Seizure Types. Workbook

Transcription

1 Faculty of Health Department of Community Health and Social Work Learning Disability Division Seizure Types Workbook Fiona Rich Senior Lecturer

2 Introduction When we think of seizures, many people tend to think of the classic Grand Mal seizure with thrashing limbs and frothing at the mouth. There are however, many different types of seizures and not all of them involve convulsions. For example, some seizures involve changes in behaviour and may be either misdiagnosed or not diagnosed as epilepsy at all. A person with epilepsy may experience more than one type of seizure, although most people only present with one type. However, the frequency, length and pattern of an individual s seizures tend to be fairly constant for that individual. Normally there is a relatively low level of electrical activity in the brain (Figure 1). In those who have epilepsy, it is known that there is a loss of inhibitory cells and there is an inability to switch off cells once they have been stimulated (Figure 2).. Figure 1 Figure 2

3 In an epileptic seizure, excessive electrical activity builds up causing uncontrolled stimulation of the brain. Excitatory cells fire in rhythmic, uncontrolled bursts which may spread from a localised area of the brain to a generalised area, eventually involving the whole brain. The brain contains millions of nerve cells (neurones). Normally, the nerve cells are constantly sending tiny electrical messages down nerves to all parts of the body. Different parts of the brain control different parts and functions of the body, therefore, the symptoms that occur during a seizure depend on where the abnormal burst of electrical activity occurs. Symptoms that may occur during a seizure can affect muscles, sensations, behaviour, emotions, consciousness, or a combination of these. The different types of seizures are discussed below. Classification of Seizures Seizures are generally classified into 2 categories: 1. Partial (or Focal) Seizures, affecting only a part of the brain. This type of seizure starts and stays in a small area of the brain, and individuals tend to have localised or 'focal' symptoms, such as identified in Figure 3 Figure 3

4 2. Generalised Seizures affecting the whole or most of the brain. This electrical disturbance starts at the base of the brain and rapidly proceeds to the midbrain and out to the lobes. If the midbrain is affected by the electrical disturbance, it will result in unconsciousness. As a result generalised seizures invariably cause changes to the level of consciousness. Seizure Types The International League Against Epilepsy (ILAE) identified the following classification of seizures in 1989 Partial (or Focal) Seizures The typical symptoms of partial seizures as already indicated above would depend on which area of the brain was involved in the abnormal burst of electrical activity. The individual may experience any of the following typical Symptoms: Localised jerking movements Tingling Sensation of déja vu Flashing lights Strange smell/taste Partial seizures may be simple or complex in nature. Simple Partial seizures: Any of the above symptoms may be experienced The individual may be fully aware and conscious May last for only a few seconds May present with additional symptoms for example: o o Simple partial seizures with motor symptoms the most common of these are jerking or spasms. Usually occurring in epilepsies in the frontal or central regions Simple partial seizures with somatosensory symptoms or special sensory manifestations (simple hallucinations). These take the form of tingling or numbness, or sometimes an electrical shocklike feeling, burning pain or a feeling of heat. The focus is usually in the central or parietal region although may occur in other areas

5 o o Simple partial seizures with autonomic symptoms such as changes in skin colour, blood pressure, heart rate, pupil size. More common in generalised or complex partial seizures, but are occasionally seen in simple partial seizures Simple partial seizures with psychic manifestations more common in complex partial seizures than simple partial and takes various forms such as loss of speech; disturbance of memory including flashbacks and déjà vu; fear; depression; anger and hallucinations (visual, auditory, gustatory or olfactory) Complex Partial seizures: Complex partial seizures usually start in the temporal lobe which is involved with controlling emotion, memory, speech and language. Seizures may be associated with unexpected movements, strange feelings, fluctuating emotions or altered behaviour e.g. appearing as if loitering with intent or stripping off clothes. This behaviour can cause problems in diagnosis as the behaviours do not resemble typical seizures i.e. there is no thrashing or frothing at the mouth etc. In addition, people with learning disabilities who present with this behaviour may be misdiagnosed and assessed as presenting with challenging behaviour or behaviour problems. Communication problems in people with learning disabilities may make diagnosing this type of seizure more difficult as they may be unable to describe what is happening to them This may result in individuals being treated with drugs such as Chlorpromazine. This is a phenothiazine which has a sedating effect and is used for difficult behaviour, but it can cause EEG changes and convulsions. The strategy of prescribing Individuals with drugs for problem behaviour when in fact they are experiencing seizures would obviously make the apparent problem behaviour worse. Figure 4 (over the page) shows the vicious circle that can arise from this situation:

6 Figure 4 5. Further deterioration of behaviour due to effects of phenothiazines increasing seizures 1. Altered Behaviour due to complex partial seizure 4. Phenothiazines Increased to reduce problem behaviour 2. Phenothiazines prescribed for problem behaviour 3. Complex partial seizures increase (behaviour seen to deteriorate) Generalised Seizures Generalised seizures are caused by a widespread disturbance of the brain where the whole of the brain is involved. The disturbance starts at the base of the brain and rapidly moves up through the midbrain to the lobes. In any seizure, where the mid brain is involved, there will be a loss of consciousness. Generalised seizures invariably affect consciousness or awareness as the mid brain is involved, this loss of consciousness however may be so brief that the individual may not be aware of a loss of consciousness. The seizure types that come under this category will be discussed later in this workbook but are classified as: Tonic-clonic Tonic Atonic Myoclonic Absence

7 Secondary Generalised Seizures Secondarily Generalised seizures unlike primarily generalised seizures where the disturbance starts at the base of the brain and rapidly moves up through the midbrain to the lobes, secondarily generalised seizures are partial seizures in any part of the brain, either simple or complex, in which the discharge spreads to the whole brain. There is usually a noticeable change in the symptoms when moving from a primary to secondarily generalised seizure. However, the changes can happen so quickly that only an EEG can show that the seizure did not start from a focus. This can cause problems with diagnosis of the seizure type until the necessary tests are done and the specialist can see where the activity first occurs. The involvement of the whole brain leads to a clonic convulsive seizure with the same characteristics as a generalised tonic-clonic seizure (discussed below). Often the effects of a simple partial seizure are so slight that the person does not feel they are experiencing a seizure (for example they may experience a strange taste, feeling or smell). Individuals often express these experiences as an aura or warning that a major seizure is imminent rather than a seizure. Tonic-clonic Seizures This is a major type of fit, which was previously thought to start with an aura but as we now know, this is a very brief partial seizure developing into a secondary generalised seizure. [INSERT TONIC CLONIC SEIZURE VIDEO] During the tonic phase of this seizure type, the muscles in the body begin to stiffen and the person falls. A cry may be heard, but this is not pain. The tonic phase usually lasts from 10 to 30 seconds. This is followed by the clonic phase where involuntary jerking movements occur, usually lasting 30 to 60 seconds. The person will be unconscious and may go blue around the lips and cheeks due to a lack of oxygen. Incontinence may also occur. The final stage of the seizure is the recovery phase where the muscles are flaccid this can last from 2 to 30 minutes. There may also be post-epileptic automatism, headache and confusion following the seizure. These are involuntary motor actions that occur in a state of unconsciousness. These motor actions could include:

8 Crying or laughing Gestural movements such as fiddling Ambulatory movements such as walking, circling or running Verbal automatisms such as meaningless sounds, humming, whistling or grunting Responsive automatisms quasi-purposeful behaviour which is seemingly responsive Violent behaviour this is never pre-meditated or remembered or well coordinated so not to be confused with challenging behaviour Clonic Seizures These are generalised seizures in which the muscles contract and relax continuously causing the person having the seizure to twitch and jerk repeatedly. Unlike tonic clonic seizures, a person does not become stiff during a clonic seizure. This type of seizure occurs most frequently in infants and young children Tonic Seizures In this type of seizure, there is a sudden increase in muscle tone and all muscles contract the person will invariably fall like a board. A cry may be heard, but again this is not a cry of pain. There is no clonic phase in this type of seizure and the seizure usually lasts for less than 60 seconds. The tonic contraction causes: Extension of neck Contraction of the facial and respiratory muscles Flexion of upper limbs and extension of the lower limbs the arms and legs will shoot out [INSERT TONIC SEIZURE VIDEO] Atonic Seizures In this type of seizure, all postural muscle tone is suddenly lost causing the individual to collapse to the ground like a puppet who has had its strings cut. It is for this reason that this seizure is often referred to as Drop Attacks. These seizures are usually short in duration and the individual will recover immediately and quickly get up again, despite seeming to fall heavily.

9 However, often the individual falls forward during these seizure and may sustain serious injuries. This type of seizure is associated with cerebral damage and learning disabilities [INSERT ATONIC SEIZURE VIDEO] Myoclonic Seizures The term myoclonic comes from 'myo', meaning muscles, and 'clonus', meaning jerk. A myoclonic seizure is a sudden contraction of a muscle, muscle group or several muscle groups caused by a cortical discharge. In this type of seizure, there are widespread single or repetitive jerks which may affect the trunk, head, and limbs or be confined to one limb. The jerks vary in severity, from an almost imperceptible twitch to a severe jerking, which may result in a sudden fall or hand-held objects being thrown out of their hands. Shorvon (2005) refers to this as the flying saucer syndrome. As this is a generalised seizure, consciousness will be lost, but the seizure may be so brief that individual may not feel that consciousness was lost. However, the individual will immediately return to the normal state of consciousness following the seizure. These seizures may be induced by sudden noise or startle and often occur on waking or going to sleep. This is because as a person goes through the process of feeling sleepy to being asleep there are changes in the electrical activity within the brain. It is thought that during these changes, individuals are more susceptible to seizures. Most people have experienced a nocturnal myoclonus a sudden jerk as they are falling asleep as though they were falling off a cliff. This is similar to the jerks experienced by someone who has myoclonic seizures. The anticonvulsant carbamazepine (Tegretol) makes myoclonic jerks worse Absence Seizures In this type of seizure (previous known as a Petit Mal ), there is an abrupt fleeting moment of loss of consciousness and all motor activity stops although muscle tone is not lost and the individual does not fall. The individual becomes temporarily unresponsive, vacant and glazed. The seizure ends as abruptly as it started and the individual resumes their activity without any confusion as though nothing had happened. The individual is often unaware that the seizure has occurred. The seizures may be so brief that they may be missed by others or misinterpreted as lacking in concentration.

10 Absence seizures can occur hundreds of times per day and often occur in clusters. As with myoclonic seizures, they may be more frequent when the individual is drifting off to sleep or on awakening. Absence seizures may be typical or atypical in nature. May also include rhythmic nodding of the head Typical Absence seizures usually last for less than 10 seconds and have an abrupt onset Atypical Absence seizures usually last for longer and occur with learning disabled people or people with neurological abnormalities; consciousness is often only partially impaired, the individual may be partially responsive and may wander. The onset and cessation of an atypical absence seizure is not so abrupt. [INSERT ATYPICAL ABSENCE SEIZURE VIDEO] Figure 5 is a summary of the partial and generalised seizures discussed above: P A R T I A L O R F O C A L o n e p a r t o f t h e b r a i n i s a f f e c t e d Figure 5 G E N E R A L I Z E D t h e w h o l e b r a i n i s a f f e c t e d b y s e i z u r e a c t i v i t y S I M P L E s e i z u r e a c t i v i t y w i t h n o l o s s o f c o n s c i o u s n e s s T O N I C C L O N I C b o d y s t i f f e n s a n d m u s c l e s t h e n c o n v u l s e C O M P L E X s e i z u r e a c t i v i t y w i t h c o n s c i o u s n e s s i m p a i r e d T O N I C w h o l e b o d y s t i f f e n s a s m u s c l e s t i g h t e n W I T H S E C O N D A R Y G E N E R A L I Z A T I O N s e i z u r e a c t i v i t y b e g i n s i n o n e s m a l l p a r t a n d s p r e a d s t o i n v o l v e t h e w h o l e b r a i n A T O N I C b o d y l o s e s a l l m u s c l e t o n e a n d g o e s f l o p p y A B S E N C E b l a n k i n g o u t a n d s t a r i n g f o r a b r i e f m o m e n t M Y O C L O N I C a r m s, h e a d o r w h o l e b o d y j e r k f o r a b r i e f m o m e n t

11 Unclassifiable Seizures Clinicians can make a diagnosis as to which seizure type the individual experiences according to the clinical features presented. However, despite the fact that the clinical features of seizures can lead to a classification, no two individuals have exactly the same seizures each person is unique and may present with very idiosyncratic seizures. For example, the seizure may be shorter in duration than typically found or a tonic-clonic seizure may appear more like a tonic or atonic seizure. EEG patterns can help to support the diagnosis of the seizure type, nevertheless, according to Shorvon (2005) up to one-third of seizures are considered unclassifiable using the current ILAE classification, taking forms that do not confirm to typical clinical features and EEG patterns.

12 Please answer these questions and the answers to 1. In your own words, explain the difference between a partial seizure, a generalised seizure and a secondary generalised seizure. 2. Discuss the clinical features of partial seizures and indicate which area of the brain will be affected. 3. Consider the following scenarios and, justifying your answers identify the seizure type you must state whether the seizures are partial, generalised or secondary generalised. Jane is a 22-year-old woman who has been diagnosed with epilepsy. The form that her seizures take includes smacking her lips, obsessive type movements and appearing distant. She does not lose consciousness Peter is a 7-year-old boy and his parents have been told that he has epilepsy. He has not convulsed but simply appears to go blank in a brief sensory unconscious state James is a 35-year-old man who has been diagnosed with epilepsy. He states that the seizures start with a strange metallic taste in his mouth then he suddenly crumples to the floor John is a 30-year-old man with learning disabilities. The form that his seizures take is as follows: initially he seems very agitated and his behaviour seems altered, he then goes very stiff and stops breathing, his limbs then begin to jerk rapidly for a few moments and then he appears to sleep. He is usually incontinent during the seizure. Often when he wakes up he seems very confused and agitated. Mary is a 14-year-old girl who has no history of epilepsy. She has recently begun to have funny turns first thing in the morning. The first time this occurred, she dropped a bottle of milk and could not understand how this happened the bottle seemed to fly out of her hands. She does not lose consciousness during these episodes.