Because absence seizures are usually quite brief, tend to strike during times of inactivity, and closely resemble daydreaming or "being off in one's own world," they may pass unnoticed by others and go undiagnosed for some time.
Absence seizures fall into two categories: typical and atypical.
Typical absence seizures begin abruptly, last 10 to 30 seconds, and resolve themselves without complication. The person simply stops in his tracks (and/or mid-sentence), and enters a staring, trance-like state...
Surgery to remove the area of the brain producing seizures
Surgery to interrupt the nerve pathways through which seizure impulses spread within the brain
Surgery to implant a device used to treat epilepsy
Surgery is considered only if the area of the brain where the seizures start, called the seizure focus, can be clearly identified, and if the area to be removed is not responsible for any critical functions, such as language, sensation and movement. Extensive evaluation and testing are necessary to determine if surgery is appropriate.
Who Is a Candidate for Epilepsy Surgery?
Surgery may be an option for people with epilepsy whose seizures are disabling and/or are not controlled by medication, or when the side effects of medication are severe and greatly affect the person's quality of life. Patients with other serious medical problems, such as cancer or heart disease, usually are not considered for epilepsy surgery.
What Surgical Options Are Available?
Different surgical procedures are available to treat epilepsy. The type of surgery used depends on the type of seizures and the area of the brain where the seizures start. The surgical options include:
Lobe resection: The largest part of the brain, the cerebrum, is divided into four paired sections, called lobes -- the frontal, parietal, occipital and temporal lobes. Temporal lobe epilepsy, in which the seizure focus is located within the temporal lobe, is the most common type of epilepsy in teens and adults. In a temporal lobe resection, brain tissue in the temporal lobe is resected, or cut away, to remove the seizure focus. The anterior (front) and mesial (deep middle) portions of the temporal lobe are the areas most often involved. Extratemporal resection involves removing brain tissue from areas outside of the temporal lobe.
Lesionectomy: This is surgery to remove isolated brain lesions -- areas of injury or defect such as a tumor or malformed blood vessel -- that are responsible for seizure activity. Seizures usually stop once the lesion is removed.
Corpus callosotomy: The corpus callosum is a band of nerve fibers connecting the two halves (hemispheres) of the brain. A corpus callosotomy is an operation in which all or part of this structure is cut, disabling communication between the hemispheres and preventing the spread of seizures from one side of the brain to the other. This procedure, sometimes called split-brain surgery, is for patients with extreme forms of uncontrollable epilepsy who have intense seizures that can lead to violent falls and potentially serious injury.
Functional hemispherectomy: This is a variation of a hemispherectomy, a radical procedure in which one entire hemisphere, or one half of the brain, is removed. With a functional hemispherectomy, one hemisphere is disconnected from the rest of the brain, but only a limited area of brain tissue is removed. This surgery generally is limited to children younger than 13 years old who have one hemisphere that is not functioning normally.
Multiple subpial transection (MST): This procedure is used to help control seizures that begin in areas of the brain that cannot be safely removed. The surgeon makes a series of shallow cuts (transections) in the brain tissue. These cuts interrupt the movement of seizure impulses but do not disturb normal brain activity, leaving the person's abilities intact.
Vagus nerve stimulation (VNS): This is a device that electronically stimulates the vagus nerve (which controls activity between the brain and major internal organs) is implanted under the skin. This reduces seizure activity in some patients with partial seizures.
Responsive neurostimulation device (RNS): This device consists of a small neurostimulator implanted within the skull under the scalp. The neurostimulator is connected to one or two wires (called electrodes) that are placed where the seizures are suspected to originate within the brain or on the surface of the brain. The device detects abnormal electrical activity in the area and delivers electrical stimulation to normalize brain activity before seizure symptoms begin.