Hemispherectomy
Encyclopedia
Hemispherectomy is a very rare surgical procedure where one cerebral hemisphere
(half of the brain
) is removed or disabled. This procedure is used to treat a variety of seizure disorders where the source of the epilepsy
is localized to a broad area of a single hemisphere of the brain. It is solely reserved for extreme cases in which the seizures have not responded to medications and other less invasive surgeries.
. The first such operation on humans was done by Walter Dandy
in 1923 for glioblastoma multiforme. In the 1960s and early 1970s, hemispherectomy involved removing half of the brain, but this resulted in unacceptable complications and side effects in many cases, predominantly filling of excessive body fluids in the skull with subsequent pressure to the remaining brain (known as hydrocephalus
). The procedure was revitalized in children in the 1980s by Dr. Ben Carson at The Johns Hopkins Hospital. In many centers, the functional hemispherectomy has largely replaced this procedure, in which the temporal lobe
is removed; a procedure known as corpus callosotomy
is performed; and the frontal
and occipital lobe
s are disconnected from the rest of the brain; however the traditional "anatomic" hemispherectomy has remained a viable procedure, due to its superiority in preventing future seizures compared with functional hemispherectomy.
on the side of the body opposite the removed or disabled portion, and may suffer problems with their vision
as well.
This procedure is almost exclusively performed in children because their brains generally display more neuroplasticity
, allowing neurons from the remaining hemisphere to take over the tasks from the lost hemisphere. This likely occurs by strengthening neural connections
which already exist on the unaffected side but which would have otherwise remained small in a normally functioning, uninjured brain.
One case, demonstrated by Smith & Sugar, 1975; A. Smith 1987, demonstrated that one patient with this procedure had completed college, attended graduate school and scored above average on intelligence tests. Studies have found no significant long-term effects on memory
, personality
, or humor after the procedure, and minimal changes in cognitive function overall. Generally, the greater the intellectual capacity of the patient prior to surgery, the greater the decline in function. Most patients end up with mild to severe mental retardation, which is usually already present before surgery. When resecting the left hemisphere, evidence indicates that some advanced language functions (e.g., higher order grammar) cannot be entirely assumed by the right side. The extent of advanced language loss is often dependent on the patient's age at the time of surgery.
Although initially thought to be limited solely to children, a recent study in 2007 by Dr. Shearwood McClelland III and Dr. Robert E. Maxwell indicated the long-term efficacy of anatomic hemispherectomy in carefully selected adults, with seizure control sustainable over multiple decades.
, who lost the right side of his cerebrum in 1987 in a gun-related work accident. He eventually regained most of his faculties, though he still required a wheelchair. It was noted that reconstructive surgery was difficult due to the gunshot shattering his skull, and he lived for the next 15 years with a large indentation on that side of his head.
was formed in 2008 to assist families with children undergoing this procedure.
Cerebral hemisphere
A cerebral hemisphere is one of the two regions of the eutherian brain that are delineated by the median plane, . The brain can thus be described as being divided into left and right cerebral hemispheres. Each of these hemispheres has an outer layer of grey matter called the cerebral cortex that is...
(half of the brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
) is removed or disabled. This procedure is used to treat a variety of seizure disorders where the source of the 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...
is localized to a broad area of a single hemisphere of the brain. It is solely reserved for extreme cases in which the seizures have not responded to medications and other less invasive surgeries.
History and changes
Hemispherectomy was first tried on a dog in 1888 by Friedrich GoltzFriedrich Goltz
Friedrich Leopold Goltz was a German physiologist and nephew of the writer Bogumil Goltz.Goltz held various university positions in Königsberg, Halle and Strasbourg, Germany...
. The first such operation on humans was done by Walter Dandy
Walter Dandy
Walter Edward Dandy, M.D. was an American neurosurgeon and scientist. He is considered one of the founding fathers of neurosurgery, along with Victor Horsley and Harvey Cushing...
in 1923 for glioblastoma multiforme. In the 1960s and early 1970s, hemispherectomy involved removing half of the brain, but this resulted in unacceptable complications and side effects in many cases, predominantly filling of excessive body fluids in the skull with subsequent pressure to the remaining brain (known as hydrocephalus
Hydrocephalus
Hydrocephalus , also known as "water in the brain," is a medical condition in which there is an abnormal accumulation of cerebrospinal fluid in the ventricles, or cavities, of the brain. This may cause increased intracranial pressure inside the skull and progressive enlargement of the head,...
). The procedure was revitalized in children in the 1980s by Dr. Ben Carson at The Johns Hopkins Hospital. In many centers, the functional hemispherectomy has largely replaced this procedure, in which the temporal lobe
Temporal lobe
The temporal lobe is a region of the cerebral cortex that is located beneath the Sylvian fissure on both cerebral hemispheres of the mammalian brain....
is removed; a procedure known as corpus callosotomy
Corpus callosotomy
Corpus callosotomy is a surgical procedure that disconnects the cerebral hemispheres, resulting in a condition called split-brain....
is performed; and the frontal
Frontal lobe
The frontal lobe is an area in the brain of humans and other mammals, located at the front of each cerebral hemisphere and positioned anterior to the parietal lobe and superior and anterior to the temporal lobes...
and occipital lobe
Occipital lobe
The occipital lobe is the visual processing center of the mammalian brain containing most of the anatomical region of the visual cortex. The primary visual cortex is Brodmann area 17, commonly called V1...
s are disconnected from the rest of the brain; however the traditional "anatomic" hemispherectomy has remained a viable procedure, due to its superiority in preventing future seizures compared with functional hemispherectomy.
Results
All hemispherectomy patients suffer at least partial hemiplegiaHemiplegia
Hemiplegia /he.mə.pliː.dʒiə/ is total paralysis of the arm, leg, and trunk on the same side of the body. Hemiplegia is more severe than hemiparesis, wherein one half of the body has less marked weakness....
on the side of the body opposite the removed or disabled portion, and may suffer problems with their vision
Visual perception
Visual perception is the ability to interpret information and surroundings from the effects of visible light reaching the eye. The resulting perception is also known as eyesight, sight, or vision...
as well.
This procedure is almost exclusively performed in children because their brains generally display more neuroplasticity
Neuroplasticity
Neuroplasticity is a non-specific neuroscience term referring to the ability of the brain and nervous system in all species to change structurally and functionally as a result of input from the environment. Plasticity occurs on a variety of levels, ranging from cellular changes involved in...
, allowing neurons from the remaining hemisphere to take over the tasks from the lost hemisphere. This likely occurs by strengthening neural connections
Neural pathway
A neural pathway, neural tract, or neural face, connects one part of the nervous system with another and usually consists of bundles of elongated, myelin-insulated neurons, known collectively as white matter...
which already exist on the unaffected side but which would have otherwise remained small in a normally functioning, uninjured brain.
One case, demonstrated by Smith & Sugar, 1975; A. Smith 1987, demonstrated that one patient with this procedure had completed college, attended graduate school and scored above average on intelligence tests. Studies have found no significant long-term effects on memory
Memory
In psychology, memory is an organism's ability to store, retain, and recall information and experiences. Traditional studies of memory began in the fields of philosophy, including techniques of artificially enhancing memory....
, personality
Personality psychology
Personality psychology is a branch of psychology that studies personality and individual differences. Its areas of focus include:* Constructing a coherent picture of the individual and his or her major psychological processes...
, or humor after the procedure, and minimal changes in cognitive function overall. Generally, the greater the intellectual capacity of the patient prior to surgery, the greater the decline in function. Most patients end up with mild to severe mental retardation, which is usually already present before surgery. When resecting the left hemisphere, evidence indicates that some advanced language functions (e.g., higher order grammar) cannot be entirely assumed by the right side. The extent of advanced language loss is often dependent on the patient's age at the time of surgery.
Although initially thought to be limited solely to children, a recent study in 2007 by Dr. Shearwood McClelland III and Dr. Robert E. Maxwell indicated the long-term efficacy of anatomic hemispherectomy in carefully selected adults, with seizure control sustainable over multiple decades.
Traumatic hemispherectomy
There are cases where a person that received major trauma to one side of the brain, such as a gunshot wound, has required a hemispherectomy and survived. The most notable case is that of Ahad IsrafilAhad Israfil
Ahad Israfil is a gunshot victim from Dayton, Ohio, remarkable for his recovery from an injury that destroyed most or all of one cerebral hemisphere....
, who lost the right side of his cerebrum in 1987 in a gun-related work accident. He eventually regained most of his faculties, though he still required a wheelchair. It was noted that reconstructive surgery was difficult due to the gunshot shattering his skull, and he lived for the next 15 years with a large indentation on that side of his head.
Foundations
The Hemispherectomy FoundationHemispherectomy Foundation
The Hemispherectomy Foundation is a 501 non-profit organization founded to provide a support structure for children, and the families of children who have had or are preparing to have hemispherectomy brain surgery. The foundation also provides scholarships for college, trade schools, and summer...
was formed in 2008 to assist families with children undergoing this procedure.
External links
- Johns Hopkins Children's Center research findings
- Hopkins Medical News article on the topic
- The Hemispherectomy Foundation
- The Deepest Cut by Christine Kenneally, The New Yorker