Weber's Syndrome Symptoms and Diagnosis

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Weber's syndrome is a neurological syndrome caused by an injury to the area of the brainstem called the midbrain. It is usually caused by a stroke, but Weber’s syndrome can be caused by a brain tumor, a traumatic injury or an infection as well. 

Weber's syndrome describes a specific neurological condition in which a person has a problem with the functions that are controlled by a small section of the midbrain. Even though the area in the brain that causes Weber’s syndrome is quite small, people with Weber’s syndrome can experience several major neurological problems.

Signs and Symptoms

If you or a loved one has been diagnosed with Weber's syndrome, that means that the midbrain was injured on either the left side, the right side or both. A stroke normally affects only one side, while an infection or a tumor can affect both sides or only one side.

The main symptoms of Weber's syndrome include blurred vision or double vision, eyelid weakness on the side of the stroke and weakness of the face, arm and leg on the opposite side. If you have experienced a right-sided midbrain stroke, then you may have trouble moving your right eye, which can result in double vision, blurred vision and difficulty in being able to look all around you.

You might also have a right-sided droopy eyelid and have trouble opening your right eye. These symptoms are caused by damage to a nerve called the third cranial nerve. It is an important nerve that controls eye movements and eyelid opening.

At the same time, if you have Weber’s syndrome, you could have weakness of the left arm, the left leg and the left side of the face. This is caused by damage to the area of the midbrain that controls the movement of the opposite side of the body.

If you had a stroke of the left midbrain, your eye problems will affect your left eye and left eyelid and you would expect to have weakness of the right side of your face and the right side of your body.

What to Expect

Weber's syndrome can cause sudden weakness and vision changes. Immediately after the stroke, the symptoms may be at their worst because there may be swelling in and around the brainstem, which exacerbates the effect of the stroke.

Most people who experience a stroke have some degree of improvement over time. In the first few weeks after a stroke, swelling in the brain diminishes, which allows some improvement. Physical therapy aids in stimulating healing of the brain injury. Physical therapy also optimizes your ability to move the muscles of your eye and the muscles of your body despite any lingering stroke damage.


Interruption of blood flow through the blood vessel that 'feeds' blood to the midbrain is the usual cause of Weber's syndrome. The blood vessel that supplies blood to the midbrain is called the posterior cerebral artery. 

Sometimes, if a tiny branch of the posterior cerebral artery is interrupted, then the symptoms of a stroke are milder and less extensive than they would be if the whole posterior cerebral artery were interrupted. This is normally the situation in Weber’s syndrome strokes—only a branch of the posterior cerebral artery is interrupted, not the whole artery.

What Is the Midbrain?

The brain has an elongated extension that connects to the spinal cord. The elongated section is called the brainstem. The brainstem has 3 sections; the midbrain, the pons, and the medulla. The midbrain is the upper part of the brainstem.

There are several well-known brainstem syndromes, including Wallenberg’s syndrome (lateral medullary syndrome,) Locked-in syndrome (central pontine syndrome) and Ondine’s curse. All of the brainstem syndromes are characterized by a collection of ‘trademark’ neurological problems caused by a very tiny injury that affects several important functions all at once.

A Word From Verywell

If you have Weber's syndrome due to a stroke, then that means that you may have some stroke risk factors. A thorough medical evaluation can determine which stroke risk factors you have so that you can make the lifestyle changes necessary or take the medications needed to prevent another stroke.

If you have Weber's syndrome due to another illness involving the brain, then you are likely to experience improvement of your symptoms once your illness is resolved.

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