Epileptic seizures are generally brief (usually seconds to minutes) and often dramatic episodes that usually alter awareness, and may cause complete loss of consciousness.
In such a circumstance, the person experiencing the epileptic seizure will have poor or no recollection of the event itself, and onlookers will need to provide a description of what happened.
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 without warning in some, people prone to seizures need to be very careful 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 requiring immediate medical attention. Other possible complications of epilepsy are discussed below.
Types of seizures
There are several different types of seizure. It’s important to classify them correctly as different seizures have differing underlying causes and often respond to specific medications.
1. Partial (focal) seizures
A partial (focal) seizure involves epileptic activity in a restricted region of the brain and does not cause loss of consciousness until it spreads to other regions of the brain.
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. This is often called a temporal lobe seizure, since the temporal lobe is the most common site for these seizures to arise. However, complex partial seizures can arise from any part 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 behaviours such as picking at their clothing, smacking their lips or wandering around 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 single region of the brain, producing restricted jerking of a limb (simple motor seizure), or an abnormal feeling.
Persistent weakness of the limbs may occasionally follow such a seizure. The person remains conscious and aware of his or her surroundings, and is able to communicate with others.
1. Generalised seizures
Generalised seizures cause loss of consciousness and imply widespread involvement of both hemispheres of the brain. However, the term is confusing; "generalised" refers to the fact that there is a widely distributed change on EEG. Many generalised seizures do not cause loss of consciousness.
A generalised tonic-clonic seizures (previously termed "grand mal" seizures), is 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. This 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.
An absence seizure ("petit mal") also involves loss of consciousness, and as such is also a generalised seizure, but is 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. These are often put down to daydreaming. Such 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. Absence seizures frequently only come to light when an individual’s 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.
When to call the doctor
Seizures in anyone other than in those with recognised, regular seizures are 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.
Professor Jonathan Carr, FCP (SA) Neurology, PhD. Head Division of Neurology, Tygerberg Hospital and University of Stellenbosch, Cape Town. February 2015.