Internal Capsule Stroke

An internal capsule stroke is a relatively small stroke that can cause profound weakness of one side of the body. If you or a loved one has been told that you had an internal capsule stroke, this is what you need to know.

What is the internal capsule?

The internal capsule describes a region deep in the brain that allows communication between areas of the cerebral cortex and areas of the brainstem. The internal capsule is referred to as ‘white matter’ in the brain because of it's appearance under a microscope.

The internal capsule is part of the subcortical area of the brain because it is located below the cerebral cortex.

The biggest job of the internal capsule is working as a relay station for the body’s motor function. This means that the internal capsule is necessary for the integration of our body’s arm, leg, trunk and face movement. The right side of the internal capsule transmits nerve signals for movement of the left side of the body and the left side of the internal capsule transmits nerve signals for movement of the right side of the body.

While the internal capsule is primarily involved in movement, it also acts as a relay station for sensation on the opposite side of the body.

What is an internal capsule stroke?

If you have had an internal capsule stroke, it can usually be visualized on Brain MRI or Brain CT scan within a short time after the stroke. A relatively small internal capsule stroke can cause profound weakness on the opposite side of the body, called hemiparesis or hemiplegia.

An internal capsule stroke can cause arm weakness, hand weakness, leg weakness or foot weakness. You might have some strength left in the affected area, or you might not be able to move it at all. Sometimes, an internal capsule stroke affects the face, making it difficult to chew, to swallow or to speak clearly.

Because the internal capsule is involved with some nerves that control your sensation, an internal capsule stroke can cause you to lose some or all sensation in the affected arm, leg or face.

Why did I have an internal capsule stroke?

An internal capsule stroke is caused by interruption of blood supply in the middle cerebral artery or one of its small branches.

Usually, an ischemic internal capsule stroke is caused by an embolic blood clot coming from elsewhere in the body, but it may be caused by a thrombotic blood clot developing within one of the small arteries that supplies oxygen rich blood to the internal capsule. It is not common for a brain aneurysm or a hemorrhagic stroke to affect the internal capsule, although it can happen.

An embolic stroke or a thrombotic stroke usually happens when cerebrovascular disease or heart disease develops after years of stroke risk factors.

Will I recover?

The vast majority of internal capsule strokes are not fatal, and most people experience a degree of recovery.

Most of the time, internal capsule strokes do not cause the severe swelling or seizures that may occur with strokes in other regions of the brain.

After an internal capsule stroke, you may continue to experience weakness of one side of your body, and you will likely experience some degree of improvement with physical therapy and rehabilitation although recovery is variable between one stroke survivor and another.

As with most strokes, a key part of recovery includes dedicated physical therapy and rehabilitation. Usually, after a stroke of the internal capsule, you will have a medical evaluation to see if you have any stroke risk factors, and you might need to make some changes in your lifestyle or start on new medications if you have any stroke risk factors.

Sources

The ischemic penumbra: the location rather than the volume of recovery determines outcome, Rosso C, Samson Y, Current Opinion in Neurology, February 2014

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