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The corpus callosum is a band of nerve fibers located
deep in the brain that connects the two halves (hemispheres) of the brain. It
helps the hemispheres share information, but it also contributes to the spread
of seizure impulses from one side of the brain to the other.
A corpus callosotomy is an operation that severs (cuts) the
corpus callosum, interrupting the spread of seizures from hemisphere to
hemisphere. Seizures generally do not completely stop after this procedure; they
continue on the side of the brain in which they originate. However, the seizures
usually become less severe, as they cannot spread to the opposite side of the
brain.
Who is a candidate for a corpus callosotomy?
This procedure, sometimes called split-brain surgery,
may be performed in patients with the most extreme and uncontrollable forms of
epilepsy, when frequent seizures affect both sides of the brain. A serious type
of seizure--called a drop attack--often results in sudden falls with a high risk
of injury. In addition, people considered for corpus callosotomy do not
experience improvement after receiving treatment with anti-seizure medications.
What happens before surgery?
Candidates for corpus callosotomy undergo an extensive
pre-surgery evaluation--including seizure monitoring, electroencephalography
(EEG), magnetic resonance imaging (MRI), and positron emission tomography (PET).
These tests help the doctor pinpoint where the seizures begin and how they
spread in the brain. It also helps the doctor determine if a corpus callosotomy
is an appropriate treatment.
What happens during surgery?
A corpus callosotomy requires exposing the brain using
a procedure called a craniotomy. (Crani refers to the skull and otomy means
"to cut into.") After the patient is put to sleep (general
anesthesia), the surgeon makes an incision (cut) in the scalp, removes a piece
of bone, and pulls back a section of the dura, the tough membrane that covers the
brain. This creates a "window" in which the surgeon inserts special
instruments for disconnecting the corpus callosum. The surgeon gently separates
the hemispheres to access the corpus callosum. Surgical microscopes are used to
give the surgeon a magnified view of the brain structures.
In some cases, a corpus callosotomy is done in two stages. In
the first operation, the front two-thirds of the structure is cut, but the back
section is preserved. This allows the hemispheres to continue sharing visual
information. If this does not control the serious seizures, the remainder of the
corpus callosum can be cut in a second operation.
After the corpus callosum is cut, the dura and bone are fixed
back into place, and the scalp is closed using stitches or staples.
What happens after surgery?
The patient generally stays in the hospital for 2 to 4
days. Most people who have a corpus callosotomy will be able to return to their
normal activities, including work or school, in 6 to 8 weeks after surgery. The
hair over the incision will grow back and hide the surgical scar. The person
will continue taking anti-seizure medication.
How effective is a corpus callosotomy?
Corpus callosotomy is successful in stopping drop
attacks in about 50-75% of cases. This can decrease the risk of injury and
improve the person’s quality of life.
What are the side effects of surgery?
The following symptoms may occur after surgery,
although they generally go away on their own:
- Scalp numbness
- Nausea
- Feeling tired or depressed
- Headaches
- Difficulty speaking, remembering things, or finding
words
What are the risks of a corpus callosotomy?
Serious problems are uncommon with a corpus callosotomy, but
there are risks, including:
- Risks associated with surgery, including infection,
bleeding, and allergic reaction to anesthesia
- Swelling in the brain
- Lack of awareness of one side of the body
- Loss of coordination
- Problems with speech, such as stuttering
- Increase in partial seizures (occurring on one side of
the brain)
- Stroke
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