Epilepsy Defined
Epilepsy, one of the oldest conditions known to mankind, is a neurological disorder characterised by recurrent, transient seizures caused by a disturbance in the electrical activity of the central nervous system. According to the World Health Organisation, up to 50 million people worldwide, equating to a prevalence of at least 50 per 100,000 of the general population will have epilepsy at any one time.
Characterised by a tendency to recurrent seizures and defined by two or more unprovoked seizures, the clinical manifestations of seizures will vary depending on where in the brain the disturbance first starts and how far it spreads. Transient symptoms can occur, such as loss of consciousness and disturbances of movement, sensation, mood or mental function. While the condition can develop at any age, it is most often diagnosed before the age of 20 and after the age of 60, and can be due to any one of several conditions, including:
- genetic
- hippocampal sclerosis
- congenital disorders
- cerebrovascular disorders
- alcohol/drugs and metabolic disorders
- cerebral infection
- brain tumours
Electro-encephalograms (EEGs) are used to diagnose epilepsy along with additional tests/techniques, while magnetic resonance imaging (MRI) scanning can determine the cause. As a result of the wide range of symptoms that can occur, epilepsy is generally classified by seizure type - partial (simple or complex) or generalised - and treatment, which involves regular long-term drug therapy, is commenced once the patient displays more than one seizure.
Types of seizures
Non Epileptic Seizures
Everyone can have a seizure and they can result from many things including low blood sugar, fever and head injury. They may involve changes in both physical (convulsions) and mental areas. There are two main categories of non-epilepsy related seizures.
- Physiological Seizures - caused by changes in the body (ie: blood oxygen level)
- Psychogenic Seizures - caused by psychological experiences (ie: trauma)
Epileptic Seizures
Since seizures are a manifestation of misfiring of neurons in the brain they can have several outward signs depending on the area of the brain that is affected. Seizures are classified by where they occur in the brain and most are broadly classified into two groups, primary generalized and partial seizures (World Health Organization, Epilepsy Ontario,Canadian Epilepsy Alliance).
Generalized Seizures
During a generalized seizure, the excessive misfiring of neurons occurs throughout the brain with no single focal point of onset or warning(Canadian Epilepsy Alliance). These will affect the entire body and may cause loss of consciousness and/or muscle contractions (Epilepsy Ontario,World Health Organization). The two most common types of generalized seizures are Generalized Absence (Petit Mal) and Tonic Clonic (Grand Mal) seizures.
Tonic Clonic Seizures
This is the type of seizure that most people associate with epilepsy (Canadian Epilepsy Alliance). During this type of seizure electrical activity immediately involves the entire brain and loss of consciousness occurs from its onset. There are two stages to tonic clonic seizures. The first is the tonic (stiffening) phase and the second is the clonic (jerking) phase.
At its onset, the individual will let out a short cry. It does not indicate pain but rather it occurs because of the stiffening of muscles that forces air through their contracted vocal chords. Due to the stiffened muscles the person will fall to the floor and may have their back arch, eyes roll back, limbs extend, difficulty breathing and skin turn bluish/grey (lack of oxygen).
Shortly following the initial tonic stage the limbs, body and head begin to jerk and twitch in a rhythmic fashion (convulse). This indicates the start of the clonic phase. The person will continue convulsing for 1-3 minutes during which saliva that was not swallowed in the previous phase may froth up in the mouth. The seizure will continue until the jerking slows and the seizure ends, at which time the person may let out a sigh as normal breathing resumes.
During the seizure the individual may have incontinence due to an increase in bladder pressure and possibly bite his/her tongue causing bleeding.
Following this extreme activity the body will be limp and the person is usually tired, confused, irritable and may have a headache. They should be given time to rest and recover. (Epilepsy Ontario, Canadian Epilepsy Alliance)
Absence Seizure
This type of seizure can often be mistaken for daydreaming and occur most often in children. In 75% of cases, absence seizures do not continue past the age of 18. Absence seizures present themselves as short staring spells, usually less than 10 seconds in which the child appears "spaced out" or "blank." During the seizure the eyes may roll back or flutter and if longer than 10 seconds the likelihood of mouth, hand and head movements accompanying the seizure increases. When over, the child will return to an alert state unaware of the seizure having occurred (Canadian Epilepsy Alliance, Epilepsy Ontario).
These seizures are usually subtle and therefore difficult to recognize, for this reason a diagnosis usually does not happen until several seizures have occurred. The frequency of absence seizures is usually high and can therefore affect the person's ability to absorb information. For this reason others such as teachers should be informed of the condition.
Myoclonic and Atonic Seizures
Firstly Myoclonic, comes from two root words, Myo meaning "muscle" and clonic meaning "jerk" as in the tonic clonic seizures. Myoclonic seizures involve sudden and sporadic muscle contractions which cause jerking in the arms, legs, neck and/or trunk (Canadian Epilepsy Alliance). It involves both sides of the body and may cause the individual to fall (Canadian Epilepsy Alliance). Myoclonic jerks are not all considered seizures, many people have had the experience of their bodies jerking them awake while trying to fall asleep. This is considered myoclonus and is a similar experience to a myoclonic seizure (Canadian Epilepsy Alliance). Atonic Seizures or "drop attacks" occur when the part of the brain responsible for muscle tone is affected. Atonic meaning "without tone", refers to the muscles of the body suddenly losing all strength and going limp. This seizure causes the person to fall to the ground and although it only lasts a few seconds can be dangerous enough to cause injury. Milder forms of these seizures can cause the head to go limp or the person to drop things (Canadian Epilepsy Alliance).
Partial Seizures
Partial seizures are quite simply seizures in which the electrical disturbance is localized to a specific area in the brain. This area also called the focal point can differ and therefore cause several manifestations of the seizure including but not limited to sudden jerking movements, distortions in sight or smell, sense of fear or anxiety, discomfort or dizziness (Epilepsy Ontario). These are divided into two subtypes the first simple partial seizures in which consciousness is maintained and the second complex partial seizures where it is lost (World Health Organization,Canadian Epilepsy Alliance). In certain conditions partial seizures may further develop into generalized seizures. This is called a secondarily generalized seizure.
Simple Partial Seizures
During the course of a simple partial seizure the individual may have several manifestations such as an unusual emotion, sensation, or movement but he/she will not loose consciousness over its course. Its manifestation is completely dependant on the area in the brain in which the seizure is occurring. For example, if the seizure is occurring in the visual part of the brain, the person may see a variety of lights. Simple partial seizures are typically short lasting from 2-10 seconds, and are sometimes reffered to as auras "warnings" that a generalized seizure is about to happen (Epilepsy Ontario,Canadian Epilepsy Alliance).
Complex Partial Seizures
As opposed to the simple partial seizure, in a complex partial seizure the person looses consciousness. It remains a partial seizure because it only affects a certain part of the brain, but in this case the part affected is the temporal or frontal lobes, which are responsible for controlling consciousness and awareness. During the 2-4 minutes of a typical seizure the person exhibits meaningless repetitious behavior such as lip smacking, picking at one's clothes and wandering around aimlessly. He or she may also stare blankly (Epilepsy Ontario). This is a very common type of seizure and unfortunately people who are having one are sometimes confused for being drunk or high on drugs(Canadian Epilepsy Alliance).
Status Epilepticus
Seizures are generally short-lived, but in some cases they may go on for longer than 30 minutes or repeat in a series. If this happens the person is in Status Epilepticus. This is a very dangerous state if not treated since it can lead to permanent brain damage or even death (World Health Organization, Canadian Epilepsy Alliance).
Postictal States
Commonly following both tonic-clonic and complex partial seizures postictal states refer to fatigue, confusion or disorientation that may last from minutes to days. There may be a tendency for the person to sleep or they may gradually become less confused until full consciousness is regained (Epilepsy Ontario).
