Stroke Etiology, Diagnosis and Management

I am getting excited for my Neurology rotation coming up and I thought it would be a good idea to go over some very basic neurology before I start.

Definition - A stroke is the acute neurologic injury that occurs as a result of ischemia or hemorrhage of the brain.

Ischemic Stroke - 80 % of strokes and include the following causes

• Thrombosis - Essentially, the stenosis of a critical artery (MCA, ACA, internal carotids or PCA). You can divide the etiology into extracranial vs intracranial vessels
• Embolism -  refers to particles of debris originating elsewhere that block arterial access to a particular brain region. Common origins of the debris include emboli from atrial fibrillation and from a DVT in a pt with a PFO or septic emboli
• Systemic hypoperfusion - from a circulatory problem causing decreased perfusion to the brain. Causes include blood disorders (Essential thrombocytopenia, PCV, factor V mutation...)

Hemorrhagic Stroke - 10 % of strokes and include the two main subtypes

• Subarachnoid - most often due to a ruptured aneurysm which bleeds directly into the subarachnoid space and CSF. Risk factors for rupture of aneurysm can be remembered by the mnemonic SHAME (Smoking, HTN, Adult Polycystic Kidney Disease, Marfan's Disease and Ehler's Danlos)
• Intracerebral -  most common causes of ICH are hypertension, trauma, bleeding diatheses, amyloid angiopathy, drug use such as amphetamines and cocaine, and vascular malformations

When a patient comes in with stroke symptoms (facial drop, weakness, slurred speech...) what labs and tests should you be ordering?

• CT of the head w/out contrast is the best initial diagnostic test
• O2 Saturation and treat with supplemental O2 if < 94%
• Blood glucose - hypoglycemia can present similar to stroke and severe hypoglycemia can actually cause neurologic damage. Hyperglycemia can cause neurologic damage as well
• INR - can reverse if pt has a high INR
• EKG - check for atrial fibrillation
• BP readings - if stroke is ischemic don't treat unless it is > 220 systolic and can use labetalol. If the patient is a candidate for tPA therapy, the BP needs to be < 185/110 and can treat with nitroprusside or nicardipine

Treatment - Once you have determined whether the stroke is ischemic or hemorrhagic and the cause, you can treat.  All pts are usually admitted to an ICU or floor with nurses trained in post-stroke managment. 

Ischemic Stroke Treatment

• tPA administration is pt is eligible for administration (within the 3 hour window) and has no contraindications (see note)
• Aspirin or if pt is allergic to aspirin, clopidogrel or dipyridamole
• If the EGK showed new onset afib, pt will need to be on a heparin drip before placed on coumadin.  Side note: If a pt is placed on coumadin without bridge therapy, the pt is at risk for warfarin skin necrosis - induced by a transient hypercoagulable state. The initiation of warfarin at standard doses leads to a decrease in protein C anticoagulant activity because if you remember, protein C will deactivate clotting factor VIII. Skin lesions occur secondary to the throbosis and will be seen on the extremities, breasts, trunk, and penis. If a product containing protein C is not rapidly administered, the affected cutaneous areas become edematous and can ultimately become necrotic.
• Echocardiogram
• Carotid angiogram and endarterectomy is the carotid is > 70% stenosed
• Have lorazepam or diazepam ready because post-stroke seizure can be seen in 1 out of 5 pts post stroke

Hemorrhagic 

• FFP if INR is high
• surgical coiling/clipping
• decreased BP to < 165 with nicardipine (a CCB that will also prevent vasospasm)
• Pt's head should be at a 30 degree incline to decrease intracranial pressure 

Contraindications to tPA

• Recent head trauma or stroke within last 3 mo
• Arterial puncture in a noncompressible vessel within the last 7 days - there may be a clot in place that is preventing that recent arterial puncture from bleeding out so you don't want to lyse that clot in particular
• Acute internal bleeding/trauma
• INR > 1.7
• BP > 185/110
• platelets < 100,000
• glucose < 50
• Any hx of intracranial bleed
• hx of a multilobar infarct