What is epilepsy?
Epilepsy is a chronic medical condition
characterized by recurrent epileptic seizures. An epileptic seizure is a finite
event of altered brain function because of abnormal or excessive electrical
discharges from brain cells. Epilepsy is one of the most common neurologic
disorders, affecting approximately 0.5% to 1% of the US population. The basic
mechanisms of epilepsy have not yet been worked out.
What are the different types of epilepsy?
Several epilepsy classifications exist, and
terminology can be confusing. It is important to remember there are different
types of seizures, different types of epilepsy syndromes, and different causes
of epilepsy. For example, both brain tumors and stroke can present with seizures
and lead to chronic epilepsy. Some of the causes can be diagnosed and treated
medically, but some require surgery.
Who treats epilepsy?
A neurologist best determines the diagnosis
of epilepsy. Some neurologists take advanced training and become epileptologists.
These physicians specialize in the diagnosis and treatment of epilepsy. This
involves determining the cause of the epilepsy and starting anticonvulsant
medication to prevent further seizures. Many internists and family practice
physicians also treat epilepsy.
What are some of the causes of epilepsy?
Overall, approximately 65% of newly
diagnosed epilepsy cases have no obvious cause. Of the remaining 35%, the more
common reasons include stroke, congenital abnormalities, brain tumors, trauma,
and infection. It is important to determine the cause to help guide treatment.
What is epilepsy surgery?
Epilepsy surgery involves the surgical
removal of the region of brain responsible for the abnormal electrical signals
that cause seizures. This region of brain is called the epileptogenic zone. It
is determined by neuroimaging studies, electrical recordings from the scalp
(EEG), and clinical signs during a seizure.
Who is a candidate for surgery?
Generally, patients with seizures that
start in a focal area of the brain are considered for surgery. This region may
be as small as a marble or involve several lobes of the brain. Surgical patients
also generally have failed medical management of their seizures. Despite recent
advances in the surgical treatment of epilepsy, it remains underutilized. By
best estimates only 50% of patients with epilepsy will respond to anticonvulsant
treatment. Of the remaining cases, 10-50% may become a surgical candidate. Only
a small percentage of these patients will ever get to see an epilepsy surgeon.
What types of surgery are performed?
Surgery involves removing the abnormal
portion of brain causing the seizures. Brain tumors, vascular abnormalities, old
strokes, and congenital malformations may also be removed. The most common type
of epilepsy surgery performed is the temporal lobectomy. This involves removal
of a portion of the temporal lobe, usually for a syndrome called mesial temporal
sclerosis.
Other types of surgery include:
- The implantation of electrodes directly
on the brain or in the brain for more accurate measurement of seizures
- Other types of lobectomies, and in some cases removal of the entire cerebral hemisphere
- The surgical removal of congenital malformations of the brain (With neuroimaging technology, these malformations are becoming increasingly recognized as a major
cause of epilepsy)
- Vagal nerve stimulation, which involves
implantation of an electrode on the vagus nerve
The pre-surgical evaluation
1.
Evaluation by epileptologist with history and physical.
2. Video-EEG monitoring: Measures electrical activity in the brain.
3. Magnetic resonance imaging of brain: Shows the anatomy of the brain.
4. Metabolic imaging of brain (PET): Shows how the brain uses fuel.
5. Neuropsychological testing: Helps to tell how the brain is functioning.
6. Intra carotid Sodium Amytal testing (WADA): Helps to tell where language and
memory are in the brain.