Posterior circulation stroke

1. POSTERIOR CIRCULATION STROKE DR.SARATH CHANDRA CHERUKURI 1 st year PG in general medicine KATURI MEDICAL COLLEGE

2. Stroke or CVA is defined as abrupt onset of neurologic deficit that is attributable to a focal vascular cause. Stroke has occured if the neurologic signs and symptoms last for >24 hours WHAT IS STROKE?

3. It is composed of the paired vertebral artery,basilar artery&paired PCA’s These major arteries give rise to short&long circumferential branches that supply the cerebellum,medulla,pons,midbrain,thalamus,hippocampus and medial temporal&occipital lobes PCA syndromes usually result from atheroma or emboli at the top of basilar artery,fibromuscular dysplasia or vertebral artery dissection STROKE WITHIN POSTERIOR CIRCULATION:

4. TERRITORY OF PCA:

5. TERRITORY OF PCA:

6. P1 SYNDROME: infarction usually occurs in the I/L subthalamus&medial thalamus and in I/L cerebral peduncle&midbrain P2 SYNDROME: Cortical temporal and occipital lobe signs SYNDROMES IN OCCLUSION OF PCA:

7. The VERTEBRAL artery has 4 segments V1,V2,V3&V4 The fourth segment courses upward to join the other vertebral artery to form the basilar artery Only V4 gives rise to branches that supply the brainstem&cerebellum The PICA,in its proximal segment supplies the lateral medulla and in its distal branches the inferior surface of cerebellum BLOOD SUPPLY OF MEDULLA:

8. MEDULLARY SYNDROMES:

9. ON SIDE OF LESION: Pain,numbness,impaired sensation over one-half of face:5 th nerve nucleus Ataxia:restiform body,cerebellar hemisphere,spinocerebellar tract Nystagmus,diplopia,vertigo,nausea,vomting:vestibular nucleus Horner’s syndrome:descending sympathetic tract Dysphagia,paralysis of palate,vocal cord,diminished gag reflex:fibres of 9 th &10 th nerves LATERAL MEDULLARY SYNDROME:

10. 6) Loss of taste:nucleus&tractus solitarius 7) Numbness of I/L arm,trunk&leg : cuneate&gracile nucleus 8) Weakness of lower face:UMN fibres to I/L facial nucleus ON SIDE OPPOSITE LESION: Impaired pain&thermal sense over half the body,sometimes face:Spinothalamic tract

11. On the side of lesion: Paralysis with atrophy of half the tongue: I/L 12 th nerve On the side opposite lesion: Paralysis of arm&leg sparing face;impaired tactile&proprioceptive sense over one half of the body:C /L pyramidal tract&medial leminiscus MEDIAL MEDULLARY OR DEJERINE SYNDROME:

12. Branches of basilar artery supply the base of the pons&superior cerebellum and fall into 3 groups: Paramedian,7-10 in number supply a wedge of pons on either side of midline Short circumferential,5-7 that supply lateral two-thirds of pons&middle,superior cerebellar peduncle B/L long circumferential(SCA&AICA) course around pons to supply the cerebellar hemispheres BLOOD SUPPLY OF PONS:

13. INFERIOR PONTINE SYNDROMES:

14. MEDIAL INFERIOR PONTINE SYNDROME: ON THE SAME SIDE: Paralysis of conjugate gaze to the side of lesion Nystagmus:vestibular nucleus Ataxia:middle cerebellar peduncle Diplopia on lateral gaze:abducens nerve ON THE OPPOSITE SIDE: Paralysis of face,arm&leg:CB&CS tracts Impaired tactile&proproiceptive sense over one-half of body:medial leminiscus

15. LATERAL INFERIOR PONTINE (AICA) SYNDROME: ON THE SIDE OF LESION: Horizontal&vertical gaze nystagmus,vertigo,nausea,vomting:vestibular nerve or nucleus Facial paralysis:7 th nerve Ataxia:middle cerebellar peduncle&cerebellar hemisphere Impaired sensation over face:descending tract&5 th nucleus ON THE SIDE OPPOSITE LESION: Impaired pain and thermal sense over one-half of body

16. MIDPONTINE SYNDROMES:

17. ON THE SIDE OF LESION: Ataxia of limbs and gait- pontine nucleii ON THE SIDE OPPOSITE LESION: Paralysis of face,arm&leg:corticobulbar and corticospinal tracts Variable impaired touch and proprioception:medial leminiscus MEDIAL MIDPONTINE SYNDROME:

18. ON THE SIDE OF LESION: Ataxia:middle cerebellar peduncle Paralysis of muscles of mastication:motor fibres or nucleus of 5 th nerve ON THE SIDE OPPOSITE LESION: Impaired pain and thermal sense on limbs and trunk:spinothalamic tract LATERAL MIDPONTINE SYNDROME:

19. SUPERIOR PONTINE SYNDROME:

20. MEDIAL SUPERIOR PONTINE SYNDROME: ON THE SIDE OF LESION: Cerebellar ataxia:superior /middle cerebellar peduncle Internuclear ophthalmoplegia:MLF Myoclonic syndrome,palate,pharynx,vocal cords-dentate projection,inferior olivary nucleus ON THE SIDE OPPOSITE LESION: Paralysis of face,arm&leg:CB&CS tract Rarely touch,vibration&position:medial leminiscus

21. LATERAL SUPERIOR PONTINE SYNDROME OR SCA OR MILLS’ SYNDROME: ON SIDE OF LESION: Ataxia:middle&superior cerebellar peduncles,dentate nucleus Dizziness,nausea,horizontal nystagmus:Vestibular nucleus Horner’s syndrome:descending sympathetic tract Tremor:red nucleus,superior cerebellar peduncle

22. ON SIDE OPPOSITE LESION: Impaired pain&thermal sense on face,limbs&trunk:spinothalamic tract Impaired touch,vibration&position sense:medial leminiscus

23. MILLARD-GUBLER SYNDROME: I/L LMN type facial nerve palsy&C /L hemiparesis due to involvement of 7 th nerve nucleus&CST FOVILLE’S SYNDROME: I/L LMN type facial nerve palsy&horizontal gaze palsy with C/L hemiparesis due to involvement of horizontal gaze centre,7 th nerve nucleus&CST RAYMOND’S SYNDROME: I/L abducens palsy C/L hemiparesis due to involvement of 6 th cranial nerve&CST CLASSICAL PONTINE SYNDROMES:

24. MIDBRAIN SYNDROMES:

25. MEDIAL MIDBRAIN SYNDROME: ON THE SIDE OF LESION: Eye”down&out ” secondary to unopposed action of 4 th &6 th cranial nerves,with dilated&unresponsive pupil(3 rd cranial nerve) ON SIDE OPPOSITE LESION: paralysis of face,arm,leg (CB&CS tracts in crus cerebri ) LATERAL MIDBRAIN SYNDROME: ON THE SIDE OF LESION: eye down&out ON THE OPP. SIDE: hemiataxia,hyperkinesias,tremor:Red nucleus,dentatorubrothalamic pathway

26. WEBER’S syndrome: third nerve palsy on the I/L side due to involvement of occulomotor nerve fascicles,Hemiplegia on C/L side due to superior cerebral peduncle involvement CLAUDE’S syndrome: I /L 3 rd nerve palsy,C /L ataxia&tremor due superior cerebellar peduncle involvement BENEDIKT’S syndrome: 3 rd nerve palsy on I/L side&C /L side hemiparesis&ataxia due involvement of red nucleus,SCP CLASSICAL MIDBRAIN SYNDROMES:

27. Lesion is dorsal midbrain Structures involved are quadrigeminal plate region,periaqeuductal gray matter Clinical findings: impaired upgaze ; convergence&retraction nystagmus NOTHNAGEL’S SYNDROME: it is more a variant of parinaud’s with U/L or B/L 3 rd nerve palsy.lesion is in midbrain tectum PARINAUD’S SYNDROME:

28. C/L homonymous hemianopia with visual sparing is the usual manifestation ACUTE MEMORY DISTURBANCES:due to medial temporal lobe&hippocampus involvement on the dominant side ALEXIA without agraphia:due to dominant hemisphere plus splenium of corpus callosum involvement PEDUNCULAR HALLUCINOSIS:due to occlusion of PCA P2 SYNDROME:

29. ANTON’S syndrome: B /L infarction in distal PCA produces cortical blindness If the visual association areas are spared and only calcarine cortex is involved,patient may be aware of his blindness BALINT’S syndrome: disorder of orderly visual scanning of the environment due to bilateral visual association area lesions,resulting from infarctions secondary to low flow in the watershed areas between the distal PCA&MCA territories Pallinopsia&asimultognosia may also be seen

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