The Cerebellum and its connections (Applied)

Dr Benzir Ahammad

MD Neurology Student (3rd part)

Dhaka Medical College

CEREBELLUM & ITS CONNECTIONCEREBELLUM & ITS CONNECTION

The cerebellum contributes only 10 percent The cerebellum contributes only 10 percent to the total weight and volume of the brain to the total weight and volume of the brain but contains half of the brain’s neurones.but contains half of the brain’s neurones.

It is an important part of motor system. It is an important part of motor system.

THREE FUNCTIONAL DIVISIONS• Vestibulocerebellu

m – Archicerebellum – Flocculonodular

lobe

• Spinocerebellum – Paleocerebellum– Vermis and

intermediate zone• Cerebrocerebellum

– Neocerebellum – Lateral zone

Flocculonodular lobe

Verm

isIn

termed

iate zon

e

Lateral zo

ne

Neocerebellum

archicerebellum

paleocerebellum

FUNCTIONAL SUBDIVISIONS OF CEREBELLUMFUNCTIONAL SUBDIVISIONS OF CEREBELLUM

i) i) Vestibulocerebellum –Archicerebellum –Flocculonodular – Mid zoneMid zone (Nucleus Fastigius) (Nucleus Fastigius)

Maintains equilibrium

Cont….

ii) Spinocerebellum –Paleocerebellum– intermediate zone (Ant.Lobe)

– N.Globosu&N.Emboliformis:

Influences posture & tone & individual movement of ipsilateral limb.

CONT..

• Paleocerebellum• VVermisermis

• Mid zoneMid zone (Nucleus Fastigius) (Nucleus Fastigius)

• Muscle tone of trunk.

Cont…iii)Cerebrocerebellum

–Neocerebellum –Lateral zone (Post.Lobe)

– Dentate nucleus

Coordination of movement of ipsilateral limb.

Clinical features of cerebellar lesion (cont)

DysarthriaNystagmusIntension tremorDysmetriaDysdiadochokinesiaHypotoniaGait disturbancesPendular reflexes

Causes of cerebellar disorders

• Developmental • Vascular

• Infective • Neoplastic

• Demyelinating

• Nutritional deficiency

• Trauma

• Degenerative

• Drugs and toxins

• Metabolic

Developmental disorders

• Agenesis/ hypoplasia

• Dandy-Walker syndrome

• Arnold-Chiari malformation

Aplasia of cerebellum

Dandy-Walker syndrome

• Ballooning of the fourth ventricle

• Aplasia of cerebellar vermis

• Nonopening of foramen of Magendie

• Hydrocephalus

Dandy-Walker Syndrome

Arnold-Chiari malformation

• There is displacement of cerebellar tonsils and vermis through the foramen magnum

• There is compression of spino-medullary junction

• Often associated with syringomyelia and hydrocephalus

Arnold-Chiari malformation

Vascular disorders

• Types-

-Ischemic-Hemorrhagic

Strokes involving cerebellum seldom give rise to cerebellar signs alone.

Frequently there are features of brain stem and cranial nerve dysfunction and headache , vertigo and vomiting which may dominate the clinical picture

Hemorrhagic stroke affecting cerebellum

• Cerebellum is one of the common sites of hemorrhagic stroke (particularly in hypertensive patients)

• Presents with sudden onset headache, vomiting, ataxia and vertigo.

• Coma develops in 50% patients within hours to days

Cerebellar HemorrhageCerebellar Hemorrhage

Cerebellar infarction

• Accounts for 1-2% of all ischemic strokes.

• Has a high mortality rate

• Diagnosis is often missed due to wide-range of clinical presentation

Cont….

Clinical Syndromes-Branch oclusion

• Superor cerebellar artery syndrome

Cerebellum-

disturbed gait,limb ataxia

Brainstem-

Ipsilateral Horner’s syndrome

Contralateral sensory loss

Superor cerebellar artery infarction

Cont…

• Anterior inferior cereballar artery syndrome

Cerebellum- ipsilateral limb ataxia Brainstem-Ipsilateral Horner’s syndrome Contralateral sensory loss + Ipsilateral sensory loss Ipsilateral facial weakness

Cont…• Posterior inferior cereballar artery

syndrome

Cerebellum-dysarthria,vertigo and nystagmus, ipsilateral limb ataxia

Brainstem-Ipsilateral Horner’s syndrome

Contralateral sensory loss

+

Ipsilateral sensory loss

Ipsilateral laryngeal and pharyngeal paralysis

MR-images of a left-sided PICA-infarction

Tumors of cerebellum

Cerebellar tumors may be –• Primary-Common in children • secondary- Common in adults

• Clinical features--ataxia-brainstem dysfunction-features of raised intracranial pressure

Primary tumors of cerebellum

• Medulloblastoma• Astrocytoma• Hemangioblastoma• Ependymoma• Oliogodendroglioma

• Medulloblastoma, astrocytoma- common in children

• Hemangioblastoma- common in adults

Haemangioblastoma

Cerebellar astrocytoma

Medulloblastoma

Metastasis to cerebellum

• Common primary sites-

-bronchus-breast-melanoma-kidney-gastrointestinal tract

Pelvic and GIT tumors show particular tendency for metastasis to cerebellum

Cerebellar

metastasis

from

Breast

carcinoma

Paraneoplastic Syndrome:

--Rapidly progressive pancerebellar Syndrome

--Usually associated with ca breast & ovary,small cell ca lung, lymphoma etc.

--MRI shows Atrophy of cerebellum

--Tumor markers: Anti yo Ab-ovarian ca Anti Hu Ab-SCLC Anti ri Ab-Ca breast

Drugs and toxins affecting cerebellum

• Alcohol

• Anticonvulsant drugs

• Chemotherapy- 5-flurouracil , cytosine arabinose

• Heavy metals-mercury , manganese , bismuth

• Chronic solvent abuse

Anticonvulsants and cerebellum

• Transient cerebellar dysfunction may be caused by many antiepileptic drugs.

• Persistent ataxia with Purkinje cell loss occur primarily in patients treated with high dose of phenytoin for prolonged periods .

• Cerebellar atrophy associated with phenytoin therapy may be asymptomatic.

• Phenytoin should be avoided in patients with ataxia or cerebellar atrophy.

Infections affecting cerebellum

• Bacterial- cerebellar abscess

• Viral- acute viral cerebellitis

• Others- prion diseases

Cerebellar abscess

• Usually results from spread of infection from-

-Mastoid/middle ear

-Sphenoid sinus

Clinical features-

- headache , vomiting , ataxia , lethargy, fever

Cerebellar abscess

Acute viral cerebellitis

• Acute cerebellar ataxia may occur after many viral infections-

-Varicella(most common)-EBV-Enteroviruses-Cytomegalovirus

• Prognosis is good

Demyelinating disorders

Multiple sclerosis--Cerebellum is often affected in multiple

scelosis-11% MS patient presents initially with

cerebellar ataxia

ADEM- -in ADEM due to chicken pox , there is often

marked cerebellar involvement

Cerebellar demyelination in MS

Metabolic disorders affecting cerebellum

• Hypothyroidism

• Hypoxia

• Hypoglycemia

• Hyponatremia

• Defeincy disorders (vitamin B1, B12, E)

• Inborn errors of metabolism( lipid /amino acid metabolism)

The inherited ataxias

• Genetically determined disorders characterized by progressive cerebellar degeneration.

• Other areas of the nervous system may be affected-

-pyramidal-exyrapyramidal-spinal cord-peripheral nerves

Inherited ataxias

Types-

• Autosomal dominant

• Autosomal recessive

• Maternal (mitochondrial)

Autosomal dominant ataxias

• Onset usually in the third to fifth decade of life• Ambulation lost over 10-15 years• Each generation of the pedigree affected

Types-

-Spinocerebellar ataxia (types 1 through 28)-Denatorubropallidoluysian atrophy-Episodic ataxia type 1 and 2

Autosomal recessive taxias

• Onset in childhood or early adolescence• Parenteral consanguinity is common

Types-

-Friedreich's ataxia – ataxia telangiectasia-abetalipoprotienemia-ataxia with isolated vitamin E defiency

Friedreich's ataxia

• Most common type of hereditary ataxia

• Onset before 25 years

• Presents initially with progressive staggering gait and frequent falls .

• The lower limbs are more severely affected than the upper limbs

• Vibration and position senses are lost early

Friedreich's ataxia(cont)

Other features-

-Diabetes

-Cardiomyopathy

-Optic atrophy

-Kyphoscoliosis

-Pes cavus

Friedreich's ataxia(cont)-primary sites of pathology

Spinal cord-

-spinocrebellar tracts,--lateral corticospinal tracts,-posterior columns

• Dorsal root ganglion

• Peripheral nerves

• Cerebellum- slight atrophy

Important features of Freidrich’s ataxia

MRI of brain in a patient with Freidrich’s ataxia

Mitochondrial ataxias

• Due to mutation of mitochondrial DNA

e.g.-

-Myoclonic epilepsy with ragged red fibers (MERRF)

-Mitochondrial encephalopathy , lactic acidosis and stroke like episodes (MELAS)

-Kearns-Sayre disease

Symmetric cerebellar signs

• Acute- intoxication (alcohol , phenytoin barbiturates) , acute viral cerebellitis

• Subacute –intoxication( chemotherapeutic drugs, mercury ,solvents), nutritional deficiency( vit B1 , vit B12,

, vit E).

• Chronic- inherited ataxias, paraneoplastic , phenytoin, hypothyroidism

Unilateral cerebellar signs

• Acute- stroke , cerebellar abscess

• Subacute- neoplasm , demyelinating disease ,AIDS –related multifocal leukoencephalopathy

• Chronic- congeninal malformation , gliosis following stroke/ MS

Approach to a patient with cerebellar ataxiaApproach to a patient with cerebellar ataxia

• Symmetric , progressive and gradual involvement indicates a toxic , degenerative or metabolic cause.

• Focal , unilateral symptoms with headache , vomiting , ipsilateral cranial nerve palsy suggests a space occupying lesion or vascular cause

Approach to patients with cerebellar Approach to patients with cerebellar ataxia (cont)ataxia (cont)

Cerebellar disorders may be –

• Symmetric/ focal and unilateral

• Acute(hours to days)/

subacute (days to weeks)/

chronic (months to years)

Apporach to a patient with cerebellar ataxia (cont)

• In summary , the following features are impotant during evaluating a case of cerebellar ataxia –

-family history-age of onset-drug history-time course of progression-associated neurological and systemic

features