1. Ahoy. Is That a Large Vessel or Small Vessel That I See
Ahoy! Is That a Large Vessel or Small Vessel That I See? Margaret Tremwel MD PhD Stroke Program Medical Director Washington Regional Medical Center Fayetteville, AR

2. Arkansas has one of the highest death rates from stroke in the nation (7th place in 2017)

3. Our Challenge
For persons with a large vessel occlusion (LVO) that requires thrombectomy, time is spent with
Initial triage in the field to arrival at SRH and PCS for tpa and then
Obtaining post tpa CTA to determine if transfer to endovascular center vs hospital that provides post tpa ICU care and then
Transfer to endovascular center

4. Our Challenge
M1, ICA, and tandem ICA/M1 thrombi are associated with low likelihood of thrombolysis with tpa alone; may need endovascular treatment
More distal M2/M3 thrombi have a higher likelihood of partial or complete recanalization with tpa alone
Patients with significant penumbra have better outcomes with successful endovascular therapy
The vulnerability of ischemic tissue that is not yet dead (penumbra) varies from person to person. This can not be determined by CT or CTA.
NIHSS is the best method to predict vessel occlusion but not penumbra

5. Our Advantages
State wide registry available to assist hospitals and EMS track and improve processes and patient outcomes related to stroke care
Training available for EMS and hospital personnel pertaining to care of suspected stroke patients
Telestroke consultation services available in nearly all hospitals

6. Our Advantages
Developing a system of care to provide ‘state of the art’ stroke care for all our residents
We have several Primary Stroke Centers (PSC) in Arkansas providing post tpa ICU care
UAMS as a Comprehensive Stroke Center is available 24/7 for endovascular treatments

7. endovascular thrombectomy, and
Our Challenge
Time is still the BEST predictor of good outcome in persons receiving thrombolysis with tpa,
endovascular thrombectomy, and
combined thrombolysis and thrombectomy

8. Our Challenge
Some hospitals provide post thrombolytic neuro-ICU care and some provide both ICU care and endovascular treatment.
Some patients may need post thrombolytic care only and others with large vessel occlusion (LVO) require additional endovascular treatment. These destinations may be different destinations
Travel costs

9. Our Challenge
How and when do we triage or transfer a patient to the SRH or PSC vs Endovascular Center?
Constellation of stroke symptoms can give us a clue to vascular etiology of stroke
Time from symptom onset:
0-6 hr: presence of penumbra is assumed. All LVO can be treated endovascularly
6-24 hours: need to demonstrate penumbra by imaging

10. Our Challenge
Availability of CT angiography at the transferring hospital
Efficiency of SRH or PSC
Door to needle time
Efficiency of Endovascular Center
Door to start of thrombectomy (groin puncture)

11. Symptoms Associated with Small vs Large Vessel Stroke
Small Vessel: Fiber tract abnormality
Large Vessel: cortical abnormality with or without fiber tract abnormality
Hemiparesis
Hemibody numbness
Isolated ataxia
Aphasia
Monocular visual loss
Neglect
Gaze deviation
Bilateral symptoms (except numbness)
Visual loss
Acute confusion ( but present in many metabolic and neurologic disorders)

12. Characteristics of a Scale that Accurately Predicts LVO
Need a high rate of correctly identifying LVO (Sensitivity (%) = true positive rate). This is the proportion of people with LVO that have a positive test result; ability to identify all LVOs
Need a high rate of correctly identifying absence of LVO (Specificity (%) = true negative rate. This is the proportion of people without an LVO that have a negative test result; ability to correctly identify no LVO

13. Characteristics of a Scale that Accurately Predicts LVO
Positive predictive value is the proportion of patients with a positive test result who have the condition (LVO)
Negative predictive value is the proportion of patients with a negative test result who do not have the condition (LVO). It is not the probability of having an LVO despite a negative test result.
The goal is 30% over-triage for EMS identification of stroke in the field(AHA policy for development of system of care)

14. Scales for triage in the ER
Patients assessed at SRH without CT angiography
NIHSS has the largest validation for predicting LVO when administered by MD or trained nursing
Threshold >10 has sensitivity 73% and specificity 74%
Threshold > 6 has sensitivity 87% and specificity 52%

15. Cortical Symptoms are More Suggestive of LVO and Thrombectomy
Cohort of 543 patients acute stroke in all vascular distributions and stroke mimics
Catagorized by symptom and whether patient had LVO as determined by imaging
Determined the likelihood of each stroke symptom to predict LVO and thrombectomy
Stroke. 2018;49:

16. Comparison of Prehospital Findings to Predict LVO
No LVO
(N=362)
SEN
SPE
PPV
NPV
ACC
hemiparesis
153
170
0.85 ( )
0.53 ( )
0.47 ( )
0.87 ( )
0.64
Any cortical symptom
165
108
0.91 ( )
0.70 ( )
0.60 ( )
0.94 ( )
0.77
Aphasia 85 65
0.47 ( )
0.82 ( )
0.57 ( )
0.76 ( )
0.70
Neglect gaze deviation
137
0.76 ( )
0.68 ( )
0.87 ( )
0.80
Cortical symptom and hemiparesis
142 67
0.79 ( )
0.88 (0.84-0/92)
Cortical symptom or hemiparesis
176
212
0.97 ( )
0.41( )
0.45 ( )
0.97 ( )
0.60
Stroke. 2018;49:

17. Comparison of Prehospital Findings to Predict Thrombectomy
MT (n=109)
No MT (n=434)
SEN
SPE
PPV
NPV
ACC
hemiparesis 95
228
0.87 ( )
0.48 ( )
0.29 ( )
0.94 ( )
0.55
Any cortical symptom 98
175
0.90 ( )
0.60 ( )
0.36 ( )
0.96 (0/ )
0.66
Aphasia 44
106
0.40 ( )
0.76 ( )
0.29 ( )
0.84 ( )
0.69
Neglect gaze deviation 87
115
0.80 ( )
0.74 ( )
0.43 ( )
0.94 ( )
0.75
Cortical symptom and hemiparesis 89
120
0.82( )
0.72 ( )
0.94 ( )
0.74
Cortical symptom or hemiparesis
104
284
0.95 ( )
0.35 ( )
0.27 ( )
0.97 ( )
0.47
Stroke 2018;49:

18. Cortical Symptoms are More Suggestive of LVO and Thrombectomy
Cortical symptoms alone are a reliable indicator of LVO
For LVO: Sensitivity 90% and specificity 70%
For thrombectomy: sensitivity 90% and specificity 60%
Motor symptoms alone
For LVO: Sensitivity 85% and specificity 53%
For thrombectomy: 87% and specificity 48%
Stroke. 2018;49:

19. Comparison of Stroke Scale to Predict LVO
#patient
hemorrhage
# items
Items
cutoff
sen
spe
acc
3I-SS
171 NO 3
LOC ,gaze, motor 4
0.67
0.92
0.86
CPSSS
303
LOC, gaze, arm weakness 2
0.83
0.40
FAST-ED
727 6
Face palsy, arm weakness, speech, gaze, neglect
> 4
0.80
0.89
0.79
LEGS
181
Leg weakness, eyes/visual fields, gaze, speech
0.69
0.81
0.77
RACE
357
YES
Face palsy, arm motor, leg motor, head and gaze deviation, aphasia, agnosia
> 5
0.85
0.68
0.82
PASS
3127
LOC, gaze palsy/deviation, arm weakness
> 2
0.66
0.74
VAN 62
Arm weakness, visual disturbance, aphasia, neglect No
1.0
0.90
Stroke 2018;49:

20. Scenarios for Traige
EMS triage of patients with suspected stroke and direct transfer to endovascular hospital vs stroke ready hospital
No one scale is superior: need more studies
For a good test, the probability of positive LVO could be > 50% depending on the underlying true prevalence, but probability of LVO with a negative test could be > 10%

21. Future Direction
Need studies to evaluate validity of LVO identification scales when administered by EMS
Need decision analysis studies to estimate cost and benefit of triage in the field by EMS to endovascular hospital vs at SRH/PSC.
Need to develop thoughtful triage and transfer policies sensitive to patient need for thrombolytic vs endovascular treatment.
Policies for triage from the field and/or transfer from the SRH or PCS should emphasize delivery of patients to the closest hospital that provides the needed services

22. Future Direction
The receiving hospitals that provide tpa, provide post tpa and endovascular care should demonstrate and publish clinical excellence as achieved through accreditation from highly recognized certification programs
Policies should always emphasize that time to recanalization is the single best predictor of good outcome

23. Time is Brain 1 minute = 2 million dead neurons
10 minute delay = reduces a patients disability free lifetime 40 days.
10 minute delay = increases health cost $10,000
1 minute = reduces a patients life 1 week
Significant time delays on average 2 hours could be prevented if EMS send patients with severe signs of stroke directly to a comprehensive stroke center.

24. Symptoms of Stroke Sudden Onset:
Numbness or weakness of face, arm or leg, especially on one side of the body
Confusion, trouble speaking or understanding
Trouble seeing in one or both eyes
Trouble walking, dizziness, loss of balance or coordination
Severe headache with no known cause

25. Scales Designed to Assist Determination of LVO
NIHSS: considered the gold standard
NIH-EMS: shortened NIHSS emphasizing LOC, motor for face, arm and leg, and dysarthria pt scale
NIH-EMS > 6 sensitivity 70.3% and specificity 80.7%
NIH > 9 sensitivity of 69% specificity of 85%
Not much data repeated to confirm results

26. Scales Designed to Assist Determination of LVO
CPSSS: Cincinnati Prehospital Stroke Severity Scale
Measures conjugate gaze deviation(2), abnormal LOC (1 any abnormality in LOC questions or commands), severe arm weakness ( 1 for inability to maintain arm raised against gravity. Total score 4.
With a cutoff of > 2, 70% sensitivity and 86.8% specificity

27. Scales Designed to Assist Determination of LVO
FAST Plus Test
Measures facial palsy (0-1), Arm motor function(0-1),
Positive if score 1 or 2 for FAST
FAST Plus evaluates severe weakness arm or leg (0-1)
Sensitivity of 93% and specificity 47%
Greater than 50% false positives

28. Scales Designed to Assist Determination of LVO
Rapid Arterial Occlusion Evaluation Scale (RACE)
Based on NIHSS items: facial palsy (0-2), arm and motor function (0-2), leg motor function (0-2), gaze abnormality (0-1) and aphasia or neglect (0-2). Total score 9.
RACE scale > 5, sensitivity 85% and specificity 68%.

29. Scales Designed to Assist Determination of LVO
Prehospital Acute Stroke Severity Scale (PASS)
3 NIHSS scores: LOC (month and age), gaze palsy/deviation, and arm weakness. Total score 3.
Score > 2 is positive, sensitivity 66%, specificity 83%

30. Scales Designed to Assist Determination of LVO
Stroke vision, aphasia, neglect (VAN) assessment
Mild, moderate or severe arm weakness.
If any weakness:
vision disturbance: absent or double
Aphasia: expressive, receptive, both
Neglect: forced gaze or can not track to one side, unable to feel on one side, ignoring one side or recognize ones own arm,
Patient must have weakness and 1 or all of above to be positive
Sensitivity 100% Specificity 90%
Needs large group repeated studies

31. Scales Designed to Assist Determination of LVO
FAST-ED: Field Assessment Stroke Triage for Emergency Destination
Facial palsy (0-1), Arm Weakness (0-2), Speech Change (0-2), Time (document decision making- no points), Eye Deviation (0-2), Denial/Neglect (0-2)
Total 9 points.
Score > 3 sensitivity 71% and specificity 78%.
Score > 4 sensitivity 60% and specificity 89% (higher prevalence of M1 occlusion
Score < 4 had high prevalence of M2 occlusion