Localization of Brain Stem Lesions

8/12/2019 Localization of Brain Stem Lesions

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Localization of Brain

Stem Lesions


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Anatomy of the Brain Stem

Part of the brain that extends from:

The rostral plane of the Superior Colliculus

To the caudal end of theMedulla Oblongata at the Foramen Magnum

Contains Structures:

Midbrain

Pons

Medulla Oblongata


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Brain Stem anter ior view

1. Optic chiasm

2. Optic nerve

3. Optic tract

4. Medial sulcus of the crus cerebri

5. Oculomotor nerve

6. Pons

7. Pyramidal eminence of the pons

8. Retroolivary fossa

9. Oliva

10. Posterolateral sulcus11. Decusssation of the pyramids

12. Anterolateral sulcus

13. Lateral funiculus

14. Pyramid

15. Foramen caecum

16. Middle cerebellar pedunculus

17. Trigeminal nerve18. Crus cerebri

19. Interpeduncular fossa,

posterior perforate substance

20. Mammillary body

21. Tuber cinereum

22. Infundibulum


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Posterior view of the brain stem

1.Pineal gland2.Thalamus ( Pulvinar )3.Superior colliculus4.Inferior colliculus

5.Lemniscal trigone6.Frenulum veli7.Superior medullary velum8.Median sulcus9.Gracile tubercle10.Cuneate tubercle11.Posterior intermediate sulcus12.Posteromedian sulcus13.Vagal trigone14.Hypoglossal trigone15.Striae medullares16.Facial colliculus17.Locus coeruleus

18.Parabrachial recess19.Crus cerebri20.Inferior collicular brachium21.Medial geniculate body22.Lateral geniculate body23.Suoerior collicular brachium24.Habenula25.Habenular commissure


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Brain Stem lateral view

1. Medial geniculate body2. Inferior collicular brachium3. Superior colliculus4. Inferior colliculus

5. Superior cerebellar peduncle6. Rhomboid Fossa7. Gracile fascicle8. Cuneate fascicle9. Lateral funiculus10. Pyramid11. Posterolateral sulcus

12. Oliva13. Retroolivary fossa14. Bulbopontine sulcus15. Pons16. Trigeminal nerve17. Lateral sulcus of the crus cerebri18. Pontomesencephalic sulcus19. Crus cerebri20. Optic nerve21. Optic tract22. Lateral geniculate body23. Leminiscal trigone24. Middle cerebellar peduncle25. Inferior cerebellar peduncle


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Medulla Oblongata (Myelencephalon)

Most caudal Portion of the brainstem

Extends from

The Rostral border of the Pons

Rostral to the emergence of the first spinal roots

Join with the spinal cord at the Foramen Magnum


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Vascular supply

Barainstems large regional arter ies

Has three types of branches

Para median branches:

supplying midline structures

Short circumferential:

supply ventrolateral & lateral surface

Long circumferential:

Supply posterior structures & Cerebellum


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Brain stem arter ies - anter ior view

1. Posterior cerebral artery

2. Superior cerebellar artery

3. Pontine branches of the basilar artery

4. Anterior inferior cerebellar artery

5. Internal auditory artery

6. Vertebral artery

7. Posterior inferior cerebellar a.

8. Anterior spinal artery

9. Basilar artery


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Para median Bulbar

branches (Para median

portion)

Vertebral arteryand

Anter ior spinal artery

1. Hypoglossal Nucleus

2. Medial longitudinal

fascicules

3. The pyramids

4. I nfer ior Ol ivary Nucleus

(medial part)

Lateral bulbar branches

(Lateral portion)

I ntracranial vertebral

artery fourth segment or

the Poster ior infer ior

Cerebellar artery

Occasionally the basilar

artery or the anter ior

I nfer ior Cerebel lar artery


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Medullary syndromes

Medial Medullary Syndrome

Cause:1. Occlusion of ( vertebral a.), (anter ior spinal a.),

(basilar a. lower segment)

2.Vertebrobasilar dissection

3.Dolichoectasia of the vertebrobasilar system

4. Embolism and meningovascular syphi l is


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Anter ior Spinal a. occlusion (Slide 7)

I psi lateral pyramid, medial lemniscus, hypoglossal nerve

Clin ical Picture:1. I psi lateral paresis, atrophy and fi bral lation of the tongue

the protruded tongue deviates toward the lesion(HN) (away

from the hemiplegia

2. Contra lateral hemiplegia (Py) (face is spared)

3. Contra lateral loss of position and vibration sense (ML)

Pain and temperature spared spinothalamic tract is not

affected

4. Occasional upbeat nystagmus (MLF involvement )

Bilateral involvemnt gives

1. Quadriparesis

2. Bi lateral LMN lesion of the tongue

3. Complete loss position and vibration sense


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Occasionally:1. HN can be spared In Anterior spinal artery occlusion.

2. Only the pyramids can be damaged givingPure motor hemiplegia

3. Central facial paresis Corti cobulbar f ibers descend ipsi laterally before

crossing to the facial nucelus of the other side.

4. Crossed motor hemiparesis Lesions of lower medul la of the crossed

f ibers of the arm and uncrosseds f ibers of to the leg.

Lateral Medull lary Syndrome( Wallenberg)I ntracranial vertebral artery or posterior infer ior cerebellar artery occlusion

Causes:

1. Spontaneous discection of the vertebral artery

2. Medul lary neoplasms Usual ly metastasis

3. Cocaine abuse

4. Abscess

5. Demyelinating disease

6. Radionecrosis, Hematoma, trauma, neck manipulations


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Characteristic Clinical Picture are:

Results of wedge shaped damage to the lateral medul la

1. I psi lateral facial hypalgesia & thermoanestesia (Tr igeminal spinal

n.and tract) I psi lateral facial pain

2. Contra lateral trunk & extr emity hypalgesia & thermoanesthesial (due

to Spinothalmic tract)

3. I psi latral palatal pharyngeal and vocal cord paralysis wit dysphagia

and dysarthr ia (Nucleus Ambiguus)

4. I psi latral Horners syndrome (Descending sympathetic f ibers)

5. Vertigo, nausea, and vomiting (Vestibular nuclei)

6. I psi lateral Cerebellar signs (I nfer ior cerebellar peduncle and

cerebellum)

7. Occasionall y Hiccups (Medul lary respiratory centers) Diplopia (LowerPons)

Rostral medul la( Severe dysphagia, Hoarsness of voice , Facial paresis)

Caudal medul la (Marked vertigo, nystagmus, gait ataxia)09

R if t ti f W ll b S d


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Rare manifestatios of Wallenbergs Syndrome:

1. Wild arm ataxia ( Lateral Cuneate n.)

2. I psi lateral l imb cllumsiness ( Suboli vary area)

3. Centr al pain associated with allodynia

4.

Contralateral hyperhydrosis with ipsilatral anhydrosis5. I nabil ity to sneeze ( Spinal n.of tr igeminal N.)

6. Loss of taste (N.Tractus Solitar ius) lateral zone

7. Autonomic dysfunction ( N.Tractus Soli tari us Medial caudal zone)

8. Failure of Automatic breating( n. Ambigiuus adjecent Reticular Formation)

Ocular motor abnormalities:

1. Dysfunction of ocular alignment ( Otol i thic vestibular n. damage) Elevation of

the contralateral eye with out vertical displacement of the ipsi latral eye.

Rssul ting in diplopia, head til t , envir onmental ti l t

2. Torsional nystagmus3. Nystagmus

4. Smooth pursui t and gaze holding abnormality( Cerebe;ar

F ll oculusParaafl loculusassoing through the infer ior peduncle.

5. Lateropulsion or ipsupulsion

6. Abnormalities of saccades (CerebellumAmplitudes control not speed ) patientshave contralateral hypometra and ipsi lateral hypermetra


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Other lesions

1. I solated vertigo with ipsi latral lateropulsion of the trunk

(Medial branch of PICA)

2. Bi lateral cerebellar infarction (PICA) Vertigo, Nystagmus

Retropullsion,ataxia,upsidedown vision)

3. Babinski-Nageotte syndrome (Hemimedul lary syndrome)

L+M syndrome I ntracranial vertebral a.

4. Tegmeental medul lary lesionMedul lary satiety

5. Opalski syndrome LM synd. I psi lateral hemiplegia Lower

med. Lesion f corticospinal tr act after pramidal decusation

6. Lateral pontomedul lary syndrome LM synd. + Pontine

findigs(Vll +VIII nerves smptoms


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THE PONS

Anatomy of the PonsPart of metencephalon

Extending caudal plane of striae medullaris posteriorly

To pontomedullar sulcus anteriorly

Inferrior colliculus dorsally and cerebellar peduncles ventrallyDorsal part referred as Tegmentum

Ventral part as Basis pontis or Ponto cerebellar portion

Contains Cranial Nerve nuclei,Fiber tracts


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Vascular supply

Paramedian Vessels 4-6 in number

arising from the Basilar a.

supplyMedial basal pons,pontine nuclei

cortico spinal

fibers

medial leminiscus

Short cir cumferential a.

ari se from Basilar a. enter the

brachium pontis supply

Ventrolateral basis pontis

Long circumferential

Superior cerebellar a..

Ar ise from Basilar a.

Suply : the dorsolateral ponsBrachium pontis

Dorsal Retiular formation

Per iaquidctal region

Ventrolateral pontine tegmentum

occasionaliyAnterior inferior cerebellara. arise

mostly fr om the basilar a.

supply: lateral tegmentum of

the lower two thi rds of the

pons

Ventrolateral cerebellum

Internal auditory a. arise fromBasilar a.

Supply: Auditory ,Facial , vestibularNs


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Pontine Syndromes

Ventral pontine syndrome

(MillardGubler syndrome)

Lesion of the ventrocaudal pons

Involves basis pontis

And fascicles of cranial nervesVll,Vl

1. Contralateral hemiplegia

(Pyramidal tract)

2. I psiaeral lateral rectus paresis

wit diplopia

3. I psi lateral per ipheral facial

paresis

Raymond syndrome

Lesion of the ventromedialpons

Af fects ipsil ater l Vl N

Corticospinal tract

Spares Vll N.

1. I psi lateral rectus paresis

2.

Contralateral hemiplegiaspar ing the face (Pyramidal

tract)


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Pure Motor Hemiparesis

Lacunar infarcts in the basis

pontis

I nvolving the corticospinal tract

Motor hemiparesis without facial

involvement

Other lesions that can give similar

findings:

internal capsule (Po. L imb)

Cerebral peduncle

Medullary pyramid

Vertigo ,dysarti ra, & gait

abnormality favor pontine

lesions

Dysarthria-Clumsy hand syndrome

Vascular leions in the basis

pontis

At the junction of the upper one

thi rd and the lower two thirds

Usual ly lacunar lesions

Facial weakness

Severe dysarthr ia

Dysphagia

Clumsiness and paresis of the hand

Simil ar fi ndings in:

Genu of the internal capsule

Deep cerebellar hemorhage


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Ataxic Hemipresis

Lesions basis pontis (U1/3 +L2/3)

Lacunar lesions mostly

Homolateral ataxia & crural

paresis

More severe in the lower l imb

Occasional :Dysarthr ia,

nystagmus, paresthesia

Simi lar f indings in:

Thalamocapsular lesions

Contralat. post.limb. of int.

capsuleContr alat. Red nucleus

Superf icial in farcts in the terr i tory

of superf icial ant.cerebral a.

Para central area

Locked in syndrome

Bilateral ventral pontine lesion

Due to: I nfarction. Tumor.Tr auma. Haemorrhage. Central

pontine myelinolysis

1. Quadriplegia Cort.Sp. Lesions

bilat.

2. Aphasia involvement ofCort.Bul . F ibers the lower

cranial nerve n.

3. Occ. I nvolvement of Vll N

fascicles

Patient is fully awake NO damageto the Reticular Formation or

supranuclear oculomotoor

pathway


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Foville sndrome

I nvolves dorsa pontine

tegmentum

I n the caudal thi rd of the pons

I t consists of:

1. Contralateral hemiplegia due

to corticospinal tr act invovment

2. I psi lateral facial palsy Vll N

3. I nabality to move te eye

conjugately to ipsi lateral side

due to Vl N. or paramedianpontine Reticular formation

Raymond-Cestan-Chenaissyndrome

Rostral lesion of the dorsal

pons

I t consists of :

1. Cerbellar signs Ataxia it coarseRubral tremors

2. Contralatral sensory modalities

are reduced ( medial lemniscus

& spinothalamic tract)

3. Ventral extensioncontralateral hemiparesis

(corticospinal tract)

Dorsal Pontine Syndrome


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Paramedian Pontinesyndrome

Several clinical syndromes exist

1. Uni lateral mediobasal infarctswit Facio-bracio-crualhemiparesis Dysarthr ia & andhomolateral or bilateral ataxia

2. Uni lateral mediolatral basalinfarcts: ataxia dysarthr iasl ight hemiparesis , ataxichemiparesis or clumsy handdysarthr ia syndrome

3 Unilateral mediocentral ormediotegmental infarcts

Clumsy handdysarthria syndrome

Ataxic hemiparesis

Without sensory or eye movt disoders

hemiparesis with contralateralfacial or abducens palsy

4. Bilateral centrobasal infarcts

Pseudobulbar palsy & bilateralsensorimotor disturbance

Common causes areSmall vessel

disease, vertebrobasilar largevessel disease & Cardiacembolism less commmonly


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Lateral Pontine syndrome

Marie_Foix Syndrome

Lesions aff ecting the brachium pontis

I si latral cerebelar ataxia ( celebellar connections)

Contralatral hemiparesis ( corti cospinal tracts)

Contralatral hemianesthesia for pain and tempature

( spinothalamic tracts)

Others


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The mesencephalon

Anatomy of the mesencephalon

Rostrally Superior Colliculus-Mamillary body plane

Caudally the plane just caudal to the Inferior Colliculus

Divided in to:

dorsal Tectum

the tegmentumand

the cerebral peduncle

Contains ascending and descending tracts reticular nuclei and well delinated

nuclear mases


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Vascular supply of the Mecencephalon

Includes Paramedian and Circumferential vessels

Paramedian vessels

Arise from the origins of the Posterior Cerebral a.

1. Thalamoperforating (supplying the thalmus

2. Pedunclar ( supplying the media peduncle) (Midbrain tegmentum

including Oculomotor n. the Red n. & SN)

Circumferential a.

Circumferential perpendicular aa.

1. Quadrigemnial aa.(from PCA supply Sup. & Inf. Colliculi)

2. Superior cerebellar aa. (Supply Cerebral pedunclesBrachium

conjunctivum, superior cerebelum)3. Posterior chroidal aa. (supply Cereberal Peduncle lat.sup. Colliculi,

Thalamus,Choroid Plexus of the third ventricle)

4. Anterior Choroidal aa.( From Int. Carotid or MCA) Cerebrl peduncle &

supramecencephalic structure

5. Posterior Cerebral aa ( Gives branch to Mecencephalic vesels)


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Mesencephalic Syndromes

Ventral Cranial Nerve ll l

Fascicular Syndrome (Weber) Lesion Cerebral Peduncle esp.

medial peduncle

May damage pyramidal f ibers

Fascicle of th ird nerve

Consists of: Contralateral Hemiplegia

including te lower face(CoS

CoB)

I psi lateral oculomotor paresis +

parasymp. Cranial N. /// (Dilatedpupil)

Dorsal Cranial N /// faciclular

syndrome(Benedikt) Lesion affecting the tegmentum

May affect Brachium conj., Red

n.

Cranial N. ///

Consists of: I psi lateral oculomotor paredis

wit dilated pupil

Contralatera Involuntary movtl ike intenti on temor ,hemichorea,

hemiatetosis (Destruction Red n.) Dorsal Red n lesions =

Brachium conj . Can give simil ar

f indings (Claude synd.)

Dorsal Mesencephal ic syndromes


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Dorsal Mesencephal ic syndromes

Mainly neuroophthalmologicabnormalities

(Sylvian aqueduct synd.Parinaud synd.)

Commonly seen in:Hydrocephalus

Tumors of Pineal origin

Consists of :

1. Paralysis of conj. Upward gaze(downward occ.)

2. Pupil lary abnormali ty(usu,Large

3. Convergence retractionNystagmus o upward gaze

4. Pathalogic lidretractionColliers sign

5. L id lag

6. Pseudo abducens palsy

Top of the Basilar Syndrome

Oclusive vascular disease rostralBA

Usually embolic

Giant aneurysms

Vasculits

Cerbral angiography

Gives infarction of:mid brain thalamus portion of

temporal and occipital lobe

Consists of :

1. Disorders of eye movt2. Pupillary abnormality

3. Behavioral abnormality

4. Visual field defects

5. Motor and sensory deficits

Localization of Brain Stem Lesions

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