What is Weber Syndrome?
Weber’s syndrome is a condition that was first identified by a physician named Hermann Weber. He noticed the disorder in a 52-year-old man who developed a facial nerve weakness on the left side and weakness on the right side of his body. This was due to an unexpected bleeding incident in his left brain stem, a part of the brain responsible for sending information between the brain and body.
Weber syndrome is often caused by a stroke in the midbrain, resulting in superior alternating weakness on one side of the body. The condition affects the eye-moving nerve fibers located between the back and front of the brain as well as the brain stem. This can result in facial nerve weakness on one side and body weakness on the other side. This usually happens when a branch of the blood vessel that sends blood to the back of the brain gets blocked.
The third cranial or eye-moving nerve has two main control centers called the main motor nucleus and the accessory parasympathetic nucleus. The main motor nucleus is located in the midbrain, controlling all the eye-moving muscles except for two particular ones, and the muscle that lifts the upper eyelid. The accessory parasympathetic nucleus, also known as the Edinger Westphal nucleus, is located behind the main motor nucleus. It sends signals through nerves to control the muscle that shrinks the pupil and allows the eye to focus.
The nerve fibers move forward and sideways through a part of the midbrain called the red nucleus, then gather at an area known as the interpeduncular fossa before leaving the midbrain. Because these nerve fibers cover a large part of the midbrain, damages in this area can lead to partial or complete facial nerve weakness. If there are damages in the lower part of the midbrain, the eye-moving muscles may be affected but the pupils will be spared. If the upper and middle parts of the midbrain are damaged, it can cause the pupils to dilate.
What Causes Weber Syndrome?
Weber syndrome is a condition that occurs due to a damage – or lesion – in a particular part of the brain called the ventromedial midbrain. This part of the brain gets its blood supply from several arteries.
The most common cause of Weber syndrome is the blockage or failure of two particular arteries – the paramedian mesencephalic branches and the peduncular perforating branches. This kind of failure is known as an “infarction”. Less common causes can be things like bleeding in the brain, growths, aneurysms (balloon-like bulges in blood vessels), and diseases that cause damage to the protective lining of nerve fibers, such as multiple sclerosis.
Weber syndrome often occurs in people who have high blood pressure, diabetes, or high cholesterol, similar to other stroke conditions.
A specific study found that only about 7.6% of cases involved damage exclusively to the midbrain, with most cases also involving damage to other parts of the blood vessel system located at the back of the brain, known as the vertebrobasilar system. The most common causes for this kind of brain damage, in decreasing order of frequency, were:
- Cardioembolism – a condition where a blood clot forms in the heart and travels to the brain;
- Thrombosis in place – a condition where a blood clot forms directly in the arteries of the brain;
- Large artery to artery embolism – another type of clot formation;
- Disease of the arteries directly supplying the brain (lacunar infarct).
Risk Factors and Frequency for Weber Syndrome
Weber syndrome is a type of stroke that primarily affects the midbrain, which is a part of the vertebrobasilar system in the brain. This specific type of stroke, known as an isolated midbrain infarction, is quite rare. In fact, one study found that it only occurred in around 0.7% of stroke patients whose stroke affected the back part of the brain (known as the posterior circulation). Very often, when Weber syndrome occurs, it’s alongside strokes in other areas of the vertebrobasilar system.
Signs and Symptoms of Weber Syndrome
Weber syndrome is a neurological condition that displays specific signs and symptoms. People with Weber syndrome often experience a drooping eyelid, double vision, and weakness in their limbs on the opposite side of their body. Other common symptoms include loss of coordination (ataxia) and body rigidity similar to Parkinson’s disease, depending on which parts of the brain are involved. However, these symptoms can vary in each case.
- Drooping eyelid and double vision
- Weakness in the upper and lower limbs on one side
- Possible ataxia or stiffness
Typically, a person’s mental abilities are not affected in Weber syndrome. If the eyelid drops, the affected eye often moves downward and outward because the muscles that usually control it are not working properly. If the upper and middle parts of the midbrain are affected, the pupils on the same side may become wide and unresponsive. However, the pupils are usually spared if only the lower part of the midbrain is affected. Some people may also experience body stiffness and loss of coordination associated with the weakness.
In some cases, Weber’s syndrome can also cause difficulty in moving the eyes vertically. This is due to a specific region of the brain (rostral interstitial nucleus of the medial longitudinal fasciculus, or riMLF) located in the midbrain. The fibers or fascicles of the oculomotor nerve in the midbrain are thought to be responsible for controlling the pupils, eye movement, and eyelid lift function.
Testing for Weber Syndrome
If someone is suspected of having a stroke, the first step for the doctor is to perform a comprehensive check of the patient’s nervous system, as well as rate their condition according to the National Institute of Health Stroke Scale. This scale is used by healthcare providers to measure the severity of a stroke. A high score typically suggests that the stroke is more severe.
The most immediate method for confirming a stroke is a quick brain scan using a computerised tomography (CT) machine. This type of scan is like an X-ray that takes a detailed look at the brain and can show if any damage has occurred. This is often chosen because it’s fast and most medical facilities have the necessary equipment.
Regardless, since a stroke can spread to other areas served by the vertebrobasilar system (the group of arteries supplying the back of the brain), additional types of scans might be needed. These can include magnetic resonance imaging (MRI), which produces even more detailed images of the brain’s tissues and structures. Doctors can also use special types of MRI scans, called angiographic and perfusion studies, to visualize better the blood flow in the brain and identify the areas affected by the stroke.
Treatment Options for Weber Syndrome
When you have a stroke, the initial treatment focuses on making sure you can breathe properly, your heart is functioning well, and that doctors understand the full extent of the damage to your brain.
Weber syndrome is a particular type of stroke that can lead to distinct symptoms, but patients with this condition usually remain stable in terms of their brain function. Sometimes, if the stroke has affected a large portion of the brain and there’s a risk of the disease spreading further, a treatment that dissolves blood clots might be needed.
There are instances where brain surgery might be necessary for patients with Weber syndrome:
1. If the stroke has impacted a large area at the back of the brain (the posterior region), emergency surgery might be required to relieve pressure.
2. If fluid starts to build up in the brain causing hydrocephalus, a hollow tube may need to be inserted to drain the excess fluid.
3. As a secondary procedure during surgery for tumors or aneurysm causing Weber syndrome.
In addition to these treatments, the basic care needs of Weber syndrome patients are crucial. This includes getting the patient moving as soon as possible, helping them manage their bathroom routines, and ensuring they receive proper nutrition.
What else can Weber Syndrome be?
There are several midbrain syndromes, and this includes Benedikt, Claude’s and Nothnagel syndromes. Here’s what you need to know about them:
- Benedikt Syndrome (also known as Paramedian midbrain syndrome) is caused by an issue in the midbrain and cerebellum areas of the brain. Symptoms include issues with eye movements (oculomotor nerve palsy) and uncontrollable, shaky movements (cerebellar ataxia) including tremors and involuntary, dance-like movements.
- Claude’s syndrome is similar to a condition called Weber syndrome. It presents with problems in eye movements on one side (oculomotor nerve palsy), weakness on the opposite side of the body (contralateral hemiparesis), and uncoordinated movements (contralateral ataxia). This happens when the eye nerve (oculomotor nerve), red nucleus, and brachium conjunctivum are involved.
- Sturge-Weber syndrome (SWS) is another form of Weber syndrome. Also known as encephalotrigeminal angiomatosis, SWS is a condition that affects the skin and nervous system. It involves skin abnormalities on the face and brain, often affecting areas close to eye and upper jaw nerves, which are controlled by the trigeminal nerve. A key symptom of SWS is a facial skin discolouration, also known as a nevus flammeus or port-wine stain.
- Klippel-Trenaunay-Weber syndrome (KTWS) is another type of Weber syndrome. KTWS involves a combination of skin discolouration (port-wine stain), enlarged veins (varicose veins), and extra growth of bones and soft tissues in one particular part of the body.
What to expect with Weber Syndrome
The outlook for Weber syndrome can vary depending on its cause. Detecting the condition early, managing it promptly, providing effective supportive care to prevent complications, and taking steps to prevent a similar stroke from happening again are crucial factors in determining how these patients’ nervous system will recover.
Possible Complications When Diagnosed with Weber Syndrome
Weber syndrome, a medical condition affecting the brain, often occurs together with a stroke in the pons region of the brain. In fact, it’s ten times more likely to happen with this type of stroke. For half of the patients who have Weber syndrome, it’s connected to a specific problem with the blood supply in the back of the brain. A severe stroke in this area can lead to a critical condition called tonsillar herniation, which can cause death. This could also lead to an overflow of fluid in the brain, also called hydrocephalus.
After the initial recovery phase from this event, it’s important to get moving as soon as possible. Why is this important? Because it helps to avoid secondary complications like muscle stiffness, bedsores, pneumonia from inhaling food or saliva, blood clots in the legs, clots travelling to the lungs, and other infections like pneumonia and urinary tract infections.
Common complications to watch out for:
- Muscle stiffness
- Bedsores
- Inhaling pneumonia
- Blood clots in legs
- Clots travelling to lungs
- Pneumonia
- Urinary tract infections
If a patient has trouble swallowing, a feeding tube placed through the nose may be needed. Early physical therapy can help to regain muscle strength, prevent muscle stiffness, and improve the person’s quality of life.
Recovery from Weber Syndrome
If a person’s limbs become paralyzed, they should begin passive full range-of-motion exercises, which means moving the limbs through their normal range of motion with the help of an outside force, like a therapist, as soon as possible. Ideally, this should start within the first 24 hours. They should also receive care from a physiotherapist or a specialized team focused on stroke rehabilitation.
When deciding on a rehabilitation plan for individuals who have had a stroke in the brainstem – the part of the brain that controls many basic bodily functions – the focus should be based on the symptoms experienced by the individual rather than the exact location of the stroke.
Just like with any other stroke patient, other rehabilitative actions are also taken. For those who are bedridden, doctors often recommend a medication called heparin, provided in the form of injections under the skin, to prevent deep vein thrombosis (blood clots in the deep veins, often in the leg) and pulmonary embolism (a blockage in the lung’s blood vessels), which can occur after prolonged immobility.
Other important steps for recovery include early bladder training, which often includes removing any indwelling catheters (tubes that allow urine to drain out of the bladder), and using laxatives and stool softeners to prevent constipation, another common issue seen in bedridden patients.
Preventing Weber Syndrome
A Transient Ischemic Attack (TIA), or a ‘mini-stroke’, that affects the back part of the brain can often go unnoticed. This is a concern because treatment using medicine to dissolve blood clots (thrombolytic therapy) could get delayed, which can increase the time between when symptoms first appear to when treatment is administered (known as door to needle time).
An additional concern is that patients facing Vertebrobasilar stenosis – a narrowing of the arteries in the neck that supply blood to the brain – have three times the risk of experiencing another stroke. Therefore, it’s crucial to enhance understanding of early signs of a stroke in the back part of the brain.
If these patients are evaluated and treated urgently, it can help prevent complications that can be life-threatening. Such patients should be promptly referred to specialized stroke care units where they can potentially receive early blood clot dissolving treatment.
