
What is Posterior Cerebral Artery Stroke (Stroke)?
To fully grasp what happens during a posterior cerebral artery (PCA) stroke, it’s important to understand the brain’s structure and blood vessels. The brain has primary blood flow from two sources: the anterior and posterior circulations, which are linked together by the posterior communicating arteries (PCOM), part of the circle of Willis. The circle of Willis, with collateral circulations, steps in to supply blood to parts of the brain when a blockage occurs in the blood vessels.
The posterior blood flow to the brain is provided by various arteries, including the vertebral arteries (VA), the basilar artery (BA), PCA, and PCOM. Notably, the VA, which come from the subclavian arteries, merge to become the BA within the skull. And most of the time, the BA divides into PCAs near the base of the brain.
In many cases, the PCAs, which supply blood to many parts of the brain, originate from the BA. However, at times, they can come from the PCOMs, or a mixture of the two.
The PCA consists of four parts, referred to as P1 to P4. These can be additionally classified into deep and superficial categories.
The deep parts are P1 and P2. The P1 segment, in particular, runs between the end of the BA and the PCOM, and it supplies the upper midbrain and thalamus. The P2, on the other hand, provides blood to specific parts of the thalamus and midbrain, among other areas.
The superficial parts, P3, and P4, supply different areas of the brain. Specifically, P3 is associated with part of the brain called the quadrigeminal segment, while P4 is involved within a groove in the brain called the calcarine fissure, and provides blood to certain parts of the brain.
What Causes Posterior Cerebral Artery Stroke (Stroke)?
Different factors can cause strokes in the part of the brain supplied by the posterior cerebral artery (PCA). These can range from large and small artery diseases, clot formation in the PCA, and other significant arteries like the basilar artery (BA) and vertebral artery (VA), to embolism (blood clots from other parts of the body like the heart, aorta, or due to blood disorders), tearing of the artery wall, bleeding, migraines, certain rare conditions like Moyamoya disease, reversible cerebral vasoconstriction syndrome, and fibromuscular dysplasia, to infections affecting the central nervous system. The most common among these are hardening of the arteries, embolism, and small artery disease.
Blood clots caused by hardened arteries, especially in the VA, BA, and the beginning part of PCA, are one of the primary reasons for large artery disease. Amongst patients with strokes in one or more areas of the brain supplied by PCA, one-third of them had this issue with proximal arteries.
Clots from the heart are the most common type of embolism; these can happen due to various heart conditions, including heart rhythm problems, heart valve diseases, abnormal blood clot formation in the heart, heart muscle enlargement, small holes in the heart, and heart failure.
Stroke due to migraines is hard to diagnose but can cause PCA strokes, typically seen along with blood clot formation in arteries or small holes in the heart. Fibromuscular dysplasia of the basilar artery, although rare, can also lead to multiple strokes, including in the area supplied by PCA.
Some rare conditions, like mitochondrial disease, can also provoke strokes at a young age. Vertebrobasilar Dolichoectasia, a condition that causes elongation and widening of arteries, occasionally results in PCA strokes as well.
Risk Factors and Frequency for Posterior Cerebral Artery Stroke (Stroke)
Stroke is one of the top causes of disability in adults and the fifth leading cause of death in the United States. Each year, around 800,000 people experience a new or recurring stroke, which also results in nearly 140,000 deaths. Currently, there are about 7 million people in the U.S. who have survived a stroke. A stroke is reported every 40 seconds, and sadly, someone dies from a stroke every 4 minutes. African Americans are particularly at risk; they’re almost twice as likely to experience a first stroke than Caucasians, and also have the highest rate of stroke-related deaths.
PCA strokes, a specific type of stroke, occur in about 5% to 10% of cases. Research shows that ‘pure’ PCA strokes made up about 6.1% of stroke cases in one study. Factors like being male and being older also play a role. In fact, the same study showed that over half (55.2%) of the PCA stroke cases were males, and the average age was around 74 years old.
Signs and Symptoms of Posterior Cerebral Artery Stroke (Stroke)
Stroke is a medical emergency, and it’s crucial to note when the symptoms first started, especially since those who have a stroke affecting the back part of their brain may not be aware of their symptoms. Doctors need to figure out when the person was last seen well and behaving normally. Once this piece of information is known, the doctor will get a brief history of the health issue and a complete physical check-up. The doctor will particularly focus on understanding if the patient had any risk factors for stroke. The risk factors for stroke can be classified into two types, unchangeable and changeable.
- Unchangeable risk factors include age, being a male, being African-American, history of transient ischemic attack (TIA) or stroke, having a family history of stroke, and certain blood clotting disorders.
- Changeable risk factors include high blood pressure, diabetes, high cholesterol, smoking, heart conditions like atrial fibrillation or bacterial infection of the inner lining of the heart, birth control pills, drugs like cocaine, unhealthy diet, obesity, not moving around much, and sleep apnea.
People with a stroke in the back part of their brain may be brought into the ER unconscious. Or, they might walk in by themselves. They may only have a headache and mild vision changes like losing vision, seeing double, not being able to see part of their view, difficulty reading or recognizing familiar faces. These symptoms could cause delay in seeking medical help, as they might not be aware they have these issues. Other symptoms they might have include problems on one side of their body, issues with sensation, problems with language, feeling dizzy, vomiting, changes in their thinking or behavior.
The doctor will do a physical exam as soon as the patient arrives. A tool called the National Institutes of Health Stroke Scale (NIHSS) gives a number value to the stroke’s severity and helps guide treatment and predict outcomes. It’s quick, it takes less than 10 minutes, and the scores range from 0 (no issues) to 42 (severely affected). But this tool may underestimate the severity of strokes affecting the back part of the brain compared to those affecting the front part.
A thorough neurologic exam is crucial to understand the issue in depth. The doctor will also check the patient’s heart and neck for abnormal sounds and the legs for signs of a deep vein thrombosis (a blood clot in a vein deep inside the body). The physical exam may show the following:
- Losing half the view on the same side in both eyes but being able to see the center
- Only being able to see the upper or lower quadrant of their view
- Numbness, tingling or other abnormal sensations
- Complete loss of vision or not being aware of their vision loss
- Not able to recognize objects
- Not able to recognize faces
- Not able to read but able to write
- Color blindness
- Problems with language, especially in understanding and naming things
- Problems with memory
- Aggressive behavior
- Seeing things that are not there
- Seeing the afterimage of a visual scene
- Weakness on one side which may or may not be associated with lack of coordination or balance
- Issues with eye movement or the reflex which controls the size of the pupils
- Sleeping excessively

Hemorrhage.
Testing for Posterior Cerebral Artery Stroke (Stroke)
Posterior circulation strokes can be hard to identify due to inconsistent and varying symptoms when they occur. It’s crucial to note the time the stroke began as this is valuable for further testing. Immediate medical care should be provided by checking:
– Vital signs
– Blood glucose levels using a finger-stick test
– Brain scans using non-contrast head computerized tomography (CT)
A system called the Alberta Stroke Program Early CT Score (ASPECTS) assists doctors in evaluating early signs of stroke. It scores up to 10 points, with points deducted for areas of the brain impacted. For posterior circulation strokes, this approach is adjusted to pc-ASPECTS.
Recommended blood tests include complete blood count (CBC), prothrombin time (PT), activated partial thromboplastin time (aPTT), international normalized ratio (INR), electrolytes, comprehensive metabolic panel (CMP), troponin, lipid panel, and A1c. Additional screenings, such as ANA with titers, ESR, CRP, ANCA for vasculitis, a hypercoagulable panel for coagulopathy, and genetic tests might be needed if the stroke’s cause remains unknown after the first round of tests.
Various types of brain scans, including CT, MRI, CT angiogram (CTA), MRA, Doppler ultrasound, PET, and SPECT can help identify the stroke and manage it. In certain instances, a four-vessel angiogram, a more detailed image of the blood vessels in the brain, may be necessary.
Also, any heart problems should be ruled out with tests including an electrocardiogram, chest X-ray, transthoracic echocardiogram, transesophageal echocardiogram, Holter monitoring, and extensive cardiac monitoring.
Treatment Options for Posterior Cerebral Artery Stroke (Stroke)
The 2018 AHA/ASA guidelines cover different stages of care for patients who have experienced an abrupt blockage of blood flow to the brain, known as acute ischemic stroke. These stages vary from pre-hospital care to immediate checks for breathing and oxygen levels. The treatment includes administering a clot-dissolving drug, tissue plasminogen activator (tPA) through an IV. However, such drug this can only be given within the first 4.5 hours after the stroke has occurred.
Matters like the patient’s blood pressure, which should be less than 180/110, and blood sugar level, which should be more than 50 mg/dL, need to be checked before administering the drug. Moreover, it’s essential to ensure the patient does not have any brain bleeding by performing a head CT scan. The recommended dose of tPA is 0.9 mg/kg with a maximum of 90 mg over an hour. About 10% of the total dose should be given initially over the course of one minute.
For patients who are not able to get to a hospital within the 4.5-hour window, other treatment options could still be considered. These include endovascular treatment (EVT), which are procedures that involve direct interaction with the blood vessels in the brain. These treatments can include expanding narrowed blood vessels with a balloon (angioplasty), installing a tiny tube to prop them open (stenting), mechanically removing a clot (mechanical embolectomy), or delivering a clot-dissolving drug directly into the artery (intra-arterial thrombolysis). Such treatments can be given within 6 hours of the stroke occurring and research has shown that they are both safe and effective.
Despite the lack of specific directives, it’s still possible to see good outcomes after some patients receive intra-arterial thrombolysis, specifically, those who have had a stroke in the back of the brain (PCA stroke). Factors that can complicate treating a PCA stroke include not knowing exactly when the symptoms started, the small size of the blood vessels involved, a low score on the National Institutes of Health stroke scale, and the absence of specific guidelines.
Overall, in addition to immediate treatment options, it’s important to prevent future strokes. Depending on what caused the stroke, patients might need to take antiplatelet or anticoagulation medication. It’s also crucial to control risk factors like high blood pressure, high cholesterol levels, and diabetes.
What else can Posterior Cerebral Artery Stroke (Stroke) be?
- Low blood sugar (hypoglycemia)
- Low blood pressure (hypotension)
- A lump found in the areas of the back of the head, side or top of the head
- Migraines
- Multiple sclerosis, a disease affecting the nervous system
- Other forms of stroke occurring in different parts of the brain such as vertebrobasilar stroke, lacunar stroke, or MCA stroke
- Seizures followed by a state of confusion or weakness (postictal state)
- Bleeding in the space between the brain and surrounding membrane (subarachnoid hemorrhage)
- Collection of blood on the surface of the brain (subdural hematoma)
- Temporary weakness in the limbs after a seizure (Todd paresis)
- Inflammation of blood vessels (vasculitis)
What to expect with Posterior Cerebral Artery Stroke (Stroke)
Stroke is a top reason for disability and the fifth main cause of death in the United States. Interestingly, strokes specifically associated with the posterior cerebral artery (PCA) are typically associated with fewer disabilities and deaths compared to other types of strokes.
Recovery from Posterior Cerebral Artery Stroke (Stroke)
Caring for stroke patients requires a team approach which includes experts from physical, occupational, and speech/cognitive therapies. It’s important to closely monitor post-stroke complications to prevent and manage them effectively.
There are a few potential urgent complications during stroke care:
- Patients treated with tPA, a drug used for stroke, may develop severe swelling or angioedema. This could become life-threatening or lead to laryngospasm, where the voice box spasms and tightens, thus making breathing difficult. If this happens, tPA should be stopped right away.
- Negative changes in brain function can occur between 72 and 96 hours after a stroke, especially in cases of bleeding within the brain (hemorrhagic transformation) or severe brain swelling (malignant cerebral edema).
- Fluid can build up in the brain (hydrocephalus) more often when the stroke affects the back part of the brain, compared to the front part. In such cases, a surgical procedure may be needed to drain the excess fluid.
Stroke patients also have a higher risk of blood clot formation, leading to conditions like pulmonary embolism and deep vein thrombosis, especially in the early months due to reduced movement. As a preventive measure, patients in the hospital are usually given medications to prevent blood clots unless it’s not safe, like if they’ve been treated with tPA within 24 hours or if there is bleeding in the brain.
Patients who struggle with swallowing (dysphagia) may require a feeding tube before leaving the hospital. They are also at a higher risk of infections such as pneumonia and urinary tract infections. However, preventive antibiotics are usually not recommended.
There is an increased risk of seizures as well but preventive seizure medication is typically not indicated. It’s also common for stroke patients to experience depression more often in the first year. A medication like fluoxetine can help manage this.
Medication can be used to help with muscle stiffness (spasticity). If oral medication isn’t effective, an injection treatment may be required. Constant or “bedbound” patients run the risk of developing bed sores. For prevention, it is beneficial to change their position every 2 hours. Mobility is encouraged to prevent deep vein thrombosis and general weakness, with the help of family and therapists, whether at the hospital, home, or a nursing facility.
Preventing Posterior Cerebral Artery Stroke (Stroke)
“BEFAST” is a quick and easy-to-remember method anyone can use to spot signs of a stroke, regardless of its cause. A stroke is a serious medical emergency, and quick response time can mean the difference between recovery and permanent damage. Here’s what BEFAST stands for:
- Balance – Did the person suddenly start losing their balance or coordination?
- Eye – Did the person suddenly start having blurred or double vision, or any other vision issues that won’t go away?
- Face – If the person tries to smile, does one or both sides of their face droop?
- Arms – If the person attempts to raise both arms, does one arm fall? Is there sudden weakness or numbness on one side?
- Speech – Is the person speaking in a slurred or confused manner? Can they repeat simple sentences?
- Time – If you notice any of these signs, it’s critical to call 911 immediately. Also, try to remember when the symptoms started.
There are ways you can lower your risk of having a stroke. These include:
- Keeping an eye on your blood pressure
- Managing your cholesterol and blood sugar levels
- Being physically active and maintaining a healthy weight
- Having a healthy diet
- Not smoking
- Managing conditions like sleep apnea
- Having regular medical check-ups