The corpus callosum connects the left and right hemispheres of the brain and allows information to pass to both sides. Injury to the corpus callosum is rare, but it can cause many strange symptoms.
You’re about to learn what to expect after corpus callosum injury, including the effects it can have on your cognitive and physical abilities. Let’s begin.
What is the Corpus Callosum?
Each hemisphere of the brain controls movement and feeling on the opposite side of the body. The corpus callosum acts as a bridge so that input from the left side of the brain can transfer to the right side and vice versa.
Besides serving as a bridge between the two hemispheres, the corpus callosum also plays its own role in higher cognitive function. Researchers have shown that it is involved in complex abilities such as:
- Executive functions
- Three-dimensional vision
- Visual reaction time
Injury to the corpus callosum can cause problems with these functions and also other, more specific issues.
Symptoms of Corpus Callosum Injury
Injury to any part of the corpus callosum can lead to loss of contact between the hemispheres, which can cause a variety of disorders.
Some of the most common symptoms of corpus callosum injury are listed below:
Pseudobulbar palsy is a condition that affects the ability to control the muscles of your face. As a result, it can cause the person to make strange facial expressions.
Some other symptoms of pseudobulbar palsy include problems such as:
- Dysarthria, or slurred speech
- Dysphagia, or difficulty swallowing
- Dysphonia, or spasms in the vocal cords that cause changes in your voice
- Emotional lability, or exaggerated mood swings
The brainstem controls most of the muscles in your face, but these signals must pass through the corpus callosum. Therefore, if it becomes damaged, problems related to facial movement can arise.
Speech and Movement Ataxia
Ataxia refers to a lack of control or coordination of voluntary movements. Depending on which muscles it affects, this could cause problems with:
- Picking up objects
- Eye movement
Since each hemisphere controls the opposite side of the body, the brain must coordinate movements with both sides. This coordination is mediated by the corpus callosum.
If the corpus callosum is injured, however, then signals cannot pass from one hemisphere to the other. This can lead to serious coordination problems.
Alien Hand Syndrome
One of the strangest symptoms of corpus callosum damage is a condition known as alien hand syndrome. While it most commonly affects the left hand, it can affect the right in some cases. This condition causes the hand to seemingly move and act on its own without any cognitive control or awareness from the person.
These movements are not simply random, involuntary muscle spasms either. Instead, the affected hand performs goal-oriented tasks, as if it is being controlled by someone else.
For example, your hand might pick up an object, or touch your face, or button your shirt without any conscious input from you. Sometimes the hand might engage in counterproductive actions, such as closing a door your other hand just opened. In some extreme cases, the hand has tried to harm the patient by choking them.
People with alien hand syndrome often feel like their hand is foreign. But they do not deny ownership of their hand, as occurs in other neurological disorders, such as left neglect.
This disorder can also occur in the leg. However, that disorder is extremely rare.
Treating Corpus Callosum Damage
Corpus callosum injuries are difficult to treat. While no proven treatment exists yet, the best approach is to address the symptoms.
For those who develop cognitive impairments such as memory loss or executive dysfunction, cognitive rehab exercises can be helpful. These exercises activate the brain’s neuroplasticity to help it rewire nerve pathways. By creating new, stronger pathways, you can recover cognitive functions.
In addition, for facial movement problems, speech therapy exercises are often effective. These can prove useful for patients with pseudobulbar palsy and speech ataxia, for instance.
Unfortunately, there are very few treatments available for alien hand syndrome. Some studies have shown promising results using mirror box therapy. However, more research is still needed.
But in the meantime, occupational therapists can help you adapt to using only one hand. They can also show you helpful ways to compensate for your unruly hand. For example, in extreme cases, it might be more practical to strap it down with an arm sling to prevent it from moving.
Understanding Corpus Callosum Injuries
The corpus callosum is a crucial brain structure that connects the right and left hemispheres. Damage to it can cause cognitive and physical deficits and, in rare cases, alien hand syndrome.
However, most cases of corpus callosum injuries will resolve after a few months as the injury heals. Speech and occupational therapy can also be used to treat some of its symptoms.
We hope this article has given you a better understanding of some of the fascinating and strange effects of corpus callosum damage.
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