioceptive impulses, especially from arm,head and neck

Spinocerebellum via ipsilateral IPC

AFFERENT TRACTS

TRANSMITS DESTINATION

Tectocerebellar Auditory and visual impulses via inferior and superior colliculi

Vermis and paravermis via SCP(equilibrium)

Corticopontocerebellar Impulses from motor and other parts of cerebral cortex via pontine nuclei

Neocerebellum via contralateral MCP

Olivocerebellar Proprioceptive input from whole body via relay in inferior olive

Spinocerebellum via contralateral IPC

CEREBELLAR OUTPUT

• Mainly from deep nuclei

• Flocculonodular cortex-vestibular nuclei.

PEDUNCLE OUTPUT

SUPERIOR Dentatothalamic

Rubrocerebellar

Reticular formation

MIDDLE NONE

INFERIOR Cerebelloriticular

Cerebellovestibular (directly from

flocculonodular lobe)

PATHWAY ORIGIN DESTINATION

GLOBOSE-EMBOLIFORM-RUBRAL

Globose and emboliformnuclei

IL motor neurons in spinal cord

DENTOTHALAMIC Dentate nucleus Controls IL motor neurons in spinal cord

FASTIGIAL VESTIBULAR

Fastigial nucleus ipsilateral motor neurons in spinal cord

FASTIGIAL RETICULAR Fastigial nucleus To neurons of reticular formation; reticulospinal tract to ipsilateral motor neurons to spinal cord

CEREBELLAR CIRCUITRY FUNCTIONALLOBE

INPUT DEEPNUCLEUS

OUTPUT FUNCTION

Lateralhemispheres

Motor and sensory cortex

Dentate Thalamus VL to premotorcortex

Movement coordination-influencescorticospinaltract

Paravermis Muscle spindles andgolgi tendon organ via spino-cerebellartract

Globose and emboliform

Red nucleus Movement modulation via ruprospinalTract

Vermis and Flocculo-nodular lobe

Vestibularsystem

Fastigial and vestibularnuclei

Vestibularsystem

Balance and truncalstability

EPIDEMIOLOGY

• 50% of ADS patients have cerebellar pathology

• MC cause of cerebellar pathology is ADS

• 2nd MC cause = stroke

• Amongst adult tumors, metastasis affects the most

ETIOLOGY

• Cerebellar damage- emotional and cognitive disturbances.

Purkinje cell

Granule cell

Inhibitory inter-

neurons

Cerebellarcortical module

Integrates excitatory and inhibitory input

Receives input from outside cerebellum and innervate purkinje cell

Basket cell+ golgi cell

SCHMAHMANN’S THEORY

• Just as the cerebellum regulates movements, it regulates consistency and appropriateness of mental/cognitive process

• “dysmetria of thought process occurs in cerebellar disorders-unpredictability and illogical to social and societal interactions”

D/D OF CEREBELLAR DISORDERS

MOTOR FEATURES-bedside signs

• Balance and speech problems.

• Disequilibrium-staggering gait- Ataxia

• Hypotonia.

• Pendular jerk

• Disdidochokinesia

• Dysmetria & Past pointing.

• Scanning speech

• Intention tremor

• Nystagmus-oscillatory movements of eyeballs

“DANISH”

COGNITIVE FEATURES

• Cognitive function= Procedural learning, executive functions, language processing, visual spatial orientation, sensory processing, timing, attention

• Executive function impairment: Defecit of attention, sequencing and timing

• Cognitive defectics : d/t hemispheral lesion

PSYCHIATRIC FEATURES

• d/t vermal lesions.

• Posterior circulation stroke-35% depression.

• Post circulation infarct: blunted affect and disinhibition.

• 75% of pts with degenerative ds of cerebellum-psychiatric manifestations within 10-15 yrs

1. 1/3rd : major depression

2. 1/3rd dysthymia, brief recurrent depression.

3. 25% personality changes

CEREBELLAR- COGNITIVE AFFECTIVE SYNDROME (CCAS)

SCHIZOPHRENIA

• Cerebellar atrophy

• Decreased blood flow in the cerebellum affectsmemory, attention, social cognition, andemotion.

• Soft neurological signs suggestive of cerebellardysfunction-ataxia,difficulties in coordination, dysdiadochokinesia, intentional tremor, dysmetria of the ocular saccadic movements are frequent in patients with schizophrenia

COURSE AND PROGNOSIS

• Personality and cognitive changes-follow the course of the ds

• Major depression-may be intermittent.

TREATMENT

• Caution with agents that may increase ataxia (CPZ)

• Cognitive t/t : supportive

• Rx the underlying nutritional and metabolic disorders.

REFERENCES

• Neuroanatomy-S udhir Sant

• Neuroanatomy-Netters-volume 2

• Neuroanatomy- Snells

• CTP- Cerebellar disorders; pg 502

• The cerebellar cognitive affective syndrome: Schmahmann JD, Sherman JC