A stroke occurs when blood flow to a part of the brain is interrupted, causing brain cell damage and loss of neurological function. The internal carotid artery (ICA) is a major blood vessel in the neck that supplies oxygenated blood to large brain regions responsible for movement, sensation, and speech. Strokes involving the ICA are serious due to the extensive areas they can affect. Prompt medical attention is paramount.
What is an Internal Carotid Artery Stroke?
An internal carotid artery stroke occurs when blood supply through this artery to the brain is severely reduced or completely blocked. The ICA originates from the common carotid artery in the neck and branches to supply the anterior and middle parts of the brain. This artery is susceptible to conditions that impede blood flow, leading to an ischemic stroke.
While strokes can also be hemorrhagic, resulting from a ruptured blood vessel, most ICA strokes are ischemic. In these cases, a blockage prevents oxygen and nutrients from reaching brain tissue. This lack of blood flow causes rapid injury to brain cells and a sudden loss of neurological function.
Recognizing the Symptoms
Symptoms of an internal carotid artery stroke appear suddenly and vary depending on the affected brain region. Common signs include abrupt weakness or numbness, typically on one side of the face, arm, or leg. This one-sided weakness, known as hemiparesis, can impact coordination and movement.
Difficulty speaking or understanding speech, known as aphasia, is another indicator. Sudden vision changes are also frequent, particularly in one eye, a condition called amaurosis fugax, often described as a curtain or shade descending over the visual field. This temporary vision loss can be a warning sign of underlying vascular disease. The “FAST” acronym—Face drooping, Arm weakness, Speech difficulty, Time to call emergency services—helps recognize potential stroke symptoms and the urgency of seeking help.
Causes and Contributing Factors
Internal carotid artery strokes are primarily caused by conditions leading to blockages within the artery. Atherosclerosis is a common culprit, where plaque—a sticky substance of fat, cholesterol, and other materials—builds up inside artery walls. This plaque buildup narrows the ICA, reducing blood flow and increasing clot formation risk. Over time, these plaques can rupture, forming blood clots that may block the artery or travel to smaller brain arteries.
Blood clots can also originate from other body parts and travel to the ICA, a process known as embolism. Atrial fibrillation, an irregular heartbeat, is a significant stroke risk factor because it can cause blood clots to form in the heart, which may then travel to the brain. Less commonly, a carotid artery dissection—a tear in the artery wall—can lead to a blockage or source of microemboli. This is a notable cause of stroke in younger individuals, often occurring spontaneously or due to minor trauma.
Several factors increase the risk of developing these conditions. High blood pressure is the most significant risk factor for stroke. Other risk factors include high cholesterol, diabetes, smoking, obesity, a sedentary lifestyle, and a family history of stroke.
Emergency Care and Diagnosis
Immediate medical attention is paramount when an internal carotid artery stroke is suspected. Emergency services should be contacted without delay. Upon hospital arrival, medical professionals conduct a physical examination and neurological assessment.
Imaging tests are crucial for diagnosis and guiding treatment. A non-contrast CT scan of the brain is often the first imaging used to quickly rule out a hemorrhagic stroke. An MRI scan can provide more detailed brain tissue imaging. To visualize the carotid arteries and identify blockages, a carotid ultrasound, CT angiography (CTA), or MR angiography (MRA) may be performed. CTA is highly accurate in detecting large vessel occlusions and stenosis.
Acute treatments aim to restore blood flow to the brain quickly. Intravenous thrombolysis with medication like recombinant tissue plasminogen activator (IV tPA or alteplase) can dissolve blood clots and is typically administered within 4.5 hours of symptom onset. For larger vessel occlusions, mechanical thrombectomy—an endovascular procedure to physically remove the clot—may be performed. This procedure can be beneficial for patients up to 6 hours after symptom onset, and in some cases, up to 24 hours.
Life After an ICA Stroke
Recovery from an internal carotid artery stroke is a multifaceted process involving comprehensive rehabilitation to regain lost functions. Physical therapy helps improve mobility and strength, while occupational therapy focuses on relearning daily activities. Speech therapy is often necessary for individuals with communication or swallowing difficulties.
Ongoing medical management is a significant part of life after an ICA stroke, aimed at preventing future events. This includes antiplatelet drugs like aspirin or clopidogrel, which reduce blood clotting. Anticoagulants are prescribed to further reduce clotting, especially if the stroke originated from the heart.
Managing underlying risk factors through lifestyle modifications is a continuous effort. This involves controlling high blood pressure and cholesterol through diet, regular exercise, and medication. Smoking cessation is strongly advised, as smoking significantly increases stroke risk. Support systems are also important after a stroke.