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 the Medulla Oblongata at
  the Foramen Magnum
• Contains Structures
• Midbrain
• Pons
• Medulla Oblongata

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• Brain Stem anterior view  1. Optic chiasm2.
  Optic nerve3. Optic tract4. Medial sulcus of
  the crus cerebri5. Oculomotor nerve6. Pons 7.
  Pyramidal eminence of the pons8. Retroolivary
  fossa9. Oliva10. Posterolateral sulcus11.
  Decusssation of the pyramids12. Anterolateral
  sulcus13. Lateral funiculus14. Pyramid15.
  Foramen caecum16. Middle cerebellar
  pedunculus17. Trigeminal nerve18. Crus
  cerebri19. Interpeduncular fossa,
• posterior perforate substance20. Mammillary
  body21. Tuber cinereum22. Infundibulum

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• Posterior view of the brain stem  1.Pineal
  gland2.Thalamus ( Pulvinar )3.Superior
  colliculus4.Inferior colliculus5.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 coeruleus18.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 colliculus5. Superior
  cerebellar peduncle6. Rhomboid Fossa7. Gracile
  fascicle8. Cuneate fascicle9. Lateral
  funiculus10. Pyramid11. Posterolateral
  sulcus12. 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 arteries
• 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 arteries - anterior view  1.
  Posterior cerebral artery2. Superior cerebellar
  artery3. Pontine branches of the basilar
  artery4. Anterior inferior cerebellar artery5.
  Internal auditory artery6. Vertebral artery7.
  Posterior inferior cerebellar a.8. Anterior
  spinal artery
• 9. Basilar artery

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• Para median Bulbar branches (Para median portion)
• Vertebral artery and Anterior spinal artery
• Hypoglossal Nucleus
• Medial longitudinal fascicules
• The pyramids
• Inferior Olivary Nucleus (medial part)

• Lateral bulbar branches (Lateral portion)
• Intracranial vertebral artery fourth segment or
  the Posterior inferior Cerebellar artery
• Occasionally the basilar artery or the anterior
  Inferior Cerebellar artery

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Medullary syndromes

• Medial Medullary Syndrome
• Cause1. Occlusion of ( vertebral a.), (anterior
  spinal a.), (basilar a. lower segment)
• 2.Vertebrobasilar dissection
• 3.Dolichoectasia of the vertebrobasilar system
• 4. Embolism and meningovascular syphilis

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• Anterior Spinal a. occlusion (Slide 7)
• Ipsilateral pyramid, medial lemniscus,
  hypoglossal nerve
• Clinical Picture
• Ipsilateral paresis, atrophy and fibrallation of
  the tongue the protruded tongue deviates toward
  the lesion(HN) (away from the hemiplegia
• Contra lateral hemiplegia (Py) (face is spared)
• Contra lateral loss of position and vibration
  sense (ML) Pain and temperature spared
  spinothalamic tract is not affected
• Occasional upbeat nystagmus (MLF involvement )
• Bilateral involvemnt gives
• Quadriparesis
• Bilateral LMN lesion of the tongue
• Complete loss position and vibration sense

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• Occasionally
• HN can be spared In Anterior spinal artery
  occlusion.
• Only the pyramids can be damaged giving Pure
  motor hemiplegia
• Central facial paresis Corticobulbar fibers
  descend ipsilaterally before crossing to the
  facial nucelus of the other side.
• Crossed motor hemiparesis Lesions of lower
  medulla of the crossed fibers of the arm and
  uncrosseds fibers of to the leg.
• Lateral Medulllary Syndrome( Wallenberg)
• Intracranial vertebral artery or posterior
  inferior cerebellar artery occlusion
• Causes
• Spontaneous discection of the vertebral artery
• Medullary neoplasms Usually metastasis
• Cocaine abuse
• Abscess
• Demyelinating disease
• Radionecrosis, Hematoma, trauma, neck
  manipulations

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• Characteristic Clinical Picture are
• Results of wedge shaped damage to the lateral
  medulla
• Ipsilateral facial hypalgesia thermoanestesia
  (Trigeminal spinal n.and tract) Ipsilateral
  facial pain
• Contra lateral trunk extremity hypalgesia
  thermoanesthesial (due to Spinothalmic tract)
• Ipsilatral palatal pharyngeal and vocal cord
  paralysis wit dysphagia and dysarthria (Nucleus
  Ambiguus)
• Ipsilatral Horners syndrome (Descending
  sympathetic fibers)
• Vertigo, nausea, and vomiting (Vestibular nuclei)
• Ipsilateral Cerebellar signs (Inferior cerebellar
  peduncle and cerebellum)
• Occasionally Hiccups (Medullary respiratory
  centers) Diplopia (Lower Pons)
• Rostral medulla( Severe dysphagia, Hoarsness of
  voice , Facial paresis)
• Caudal medulla (Marked vertigo, nystagmus, gait
  ataxia)09

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• Rare manifestatios of Wallenbergs Syndrome
• Wild arm ataxia ( Lateral Cuneate n.)
• Ipsilateral limb cllumsiness ( Subolivary area)
• Central pain associated with allodynia
• Contralateral hyperhydrosis with ipsilatral
  anhydrosis
• Inability to sneeze ( Spinal n.of trigeminal N.)
• Loss of taste (N.Tractus Solitarius) lateral zone
• Autonomic dysfunction ( N.Tractus Solitarius
  Medial caudal zone)
• Failure of Automatic breating( n. Ambigiuus
  adjecent Reticular Formation)
• Ocular motor abnormalities
• Dysfunction of ocular alignment ( Otolithic
  vestibular n. damage) Elevation of the
  contralateral eye with out vertical displacement
  of the ipsilatral eye. Rssulting in diplopia,
  head tilt , environmental tilt
• Torsional nystagmus
• Nystagmus
• Smooth pursuit and gaze holding abnormality(
  Cerebear FlloculusParaaflloculusassoing through
  the inferior peduncle.
• Lateropulsion or ipsupulsion
• Abnormalities of saccades (Cerebellum Amplitudes
  control not speed ) patients have contralateral
  hypometra and ipsilateral hypermetra

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• Other lesions
• Isolated vertigo with ipsilatral lateropulsion
  of the trunk (Medial branch of PICA)
• Bilateral cerebellar infarction (PICA) Vertigo,
  Nystagmus Retropullsion,ataxia,upsidedown vision)
• Babinski-Nageotte syndrome (Hemimedullary
  syndrome) LM syndrome Intracranial vertebral a.
• Tegmeental medullary lesion Medullary satiety
• Opalski syndrome LM synd. Ipsilateral hemiplegia
  Lower med. Lesion f corticospinal tract after
  pramidal decusation
• Lateral pontomedullary syndrome LM synd.
  Pontine findigs (Vll VIII nerves smptoms

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THE PONS

• Anatomy of the Pons
• Part of metencephalon
• Extending caudal plane of striae medullaris
  posteriorly
• To pontomedullar sulcus anteriorly
• Inferrior colliculus dorsally and cerebellar
  peduncles ventrally
• Dorsal part referred as Tegmentum
• Ventral part as Basis pontis or Ponto cerebellar
  portion
• Contains Cranial Nerve nuclei,Fiber tracts

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• Long circumferential
• Superior cerebellar a..
• Arise from Basilar a.
• Suply the dorsolateral pons
• Brachium pontis
• Dorsal Retiular formation
• Periaquidctal region
• Ventrolateral pontine tegmentum occasionaliy
• Anterior inferior cerebellar a. arise mostly from
  the basilar a. supply lateral tegmentum of the
  lower two thirds of the pons
• Ventrolateral cerebellum
• Internal auditory a. arise from Basilar a.
• Supply Auditory ,Facial , vestibular Ns

• Vascular supply
• Paramedian Vessels 4-6 in number arising from
  the Basilar a. supply Medial basal pons,
  pontine nuclei cortico spinal fibers
  medial leminiscus
• Short circumferential a.
• arise from Basilar a. enter the brachium pontis
  supply Ventrolateral basis pontis

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Pontine Syndromes

• Ventral pontine syndrome
• (Millard Gubler syndrome)
• Lesion of the ventrocaudal pons
• Involves basis pontis
• And fascicles of cranial nerves Vll,Vl
• Contralateral hemiplegia (Pyramidal tract)
• Ipsiaeral lateral rectus paresis wit diplopia
• Ipsilateral peripheral facial paresis

• Raymond syndrome
• Lesion of the ventromedial pons
• Affects ipsilaterl Vl N
• Corticospinal tract
• Spares Vll N.
• Ipsilateral rectus paresis
• Contralateral hemiplegia sparing the face
  (Pyramidal tract)

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• Pure Motor Hemiparesis
• Lacunar infarcts in the basis pontis
• Involving the corticospinal tract
• Motor hemiparesis without facial involvement
• Other lesions that can give similar findings
  internal capsule (Po. Limb)
• Cerebral peduncle
• Medullary pyramid
• Vertigo ,dysartira, gait abnormality favor
  pontine lesions

• Dysarthria-Clumsy hand syndrome
• Vascular leions in the basis pontis
• At the junction of the upper one third and the
  lower two thirds
• Usually lacunar lesions
• Facial weakness
• Severe dysarthria
• Dysphagia
• Clumsiness and paresis of the hand
• Similar findings in
• Genu of the internal capsule
• Deep cerebellar hemorhage

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• Locked in syndrome
• Bilateral ventral pontine lesion
• Due to Infarction. Tumor. Trauma. Haemorrhage.
  Central pontine myelinolysis
• Quadriplegia Cort.Sp. Lesions bilat.
• Aphasia involvement of Cort.Bul. Fibers the
  lower cranial nerve n.
• Occ. Involvement of Vll N fascicles
• Patient is fully awake NO damage to the Reticular
  Formation or supranuclear oculomotoor pathway

• Ataxic Hemipresis
• Lesions basis pontis (U1/3 L2/3)
• Lacunar lesions mostly
• Homolateral ataxia crural paresis
• More severe in the lower limb
• Occasional Dysarthria, nystagmus, paresthesia
• Similar findings in
• Thalamocapsular lesions
• Contralat. post.limb. of int. capsule
• Contralat. Red nucleus
• Superficial infarcts in the territory of
  superficial ant.cerebral a. Para central area

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Dorsal Pontine Syndrome

• Foville sndrome
• Involves dorsa pontine tegmentum
• In the caudal third of the pons
• It consists of
• Contralateral hemiplegia due to corticospinal
  tract invovment
• Ipsilateral facial palsy Vll N
• Inabality to move te eye conjugately to
  ipsilateral side due to Vl N. or paramedian
  pontine Reticular formation

• Raymond-Cestan-Chenais syndrome
• Rostral lesion of the dorsal pons
• It consists of
• Cerbellar signs Ataxia it coarse Rubral tremors
• Contralatral sensory modalities are reduced (
  medial lemniscus spinothalamic tract)
• Ventral extension contralateral hemiparesis
  (corticospinal tract)

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Paramedian Pontine syndrome

• Several clinical syndromes exist
• Unilateral mediobasal infarcts wit
  Facio-bracio-crual hemiparesis Dysarthria and
  homolateral or bilateral ataxia
• Unilateral mediolatral basal infarcts ataxia
  dysarthria slight hemiparesis , ataxic
  hemiparesis or clumsy hand dysarthria syndrome

• Unilateral mediocentral or mediotegmental
  infarcts
• Clumsy hand dysarthria syndrome
• Ataxic hemiparesis
• Without sensory or eye movt disoders hemiparesis
  with contralateral facial or abducens palsy
• Bilateral centrobasal infarcts
• Pseudobulbar palsy bilateral sensorimotor
  disturbance
• Common causes are Small vessel disease,
  vertebrobasilar large vessel disease Cardiac
  embolism less commmonly

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Lateral Pontine syndrome

• Marie_Foix Syndrome
• Lesions affecting the brachium pontis
• Isilatral cerebelar ataxia ( celebellar
  connections)
• Contralatral hemiparesis ( corticospinal 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 tegmentum and
• 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.
• Thalamoperforating (supplying the thalmus
• Pedunclar ( supplying the media peduncle)
  (Midbrain tegmentum including Oculomotor n. the
  Red n. SN)
• Circumferential a.
• Circumferential perpendicular aa.
• Quadrigemnial aa.(from PCA supply Sup. Inf.
  Colliculi)
• Superior cerebellar aa. (Supply Cerebral
  pedunclesBrachium conjunctivum, superior
  cerebelum)
• Posterior chroidal aa. (supply Cereberal Peduncle
  lat.sup. Colliculi, Thalamus,Choroid Plexus of
  the third ventricle)
• Anterior Choroidal aa.( From Int. Carotid or MCA)
  Cerebrl peduncle supramecencephalic structure
• Posterior Cerebral aa ( Gives branch to
  Mecencephalic vesels)

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Mesencephalic Syndromes

• Ventral Cranial Nerve lll Fascicular Syndrome
  (Weber)
• Lesion Cerebral Peduncle esp. medial peduncle
• May damage pyramidal fibers
• Fascicle of third nerve
• Consists of
• Contralateral Hemiplegia including te lower
  face(CoS CoB)
• Ipsilateral oculomotor paresis parasymp.
  Cranial N. /// (Dilated pupil)

• Dorsal Cranial N /// faciclular
  syndrome(Benedikt)
• Lesion affecting the tegmentum
• May affect Brachium conj., Red n.
• Cranial N. ///
• Consists of
• Ipsilateral oculomotor paredis wit dilated pupil
• Contralatera Involuntary movt like intention
  temor ,hemichorea, hemiatetosis (Destruction Red
  n.)
• Dorsal Red n lesions Brachium conj. Can give
  similar findings (Claude synd.)

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• Dorsal Mesencephalic syndromes
• Mainly neuroophthalmologic abnormalities
• (Sylvian aqueduct synd. Parinaud synd.)
• Commonly seen in Hydrocephalus
• Tumors of Pineal origin
• Consists of
• Paralysis of conj. Upward gaze (downward occ.)
• Pupillary abnormality( usu,Large
• Convergence retraction Nystagmus o upward gaze
• Pathalogic lid retractionColliers sign
• Lid lag
• Pseudo abducens palsy

• Top of the Basilar Syndrome
• Oclusive vascular disease rostral BA
• Usually embolic
• Giant aneurysms
• Vasculits
• Cerbral angiography
• Gives infarction of
• mid brain thalamus portion of
• temporal and occipital lobe
• Consists of
• Disorders of eye movt
• Pupillary abnormality
• Behavioral abnormality
• Visual field defects
• Motor and sensory deficits