An Overview of Weber’s Syndrome

Weber’s syndrome is a neurological condition caused by an injury to the midbrain, the uppermost section of the brainstem. It’s usually caused by a stroke (infarction), but in rare cases, Weber’s syndrome can also be caused by a brain tumor, a traumatic injury, or infection.

The midbrain is already one of the smallest regions of the brain, and Weber’s syndrome affects functions controlled by a small section of this region—eye movement being one. Even though this area of the brain is quite small, people with Weber’s syndrome can experience several major neurological problems.

This article covers the symptoms and causes of Weber’s syndrome. You'll also learn how this condition is diagnosed and treated.

What Are the Symptoms of Weber’s Syndrome?

Weber’s syndrome can cause sudden weakness and vision changes, usually blurred or double vision, and eyelid droopiness. Weakness in the muscles of the face, arms, and legs is also possible.

In the case of a stroke, eye movement and eyelid function are affected on the side of the infarction, with weakness of the face, arm, and leg on the opposite side. For example, a left-side stroke would affect the left eye and right face, arm, and leg.

Immediately after the stroke, symptoms may be at their worst because there may be swelling in and around the brainstem, which exacerbates the effect of the event.

Causes of Weber’s Syndrome

Weber’s syndrome indicates an injury to the left, right, or both sides of the midbrain. A stroke normally affects only one side, while an infection or injury can affect one or both sides.

In the setting of a stroke, patients with Weber’s syndrome usually have an interruption of blood flow through the left or right posterior cerebral artery, the main vessels supplying blood to the midbrain. This interruption can damage the third cranial nerve, a key motor nerve that helps control eye and eyelid movement.

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 was interrupted. Normally, only a branch of the artery is interrupted in Weber’s syndrome strokes, though severity can vary.

Though causes aside from stroke are rare and not well-documented, there have been reports of Weber’s syndrome caused by:

• Tumor
• Penetrating head wounds
• Tuberculoma of the brain, a rare manifestation of tuberculosis
• Aneurysm of the midbrain blood vessels
• Acute leukemia
• Brainstem encephalitis

In these rare cases, Weber’s syndrome would appear to be a diagnosis that comes after the initial malady is examined and treated. Whether Weber’s syndrome resolves in these types of cases will depend on the unique circumstances.

How Is Weber’s Syndrome Diagnosed?

Your medical team will base your diagnosis on visible symptoms and a physical examination, but pinpointing Weber’s syndrome can be tricky.

One tool that has become key in diagnosing midbrain strokes is diffusion-weighted imaging (DWI), a form of magnetic resonance imaging (MRI). In one study, combined DWI techniques improved midbrain infarction detection rates without extra time expenditure.

Note: Weber’s syndrome is not the same as Sturge-Weber syndrome, a rare condition diagnosed in newborns who have abnormal blood vessels on their face that can cause stroke-like weakness.

Treatment for Weber’s Syndrome

Any brain injury is a serious medical emergency, and urgent treatment is necessary. According to the Centers for Disease Control and Prevention (CDC), stroke patients who go to the hospital via ambulance may be diagnosed and treated faster than those who don’t call 911.

After initial care that addresses the cause of your symptoms, most people experience some improvement over time because swelling and inflammation in the brain diminish.

Your healthcare provider will guide your recovery depending on the specifics of your case. Physical therapy (PT) aids in stimulating the healing of the brain injury and will likely be a key part of treatment. PT can also optimize your ability to move the muscles of your eye (in addition to those elsewhere in your body) despite any lingering brain damage.

Recovery can take weeks, months, or years, depending on the severity of your midbrain injury, and may never be total. Your healthcare provider will be able to advise you on your prognosis.

Summary

Weber’s syndrome is a neurological condition that may cause weakness, sudden vision changes, or eyelid droopiness. It results from an injury to the midbrain, most often a stroke. Less common causes include brain tumors, traumatic brain injury, and infection.

Get immediate medical help if you or someone else has symptoms of a stroke. Treatment of the initial symptoms will be the first goal of emergency care. Diagnosing Weber’s syndrome may require the use of special MRI imaging techniques. Recovery will likely involve physical therapy to help regain any lost function.