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When the brain is functioning normally, brain cells communicate with one another by way of seemingly random electrical activity, in order to control the body's functions.
A seizure is produced when the electrical activity of thousands to millions of brain cells activate in a synchronous fashion. Epilepsy is a disorder defined by the unprovoked tendency to have recurrent seizures.
A single seizure does not necessarily warrant a diagnosis of epilepsy. Approximately 10% of North Americans will have at least one seizure in their lifetime for various reasons. Some possible causes of seizures include head injury, brain tumors, stroke, inherited brain disease, disorders causing lack of oxygen to the brain, substance abuse, high fevers, degenerative diseases and brain infections. The worldwide prevalence of epilepsy is approximately 1%, with variance between countries
Symptoms
There are multiple seizure subtypes, however these can be broadly divided into seizures that involve one region of the brain (focal seizures) versus the entire brain at once (generalized seizures, the most common of which are convulsions however other subtypes such as absence and atonic seizures also exist).
Focal seizures may or may not result in alteration of awareness, accompanied by one or more of the following: uncontrolled movements of one body part, unresponsiveness, staring, facial movements, confusion or, rarely, aggressive behavior. These seizures may be preceded by an "aura", which may include sudden onset of fear, deja vu, unusual odors or tastes, nausea or stomach discomfort. These events tend to last no more than 2-3 minutes.
Convulsions tend to always result in a loss of awareness and are typically associated with initial stiffening of all muscles, followed by alternating periods of flexion and extension of muscles. This is frequently accompanied by involuntary crying out, falls, foaming at the mouth, inability to breathe for a brief period and possible tongue biting. These seizures generally last no more than 90 seconds to 2 minutes.
The more rare generalized seizure subtypes tend to be very brief (seconds) and are usually characterized by brief episodes of loss of consciousness (absence seizures) or body tone (atonic seizures). They may resemble daydreaming or a sudden unprovoked fall respectively to the outside observer.
The most appropriate approach to a seizure is to ensure that the patient remains safe and to allow the seizure to run its course. A link to seizure first aid is provided below. Notably, a seizure lasting more than 5 minutes should be evaluated emergently.
Diagnosis
The diagnosis of seizures is largely dependent upon a comprehensive neurological history, including an accurate account of what happened at the time of the apparent seizure. Witness accounts are often very helpful in this regard. The diagnosis may be aided by the use of electroencephalography (EEG) to evaluate the brain's electrical activity and magnetic resonance imaging (MRI) to evaluate the brain for structural abnormalities which may contribute. Extended EEG recordings are often utilized to improve the yield of a study, and this can be achieved in the outpatient (ambulatory EEG) or controlled lab setting (video EEG). In specific instances where a heritable epilepsy syndrome is suspected, genetic screening may be used as an additional diagnostic tool.
Treatment
People with epilepsy are generally maintained on one or more antiseizure drugs (ASDs). These medications are started and altered as necessary to maintain seizure freedom and freedom from side effects. ASDs can be broadly classified into those with effect on focal seizures, generalized seizures, or both. Often, a broad-spectrum ASD which works on several seizure types is selected as initial therapy. Examples include levetiracetam, lamotrigine, valproic acid or divalproex sodium, topiramate, clobazam, zonisamide or felbamate. It is duly noted several new ASDs have mechanisms or spectrums of actions which are yet poorly delineated, such as cenobamate.
The selection of an ASD is complex and requires consideration of many factors by the treating physician, including but not limited to seizure subtype and frequency, the patient's age and lifestyle, childbearing potential, co-morbid conditions, likelihood of adherence and side effect profile. Anti-convulsant therapy tends to be life-long, however there are rare exceptions.
For patients who don't respond to two or more medications, there are several options:
- Neuromodulation, where a device is surgically implanted in the body or brain to reduce seizure potential, may provide a significant added seizure reduction without typical medication side effects. Furthermore, in contrast to medications, the efficacy of these devices appears to improve over the implantation period rather than diminish. Three devices are currently approved by the FDA for epilepsy, specifically vagal nerve stimulators (VNS), responsive neurostimulators (RNS) and deep brain stimulation (DBS). VNS is the most commonly utilized in the outpatient setting, as it is located extracranially in the left chest area. The latter two devices are placed intracranially, typically at a specialized center.
- The ketogenic diet and Modified Atkins Diet (MAD) are also reasonable adjunctive options for epilepsy, which can also significantly reduce, though often not eliminate, seizures or the need for seizure medications. This requires the close supervision of a specialized team and is most often initiated and monitored in a specialized center.
- There are also several subtypes of epilepsy surgeries which are aimed at destroying the specific area of the brain causing the seizures. Patients with focal medically refractory seizures may greatly benefit from these procedures, and in some cases, such as in temporal lobe epilepsy, seizure freedom can be achieved.
Avoidance of potential seizure triggers is also an important aspect of epilepsy management. Common examples include:
- Sleep deprivation or overtiredness
- Alcohol, especially in excess or acute withdrawal
- Use of illicit or high-risk prescription drugs
- Excessive caffeine
- Strobe lights and other provocatory light effects
- Severe stressors
- Fevers or other illness
- Hypoglycemia
- Hormonal cycles in women
Infrequently, patients have unusual triggers, such as startling noises or hot water.
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