Update your management of stroke and TIA in primary care. Stroke neurologist, Chris Favilla MD (University of Pennsylvania), walks us through the plumbing of the brain, so we can identify ischemic risks in stroke and TIA patients to prevent recurrences. Learn factors that make a TIA high risk, which imaging studies to order, new research around aspirin dosing, dual antiplatelets, DOACs, cardiac monitoring and more!
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A TIA manifests as a focal neurologic symptom with quick onset to maximal intensity. Dr. Favilla notes, vague, diffuse confusion or bilateral symptoms are rarely TIA.
High risk features for progression of TIA to stroke include recent event, recurrent symptoms of the same vascular territory, high ABCD2 score, and findings of ischemia on MRI.
To workup a stroke or TIA: evaluate the brain parenchyma (MRI without contrast), and follow the plumbing (blood flow) –intracranial vessels (MRA or CTA), neck vessels (MRA, CTA or carotid US), heart (echo and cardiac monitor), and blood.
Choose CTA/MRA as neck imaging (rather than carotid ultrasound) if you’re not sure about anterior vs posterior circulation as the origin of symptoms. A carotid ultrasound will miss posterior circulation atherosclerosis (Dr Favilla’s expert recommendation).
Transient Ischemic Attack (TIA) is a temporary neurologic deficit attributable to vascular ischemia, but not infarction. It can be thought of as a stroke that was fortunate enough to dissolve without lasting pathology. The important thing is differentiating this from other transient neurologic episodes. TIA symptoms last <24 hours and show no sign of infarction on MRI (Panuganti 2019).
Vascular events (stroke and TIA) will be sudden and close to maximal in onset, rather than slowly evolving the way a migraine or seizure could. It should be focal in nature, think in terms of laterality to start narrowing down a vascular territory- symptoms should not be diffuse or scattered. More diffuse symptomatology like confusion or not thinking straight is unlikely to be a TIA or stroke (Simmons 2012).
It can be hard to differentiate complex migraine from TIA since the symptoms can be very similar. For the first complex migraine, evaluate vascular risk factors and consider full TIA workup. Dr. Favilla points out that only after recurrent similar events or in a young person with clear association with headache and photophobia, is the diagnosis of complex migraine most convincing.
The biggest predictor of future stroke is prior stroke on MRI (Giles 2011).
TIA to stroke conversion is a front loaded problem, the longer the time since the TIA the risk tapers off (Simmons 2012)
Patients with recurrent, or fluctuating symptoms (ie two TIAs with the same vascular territory and symptoms a few days apart) are more worrisome. (Chatzikonstantinou 2013)
ABCD2 score can be helpful- age, blood pressure, diabetes history, clinical features, and duration of symptoms to help risk stratify to high, medium, and low risk. Very low ABCD2 scores have very low risk of stroke (1% one week risk, 2-3% 90 day risk) —see MDCalc for Evidence summary. If someone scores high, ie above 3 points, an aggressive short term workup is suggested. Consider hospitalization. (Simmons 2012).
Stroke and TIA are plumbing problems– by tracing your footsteps through the blood flow system to the brain- evaluating intracranial vascular imaging, cervical (carotid) imaging, cardiac imaging, and blood work to look at the fluid going through the vessels you will catch major causes for ischemia.
Order an MRI and CTA or MRA brain to look for intracranial stenosis that localizes to the vascular territory of symptoms (Coutts 2017). There is no need to use contrast. On MRI, look for acute ischemia on diffusion weighted imaging (DWI). Use FLAIR or T2 to look for old injury or chronic infarcts. Microvascular disease (or nonspecific white matter disease) on MRI suggests increased risk of future stroke (Chutinet 2014). Think of the MRI changes as evidence of end organ damage –similar to retinopathy or proteinuria in a diabetic or hypertensive. Chronic embolic appearing infarcts should direct an evaluation for sources of emboli.
Amaurosis fugax/MCA distribution are usually from carotid disease. Check carotid ultrasound, CTA, or MRA of the neck. Dr. Favilla explains that an MRA of the neck vessels without contrast is lower quality. So, order it with contrast!
If someone has a posterior circulation issue (hemifield loss in vision or cerebellar syndrome), then look at the vertebrobasilar syndrome. Carotid ultrasound is insufficient. You’ll need a CTA or MRA. It’s difficult to pick up on hyperacute symptoms in the posterior circulation. Thus, early signs/symptoms are often missed (Merwick 2014). The HINTS exam (Head Impulse Nystagmus and Test of Skew) is a good way to evaluate the possibility of a posterior circulation stroke in the patient who presents with dizziness/vertigo (Curbsiders #49 with David Newman-Toker ) .
Kashlak Pearl: Dr. Favilla notes, it’s a safe bet to choose CTA/MRA as neck imaging (rather than carotid ultrasound) if you’re not sure about anterior vs posterior circulation as the origin of symptoms. A carotid ultrasound will miss posterior circulation atherosclerosis.
Dr. Favilla recommends an echo on everyone with stroke and TIA. Look for risk factors strong enough to warrant anticoagulation. Focus on obvious risks e.g. seriously reduced EF, LV thrombus, valvular vegetations (AHA/ASA Guideline 2014).
Dr. Favilla suggests the bubble study should be reserved for patients younger than 60 years old. It’s difficult to implicate a PFO as the cause of stroke and TIA because because PFOs are common (about 1 in 4 people). The biggest correlation between PFO closure and reduction in stroke is in young patients with cryptogenic stroke (Collado 2018).
Monitoring for arrhythmia is an evolving topic. Patients with a very low probability of afib (e.g. a healthy 30 yo) can be placed on telemetry for 24 hours in the hospital to rule out atrial fibrillation. In contrast, a 75 yo has a high risk of afib, so Dr. Favilla suggests a 28 day monitor or an implantable loop recorder (Thijs 2017).
Send a lipid panel– emphasis on LDL levels. Also, test for other risk factors such as diabetes and/or syphilis. The tests should depend on your practice patterns/patient’s risk factors. Generally, a CBC will be checked for serious abnormalities. There’s no need for a thrombophilia workup. That said, caveats might include very young patients or those with an H&P that suggests thrombophilia (ASA/AHA Guideline 2014).
The TOAST trial (Adams 1993) provides a classification for stroke. Cardioembolic, small vessel (lacunar), large vessel (carotid or intracranial), cryptogenic (no etiology identified 20-25% of strokes after significant eval), or other (drug induced, carotid dissection).
ESUS (embolic stroke of unknown source) is a subgroup of cryptogenic stroke. It’s diagnosed when neuroimaging suggests an embolic source (e.g. bilateral and multiple infarcts), but no clear etiology is found.
In the acute setting, aspirin 325mg is appropriate. For long term prevention, continue aspirin 81 mg daily. Short of a clear, compelling alternative cause for the vascular event (ie afib), aspirin should be continued long term as secondary prevention.
Note: Dosing is controversial at this point! Some data suggest higher doses may be beneficial (e.g. heavier patients might require weight based dosing Rothwell 2018).
The SPARCL Investigators 2006 treated patients with atorvastatin 80 mg. Achieving an LDL of 70 reduced the risk of stroke. However, Dr. Favilla suggests there might be less benefit from aggressive lipid control if another etiology for the stroke is found (ie afib). In these cases, its okay not to push high dose statins.
Dr. Favilla’s view of the literature is that there is no convincing evidence that one antiplatelet is clearly best (aspirin vs aspirin/dipyridamole vs clopidogrel). The CAPRIE study (Creager 1998) showed slight benefit of clopidogrel over aspirin. That said, this needs to be balanced with the higher cost and inconvenience of clopidogrel requiring a prescription.
POINT trial (Johnston 2018) looked at an international population of patients with minor stroke or TIA. Patients were treated with aspirin plus clopidogrel (with loading dose) started within the first 24 hours of symptoms and continuing for 3 months. There was a reduction in stroke and a slight increase in hemorrhage. The CHANCE trial (Wang 2013) had shown the same results in a Chinese population. The benefit to dual antiplatelet is greatest early on. Dr. Favilla suggests there is an adoption of 21 day dual treatment, and then limit to aspirin monotherapy thereafter (expert opinion).
The DOACs (Rivaroxaban, apixaban, dabigatran) are noninferior to warfarin in afib for stroke prevention. Apixaban versus warfarin was the only DOAC to demonstrate superiority and improved mortality (Saraiva 2018).
Listeners will be able to evaluate and treat transient ischemic attacks and ischemic stroke in the acute and chronic setting.
After listening to this episode listeners will…
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Stroke, CVA, cerebrovascular event, TIA, transient ischemic attack, amaurosis, neurology, brain, PFO, afib, ABCD2, lipids, atherosclerosis, antiplatelet, asa, DOAC, imaging, mri, primary care, assistant, care, doctor, education, family, FOAM, FOAMim, FOAMed, health, hospitalist, hospital, internal, internal medicine, internist, meded, medical, medicine, nurse, practitioner, professional, primary, physician, resident, student
Dr Chris Favilla reports no relevant financial disclosures. The Curbsiders report no relevant financial disclosures.
Favilla C, Heublein M, Brigham SK, Okamoto E, Watto MF. “#164 Stroke and TIA Deconstructed”. The Curbsiders Internal Medicine Podcast. http://thecurbsiders.com/episode-list August 5, 2019.
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