Multiple subpial transection
Encyclopedia
In the treatment of epilepsy
, if partial seizures
originate in areas of the brain
that cannot be removed safely, multiple subpial transections are an alternative. The surgeon makes a series of shallow cuts (transections) into the brain's cerebral cortex
. These cuts are thought to interrupt some fibers that connect neighboring parts of the brain, but they do not appear to cause long-lasting impairment in the critical functions that these areas perform.
Multiple subpial transections can help to reduce or eliminate seizures arising from vital functional areas of the cerebral cortex. This procedure has been successful in an unusual type of epilepsy called Landau-Kleffner syndrome
, at least for a limited time.
Bleeding at the site of the transection is possible, but the procedure is generally well tolerated. Major complications appear to be rare. Transections in language
areas of the brain may mildly impair the language function served by that area.
In children, the definition of medically refractory is even more individualized to the specific child's situation. Surgery may be considered for some children after weeks to months of treatment with seizure medicines.
In general, a person is considered to be a potential candidate for surgery if adequate trials of two first-line seizure medicines (ones that are commonly effective in controlling the type of seizures the person is experiencing) and one two-drug combination all have failed to control the seizures. A trial of a medication is considered adequate when it has been increased gradually to the maximum dosage that does not cause serious side effects and then is given for a long enough period. If the person has frequent seizures, any improvement will be obvious after a short time. If the seizures generally occur far apart, however, it may take months to determine whether the time between seizures is increasing.
At some epilepsy centers, patients are offered additional conventional or experimental medications before surgery is considered. But research suggests that each time a trial of medication fails to control a person's seizures, it becomes less likely that a different medicine or combination will be successful. Since uncontrolled seizures present serious physical risks and social and psychological consequences, the trend these days is to proceed with surgery much sooner than in years past if it seems appropriate for that person.
If a review of the person's experiences with seizure medicines shows that adequate tests of at least a few different medications have not succeeded in controlling the seizures, then the person may be referred to a specialist for a preoperative (or presurgical) assessment.
The preoperative assessment has two general objectives:
The number and type of tests that make up the preoperative assessment will depend on the type of surgery being considered. General objectives of the tests include:
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...
, if partial seizures
Complex partial seizure
A complex partial seizure is an epileptic seizure that is associated with bilateral cerebral hemisphere involvement and causes impairment of awareness or responsiveness, i.e. loss of consciousness.-Presentation:...
originate in areas 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,...
that cannot be removed safely, multiple subpial transections are an alternative. The surgeon makes a series of shallow cuts (transections) into the brain's cerebral cortex
Cerebral cortex
The cerebral cortex is a sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. It plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. It is constituted of up to six horizontal layers, each of which has a different...
. These cuts are thought to interrupt some fibers that connect neighboring parts of the brain, but they do not appear to cause long-lasting impairment in the critical functions that these areas perform.
Multiple subpial transections can help to reduce or eliminate seizures arising from vital functional areas of the cerebral cortex. This procedure has been successful in an unusual type of epilepsy called Landau-Kleffner syndrome
Landau-Kleffner syndrome
Landau–Kleffner syndrome , also called infantile acquired aphasia, acquired epileptic aphasia or aphasia with convulsive disorder, is a rare, childhood neurological syndrome....
, at least for a limited time.
Bleeding at the site of the transection is possible, but the procedure is generally well tolerated. Major complications appear to be rare. Transections in language
Language
Language may refer either to the specifically human capacity for acquiring and using complex systems of communication, or to a specific instance of such a system of complex communication...
areas of the brain may mildly impair the language function served by that area.
Who is a candidate?
Epilepsy surgery is reserved for people whose seizures are not well controlled by seizure medicines. (This situation is sometimes called being "medically refractory.") In the past, epilepsy patients were referred for surgery only after they had taken medicine after medicine without success, often for 10 years or more. Today, however, the definition of medically refractory has changed, and surgery is being performed as early as 1 to 2 years after the diagnosis of epilepsy is first made.In children, the definition of medically refractory is even more individualized to the specific child's situation. Surgery may be considered for some children after weeks to months of treatment with seizure medicines.
In general, a person is considered to be a potential candidate for surgery if adequate trials of two first-line seizure medicines (ones that are commonly effective in controlling the type of seizures the person is experiencing) and one two-drug combination all have failed to control the seizures. A trial of a medication is considered adequate when it has been increased gradually to the maximum dosage that does not cause serious side effects and then is given for a long enough period. If the person has frequent seizures, any improvement will be obvious after a short time. If the seizures generally occur far apart, however, it may take months to determine whether the time between seizures is increasing.
At some epilepsy centers, patients are offered additional conventional or experimental medications before surgery is considered. But research suggests that each time a trial of medication fails to control a person's seizures, it becomes less likely that a different medicine or combination will be successful. Since uncontrolled seizures present serious physical risks and social and psychological consequences, the trend these days is to proceed with surgery much sooner than in years past if it seems appropriate for that person.
Pre-operative Assessment
Success rates for epilepsy surgery are constantly improving, and advances in preoperative assessments are largely responsible. Proper patient selection and a thorough presurgical workup are the cornerstones of surgical success.If a review of the person's experiences with seizure medicines shows that adequate tests of at least a few different medications have not succeeded in controlling the seizures, then the person may be referred to a specialist for a preoperative (or presurgical) assessment.
The preoperative assessment has two general objectives:
- to maximize seizure control after surgery
- to minimize disruption of normal brain functioning.
The number and type of tests that make up the preoperative assessment will depend on the type of surgery being considered. General objectives of the tests include:
- assessing the person's current status
- determining the exact location of seizure activity
- evaluating the surrounding areas of the brain to determine what kinds of problems the patient might experience after surgery.