1. Ischemic Posterior Circulation Stroke Christopher Lewandowski, M. D
Ischemic Posterior Circulation Stroke Christopher Lewandowski, M.D. Residency Program Director Department of Emergency Medicine Henry Ford Hospital, Detroit, MI Sunitha Santhakumar, M.D. Department of Emergency Medicine Henry Ford Hospital, Detroit, MI 54 1 54

2. Case Study
HPI:
The patient is 41 y.o. male, with a past history of alcohol abuse, hypertension who presents to the ED with a chief complaint of right -sided weakness, slurred speech, and loss of balance.
The symptoms began 90 minutes prior to arrival.

3. Case Study PMHx: Medications Social Hx
Alcohol Abuse, quit for 3 years
Hypertension
Seizures, Generalized, none for past 7 years
Medications
Dyazide
Social Hx
Smoking- 2 pack per day
ROS: Mild dizzy spells for the past 2 weeks, each lasting 5-10 minutes

4. Case Study Physical Exam: BP- 149/79, P-100, RR-18, T-36.9
A&Ox3 on presentation, later became stuporous
CN: dysarthria, pupils: R 3.5/ L 3.0 reactive
L facial droop, gaze palsy to the L
Motor: R arm and R leg weakness (3/5)
Sensory: Decreased to light touch and pinprick on R
Coordination: dysmetria on R (not out of proportion to weakness)
NIH Stroke Scale score = 14

5. What does this patient have?
Differential Diagnosis
Stroke
Intracerebral Hemorrhage
Tumor
VBI
Migraine
Seizure

6. Epidemiology Stroke - leading cause of adult disability in the USA
20% of strokes involve the vertebrobasilar arteries
20% of global cerebral blood flow is vertebrobasilar
Vertebrobasilar ischemia ranges from intermittent vascular insufficiency (VBI) to total basilar artery occlusion (BAO)
20% - 60% with unfavorable outcome
Overall mortality 4%, BAO - 90% mortality

7. Risk Factors: Uncontrollable
Age
Stroke risk doubles for every decade over 55
Gender, Males x
Males have a higher risk, but females live longer, therefore there are more female stroke survivors
Heredity
African Americans - 2x
Family History
Previous stroke or TIA - 10x
Diabetes - 3x (even if well controlled)

8. Risk Factors: Controllable
Hypertension - 6x (consistently >140/90)
Atrial Fibrillation - 6x
Smoking - 2x
Hypercholesterolemia > 200
Heart Disease - 2x
Alcohol, (> 4oz/day)
Obesity
BMI > 30
35 inch waist in women, 40 inches in men

9. Risk Factors Vertebrobasilar Ischemia
Risk factors for the Posterior circulation are the same as for the anterior circulation
Hypertension, diabetes mellitus, hyperlipidemia, and tobacco are especially important for the posterior circulation

10. Posterior Circulation Stroke: Anatomy

11. Posterior Circulation Stroke: Anatomy

12. Pathology Atherosclerosis In situ thrombosis Often complete occlusion
90% mortality
Embolization (20%-50%)
Heart or proximal vessels
May cause VBI
Good prognosis
Subclavian steal syndrome
Symptoms brought on by arm exercise
Trauma
Especially in the young
Vertebral artery dissection
Lacunar (small vessel disease)

13. Emergency Department Presentation
Prodrome very common
60 % of patients with Basilar artery thrombosis
Stuttering or progressive onset of symptoms
2 weeks prior to ED presentation

14. Emergency Department Presentation
Prodromal Symptoms (in order of frequency)
Vertigo and Nausea (30%)
Headache, Neckache (20%)
Hemiparesis (10%)
Dysarthria, Diplopia (10%)
Hemianopia ( 6%)
Ferbert, Stroke 1990

15. Emergency Department Presentation
Clinical Findings: Depends on the syndrome
Range: asymptomatic to comatose
The 5 Ds: Dizziness, Diplopia, Dysarthria, Dysphagia, Dystaxia
Hallmarks: Crossed findings
Cranial nerve deficits - Ipsilateral
Motor / Sensory deficits - Contralateral

16. Vertigo
Hallucination of movement of the patient or the environment, not associated with loss of consciousness
Visual, proprioceptive, and vestibular systems maintain position (Romberg test)
Semicircular canals connect to the vestibular nuclei in the brainstem via CN VIII
Vestibular nuclei connect to the cerebellum, MLF (eye movement) and the vestibulospinal tract

17. Nystagmus
Nystagmus means “nodding” off (as in sleeping during this lecture, slow sleep phase with rapid correction)
Nystagmus is named for its fast component
Medial longitudinal fasciculus coordinates the ipsilateral medial rectus (CN III) and the contralateral lateral rectus (CN VI)
Inner ear provides symmetric resting discharge

18. Nystagmus Loss of input from one side leaves the other side unopposed
Unopposed stimulation causes a slow drift toward the diseased side
Cerebral cortex corrects for slow drift with a very rapid return toward a more normal position
The brainstem can compensate for asymmetric peripheral inputs leading to latency, fatigue, and habituation

19. Vertebrobasilar Ischemia: Syndromes
VBI
Common term for TIAs of the vertebrobasilar system
Patients often asymptomatic in ED
Frequent episodes, especially as prodromal sx
Requires evaluation of etiology
Very rare to present as vertigo alone
Difficult to distinguish from other causes of dizziness

20. Was this Patient’s Dizziness Central or Peripheral
Central Peripheral
Intensity Mild Severe
Tinnitis Rare Common
CN findings Frequent None
Nystagmus:
Visual fixation No inhibition Inhibits
Horizontorotary Rare Common
Latency None sec
Fatigue None yes

21. Posterior Circulation Stroke: Syndromes
VBI, brainstem TIAs:
Occur over days-weeks
Intermittent fluctuating brainstem sx
Dizziness plus cranial nerve symptoms
Rarely dizziness alone

22. Vertebrobasilar Ischemia: Syndromes
Branch artery occlusions
Produce a specific stroke syndrome for each artery
Longer and circumfrential arteries
Small penetrating branches supplying midline structures and causing lacunar syndromes
Characterized by the 5Ds and crossed findings
The severity of the stroke depends on the collateral blood flow and the location of the occlusion

23. Posterior Circulation Stroke: Syndromes

24. Vertebrobasilar Ischemia: Syndromes
Basilar artery occlusion
75% with prodromal symptoms
63% with gradual and progressive onset
Can produce a locked-in syndrome
Awake, quadriplegia, bilateral facial and oropharyngeal palsy, preserved vertical gaze
May present comatose if reticular activating system is involved

25. Emergency Department Diagnosis
History
Prodrome
Dizziness
Physical Exam,
Blood pressure in both arms
Diagnostic Studies
Blood tests,CXR, EKG
Imaging

26. Emergency Department Diagnosis
Confirm the Diagnosis (Emergent)
CT Scan
MRI, MRA, DWI
TCD
Angiography (DSA)
Evaluation of Stroke Etiology (Inpatient)
MRA / Angiography
Echo / TEE
TCD
Carotid Doppler

27. Emergency Department Evaluation
CT scan - head, noncontrast
Necessary to rule out intracerebral hemorrhage
Most sensitive test for ICH
Poor for posterior fossa visualization
Bone artifact
Can pick up Basilar artery thrombosis
Highly specific sign, very low sensitivity
CT Angiography (spiral CT)
Reliably assesses basilar artery patency, inconclusive in patients with advanced arterial calcification

28. Case Study: CT Scan

29. Baseline CT scan

30. Emergency Department Evaluation
MRI - long scan times, unavailable, access to patient is poor
Standard MRI, not reliable for ICH in first hours
Major advantage is Posterior Fossa imaging
MR Angiography -reliable evaluation of arteries for VBI, BAO
DWI - Diffusion weighted imaging demonstrates infarcted tissue, this is not a contraindication to thrombolysis

31. MRI-DWI in the posterior fossa

32. Emergency Department Evaluation
TCD
Assesses flow through Vertebrobasilar system
Limited in BAO
Patient anatomy, penetration to distal BA difficult
Brandt: TCD diagnostic in 7 of 19 patients with suspected BAO, 2 of 19 false negatives
Low sensitivity for BAO, not useful in ED

33. Emergency Department Evaluation
Digital subtraction angiography
Gold Standard for diagnosis of BAO
Time consuming, expensive, invasive
Requires patient cooperation, anesthesia
Allows for intra-arterial intervention
Thrombolysis, angioplasty

34. Emergency Department Management
Stabilization
Ensure oxygenation and ventilation
Optimize cerebral blood flow by managing the blood pressure and hydration carefully, as autoregulation lost, ischemic areas become perfusion dependant
Avoid glucose, avoid hypotension, treat fevers aggressively
Evaluate for anticoagulation or thrombolysis

35. Emergency Department Management
Conservative Treatment
Antiplatelet and Antithrombotic
Thrombolytic Treatment
Intravenous: within 3 hours symptom onset and the patient meets all treatment criteria
Intra-Arterial Therapy: infusion of thrombolytic agent into vessel or clot within 24 hours of onset of symptoms

36. Posterior Circulation Stroke: Treatment
Conservative Treatment
Antiplatelet and Anti thrombotic Therapy
Uncontrolled, Retrospective Studies , 1950s & 1960s
Compared to historical controls, patients treated with heparin had lower mortality (8-15% vs %)
Stopped progression of VBI to infarction
TOAST Trial
No evidence to support heparinization in acute stroke

37. Posterior Circulation Stroke: Treatment
Intravenous Thrombolysis
NINDS rt-PA Acute Stroke Trial
t-PA approved within 3 hours of symptom onset
Few posterior circulation strokes

38. Posterior Circulation Stroke: Treatment
Intra-arterial Thrombolysis
No randomized controlled trials completed
Multiple small series and reports
Results (Over 200 patients treated)
Mortality % , assoc. with lack of recanalization
Favorable outcomes in 25%-60%
ICH rate low, 0-15%

39. Posterior Circulation Stroke Future Treatment
Intra-arterial Thrombolysis
Superselective approach, micro-catheters
Angioplasty
Angio-jet

40. What is the prognosis for this patient ?
All Posterior Circulation Strokes
New England Medical Center Posterior Circulation Stroke Registry:
Mortality = 4%
Minor or no Disability = 79%
Locked In Syndrome (Basilar artery occlusion)
Mortality > 90%
How do you know if a patient will progress to locked-in syndrome ? Observation

41. Case Study: Outcome
The patient mental status deteriorated, repeat NIH-SS score was 22
He received intravenous thrombolysis
He had significant early improvement but without complete resolution of symptoms
On day 4, the NIH - SS score was 10
MRA : L sup. cerebellar art. and R&L Ant-Inf cerebellar arteries were non-visualized,
Cardiac evaluation was negative
He was discharged on Coumadin to Rehab

42. Case Study: MRI - DWI <12 Hours 4 Days

43. Summary
Posterior Circulation Strokes are characterized by the 5D’s and crossed findings
Maintain a high index of suspicion for prodromal symptoms - vertigo with CN sx
The locked-in syndrome consists of quadriplegia, bilateral facial and oropharyngeal palsy; but preservation of cortical function and vertical gaze

44. Summary
The prognosis for vertebrobasilar ischemia is generally good, except for locked-in syndrome (basilar artery occlusion)
Treatment consists of conservative therapy (aspirin and heparin) or IV thrombolysis (<3 hrs) or IA thrombolysis (up to 24 hours)

45. Question 1
All of the following are posterior circulation syndromes except:
Ipsilateral CN III palsy with contralateral
hemiplegia
B) Ipsolateral facial palsy with contralateral
C) Hemiaplegia and hemisensory loss of the face arm and leg on one side of the body
D) Ipsilateral ataxia and Horner”s with contralateral
loss of pain and temperature sensation

46. Question 2 Locked-in Syndrome consists of: A) Coma with quadriplegia
B) Bilateral upper extremity weakness greater than lower extremity weakness
C) Quadriplegia, bilateral facial and oropharyngeal palsy but preservation of cortical function and vertical gaze
D) cranial nerve findings contralateral to motor and sensory findings

47. Question 3 Vertigo of central origin is:
A)Generally severe and sudden in onset
B) Is a very common isolated prodromal symptom of VBI
C) Is often associated with tinnitus
D) Fatigues easily
E)Is generally associated with cranial nerve findings

48. Question 4 Proven therapy for posterior circulation stroke includes:
A) Heparin
B) Low molecular weight heparin
C) IV thrombolysis
D) Intra-arterial regional thrombolysis
E) Intra-arterial local thrombolysis

49. Question 5 Overall mortality for posterior circulation strokes is:
B) 20%
C) 40%
D) 70%
E) > 90%

50. Question 6 Mortality for Locked-in Syndrome is: A) < 5% B) 20%