Commissurotomy
Encyclopedia
A commissurotomy is a surgical 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
, 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.
, 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.
, a commissurotomy may be performed to sever the corpus callosum
; doing so has been used in cases of severe epilepsy
to prevent the two hemispheres of the brain communicating, thus restraining the epilepsy to one hemisphere.
Though no effect on behavior was observed after commisurotomy was performed on monkeys, it gave peculiar effects on human perception. Different functions of cognition are predominately 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 commisurotomy 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.
Commissure
A commissure is the place where two things are joined. The term is used especially in the fields of anatomy and biology.In anatomy, commissure refers to a bundle of nerve fibers that cross the midline at their level of origin or entry .* The most common usage of the term refers to the brain's...
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
Systemic sclerosis or systemic scleroderma is a systemic autoimmune disease or systemic connective tissue disease that is a subtype of scleroderma.-Skin symptoms:...
, 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.
In cardiac valves
Commissurotomy of cardiac valves is called valvulotomyValvulotomy
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....
, 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.
In neurosurgery
In neurosurgeryNeurosurgery
Neurosurgery is the medical specialty concerned with the prevention, diagnosis, treatment, and rehabilitation of disorders which affect any portion of the nervous system including the brain, spine, spinal cord, peripheral nerves, and extra-cranial cerebrovascular system.-In the United States:In...
, a commissurotomy may be performed to sever the corpus callosum
Corpus callosum
The corpus callosum , also known as the colossal commissure, is a wide, flat bundle of neural fibers beneath the cortex in the eutherian brain at the longitudinal fissure. It connects the left and right cerebral hemispheres and facilitates interhemispheric communication...
; doing so has been used in cases of severe epilepsy
Epilepsy
Epilepsy is a common chronic neurological disorder characterized by seizures. These seizures are transient signs and/or symptoms of abnormal, excessive or hypersynchronous neuronal activity in the brain.About 50 million people worldwide have epilepsy, and nearly two out of every three new cases...
to prevent the two hemispheres of the brain communicating, thus restraining the epilepsy to one hemisphere.
Though no effect on behavior was observed after commisurotomy was performed on monkeys, it gave peculiar effects on human perception. Different functions of cognition are predominately 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 commisurotomy 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.