What is Vertebrobasilar Stroke (Stroke)?
Vertebrobasilar strokes, though less common, cause an exceptional amount of sickness and death compared to other types of strokes. These strokes occur when blood flow to the back part of the brain is disrupted. One of the reasons these strokes are so dangerous is that their symptoms are often mistaken for non-stroke health issues. For example, people might experience sudden nausea or dizziness, which doesn’t immediately suggest a stroke. This can lead to delays in seeking the right kind of medical attention, and potentially missing out on treatments that are most effective when applied promptly after the stroke.
The arteries most affected in these strokes are the ‘vertebral’ and ‘basilar’ arteries, which are responsible for supplying blood to the brainstem, including the midbrain, pons, and medulla parts of the brain. This area controls lots of our basic bodily functions, and therefore a stroke here is especially dangerous. So, dealing with these strokes requires a team of medical experts from several fields, including neurologists, radiologists, emergency physicians, specialized nurses, neurosurgeons, and therapists, to correctly diagnose, treat and manage the condition.
One of the signs that medical professionals look for to diagnose these strokes is something known as “crossed paresis”. This is a sign of damage to the brainstem and involves one side of the face being paralyzed (on the same side as the stroke), while the opposite limb experiences weakness, along with cranial nerve impairments.
What Causes Vertebrobasilar Stroke (Stroke)?
A stroke is often the final result of several long-lasting and poorly managed health conditions. The causes of a stroke, especially those affecting the vertebral or basal arteries in the brain, include high blood pressure, diabetes, smoking, obesity, irregular heartbeat, lack of exercise, high cholesterol levels, the use of drugs like cocaine, or conditions that make the blood more likely to clot. The risk gets amplified when multiple conditions are present all at once, with high blood pressure being the most common having been found in about 70% of stroke patients.
Strokes can be sorted into two chief types: ischemic and hemorrhagic. The term ischemic implies that the stroke was caused by a part of the brain not getting enough blood, which can happen due to a blood clot, an obstruction in the arteries, or poor blood flow in small vessels. The term hemorrhagic implies that the stroke was caused by bleeding in the brain, which can occur due to conditions like a ruptured aneurysm or uncontrolled high blood pressure.
The subtypes of an ischemic stroke include lacunar, thrombotic, and embolic. Lacunar strokes happen when high blood pressure isn’t properly managed, leading to poor blood flow in small vessels usually located within the internal capsule, thalamus, or sometimes in the brainstem. Thrombotic strokes occur when there’s too much build-up of plaque on the walls of arteries, ultimately obstructing the vessel. Embolic strokes are caused by a blood clot or a broken off chunk of plaque travelling from somewhere else in the body and eventually blocking a part of the brain’s blood vessels. Hemorrhagic strokes are often the consequence of aneurysm ruptures, uncontrolled high blood pressure, complications with blood vessels, cancer spread, or diseases involving brain vessels.
Risk Factors and Frequency for Vertebrobasilar Stroke (Stroke)
Even though the death rate and occurrence of strokes have gone down over the past thirty years, the situation still varies based on factors like race, where you live, and other health conditions. Stroke is now the third most common cause of death in the United States.
For instance, people who live in a region known as the “stroke belt”, mainly in the Southeast United States, have a 20% higher death rate from strokes than people outside that area. Women also have a higher risk of suffering a stroke in their lifetime and are more likely to die from it even though strokes are more common in men.
Strokes also commonly appear among minority groups, especially among Hispanic and Black communities, where it often causes death in younger people compared to their white counterparts. Also, the more health conditions a person has (comorbidities), the higher their risk of a stroke. Again, those who have several uncontrolled risk factors are more likely to suffer from recurrent strokes.
Finally, it’s important to note that almost 20% of all strokes are known as posterior circulation strokes.
Signs and Symptoms of Vertebrobasilar Stroke (Stroke)
A stroke involving the vertebral or basilar artery might be suspected if a patient is experiencing issues with balance and coordination (vestibulocerebellar symptoms). These might include dizziness, uncontrolled eye movements, poor coordination of the trunk and/or limbs, muscle weakness on one side, blurred vision during movement, or issues with the cranial nerves.
There are different types of strokes that can happen in these arteries, with each type producing different symptoms:
- Lateral medullary infarction (Wallenberg syndrome): This stroke typically leads to a hoarse voice, difficulties swallowing, poor coordination, and dizziness, as well as a strange sensation of crossed half-body numbness which indicates a brainstem issue.
- Medial Medullary Infarction (Dejerine syndrome): Due to a stroke in this area, patients may experience paralysis of the tongue on one side, weakness and numbness of the limbs on the other side due to issues with nerve pathways.
- Hemimedullary Infarction: This rare stroke affects both the medial and lateral medulla due to blockage in the vertebral artery. The symptoms are a mix of those from both lateral and medial medullary syndrome.
- Cerebellar Infarction (Pseudotumoral Cerebellar Syndrome): Depending on the specific artery affected, symptoms can include vertigo, problems with coordination, uncontrolled eye movements, poor coordination of voluntary movements, hearing loss on one side, facial paralysis, and even vomiting.
- Top of the Basilar Syndrome: This type of stroke typically causes issues with vertical eye movement, pupil constriction, excessive sleepiness, lack of motivation, memory loss, and visual hallucinations. However, it usually does not impact sensation or movement.
- Inferior Medial Pontine Syndrome (Foville Syndrome): This results from a blockage in the arteries serving the pons region and can lead to issues with the sixth and seventh cranial nerves, as well as weakness and numbness of the limbs on the other side.
- Ventral Caudal Pontine Infarct (Millard-Gubler Syndrome): Often resulting from compression due to tumors or other diseases, this syndrome results in facial and eye muscle paralysis on one side and limb paralysis on the other side.
- Ventral Medial Pontine Infarct (Raymond Syndrome): This rare stroke causes paralysis of the sixth cranial nerve on one side, facial nerve paralysis, and limb weakness on the other side.
- Raymond–Cestan Syndrome: This syndrome leads to poor coordination, tremor, paralysis of face muscles, and loss of sensation in the face on one side, and weakness and sensory loss in the body on the other side.
- Gasperini Syndrome: This rare syndrome usually results from issues with the lower pons and can lead to issues with several cranial nerves on one side and numbness of limbs on the other side.
- Lateral Pontine Syndrome (Marie Foix Syndrome): This rare stroke can cause facial nerve deficits, loss of facial pain and temperature, hearing issues, eye issues, body weakness, and sensory and coordination loss on the opposite side.
- Weber Syndrome (Superior Alternating Hemiplegia): This syndrome involves the third cranial nerve and leads to its paralysis on one side and body and facial paralysis on the other side, and might also present with issues in vertical gaze.
- Paramedian Midbrain Syndrome (Benedikt Syndrome): This syndrome involves an occluded basilar artery and leads to the third cranial nerve’s paralysis on one side, loss of sense of position, vibration, and coordination problems on the other side.
Each of these stroke syndromes has its unique characteristic signs and symptoms caused by the specific area of the brain affected.
Testing for Vertebrobasilar Stroke (Stroke)
First responders use quick tests for possible stroke patients, with the most common being the Cincinnati Prehospital Stroke Assessment. This checks for facial droop, movement in the arm, and changes in speech. The responder will also record the last time the patient appeared to be in their usual state of health. This can help in deciding if the patient should be sent to a specialist stroke center.
At these centers, a neurologist will carry out a quick initial assessment using a test called the National Institute of Health’s Stroke Scale. This test helps identify the location of the stroke and also serves as a standardized record that can be used to monitor how the stroke progresses. This test scores 0 to 42 on various measures including awareness, eye movement, visual fields, facial movement, limb movement, balance, sensation, speech, and attention.
Within the first 20 minutes of arriving at the hospital, the patient should have a particular type of head or brain scan (a non-contrast CT or MRI). This helps check for any bleeding on the brain. They should also have specialist scans of the head and neck (known as vessel angiography) to look for any large blood vessels that may be blocked. If a blockage is identified, it may be possible to remove it manually with a procedure called a thrombectomy to restore blood flow and limit damage to the area around it. If a hospital can’t do these scans, they are recommended to speak to a stroke specialist at another hospital for advice on what to do next, such as starting clot-busting medication.
In addition, blood tests will be done to check sugar levels and rule out low blood sugar as being the cause of symptoms, as well as obtain a complete blood count, test kidney and liver function, and look for signs of heart damage or clotting disorders. An ultrasound scan of the heart (an echocardiogram) may also be performed to rule out any related heart conditions.
Treatment Options for Vertebrobasilar Stroke (Stroke)
Strokes need to be treated by a dedicated team of professionals found at centers that specialize in stroke care. This team usually includes neurologists, neurosurgeons, intensive care doctors specialized in neurology, specially trained nurses, and rehabilitation specialists involving physical, occupational, and speech therapists.
Ischemic Strokes
The treatment of ischemic strokes, which occur when blood supply to the brain is blocked, is highly dependent on timing. If stroke symptoms start less than 4.5 hours before treatment, and there’s no evidence of bleeding on a CT scan without contrast, the patient can be treated with tissue plasminogen activator, most commonly IV alteplase. This medication is carefully dosed according to patient’s weight, with a maximum dose of 90mg, and is administered over about an hour. The patient needs to understand the benefits and risks associated with this treatment before providing consent.
The key factors that make a patient ineligible for this treatment include recent brain surgery or trauma, active internal bleeding, bleeding in the brain, or very high blood pressure. The patient must also exhibit measurable neurological deficits and have experienced stroke symptoms within the last 4.5 hours.
There’s emerging evidence that suggests thrombectomy, a procedure that manually removes clots from blood vessels in the brain, can effectively treat strokes that occur in the back part of the brain. This procedure comes with a lower rate of bleeding and is performed via a small puncture to the femoral artery.
After treatment, close monitoring of patients takes place within a dedicated neuro intensive care unit. Blood pressure is allowed to rise slightly to aid the recovery of the affected brain tissue. Depending on whether the patient received treatment and their specific circumstances, different medications can be used to manage their blood pressure. Regular checks are performed to quickly identify any changes in the patient’s neurological status.
Hemorrhagic Strokes
Hemorrhagic strokes, which involve bleeding in the brain, are very serious and may need immediate intervention from a neurosurgeon, depending on the amount and location of the bleeding. A head CT scan will help locate the bleeding and identify whether surgery is necessary.
Similar to ischemic stroke patients, those who experience hemorrhagic strokes are also closely monitored in a neuro ICU setting. In some cases, a drainage tube may be inserted to drain excessive fluid and relieve pressure if the bleeding has blocked the flow of fluid around the brain. Careful control of blood pressure is critical, and any anticoagulant medication or preventative drugs for blood clots are temporarily paused to prevent further bleeding.
What else can Vertebrobasilar Stroke (Stroke) be?
Doctors may diagnose the following conditions when encountering symptoms like dizziness or loss of balance:
- Benign positional paroxysmal vertigo (A disorder that causes brief episodes of mild to intense dizziness)
- Brainstem migraine (A rare type of migraine with symptoms affecting the brainstem)
- Dolichoectasia of the vertebral or basilar artery (An abnormal enlargement of arteries at the back of the neck)
- Intracranial tumor (A tumor within the skull)
- Labrythnthitis (An inflammation of the inner ear causing dizziness and loss of balance)
- Postictal state with Todd paralysis (A condition of temporary weakness or paralysis after a seizure)
- Thyroid disease (Disorders affecting the thyroid gland which can disrupt the body’s normal functioning)
- Transient ischemic attack (A temporary blockage of blood flow to the brain)
- Vertebrobasilar insufficiency (Restricted blood flow to the back of the brain)
- Vestibular neuritis (An inflammation of the inner ear causing sudden severe vertigo)
It’s crucial that these possibilities are thoroughly examined and appropriate tests be undertaken to ensure the accurate diagnosis of the condition.
What to expect with Vertebrobasilar Stroke (Stroke)
The outcome of vertebrobasilar strokes greatly depends on the extent of reduced blood flow to the brain and the type of treatment received. Other factors such as a person’s health condition before the stroke, their age, and their ability to participate in physical therapy can also significantly alter the expected recovery.
Possible Complications When Diagnosed with Vertebrobasilar Stroke (Stroke)
The drug TPA can lead to several side effects like bleeding in the brain, feeling of sickness (nausea), and swelling of the tongue (angioedema). If the tongue swelling occurs, it can be handled fast by immediately stopping TPA and medications known as ACE inhibitors, giving IV steroids, and inserting a tube into the windpipe to help with breathing.
People who have a serious stroke, both clot-based and bleeding-based, can sometimes experience a type of swelling in the brain caused by fluid leakage or cell damage. This swelling can cause increased pressure inside the skull and can cause crowding of the brain, making it shift to the middle and downwards. In very severe instances, parts of the brain can push downwards through the large hole at the base of the skull (foramen magnum). Before this progresses to a severe level, patients might be given medications like mannitol and/or a high-salt solution to try and prevent a surgery, called hemicraniectomy, which involves removing part of the skull.
Preventing Vertebrobasilar Stroke (Stroke)
If you suddenly feel dizzy or sick and experience a loss of strength or sensation, it’s vital to get checked immediately by healthcare professionals. These symptoms could indicate a stroke, a serious medical condition. To confirm this, doctors will conduct imaging tests on your head to decide the best course of treatment.
Time is of the essence in such cases. For instance, a medicine called TPA, used for treatment, needs to be administered within 4.5 hours of symptom onset. If the doctors find a reachable blood clot causing the stroke, they may opt for a special procedure known as a thrombectomy to remove it.
Several factors increase your chances of experiencing a stroke. These include high blood pressure, diabetes, high cholesterol levels, smoking, obesity, and a lack of physical activity.
