A commissurotomy () is a
surgical
Surgery ''cheirourgikē'' (composed of χείρ, "hand", and ἔργον, "work"), via la, chirurgiae, meaning "hand work". is a medical specialty that uses operative manual and instrumental techniques on a person to investigate or treat a pa ...
incision of a
commissure in the body, as one made in the heart at the edges of the commissure formed by
cardiac valves, or one made in the brain to treat certain psychiatric disorders.
Patients with
scleroderma
Scleroderma is a group of autoimmune diseases that may result in changes to the skin, blood vessels, muscles, and internal organs. The disease can be either localized to the skin or involve other organs, as well. Symptoms may include areas o ...
, a disease that thickens and hardens the skin, sometimes require oral commissurotomy to open the corners of the mouth, the commissures, to allow dental treatment. This procedure often leaves characteristic scars.
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In cardiac valves
Commissurotomy of
cardiac valves is called
valvulotomy, and consists of making one or more incisions at the edges of the commissure formed between two or three valves, in order to relieve constriction such as occurs in
valvular stenosis, especially
mitral valve stenosis
Mitral stenosis is a valvular heart disease characterized by the narrowing of the opening of the mitral valve of the heart. It is almost always caused by rheumatic valvular heart disease. Normally, the mitral valve is about 5 cm2 during ...
.
In neurosurgery
In
neurosurgery
Neurosurgery or neurological surgery, known in common parlance as brain surgery, is the medical specialty concerned with the surgical treatment of disorders which affect any portion of the nervous system including the brain, spinal cord and ...
, as a treatment for severe epilepsy, the corpus callosum, or the area of the brain that connects the two hemispheres, would be completely bisected. By eliminating the connection between the two hemispheres of a patient's brain, electrical communication would be cut off greatly diminishing the amount and severity of the epileptic seizures. For some, seizures would be completely eliminated.
Though no effect on behavior was observed after commissurotomy was performed on monkeys, it gave peculiar effects on human perception. Different functions of cognition are predominantly located on one of the hemispheres. For example, Brocas area, crucial for forming sentences, is on most people situated in the left hemisphere ventral to the facial motor cortex. The left hemisphere is referred to as the "talking" hemisphere and the right the "silent". A commisurotomy prevents any sensory input to the silent hemisphere from reaching the talking hemisphere. Since the left visual field is processed in the right hemisphere, a person with a commissurotomy is unable to describe objects to the left, because the "talking" hemisphere has not seen anything. It appears as though the person hadn't seen anything at all, and it doesn't bother him either. It can be demonstrated that stimuli to the right hemisphere for example give emotional response, but because of the severed corpus callosum it cannot be verbalized.
[Bear, Connors, Neuroscience third edition]
References
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Cardiac surgery