What is Anterior Cerebral Artery Stroke (Stroke)?
Infarcts, or tissue death, in the area served by the anterior cerebral artery (ACA) are rare, making up only a small portion of all stroke cases caused by the blockage of blood flow (ischemic infarcts). The risk factors causing these strokes are the same as other major brain arteries: high blood pressure, high cholesterol, diabetes, smoking, artery hardening, and blood clots from the heart. However, the unique symptoms of strokes in this part of the brain and potential for unnoticed (or “silent”) strokes could lead to these strokes being underdiagnosed.
The ACA is a vital artery in your brain. It starts from a section of the large artery that brings blood to the brain (the internal carotid artery), before moving forward and inward towards a deep groove in the brain’s surface. It’s there where another artery forms, linking the two ACAs. From this point, each ACA moves between and over the two halves of the brain towards the back. Along its route, it sprouts off smaller arteries named after the parts of the brain they serve. The ACA typically divides into five segments, labeled A1 through A5, or grouped into three main sections: proximal (A1), ascending (A2, A3), and horizontal.
One interesting feature of the ACA is its strong network of connections with other arteries, which could contribute to the low occurrence of strokes here. Interestingly, strokes affecting both halves of the brain can also happen, though these are rare. They typically result from significant variations in the structure of both ACAs at any point along its path. Some recognizable variations include a single (azygos), two-sided (bihemispheric), and ACA with a small or missing first segment.
What Causes Anterior Cerebral Artery Stroke (Stroke)?
High blood pressure, high cholesterol, diabetes, and smoking are all known risk factors for heart disease that are often seen in patients who have had a stroke. These factors can lead to a condition called atherosclerosis, where the arteries get blocked with fatty build-ups. Atrial fibrillation, an irregular and often fast heart rate, is also a significant risk factor and is more common than high cholesterol in patients who have had a specific type of stroke known as ACA stroke.
Atherosclerosis is a leading cause of ischemic stroke, a type which happens when blood can’t flow to certain sections of the brain. One medical study using imaging technology found that atherosclerosis-related strokes in the ACA, a part of the brain, were the same as those found in another part called the MCA. A stroke caused by atherosclerosis usually happens because of -> a blockage in a local branch of the artery caused by plaque, a small fragment of hardened cholesterol <- or an in-place blood clot. The last one is the most common cause of ACA infarction, a type of stroke. Atherosclerosis is the most reported cause among Asian patients in particular. Heart embolism, a condition where a piece of a blood clot travels to the heart, can also cause ACA infarction. This can result from different sources, including atrial fibrillation, a blood clot inside the heart, diseases of heart valves, and tumors. Some studies suggest that heart embolism more commonly causes ACA strokes than strokes in other parts of the brain. A hypoplastic or absent A1 segment, a specific part of the artery, is suggested to enables embolic strokes due to increased blood flow through this unique section. Arterial dissection, a tear in the inner lining of an artery, is another important cause of ACA strokes. While it's rarely reported in Western populations, high prevalence is observed among Japanese patients. These strokes often happen in younger people. Other less common causes include inflammation of blood vessels called vasculitis and imbalances in the proteins responsible for blood clotting. Another cause is called vasospasm, a sudden constriction of a blood vessel, which can be triggered by things like bleeding in the space surrounding the brain or a sudden, usually severe headache often accompanied by nausea, vomiting, and a brief loss of consciousness. Finally, a type of stroke called distal vessel occlusion can also occur as a result of lost or fragmented blood clots associated with procedures like thrombolysis and mechanical thrombectomy, treatments to break up or remove clots. One study found that this was a potential cause in 11.4% of the studied cases and could result in negative outcomes following these procedures.
Risk Factors and Frequency for Anterior Cerebral Artery Stroke (Stroke)
Infarctions, or blockages, in the anterior cerebral artery (ACA) and its branches are quite rare, contributing to between 0.3% and 4.4% of all cases of strokes. Studies indicate that men seem to get these infarctions more frequently than women. Those affected are generally older, with average ages reported between 59 and 74.4 years. It’s also been noticed that these ACA blockages are more common in people over the age of 85. Another noteworthy observation is that these blockages tend to occur more often on the left side of the ACA.
- Infarctions in the ACA are rare, making up about 0.3% to 4.4% of stroke cases.
- Males are generally more affected by these infarctions than females.
- The average age of patients with ACA infarction is between 59 and 74.4 years.
- The prevalence of ACA infarctions is higher in people aged over 85.
- These infarctions are more common on the left side of the ACA.
Signs and Symptoms of Anterior Cerebral Artery Stroke (Stroke)
People who suffer a stroke that affects the anterior cerebral artery (ACA) may experience different symptoms depending on which area of the artery or its branches are affected. The size of the stroke also influences symptoms. Most often, patients will have weakness in the leg on the opposite side of the body from where the stroke occurred. This is common in about 86.3% to 90% of patients.
Other symptoms may include weakness on the opposite side of the face and arm resulting from damage to specific regions in the brain. Some people may experience a condition composed of uncoordinated movements and weakness in the leg on the same side. There have been cases of patients with isolated weakness impacting muscles along the spine due to strokes in the brain’s motor cortex. Other possible motor disorders related to an ACA stroke can include reduced range of movement, slowed movements, complete lack of movement, loss of coordination, unsteady gait, tremors, abnormal muscle contractions, and inability to acknowledge motor deficits. A rare disorder, where one hand appears to act on its own without the patient’s control can occur due to damage in specific regions of the brain.
Sensory deficits are less common. If they do occur, they are often associated with a weak limb. Patients may also present with a range of neurological and psychological symptoms such as lack of initiative, restlessness, repetitive movement, memory impairments, emotional instability, incontinence, and unawareness of their condition. Altered consciousness and speech disorders have also been identified in patients with ACA infarcts. Some patients may experience a type of aphasia, a condition that affects the ability to communicate, after a period of muteness.
It is rare for a stroke to affect both ACAs. In such cases, patients may show signs of impulsive behaviour such as repetitive blinking, forceful grasping, puckering of the lips, or other primitive reflexes. These episodes often happen even when areas of the brain involved in managing these behaviours are not affected by the stroke. Bilateral ACA stroke can also result in paralysis or weakness of the limbs and conditions such as immobility combined with muteness.
Headaches may also be associated with an ACA infarction, especially if it is a result of an arterial dissection, which is a tear in the inner lining of the artery.
Testing for Anterior Cerebral Artery Stroke (Stroke)
When a person is suspected to have had an acute ischemic stroke, there are specific steps that doctors take to confirm this. Firstly, they assess the patient’s airway, breathing, and circulation, check their blood sugar levels, and find out the exact time when the symptoms first appeared or when the patient was last well. They also use a standardized method called the National Institutes of Health Stroke Scale (NIHSS), which helps quantify stroke symptoms. This scale ranges from 0 to 42, with a higher score indicating a higher likelihood of disability. However, what counts as “disabling” varies depending on factors like a person’s age, job, existing health conditions, and any advanced directives they have.
The central part of stroke evaluation is to employ brain imaging to identify the type and characteristics of the stroke. The preferred method of imaging in these cases is a non-contrast computed tomography (CT) of the head. This scan can help determine whether the stroke is acute, subacute, or chronic based on when the symptoms started. It can also rule out any intracranial hemorrhage. If hemorrhage is present, doctors have to look into a potential aneurysmal rupture, which could lead to a stroke. A CT scan might miss some anterior cerebral artery strokes based on their location or size. In such cases, contrast injection or angiography can often spot them.
Occasionally, a CT scan spots a dense lesion in the anterior cerebral artery. This can help diagnose a stroke in its early stages, especially when it’s hard to identify using other methods. The chance of spotting such a sign with this type of stroke is as probable as spotting it with other types of strokes.
Other than CT scans, Magnetic Resonance Imaging (MRI) plays an essential role in diagnosing strokes that affect the anterior cerebral artery. A type of MRI, known as diffusion-weight imaging (DW-MRI), is particularly valuable as it helps to pinpoint the exact boundaries of the ischemic area in the brain’s anterior cerebral artery territory. An MR angiography can also be used to help understand what has caused the stroke.
In terms of timing, the goal is to finish either a head CT or MRI within 25 minutes following a patient’s arrival at the hospital. The National Institutes of Neurological Disorders and Stroke (NINDS) have set some time-related goals for evaluating stroke patients, such as reaching a doctor within 10 minutes of arriving, getting to the stroke team within 15 minutes, and getting any medication within 60 minutes.
Alongside this rapid and thorough imaging, doctors will run lab tests which may include checking the blood glucose level, complete blood count, chemical balance, blood clotting ability, how well the body has been controlling the blood glucose levels over the previous three months (hemoglobin A1c), and fat content in the blood. They will also look for any signs of increased clot formation or inflammation. A medication checklist, which specifically takes note of any recent use of blood thinners, is seen as vital, as this might nécessitate a fast assessment of whether breaking up the blood clot (thrombolysis) can be executed safely. Additionally, the diagnosis may involve checking for heart origin of blood clots via an electrocardiogram (EKG) and an echocardiogram.
Treatment Options for Anterior Cerebral Artery Stroke (Stroke)
Pulse oximetry is a tool that helps regulate the use of extra oxygen to maintain blood oxygen levels above 94%. In patients suffering from a stroke, too much oxygen can be harmful. High blood pressure is often seen during a stroke, a low blood pressure may mean a worsening of a prior stroke due to poor blood flow. If the blood pressure reaches 220/120 mmHg, it should be treated. There is a general practice of allowing high blood pressure up to 220/120 mmHg for patients who aren’t suitable for clot-dissolving treatments.
However, for patients who qualify for the drug alteplase, blood pressure control should begin immediately, with the goal of reaching a blood pressure of 185/110 mmHg. It’s preferable to use drugs that can steadily lower blood pressure to avoid dropping it too much. Some possible drugs include labetalol, nicardipine, clevidipine, hydralazine, and enalaprilat.
Quick decision-making is crucial for patients who come in during the therapeutic window-period when treatment is most effective. These patients can be eligible for treatment with intravenous alteplase (administered within 4.5 hours of the first symptoms) or for a mechanical thrombectomy. Currently, it’s recommended that alteplase treatment starts between 3 to 4.5 hours of symptom onset in patients under 80 without a history of diabetes and prior stroke, those not on anticoagulants, and with an NIHSS score below 25. According to studies, administering alteplase decreases disability after a stroke, but only patients with serious symptoms are considered for this treatment.
Unfortunately, over half the patients come in after the therapeutic window has closed and thus, cannot be treated with thrombolysis. This delay might be due to misjudging the symptoms as stroke, and the harm increases with time since symptom onset. This concern is particularly relevant in cases of Anterior cerebral artery (ACA) strokes, which might not display typical symptoms.
Another effective treatment for acute stroke is mechanical thrombectomy (MT), but it is strongly dependent on time. This treatment is only available at specialist hospitals and requires a skilled stroke team who can perform the procedure promptly. The outcomes from MT are frequently unsatisfactory in patients with ACA stroke, likely because of greater ischemic damage and longer times to remove the clot.
New guidelines suggest that for stroke patients detected within 6 to 24 hours with a large vessel blockage in the anterior circulation, CT scans or MRIs should be performed to help decide if mechanical thrombectomy should be done. However, only the specific criteria from two trials (DAWN and DEFUSE 3) that showed the benefits of mechanical thrombectomy should be used for patient selection.
An ACA stroke can also happen after the rupture of an anterior communicating artery aneurysm. This could be due to an undesired surgical clipping of the arteries or blood vessels. Using a fluorescent dye during surgery can reduce these complications.
Besides immediate stroke care, other treatments like antihypertensives, dual antiplatelet therapy, anticoagulants, and carotid endarterectomy can prevent further strokes. Aspirin or other similar drugs should not be administered within 24 hours of giving alteplase. Dual antiplatelet therapy (aspirin and clopidogrel) can be started within 24 hours of a minor stroke for preventing another stroke in the early stages. Few trials have shown that this therapy is better than just aspirin.
Ticagrelor isn’t recommended over aspirin in treating stroke according to the SOCRATES trial. Although, Ticagrelor may be a suitable alternative for patients who can’t take aspirin. The efficacy of other drugs like tirofiban and eptifibatide is still uncertain.
Lastly, managing risk factors is crucial to prevent future strokes and improve outcomes from the primary event.
What else can Anterior Cerebral Artery Stroke (Stroke) be?
There are many conditions that could be mistaken for a stroke, especially one impacting the anterior cerebral artery. Some of these include metabolic disorders, low blood sugar, infections causing fever or sepsis, cardiovascular conditions such as fainting, migraines, tumors, abscesses, muscle or nerve disorders, and various mental health conditions.
Doctors need to stay alert and use strategies that lower the chances of missing a stroke diagnosis since treating it quickly is really important. This could involve suspecting a stroke when there are sudden symptoms affecting the nervous system, being aware of less common stroke syndromes and conducting a careful neurological exam to better understand the issue.
What to expect with Anterior Cerebral Artery Stroke (Stroke)
The death rate for patients in hospitals suffering from anterior cerebral artery (ACA) strokes can vary from 0 to 7.8%. This is significantly lower than the 17.3% death rate seen for patients with MCA strokes, according to a study that looked into ACA strokes. There’s also generally good news for ACA stroke patients, with about 68% of patients in one study showing a modified Rankin scale score of 2 or less upon leaving the hospital.
In terms of specific disabilities, studies have indicated that speech impairments resulting from ACA strokes generally see improvement quickly. This is in contrast to cases where the stroke has occurred in the MCA region. The size of the stroke or ‘infarct’ doesn’t seem to have a strong connection with how well a patient recovers.
There was one particular instance where a condition known as ‘akinetic mutism’ (an inability to move or speak) was reversed using L-dopa therapy.
However, patients who experience major neurological damage generally face a higher risk of poor outcomes, regardless of whether they are treated with alteplase or not.
Possible Complications When Diagnosed with Anterior Cerebral Artery Stroke (Stroke)
People who have experienced severe strokes have a high chance of developing brain swelling. It’s recommended for such patients to be transferred early to a healthcare facility that specializes in brain surgery.
If a person experiences repeated seizures after a stroke, they should be given anti-seizure medication. However, these medications shouldn’t be used as a prevention method if the seizures are not recurrent.
Using IV alteplase, a drug to treat strokes, can lead to complications like bleeding in the brain and swellings known as angioedema. If a person being treated with this drug starts showing symptoms like headache, nausea, vomiting, or worsening neurological problems, it could suggest a potential brain hemorrhage. In such cases, the administration of IV alteplase should be stopped immediately and a head CT scan should be conducted urgently.
If signs or symptoms of angioedema are observed, the main priority should be to ensure that the patient’s airway remains open. Along with stopping the use of alteplase, the patient should be given IV methylprednisolone and diphenhydramine. Other potential treatments that could be considered include epinephrine, icatibant (which specifically blocks bradykinin B2 receptors), or a C1 esterase inhibitor derived from plasma.
Recovery from Anterior Cerebral Artery Stroke (Stroke)
The advice is to start rehab as soon as possible in places that offer coordinated, multi-professional stroke care. This approach is shown to enhance the recovery process for stroke patients.
Preventing Anterior Cerebral Artery Stroke (Stroke)
People who have high blood pressure, high cholesterol, diabetes, irregular heartbeat, or those who smoke are at a higher risk of having a stroke. It’s important for these individuals to know the signs and symptoms of a stroke. If they experience any stroke symptoms, they should immediately call 911 as getting quick emergency help often results in better health outcomes.
Making certain lifestyle changes like losing weight, reducing the intake of carbohydrates and salt in their diet, and quitting smoking can help decrease their risk of stroke. It’s also crucial for individuals who have had a stroke to understand how important it is to take their medication as prescribed and be aware of the possible consequences if they don’t follow their treatment plan properly.
