Stroke and TIA

Strokes and TIAs Introduction

A stroke is an interruption of blood flow to the brain. There are two main types of strokes: hemorrhagic strokes and ischemic strokes. Strokes are the third leading cause of death in the United States and are the leading cause of disability in the United States.1

Ischemic Stroke: Ischemic strokes are caused by blot clots that inhibit blood flow to the brain. Due to lack of oxygen and nutrients, brain cells die the longer blood flow is occluded. Ischemic strokes can be further divided into thrombotic strokes and embolic strokes. Thrombotic strokes occur when a blood clot forms inside the brain whereas embolic strokes occur when a blood clot forms elsewhere in the body and lodges itself in the brain. Ischemic strokes make up around 87% of all strokes.2

Hemorrhagic Stroke: Hemorrhagic strokes occur when there is a rupture of a blood vessel in the brain or a blood vessel that supplies the brain with blood. This stops the brain from being delivered oxygen or nutrients and causes death of brain tissue. This bleeding can also cause increased ICP (inter-cranial pressure) leading to brain swelling and further anoxic brain injury. Hemorrhagic strokes make up about 13% of all strokes.2

Stroke Screening Tools

Strokes fall under the large umbrella of altered mental status. The key symptoms of a stroke are:

Sudden onset of confusion
Altered mental status
Lack of coordination
Vision or balance issues,
Weakness in the arm, leg, or face, specifically in one side.
Sometimes right before the change in mentation or strength, the patient will report a splitting headache.

There are specific algorithms used to help determine the likelihood of a stroke and one of them is the Cincinnati Prehospital Stroke Scale (CPSS). 3 The CPSS evaluates facial droop, arm drift, and speech on a normal or abnormal scale. This scale has been built upon by many local protocols, with an example being the Portland Prehospital Stroke Screen. The Portland Prehospital Screen accounts for altered mental status being a signature symptom of a stroke by ruling out other common causes of altered mental status prior to prehospital providers calling a stroke alert and mobilizing the stroke team at the receiving hospital. After ruling out causes of altered mental status and acute onset of the condition, the screening process moves to an evaluation similar to the CPSS.

If the prehospital scale states positive, an additional evaluation of the Cincinnati Stroke Triage Assessment Tool is performed. This is a screening

tool used to help prehospital providers determine the chance of large vessel occlusion. If the patient is positive on the CSTAT assessment, it is imperative that they are taken to a stroke center if possible as mechanical thrombectomy is the best possible care for them.

Prehospital Treatment

As usual, start with a scene size-up and provider safety first. Do a primary assessment to make sure the patient is alive and for assessment of ABSs. Stroke patients are generally altered so start an evaluation of altered mental status right away, with no delay as every minute counts when it comes to preserving brain tissue. If you have a high index of suspicion for a stroke, do a quick CPSS right away and look for deficits. Get capillary blood glucose, blood pressure, oxygen saturation, and cardiac rhythm to investigate other possible causes of altered mental status. Work through the stroke screening tools while also considering trauma, infection/sepsis, and drug ingestion or poisoning as well. If the patient is determined to have a stroke, definitive care is at the hospital. EMTs and Paramedics do not have the tools to fix the stroke in the field so rapid transport to the hospital is necessary. Making sure to choose the best destination is important, specifically based on your local protocols. Different hospitals will have different capabilities including some that are able to handle CSTAT negative strokes but not CSTAT positive strokes. It is important to understand the capabilities of the facilities within the area you work and serve. If ALS capabilities are available, establishing a large bore (generally 18ga or larger) IV, allows the hospital to use the IV for CT and speed up the patient treatment course.

Scenario

A construction manager called 911 for a 55-year-old male on his staff with a sudden onset of slurred speech and weakness. Scene Size Up and Primary Survey: Scene is safe and patient is altered, but ABCs appear to be intact Perform a quick and complete altered mental status assessment. Oxygen: 96% CBG: 130 Cardiac: Sinus Rhythm at a rate of 85 Stroke Scale: The patient has a left-sided facial droop and is slurring speech You ask the manager if the patient has been sick recently (possible infection) and he says no. No signs of trauma on physical assessment and no signs of drug use as well. Stroke Scale now determined to be POSITIVE Initiate Rapid Transport:

Gather all necessary information for the patient and initiate rapid transport. CSTAT test shows patient unable to hold arms up and unable to follow commands CSTAT POSITIVE
Transport to nearest stroke center as local protocols allow
Monitor vital signs en route and establish IV access (18ga or larger if possible) Reassess symptoms throughout transport

Final Thoughts EMS do not have the ability to provide definitive care for stroke patients. The most important thing EMS providers can do is quick and complete assessments of altered mental status patients to catch strokes as quickly as possible. Then scene time should be minimized such that almost all interventions are done en-route to the hospital. This decreases time the patient has lack of oxygen to the brain and increases the patients chances at having a positive outcome.