What is seizure disorder?
Epileptic seizures are sudden, often dramatic "electrical storms" in the brain that affect about 0.5% of the population. All may be seen as symptoms of a wide variety of underlying disorders of brain or body that promote seizure activity.
There are several different seizure types. Some seizures cause convulsions with loss of consciousness and violent muscle spasms, while others may involve unusual sensations, brief periods of "blanking out" or manifest simply as altered behavior. The term epilepsy is used when seizures are recurrent over an extended time period.
The following examples describe two quite different settings in which seizures may occur: A solitary seizure associated with alcohol withdrawal is best thought of as an isolated seizure with a clearly defined cause, whereas a child with developmental delay and recurrent seizures as a result of birth injury to the brain should be regarded as having epilepsy.
Epileptics are frequently stigmatised by others for their disease, and it should be emphasized that the tendency to have seizures is quite distinct from mental retardation or low intelligence. Although seizures are usually not life-threatening in themselves, the consequences of seizing (e.g. while driving or swimming) may be fatal. Convulsive seizures are frightening events to experience either directly or as an onlooker. Knowing something about seizures and the ways in which they can be managed is a first step towards taking control.
What causes epilepsy?
A seizure is best thought of as an uncontrolled, abnormal burst of electrical and chemical activity that spreads rapidly between nerve cells (millions upon millions of them) in the brain. A seizure may start in one region of the brain (the "focus") and spread to other parts. The first symptoms of a seizure, referred to as the "aura" (often a strange sensation or smell) reflect the function of that part of the brain first affected by the epileptic activity. A seizure that initially causes only twitching of one hand and then goes on to convulsions with loss of consciousness, for example, reflects seizure activity that starts in the front part of one hemisphere and then spreads to involve widespread areas on both sides of the brain.
Seizures are a feature of a variety of states of ill-health, and have many differing causes. Seizures may be the only manifestation of disease, may be caused by a specific brain disorder, or are seen as part of a more generalised bodily illness.
Primary epilepsy refers to seizures, often seen in children, where the brain is abnormally prone to seizure activity. Secondary seizures, on the other hand, are the result of specific, identifiable causes. Seizures may cease if the underlying condition is treated and in this sense, seizures may be regarded as symptoms of the underlying condition. Meningitis and other infections, strokes, head injury, brain surgery, drug and alcohol abuse, brain tumours and fever are among the many causes of seizures. In a significant proportion of patients, however, no cause can be identified.
In all forms of epilepsy, stress, sleep deprivation, a change in diet or medication, alcohol, certain specific activities, and menstruation and pregnancy in women may precipitate individual seizures.
Symptoms and signs of epilepsy
Epileptic seizures are generally brief (usually seconds to minutes), often dramatic episodes that usually alter awareness, and may cause complete loss of consciousness. In such a circumstance, the person experiencing the seizure will have an incomplete recollection, or none at all of the event itself, and onlookers will need to provide a description of what happened to health personnel. The initial symptoms (e.g. sudden loss of consciousness, involuntary twitching of a limb or a strange feeling or sensation) are often the most helpful in categorising a particular seizure.
Furthermore, because awareness can be lost very rapidly, and in some cases without warning, those prone to seizures need to be very circumspect about certain activities. Seizing while driving, swimming, bathing alone or using machinery, for example, has the potential for harm to self or others. Most seizures are self-limited, and not life-threatening in themselves. Occasionally, seizures do not stop, a situation known as status epilepticus. This is a medical emergency, has a high mortality, and requires immediate medical attention. Other possible complications of epilepsy are discussed below.
There are several different types of seizure. Classification is important because different seizures have differing underlying causes, and often respond to specific medications:
Partial seizures involve epileptic activity in a restricted region of the brain and do not cause loss of consciousness.
A partial seizure that develops into a generalised seizure is referred to as a secondarily generalised seizure, at which point convulsions and loss of consciousness occur.
The most frequent type of partial seizure is the so-called complex-partial seizure. These seizures involve the temporal or less frequently the frontal lobe of one side of the brain. Patients typically experience a strange feeling or odd smell (the aura) followed soon afterwards by an alteration of consciousness. This causes mental clouding and a "spaced out" manner. In general, patients will not respond to commands and may manifest unusual behaviors such as picking at their clothing, smacking their lips or wandering in a purposeless manner. Unconsciousness, convulsions and collapse do not occur.
A less common type of partial seizure is the simple partial seizure. Here, seizure activity is restricted to a region of the brain that controls movement or receives sensation, producing restricted jerking of a limb (simple motor seizure), or an abnormal feeling. Occasionally, persistent weakness of the limbs may follow such a seizure. The person remains conscious and aware of his or her surroundings, and is able to communicate with others.
Generalised seizures are those that cause loss of consciousness, and imply widespread involvement of both hemispheres of the brain.
Generalised tonic-clonic seizures, previously termed "grand mal" seizures, are the most dramatic and frightening kind of seizure. Sudden collapse with loss of consciousness is followed by muscle spasm ("tonic") and violent jerking ("clonic") of the limbs that builds to a climax and then subsides and stops on its own after several minutes. The involuntary contraction of muscles can cause tongue biting, temporary arrest of breathing, and incontinence. Injury may occur in falling to the ground and as a result of the violent movements of the limbs. Exhaustion, muscle aches and headache are common for several hours after the seizure has settled, in the so-called "post-ictal" period.
Absence seizures ("petit mal") also involve loss of consciousness, and as such are also generalised seizures, but are quite distinct from tonic-clonic convulsions. Seen most frequently in children, absences involve very brief periods (seconds) of "blanking out" that may occur many times a day, and are often put down to daydreaming. These staring spells briefly interrupt whatever the child is doing and may be associated with fidgeting or picking at clothes (automatisms). The child and his or her family may be quite unaware of anything unusual, and absence seizures frequently only come to light when schoolwork suffers.
Other varieties of generalised seizure may involve sudden loss of muscle tone with collapse or large-scale jerks of the whole body, but these are rare.
How is epilepsy diagnosed?
Obtaining a clear description of the seizure either from the patient themselves, or more often from reliable eyewitnesses, is the initial and most important step in diagnosing an epileptic seizure. The physician needs to recognise features that suggest a seizure and distinguish it from other kinds of brief neurological events. These include TIAs (transient ischaemic attacks – "mini-strokes"), fainting spells, behavioral problems and a range of involuntary movements. Seizures are characterised by the presence of an aura, rhythmical jerking, alteration or loss of consciousness, and a post-ictal period of recovery. A careful history may also provide clues to finding a cause for seizures, such as a head injury or alcohol or drug addiction.
Usually patients have no signs of epilepsy or ill-health between seizures, and a physical examination may be quite normal. In some patients, signs of neurological disease may point towards a cause for the seizures.
An electroencephalogram (EEG) is a recording of the brain's electrical activity as measured by electrodes stuck on the outside of the scalp. A recording made during the normal interval between seizures in an epileptic often reveals a seizure "signature" – spiky waves on the smooth, regular background pattern of normal brain waves – and can provide important information about the type and location of the seizure. A normal EEG does not rule out the diagnosis of epilepsy, however. During a seizure, abnormal activity tends to be clearly evident on the EEG recording. Certain patients may be admitted to an epilepsy unit for long-term monitoring. Here, a video recording of the patient asleep and awake and an EEG tracing are obtained over many hours, and the two can be compared side by side.
Other investigations, including various blood tests, and CT or MRI scans of the brain help to determine a cause, and are often obtained as part of the workup of a first seizure.
How is epilepsy treated?
Many seizures are the direct result of an underlying brain or bodily disorder. In such a case, treatment of the underlying condition will often be sufficient to prevent seizures from recurring, and the seizures themselves will need no specific management. In general, seizures that have only occurred once are not treated unless they recur. Once seizures are recurrent, specific anti-epileptic medication will generally be needed. Some epileptics will only have seizures in certain settings, or find that their seizures are reliably provoked by specific triggers. Alcohol use and sleep deprivation are frequently responsible.
There has recently been an explosion of new drugs for treating epilepsy. These new-generation medications are better tolerated, are somewhat more efficacious, and are all considerably more expensive than the older medications, which remain the mainstay of treatment. Examples of widely-used established medications are Carbamazepine, Phenytoin, Phenobarbital, Valproic acid and Ethosuximide. Examples of newer medications are Levetiracetam, Lamotrigine, Topiratmate and Gabapentin. Choosing the best agent is a complex task best done by a neurologist with a special interest in epilepsy. The choice will rest on the type of seizure, as well as the efficacy of the medication and how well it is tolerated by the individual patient. All medications have side-effects, need to be taken regularly, and must be monitored carefully. Most patients are rendered seizure-free with the use of a single medication, or, if necessary, medications in various combinations.
Follow-up should occur at least annually. Monitoring drug levels in the blood is important for continued control of seizures and reduction of side-effects. Illness, pregnancy, sleep deprivation, skipping medication doses and using drugs, alcohol or certain medications may cause seizures in someone with previously well-controlled epilepsy. People with epilepsy should wear Medic-Alert bracelets, and family members should be instructed in how to assist during a seizure.
The last decade has seen the development of effective surgery for seizures of certain kinds. In general, surgery is reserved for patients with a seizure focus that can be precisely identified, and who have failed drug therapy. Workup for surgery is complex, but when successful, surgery may render patients seizure-free without having to use medications. Other modalities of treatment, such as the vagal nerve stimulator, are also used in specific cases.
Emergency first-aid treatment for a convulsive seizure
- At the onset of the seizure, before the tonic phase begins, it is appropriate for an experienced person to insert an oral airway, padded tongue blade or other soft object between the teeth. Don't try to force a hard object between the teeth once the jaws are closed, as the teeth or object may break and fragments may be inhaled.
- Protect the person from injury. Clear the area of furniture or other objects that may cause injury. Cradle the head with a pillow if it is on a hard surface, but don't restrain the person's movements.
- Turn the person onto one side with the head down. This allows drainage of saliva and prevents inhalation of vomit.
- The vast majority of seizures will end spontaneously after a minute or two, and no specific treatment is necessary. When seizures continue, or consciousness is not regained between seizures, status epilepticus is diagnosed and requires urgent management that may be started by the emergency medical service, but is best performed in a hospital.
What is the outcome of epilepsy?
Although epilepsy tends to be a lifelong condition, effective management is available for most, allowing a seizure-free, productive life. Most occupations and recreational activities are open to people with controlled epilepsy, and most countries allow driving after a seizure-free period of 6-12 months (on or off medication).
Complications of seizures can occur in many forms. Although seizures themselves tend to be self-limiting, the consequences of abruptly losing contact with the environment can be dangerous. These include: accidents while driving, bathing, swimming or using machinery; injuries sustained from falling or trauma to flailing limbs; and aspiration of vomit, leading to choking or aspiration pneumonia.
Status epilepticus refers to seizures that do not stop, or are so close together that consciousness is not regained. In this serious circumstance, respiratory and metabolic failure occurs, and mortality is high, even with intensive care treatment.
Even when seizures do not directly threaten life or limb, the condition can be damaging. If absence seizures are not recognized in children, these brief interruptions of attention throughout the day can lead to learning disability. Older children and adults may find the prospect of seizures so socially embarrassing or frightening that they withdraw from the world. Explanation of the condition, the broader education of the public, and contact with other people affected by seizures can do much to alleviate this.
Lastly, all anti-epileptic drugs have side-effects, and in an individual patient this often governs the choice of agent. Most of these side-effects are reversible and simply represent individual intolerance to a particular medication or excessively high dose. Rarely, side-effects can be unpredictable and serious. Pregnant women need especially careful choice of medication, and younger women who may fall pregnant need effective contraceptive advice.
Can epilepsy be prevented?
If seizures occur as the result of an underlying disease of the brain (e.g. a tumour) or the body (e.g. kidney failure), treatment of these primary conditions can prevent seizures from occurring, and anti-epileptic medication may become unnecessary. In other circumstances, drug treatment or surgery for epilepsy can prevent seizures from recurring. Occasionally, drug therapy is prescribed prophylactically – as is the case after brain surgery, where a short course of anti-epileptic medication is often prescribed routinely to all patients, even those with no history of seizures.
In established epilepsy, avoiding changes in routine, disturbed sleep, drugs and alcohol, and (in a minority of patients) certain situations or activities known to promote seizures, are other practical forms of prevention.
When to call the doctor
Seizures in anyone other than in those with recognized, regular seizures is cause for concern, and medical advice should follow. This is especially true in the case of a first seizure where the cause needs investigation. In most cases, the seizure will be over by the time the patient sees a doctor, so it is important for eyewitnesses to describe what happened.
Status epilepticus is a medical emergency and the relevant services should be contacted without delay.
In established patients on anti-epileptic medication, contact with your doctor may be necessary if you suspect that the medication is making you feel unwell. This is particularly likely when a new drug has been started, dosage altered, or if any other medications are taken as these may interact with the antiepileptic drugs.
Reviewed by Dr Andrew Rose-Innes, MD, Department of Neurology, Yale University School of Medicine, New Haven.