11

Localization of Brain Localization of Brain Stem LesionsStem Lesions

22

Anatomy of the Brain StemAnatomy of the Brain Stem

Part of the brain that extends from: Part of the brain that extends from: The rostral plane of the The rostral plane of the Superior ColliculusSuperior Colliculus

To the caudal end of the To the caudal end of the Medulla OblongataMedulla Oblongata at the Foramen Magnum at the Foramen Magnum

Contains Structures:Contains Structures: MidbrainMidbrain PonsPons Medulla OblongataMedulla Oblongata

33

Brain Stem anterior view Brain Stem anterior view   1. Optic chiasm1. Optic chiasm2. Optic nerve2. Optic nerve3. Optic tract3. Optic tract4. Medial sulcus of the crus cerebri4. Medial sulcus of the crus cerebri5. Oculomotor nerve5. Oculomotor nerve6. Pons 6. Pons 7. Pyramidal eminence of the pons7. Pyramidal eminence of the pons8. Retroolivary fossa8. Retroolivary fossa9. Oliva9. Oliva10. Posterolateral sulcus10. Posterolateral sulcus11. Decusssation of the pyramids11. Decusssation of the pyramids12. Anterolateral sulcus12. Anterolateral sulcus13. Lateral funiculus13. Lateral funiculus14. Pyramid14. Pyramid15. Foramen caecum15. Foramen caecum16. Middle cerebellar pedunculus16. Middle cerebellar pedunculus17. Trigeminal nerve17. Trigeminal nerve18. Crus cerebri18. Crus cerebri19. Interpeduncular fossa, 19. Interpeduncular fossa,

posterior perforate substanceposterior perforate substance20. Mammillary body20. Mammillary body21. Tuber cinereum21. Tuber cinereum22. Infundibulum22. Infundibulum

44

Posterior view of the brain stem Posterior view of the brain stem   1.Pineal gland1.Pineal gland2.Thalamus ( Pulvinar )2.Thalamus ( Pulvinar )3.Superior colliculus3.Superior colliculus4.Inferior colliculus4.Inferior colliculus5.Lemniscal trigone5.Lemniscal trigone6.Frenulum veli6.Frenulum veli7.Superior medullary velum7.Superior medullary velum8.Median sulcus8.Median sulcus9.Gracile tubercle9.Gracile tubercle10.Cuneate tubercle10.Cuneate tubercle11.Posterior intermediate sulcus11.Posterior intermediate sulcus12.Posteromedian sulcus12.Posteromedian sulcus13.Vagal trigone13.Vagal trigone14.Hypoglossal trigone14.Hypoglossal trigone15.Striae medullares15.Striae medullares16.Facial colliculus16.Facial colliculus17.Locus coeruleus17.Locus coeruleus18.Parabrachial recess18.Parabrachial recess19.Crus cerebri19.Crus cerebri20.Inferior collicular brachium20.Inferior collicular brachium21.Medial geniculate body21.Medial geniculate body22.Lateral geniculate body22.Lateral geniculate body23.Suoerior collicular brachium23.Suoerior collicular brachium24.Habenula24.Habenula25.Habenular commissure 25.Habenular commissure

55

Brain Stem lateral view Brain Stem lateral view   1. Medial geniculate body1. Medial geniculate body2. Inferior collicular brachium2. Inferior collicular brachium3. Superior colliculus3. Superior colliculus4. Inferior colliculus4. Inferior colliculus5. Superior cerebellar peduncle5. Superior cerebellar peduncle6. Rhomboid Fossa6. Rhomboid Fossa7. Gracile fascicle7. Gracile fascicle8. Cuneate fascicle8. Cuneate fascicle9. Lateral funiculus9. Lateral funiculus10. Pyramid10. Pyramid11. Posterolateral sulcus11. Posterolateral sulcus12. Oliva12. Oliva13. Retroolivary fossa13. Retroolivary fossa14. Bulbopontine sulcus14. Bulbopontine sulcus15. Pons15. Pons16. Trigeminal nerve16. Trigeminal nerve17. Lateral sulcus of the crus cerebri17. Lateral sulcus of the crus cerebri18. Pontomesencephalic sulcus18. Pontomesencephalic sulcus19. Crus cerebri19. Crus cerebri20. Optic nerve20. Optic nerve21. Optic tract21. Optic tract22. Lateral geniculate body22. Lateral geniculate body23. Leminiscal trigone23. Leminiscal trigone24. Middle cerebellar peduncle24. Middle cerebellar peduncle25. Inferior cerebellar peduncle25. Inferior cerebellar peduncle

66

Medulla Oblongata (Myelencephalon)Medulla Oblongata (Myelencephalon) Most caudal Portion of the brainstemMost caudal Portion of the brainstem Extends fromExtends from

The Rostral border of the PonsThe Rostral border of the Pons

Rostral to the emergence of the first spinal rootsRostral to the emergence of the first spinal roots

Join with the spinal cord at the Foramen MagnumJoin with the spinal cord at the Foramen Magnum

77

88

99

1010

Vascular supplyVascular supply

Barainstems Barainstems large regional arterieslarge regional arteries

Has three types of branchesHas three types of branches Para median branchesPara median branches::

supplying midline structuressupplying midline structures Short circumferentialShort circumferential::

supply ventrolateral & lateral surfacesupply ventrolateral & lateral surface Long circumferentialLong circumferential::

Supply posterior structures & Supply posterior structures & CerebellumCerebellum

1111

Brain stem arteries - anterior view Brain stem arteries - anterior view   1. Posterior cerebral artery1. Posterior cerebral artery2. Superior cerebellar artery2. Superior cerebellar artery3. Pontine branches of the basilar artery3. Pontine branches of the basilar artery4. Anterior inferior cerebellar artery4. Anterior inferior cerebellar artery5. Internal auditory artery5. Internal auditory artery6. Vertebral artery6. Vertebral artery7. Posterior inferior cerebellar a.7. Posterior inferior cerebellar a.8. Anterior spinal artery8. Anterior spinal artery

9. Basilar artery9. Basilar artery

1212

Para median Bulbar Para median Bulbar branches (Para median branches (Para median portionportion))

Vertebral arteryVertebral artery and and Anterior spinal arteryAnterior spinal artery

1.1. Hypoglossal NucleusHypoglossal Nucleus

2.2. Medial longitudinal Medial longitudinal fasciculesfascicules

3.3. The pyramidsThe pyramids

4.4. Inferior Olivary Nucleus Inferior Olivary Nucleus (medial part)(medial part)

Lateral bulbar branches Lateral bulbar branches (Lateral portion)(Lateral portion)

Intracranial vertebral Intracranial vertebral artery fourth segment or artery fourth segment or the Posterior inferior the Posterior inferior Cerebellar arteryCerebellar artery

Occasionally the basilar Occasionally the basilar artery or the anterior artery or the anterior Inferior Cerebellar arteryInferior Cerebellar artery

1313

Medullary syndromesMedullary syndromes

Medial Medullary SyndromeMedial Medullary Syndrome

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

(basilar a. lower segment(basilar a. lower segment))

2.Vertebrobasilar dissection2.Vertebrobasilar dissection

3.Dolichoectasia of the vertebrobasilar system3.Dolichoectasia of the vertebrobasilar system

4. Embolism and meningovascular syphilis4. Embolism and meningovascular syphilis

1414

Anterior Spinal a. occlusion (Anterior Spinal a. occlusion (Slide 7Slide 7)) Ipsilateral pyramid, medial lemniscus, hypoglossal nerveIpsilateral pyramid, medial lemniscus, hypoglossal nerveClinical Picture:Clinical Picture:1.1. Ipsilateral paresis, atrophy and fibrallation of the tongue Ipsilateral paresis, atrophy and fibrallation of the tongue

the protruded tongue deviates toward the lesion(HN) (away the protruded tongue deviates toward the lesion(HN) (away from the hemiplegiafrom the hemiplegia

2.2. Contra lateral hemiplegia (Py) (face is spared)Contra lateral hemiplegia (Py) (face is spared)3.3. Contra lateral loss of position and vibration sense (ML) Contra lateral loss of position and vibration sense (ML)

Pain and temperature spared spinothalamic tract is not Pain and temperature spared spinothalamic tract is not affectedaffected

4.4. Occasional upbeat nystagmus (MLF involvement )Occasional upbeat nystagmus (MLF involvement )Bilateral involvemnt givesBilateral involvemnt gives1.1. QuadriparesisQuadriparesis2.2. Bilateral LMN lesion of the tongueBilateral LMN lesion of the tongue3.3. Complete loss position and vibration senseComplete loss position and vibration sense

1515

OccasionallyOccasionally::1.1. HN HN can be spared In Anterior spinal artery occlusioncan be spared In Anterior spinal artery occlusion..

2.2. Only the pyramids can be damaged givingOnly the pyramids can be damaged giving Pure motor hemiplegiaPure motor hemiplegia

3.3. Central facial paresis Corticobulbar fibers descend ipsilaterally before Central facial paresis Corticobulbar fibers descend ipsilaterally before crossing to the facial nucelus of the other side.crossing to the facial nucelus of the other side.

4.4. Crossed motor hemiparesis Lesions of lower medulla of the crossed Crossed motor hemiparesis Lesions of lower medulla of the crossed fibers of the arm and uncrosseds fibers of to the leg.fibers of the arm and uncrosseds fibers of to the leg.

Lateral Medulllary Syndrome( WallenbergLateral Medulllary Syndrome( Wallenberg))

Intracranial vertebral artery or posterior inferior cerebellar artery occlusionIntracranial vertebral artery or posterior inferior cerebellar artery occlusion

Causes:Causes:

1.1. Spontaneous discection of the vertebral arterySpontaneous discection of the vertebral artery

2.2. Medullary neoplasms Usually metastasisMedullary neoplasms Usually metastasis

3.3. Cocaine abuseCocaine abuse

4.4. AbscessAbscess

5.5. Demyelinating diseaseDemyelinating disease

6.6. Radionecrosis, Hematoma, trauma, neck manipulationsRadionecrosis, Hematoma, trauma, neck manipulations

1616

Characteristic Clinical Picture are:Characteristic Clinical Picture are:Results of wedge shaped damage to the lateral medullaResults of wedge shaped damage to the lateral medulla

1.1. Ipsilateral facial hypalgesia & thermoanestesia (Trigeminal spinal Ipsilateral facial hypalgesia & thermoanestesia (Trigeminal spinal n.and tract) Ipsilateral facial painn.and tract) Ipsilateral facial pain

2.2. Contra lateral trunk & extremity hypalgesia & thermoanesthesial (due Contra lateral trunk & extremity hypalgesia & thermoanesthesial (due to Spinothalmic tract)to Spinothalmic tract)

3.3. Ipsilatral palatal pharyngeal and vocal cord paralysis wit dysphagia Ipsilatral palatal pharyngeal and vocal cord paralysis wit dysphagia and dysarthria (Nucleus Ambiguus)and dysarthria (Nucleus Ambiguus)

4.4. Ipsilatral Horners syndrome (Descending sympathetic fibers)Ipsilatral Horners syndrome (Descending sympathetic fibers)

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

6.6. Ipsilateral Cerebellar signs (Inferior cerebellar peduncle and Ipsilateral Cerebellar signs (Inferior cerebellar peduncle and cerebellum)cerebellum)

7.7. Occasionally Hiccups (Medullary respiratory centers) Diplopia (Lower Occasionally Hiccups (Medullary respiratory centers) Diplopia (Lower Pons)Pons)

Rostral medulla( Severe dysphagia, Hoarsness of voice , Facial paresis)Rostral medulla( Severe dysphagia, Hoarsness of voice , Facial paresis)

Caudal medulla (Marked vertigo, nystagmus, gait ataxia)09Caudal medulla (Marked vertigo, nystagmus, gait ataxia)09

1717

Rare manifestatios of Wallenberg’s SyndromeRare manifestatios of Wallenberg’s Syndrome::1.1. Wild arm ataxia ( Lateral Cuneate n.)Wild arm ataxia ( Lateral Cuneate n.)2.2. Ipsilateral limb cllumsiness ( Subolivary area)Ipsilateral limb cllumsiness ( Subolivary area)3.3. Central pain associated with allodyniaCentral pain associated with allodynia4.4. Contralateral hyperhydrosis with ipsilatral anhydrosisContralateral hyperhydrosis with ipsilatral anhydrosis5.5. Inability to sneeze ( Spinal n.of trigeminal N.)Inability to sneeze ( Spinal n.of trigeminal N.)6.6. Loss of taste (N.Tractus Solitarius) lateral zoneLoss of taste (N.Tractus Solitarius) lateral zone7.7. Autonomic dysfunction ( N.Tractus Solitarius Medial caudal zone)Autonomic dysfunction ( N.Tractus Solitarius Medial caudal zone)8.8. Failure of Automatic breating( n. Ambigiuus adjecent Reticular Formation)Failure of Automatic breating( n. Ambigiuus adjecent Reticular Formation)

Ocular motor abnormalitiesOcular motor abnormalities::

1.1. Dysfunction of ocular alignment ( Otolithic vestibular n. damage) Elevation of Dysfunction of ocular alignment ( Otolithic vestibular n. damage) Elevation of the contralateral eye with out vertical displacement of the ipsilatral eye. the contralateral eye with out vertical displacement of the ipsilatral eye. Rssulting in diplopia, head tilt , environmental tiltRssulting in diplopia, head tilt , environmental tilt

2.2. Torsional nystagmusTorsional nystagmus3.3. NystagmusNystagmus4.4. Smooth pursuit and gaze holding abnormality( Cerebe;ar Smooth pursuit and gaze holding abnormality( Cerebe;ar

FlloculusParaaflloculusassoing through the inferior peduncle.FlloculusParaaflloculusassoing through the inferior peduncle.5.5. Lateropulsion or ipsupulsionLateropulsion or ipsupulsion6.6. Abnormalities of saccades (Cerebellum –Amplitudes control not speed ) Abnormalities of saccades (Cerebellum –Amplitudes control not speed )

patients have contralateral hypometra and ipsilateral hypermetrapatients have contralateral hypometra and ipsilateral hypermetra

1818

Other lesionsOther lesions1.1. Isolated vertigo with ipsilatral lateropulsion of the trunk Isolated vertigo with ipsilatral lateropulsion of the trunk

(Medial branch of PICA)(Medial branch of PICA)

2.2. Bilateral cerebellar infarction (PICA) Vertigo, Nystagmus Bilateral cerebellar infarction (PICA) Vertigo, Nystagmus Retropullsion,ataxia,upsidedown vision)Retropullsion,ataxia,upsidedown vision)

3.3. Babinski-Nageotte syndrome (Hemimedullary syndrome) Babinski-Nageotte syndrome (Hemimedullary syndrome) L+M syndrome Intracranial vertebral a.L+M syndrome Intracranial vertebral a.

4.4. Tegmeental medullary lesion –Medullary satietyTegmeental medullary lesion –Medullary satiety

5.5. OpalskiOpalski syndrome LM synd. Ipsilateral hemiplegia Lower syndrome LM synd. Ipsilateral hemiplegia Lower med. Lesion f corticospinal tract after pramidal decusationmed. Lesion f corticospinal tract after pramidal decusation

6.6. Lateral pontomedullary syndrome LM synd. + Pontine Lateral pontomedullary syndrome LM synd. + Pontine findigsfindigs ( (Vll +VIII nerves smptomsVll +VIII nerves smptoms

1919

THE PONSTHE PONS

Anatomy of the PonsAnatomy of the PonsPart of metencephalonPart of metencephalon

Extending caudal plane of striae medullaris posteriorlyExtending caudal plane of striae medullaris posteriorly

To pontomedullar sulcus anteriorlyTo pontomedullar sulcus anteriorly

Inferrior colliculus dorsally and cerebellar peduncles ventrallyInferrior colliculus dorsally and cerebellar peduncles ventrally

Dorsal part referred as Dorsal part referred as TegmentumTegmentum

Ventral part as Basis pontis or Ponto cerebellar portionVentral part as Basis pontis or Ponto cerebellar portion

Contains Cranial Nerve nuclei,Fiber tractsContains Cranial Nerve nuclei,Fiber tracts

2020

2121

2222

Vascular Vascular supplysupply

Paramedian Vessels 4-6 in numberParamedian Vessels 4-6 in number arising from the Basilar a. arising from the Basilar a. supply –Medial basal pons, supply –Medial basal pons,

pontine nucleipontine nucleicortico spinal cortico spinal

fibers fibers

medial leminiscusmedial leminiscus

Short circumferential a.Short circumferential a. arise from Basilar a. enter the arise from Basilar a. enter the

brachium pontis supply brachium pontis supply Ventrolateral basis pontisVentrolateral basis pontis

Long circumferentialLong circumferentialSuperior cerebellar aSuperior cerebellar a....Arise from Basilar a.Arise from Basilar a.Suply : the dorsolateral ponsSuply : the dorsolateral pons

Brachium pontisBrachium pontisDorsal Retiular Dorsal Retiular

formationformationPeriaquidctal regionPeriaquidctal region

Ventrolateral pontine tegmentum Ventrolateral pontine tegmentum occasionaliyoccasionaliy

Anterior inferior cerebellarAnterior inferior cerebellar a. arise a. arise mostly from the basilar a. mostly from the basilar a. supply: lateral tegmentum of supply: lateral tegmentum of the lower two thirds of the the lower two thirds of the ponsponsVentrolateral cerebellumVentrolateral cerebellum

Internal auditory Internal auditory aa. arise from . arise from Basilar a.Basilar a.

Supply: Auditory ,Facial , vestibular Supply: Auditory ,Facial , vestibular NsNs

2323

Pontine SyndromesPontine Syndromes

Ventral pontine syndromeVentral pontine syndrome (Millard –Gubler syndrome)(Millard –Gubler syndrome) Lesion of the ventrocaudal ponsLesion of the ventrocaudal pons Involves basis pontisInvolves basis pontis And fascicles of cranial nerves And fascicles of cranial nerves

Vll,VlVll,Vl

1.1. Contralateral hemiplegia Contralateral hemiplegia (Pyramidal tract)(Pyramidal tract)

2.2. Ipsiaeral lateral rectus paresis Ipsiaeral lateral rectus paresis wit diplopia wit diplopia

3.3. Ipsilateral peripheral facial Ipsilateral peripheral facial paresisparesis

Raymond syndromeRaymond syndrome Lesion of the ventromedial Lesion of the ventromedial

ponspons Affects ipsilaterl Vl NAffects ipsilaterl Vl N Corticospinal tract Corticospinal tract Spares Vll N.Spares Vll N.

1.1. Ipsilateral rectus paresisIpsilateral rectus paresis2.2. Contralateral hemiplegia Contralateral hemiplegia

sparing the face (Pyramidal sparing the face (Pyramidal tract)tract)

2424

Pure Motor HemiparesisPure Motor Hemiparesis Lacunar infarcts in the basis Lacunar infarcts in the basis

pontispontis Involving the corticospinal tractInvolving the corticospinal tract Motor hemiparesis without facial Motor hemiparesis without facial

involvementinvolvementOther lesions that can give similar Other lesions that can give similar

findings:findings: internal internal

capsule (Po. Limb)capsule (Po. Limb)Cerebral peduncleCerebral peduncleMedullary pyramidMedullary pyramid

Vertigo ,dysartira, & gait Vertigo ,dysartira, & gait abnormality favor pontine abnormality favor pontine lesionslesions

Dysarthria-Clumsy hand syndromeDysarthria-Clumsy hand syndrome Vascular leions in the basis Vascular leions in the basis

pontispontis At the junction of the upper one At the junction of the upper one

third and the lower two thirdsthird and the lower two thirds Usually lacunar lesionsUsually lacunar lesionsFacial weaknessFacial weaknessSevere dysarthriaSevere dysarthriaDysphagiaDysphagiaClumsiness and paresis of the handClumsiness and paresis of the handSimilar findings in:Similar findings in:Genu of the internal capsuleGenu of the internal capsuleDeep cerebellar hemorhageDeep cerebellar hemorhage

2525

Ataxic HemipresisAtaxic Hemipresis Lesions basis pontis (U1/3 +L2/3)Lesions basis pontis (U1/3 +L2/3) Lacunar lesions mostlyLacunar lesions mostly Homolateral ataxia & crural Homolateral ataxia & crural

paresisparesis More severe in the lower limbMore severe in the lower limb Occasional :Dysarthria, Occasional :Dysarthria,

nystagmus, paresthesia nystagmus, paresthesia

Similar findings in:Similar findings in:

Thalamocapsular lesionsThalamocapsular lesions

Contralat. post.limb. of int. Contralat. post.limb. of int. capsulecapsule

Contralat. Red nucleusContralat. Red nucleus

Superficial infarcts in the territory of Superficial infarcts in the territory of superficial ant.cerebral a. Para superficial ant.cerebral a. Para central areacentral area

Locked in syndromeLocked in syndrome Bilateral ventral pontine lesionBilateral ventral pontine lesion Due to: Infarction. Tumor. Due to: Infarction. Tumor.

Trauma. Haemorrhage. Central Trauma. Haemorrhage. Central pontine myelinolysispontine myelinolysis

1.1. Quadriplegia Cort.Sp. Lesions Quadriplegia Cort.Sp. Lesions bilat.bilat.

2.2. Aphasia involvement of Aphasia involvement of Cort.Bul. Fibers the lower Cort.Bul. Fibers the lower cranial nerve n. cranial nerve n.

3.3. Occ. Involvement of Occ. Involvement of Vll N Vll N fasciclesfascicles

Patient is fully awake NO damage Patient is fully awake NO damage to the Reticular Formation or to the Reticular Formation or supranuclear oculomotoor supranuclear oculomotoor pathwaypathway

2626

Foville sndromeFoville sndrome Involves dorsa pontine Involves dorsa pontine

tegmentumtegmentum In the caudal third of the ponsIn the caudal third of the pons It consists of:It consists of:1.1. Contralateral hemiplegia due Contralateral hemiplegia due

to corticospinal tract invovmentto corticospinal tract invovment2.2. Ipsilateral facial palsy Ipsilateral facial palsy Vll NVll N3.3. Inabality to move te eye Inabality to move te eye

conjugately to ipsilateral side conjugately to ipsilateral side due to due to Vl N. Vl N. or paramedian or paramedian pontine Reticular formationpontine Reticular formation

Raymond-Cestan-Chenais Raymond-Cestan-Chenais syndromesyndrome

Rostral lesion of the dorsal Rostral lesion of the dorsal ponspons

It consists of :It consists of :1.1. Cerbellar signs Ataxia it coarse Cerbellar signs Ataxia it coarse

Rubral tremorsRubral tremors2.2. Contralatral sensory modalities Contralatral sensory modalities

are reduced ( medial lemniscus are reduced ( medial lemniscus & spinothalamic tract)& spinothalamic tract)

3.3. Ventral extension – Ventral extension – contralateral hemiparesis contralateral hemiparesis (corticospinal tract) (corticospinal tract)

Dorsal Pontine SyndromeDorsal Pontine Syndrome

2727

Paramedian Paramedian PontinePontine syndrome syndrome

Several clinical syndromes existSeveral clinical syndromes exist1.1. Unilateral mediobasal infarcts Unilateral mediobasal infarcts

wit Facio-bracio-crual wit Facio-bracio-crual hemiparesis Dysarthria &and hemiparesis Dysarthria &and homolateral or bilateral ataxiahomolateral or bilateral ataxia

2.2. Unilateral mediolatral basal Unilateral mediolatral basal infarcts: ataxia dysarthria infarcts: ataxia dysarthria slight hemiparesis , ataxic slight hemiparesis , ataxic hemiparesis or clumsy hand hemiparesis or clumsy hand dysarthria syndromedysarthria syndrome

33 Unilateral mediocentral or Unilateral mediocentral or mediotegmental infarctsmediotegmental infarcts

Clumsy hand –dysarthria syndromeClumsy hand –dysarthria syndromeAtaxic hemiparesisAtaxic hemiparesisWithout sensory or eye mov’t disoders Without sensory or eye mov’t disoders

hemiparesis with contralateral hemiparesis with contralateral facial or abducens palsyfacial or abducens palsy

4.4. Bilateral centrobasal infarctsBilateral centrobasal infarctsPseudobulbar palsy & bilateral Pseudobulbar palsy & bilateral

sensorimotor disturbancesensorimotor disturbanceCommon causes areCommon causes are Small vessel Small vessel

disease, vertebrobasilar large disease, vertebrobasilar large vessel disease & Cardiac vessel disease & Cardiac embolism less commmonlyembolism less commmonly

2828

Lateral Pontine syndromeLateral Pontine syndrome

Marie_Foix SyndromeMarie_Foix Syndrome

Lesions affecting the brachium pontisLesions affecting the brachium pontis Isilatral cerebelar ataxia ( celebellar connections)Isilatral cerebelar ataxia ( celebellar connections) Contralatral hemiparesis ( corticospinal tracts) Contralatral hemiparesis ( corticospinal tracts) Contralatral hemianesthesia for pain and tempatureContralatral hemianesthesia for pain and tempature

( spinothalamic tracts)( spinothalamic tracts)

OthersOthers

2929

The mesencephalonThe mesencephalon

Anatomy of the mesencephalonAnatomy of the mesencephalon Rostrally Superior Colliculus-Mamillary body plane Rostrally Superior Colliculus-Mamillary body plane Caudally the plane just caudal to the Inferior ColliculusCaudally the plane just caudal to the Inferior Colliculus Divided in to:Divided in to:

dorsal dorsal TectumTectum

the the tegmentumtegmentum and and

the the cerebral pedunclecerebral peduncle

Contains ascending and descending tracts reticular nuclei and well Contains ascending and descending tracts reticular nuclei and well delinated nuclear masesdelinated nuclear mases

3030

3131

3232

3333

Vascular supply of the MecencephalonVascular supply of the Mecencephalon

Includes PIncludes Paramedian aramedian and and Circumferential vesselsCircumferential vessels Paramedian vesselsParamedian vessels

Arise from the origins of the Posterior Cerebral a.Arise from the origins of the Posterior Cerebral a.

1.1. Thalamoperforating (supplying the thalmusThalamoperforating (supplying the thalmus

2.2. Pedunclar ( supplying the media peduncle) (Midbrain tegmentum Pedunclar ( supplying the media peduncle) (Midbrain tegmentum including Oculomotor n. the Red n. & SN)including Oculomotor n. the Red n. & SN)

Circumferential a.Circumferential a.

Circumferential perpendicular aa.Circumferential perpendicular aa.

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

2.2. Superior cerebellar aa. (Supply Cerebral pedunclesBrachium Superior cerebellar aa. (Supply Cerebral pedunclesBrachium conjunctivum, superior cerebelum)conjunctivum, superior cerebelum)

3.3. Posterior chroidal aa. (supply Cereberal Peduncle lat.sup. Colliculi, Posterior chroidal aa. (supply Cereberal Peduncle lat.sup. Colliculi, Thalamus,Choroid Plexus of the third ventricle)Thalamus,Choroid Plexus of the third ventricle)

4.4. Anterior Choroidal aa.( From Int. Carotid or MCA) Cerebrl peduncle & Anterior Choroidal aa.( From Int. Carotid or MCA) Cerebrl peduncle & supramecencephalic structuresupramecencephalic structure

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

3434

Mesencephalic SyndromesMesencephalic Syndromes Ventral Cranial Nerve lll Ventral Cranial Nerve lll

Fascicular Syndrome (Weber)Fascicular Syndrome (Weber) Lesion Cerebral Peduncle esp. Lesion Cerebral Peduncle esp.

medial pedunclemedial peduncle May damage pyramidal fibersMay damage pyramidal fibers Fascicle of third nerveFascicle of third nerveConsists of:Consists of: Contralateral Hemiplegia Contralateral Hemiplegia

including te lower face(CoS including te lower face(CoS CoB)CoB)

Ipsilateral oculomotor paresis + Ipsilateral oculomotor paresis + parasymp. Cranial N. /// parasymp. Cranial N. /// (Dilated pupil)(Dilated pupil)

Dorsal Cranial N /// faciclular Dorsal Cranial N /// faciclular syndrome(Benedikt)syndrome(Benedikt)

Lesion affecting the tegmentumLesion affecting the tegmentum May affect Brachium conj., Red May affect Brachium conj., Red

n.n. Cranial N. ///Cranial N. ///Consists of:Consists of: Ipsilateral oculomotor paredis Ipsilateral oculomotor paredis

wit dilated pupilwit dilated pupil Contralatera Involuntary mov’t Contralatera Involuntary mov’t

like intention temor ,hemichorea, like intention temor ,hemichorea, hemiatetosis (Destruction Red n.)hemiatetosis (Destruction Red n.)

Dorsal Red n lesions = Dorsal Red n lesions = Brachium conj. Can give similar Brachium conj. Can give similar findings (Claude synd.)findings (Claude synd.)

3535

Dorsal Mesencephalic syndromesDorsal Mesencephalic syndromes Mainly neuroophthalmologic Mainly neuroophthalmologic

abnormalitiesabnormalities (Sylvian aqueduct synd. (Sylvian aqueduct synd.

Parinaud synd.)Parinaud synd.) Commonly seen in: Commonly seen in:

HydrocephalusHydrocephalusTumors of Pineal originTumors of Pineal origin

Consists of :Consists of :1.1. Paralysis of conj. Upward gaze Paralysis of conj. Upward gaze

(downward occ.)(downward occ.)2.2. Pupillary Pupillary

abnormality( usu,Largeabnormality( usu,Large3.3. Convergence retraction Convergence retraction

Nystagmus o upward gazeNystagmus o upward gaze4.4. Pathalogic lid Pathalogic lid

retractionCollier‘s signretractionCollier‘s sign5.5. Lid lagLid lag6.6. ““Pseudo abducens palsy”Pseudo abducens palsy”

Top of the Basilar SyndromeTop of the Basilar Syndrome Oclusive vascular disease Oclusive vascular disease

rostral BArostral BA Usually embolicUsually embolic Giant aneurysmsGiant aneurysms VasculitsVasculits Cerbral angiographyCerbral angiography

Gives infarction of:Gives infarction of: mid brain thalamus portion of mid brain thalamus portion of temporal and occipital lobetemporal and occipital lobe

Consists of :Consists of :1.1. Disorders of eye mov’tDisorders of eye mov’t2.2. Pupillary abnormalityPupillary abnormality3.3. Behavioral abnormalityBehavioral abnormality4.4. Visual field defectsVisual field defects5.5. Motor and sensory deficitsMotor and sensory deficits