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CHAPTER 6 : EPILEPSY

GERALDINE CASSIDY

INTRODUCTION

An epileptic seizure is a sudden paroxysmal, synchronous and repetitive discharge of cerebral neurons, the clinical manifestations of which depend on where the discharge started, its spread and duration. Seizures result in interruptions or abnormality in brain function and may affect the level of consciousness, movement, sensation, autonomic or psychic phenomena. . They are usually self limiting. They may be provoked but usually appear to be spontaneous. A person is said to have epilepsy if they a recurrent tendency to have seizures( Betts, 1998 ).

Epileptic activity starts at cellular level and spreads to neighbouring cells which discharge repeatedly and synchronously so that the epileptic activity propagates. The electrical activity can be recorded by surface electroencephalogram (EEG ) provided it is large enough and near enough to be recorded. Epileptic activity may spread to other parts of the brain along neuronal pathways though other mechanisms may exist. The initiation, continuation and suppression of the activity is mediated by neurotransmitters such as glutamate which is excitatory and gama-aminobutyric acid (GABA ) which is inhibitory. Seizure activity may cause changes in the brain cells and even cell death.

EPILEPSY AND PEOPLE WITH LEARNING DISABILITIES

Epilepsy is commonly associated with learning disability . People with learning disabilities and epilepsy  deserve the best in epilepsy care, with the optimum balance between seizure suppression and potential adverse effects from anti-epileptic medication. For the affected person, epilepsy is more than seizures and quality of life also depends on non-medical aspects of management, such as the attitudes of carers to epilepsy and to taking calculated risks.

Total population surveys on prevalence suggest that 3 to 10 people in 1000 suffer from epilepsy ( defined as two or more seizures , at least one in the previous five years and /or receiving drug treatment for epilepsy ).Contrary to the previously held belief that epilepsy is more common among children, modern epidemiological studies suggest that the onset of epilepsy is almost as common in middle age and late age as it is in childhood and that the prevalence rises with age (Hopkins and Shorvon,1995). Earlier studies of epilepsy in people with learning disabilities show various methodological errors such as the use of non-standardised definitions and institutionalised study samples. These factors overestimate the prevalence of epilepsy. The use of guidelines for epidemiological studies produced by the International League Against Epilepsy (ILAE) in 1993 will overcome some of these difficulties in future studies. In spite of these difficulties, the rate of epilepsy  in people with learning disabilities is higher than in the general population , with the rate increasing with the degree of disability. Table 1 shows the rates of epilepsy in children and adults with mild, moderate and severe learning disabilities.

Diagnosis of epilepsy can be difficult in people with severe learning disabilities. This chapter will address the complex interaction between epilepsy and learning disabilities, causation, assessment and treatment, investigative techniques, drug therapy and the effect on life style. In addition the relationship between epilepsy, mental illness and behaviour disorders will be explored .

CAUSES OF EPILEPSY AND CLASSIFICATON

In many cases the aetiology or the cause of the learning disability and the epilepsy is the same, each disability being the consequence of brain damage arising either before or after birth. In the ILAE classificatory system those people who have a known cause for their epilepsy with significant brain abnormality being found are said to have symptomatic epilepsy. The term cryptogenic epilepsy is used when no significant brain abnormality is found but it is presumed to be symptomatic. In those people where the causation is unknown the term idiopathic epilepsy is used.  Many cases of epilepsy in people with learning disabilities  are therefore symptomatic. 

Causes can be divided into genetic or acquired.  Genetic causes include chromosomal abnormalities, (e.g. Downs syndrome or fragile X) or single gene defects, (e.g. tuberose sclerosis, phenylketonuria).  Acquired disorders include infections such as meningitis and encephalitis, metabolic disorders, brain tumours, trauma or haemorrhage. Premature infants are particularly vulnerable to metabolic disorders and brain haemorrhage in the peri-natal period.  People with Down syndrome may have epileptic seizures with ageing in association with the onset of Alzheimer type Dementia and the outcome  in this event is  poor.

Given the wide variety of disorders which may be associated with both epilepsy and learning disability it is extremely important that those presenting with seizures are assessed carefully to find the underlying cause.  The neurocutaneous disorders with involvement of the nervous system and skin, such as tuberose sclerosis and Sturge Weber syndrome are particularly important in this respect as the individual may have several body systems involved and because of the need for genetic counselling for other family members. A useful review on the neurocutaneous syndromes is provided by Kotagal and Rothner (1993).  With full knowledge of underlying causation it is easier to give information on prognosis and to select appropriate therapy.

The diagnosis and classification of seizures and epilepsy syndrome follow the guidelines suggested by the International League against epilepsy (ILAE, 1981, 1989), outlined in Tables 2 and 3.  This system of classification is accepted by the majority of epileptologists  world wide.

In 1981, the International League against Epilepsy (ILAE)  proposed classifying epilepsy based on whether both hemispheres of the brain were affected and on the level of consciousness. Partial seizures are those in which , in general, the first clinical electroencephalographic changes indicate initial activation of neurons limited to one cerebral hemisphere. When consciousness is not impaired in partial seizure it is classified as a simple partial seizure. When consciousness is impaired , it is a complex partial seizure. Impaired consciousness is the inability to respond normally to external stimuli by virtue of altered awareness and /or responsiveness. In generalised seizures , the first clinical changes indicate initial involvement of both hemispheres. Consciousness may be impaired and this may be the initial manifestation (ILAE ). Epileptic activity in partial seizures may spread to the other hemisphere and this is called secondary generalisation. Table 1 shows the classification of seizures according to ILAE.

A person with learning disabilities may sometimes be unable to give a clear account of their seizures and it is likely therefore that partial seizures are often missed in this population. They may have multiple or indeed unclassifiable seizures types.  Video telemetry EEG or ambulatory recording may be useful in such instances where there is marked diagnostic uncertainty.

Epilepsy can also be classified according to syndromes. The ILAE recognises a number of epilepsy syndromes which are determined by age of onset, seizure type, EEG abnormality and associated neurological abnormality and Table 3 gives a list of them. It is important to recognise a true epileptic syndrome as it can imply aetiology, prognosis and correct management.  Epileptic syndromes with onset early in life tend to be associated with a poorer outcome. West syndrome and Lennox-Gastaut syndrome are of particular importance as they manifest themselves in childhood and may lead to significant degrees of learning disabilities. Seizures in the new-born suggest a brain insult arising around the time of birth. Both morbidity and mortality are high and many infants may go on to suffer seizures or learning disability.

West syndrome or infantile spasm is associated with a characteristic appearance of hypsarrhythmia (a chaotic mixture of high amplitude slow waves with variable spike and sharp waves ) on EEG and spasms with most children having severe learning disabilities when they grow up. Seizures have their onset between three and six months of age and have a limited response to treatment although some success has been achieved with benzodiazepines, adrenocorticotropic hormone (ACTH) and the newer anti-epileptic drug vigabatrin.  Lennox Gastaut Syndrome presents with intractable seizures which are mixed in type, learning disability and again a characteristic EEG appearance (diffuse, slow spike and waves between seizures and bursts of fast activity in sleep ).  This disorder has its onset in the 3  to 5 year old age group and may follow on from West Syndrome.  Many of the children affected have learning disabilities in the long term.

Sufficient information to make precise distinction between symptomatic, idiopathic and cryptogenic epilepsy may not be to hand, particularly for adults with learning disabilities as found by Mariani et al (1993) who could classify only 28% into specific syndromes.  For the great majority,  classification into partial or generalised seizure types is possible and is crucial to ensure selection of the correct anti-epileptic.

CLINICAL DESCRIPTIONS

GENERALISED SEIZURES

Tonic Clonic seizures ( Grand mal in previous classifications)

This primary generalised seizure starts with no warning. There is a sudden cry followed by total muscular rigidity, falling and powerful jerking movements of all four limbs, usually lasting less than two minutes. This is follows by a phase of unresponsive coma lasting a few minutes. There may be seizure related injuries and emptying of the bladder. The person may remain confused for up to twenty four hours.

Absence Seizures

Typically absence or petit mal seizures occur in children and are characterised by three per minute spike and slow waves in the EEG. The child may have a brief lapse of consciousness lasting less than 45 seconds during which the child is usually motionless but eye blinking, myoclonus or drop attacks may be observed. Typical absences are rare in adults.

Atypical absences may appear similar clinically but the EEG appearance is quite different. They are usually found with other forms of epilepsy.

Myoclonic seizures

This consists of stereotyped jerking of either all or some of the limbs with or with out jerking of the head. These seizures are particularly seen in people with learning disabilities in conjunction with other forms of epilepsy and may be difficult to control.

Atonic Seizures

There is a sudden loss of postural tone associated with a fall. There is a risk of significant injury with these seizures.

PARTIAL SEIZURES

Simple Partial Seizures

There is no disturbance of consciousness in these seizures. If the motor cortex is involved as in the commonest form of simple partial seizures there may be focal spasms of a group of muscles . This kind of epilepsy has been called Jacksonian epilepsy. There may a period of paralysis in the affected muscles called Todd’s paralysis. Sensory seizures are more rare. There may be a sensation of pins and needles . Visual and auditory hallucinations  and auras of taste and smell are examples of simple sensory seizures.

Complex Partial Seizures

In complex partial seizures there is a disturbance of consciousness. Automatisms occur and vary from simple ones like chewing and  smacking of the lips to complex semi-purposive behaviour such as undressing  and walking. Such behaviours usually last less than five minutes but recent evidence suggests that complex partial status epilepticus (where the epileptic activity goes on for a prolonged period of time) may occur particularly in people with learning disabilities. The individual can present with a wide variety of symptoms such as irritability, wandering and psychotic symptoms.

All partial seizures, both simple and complex can evolve into generalised seizures. When this happens , it may be possible to observe the progression of events and the phenomenon is called secondary generalisation. 

Status Epilepticus

This refers to a continuous succession of seizures occurring without any period of recovery. Both generalised and partial seizures can produce status epilepticus. Generalised convulsive status epilepticus is defined as two or more seizures with out full recovery or more or less continuous seizure activity for 30 minutes or more. This is a medical emergency due to the potential for profound neuronal and systemic damage. It can happen if the medication is withdrawn abruptly or it is taken irregularly. 

ASSESSMENT

The diagnosis of epilepsy is essentially a clinical one based largely on an accurate description of events from carers.  Patients with learning disabilities are not usually able to describe the complex and often unpleasant experiences associated with the aura before a generalised seizure or during complex partial seizures and they may be very frightened.  In the past, the diagnosis of epilepsy has probably been made inappropriately with the use of anti-epileptic drugs and associated side effects. The doctor making the assessment needs to consider other disorders which may be mistaken for epilepsy, including faints, cardiac arrhythmias, transient ischaemic attacks and behavioural disorders. Non-epileptic seizures or pseudoseizures also occur in people with learning disabilities, sometimes in a person with true epilepsy.   These can be difficult to diagnose and treat. Jenkins and Brown (1992) review the assessment process and stress the need for a holistic approach considering social, psychological and psychiatric aspects in addition to the medical. Information on the seizures themselves should include a description of the person before, during and after the event, noting any precipitants such as anxiety or infection. Some medications, particularly anti-depressants and anti-psychotics increase the likelihood of seizures in susceptible individuals and in this case withdrawal of the offending drug may be all that is required.  A developmental history should be taken followed by an assessment of skills and disabilities. Information on behaviour and personality should be obtained because of the relationship between seizures and behavioural disorders. Mental state and cognitive examination are also important, with an assessment of associated psychiatric disorder and degree of cognitive impairment.

Patients attending an epilepsy clinic for the first time will usually have a physical examination to assess general physical and nutritional status, side effects of medications and seizure related injuries.  Physical stigmata of disorders known to cause learning disability and epilepsy should be noted.

Investigations will include baseline haematological and biochemical profiles. Screening for metabolic and degenerative disorders is usual, particularly in children presenting with learning disability and epilepsy.  In the past, anticonvulsant serum level monitoring was performed excessively.  Coulter (1993) advocates such testing only in specific instances, for drugs whose levels can be measured:-

1. After commencement of a new anti-epileptic

2. On suspicion of toxicity.  Signs of toxicity may be minimal or absent in some cases and it is difficult to differentiate between such signs and long-standing neurological problems in some people with cerebral palsy.

 3. Failure to control seizures, (too a low dose or non-compliance may be responsible).

A baseline electroencephalogram (EEG) examination will be part of the initial assessment and this test measures electrical activity using electrodes placed on the head..  The routine EEG gives an idea of the likelihood of epilepsy being present but must be cautiously interpreted as a proportion of people with epilepsy have normal recordings between seizures and some people show epileptiform abnormalities in the absence of clinical symptoms. It may be difficult to achieve a satisfactory recording in some people with learning disabilities who may be frightened by the procedure and the role of familiar staff providing support and reassurance in such situations cannot be overestimated. The chances of achieving a successful recording are increased if the technicians are able to be patient and tolerant. Some specialist facilities provide a peripatetic service where the technicians go into schools, training centres or people’s homes where they may be more co-operative with the procedure. In some cases sedation may be required.  Ambulatory recording and video telemetry are useful in several instances , for e.g. to elucidate the relationship between seizures and behaviour or when non-epileptic seizures are suspected.

Computerised Tomography (CT) and Magnetic Resonance Imaging (MRI) are useful to identify focal lesions particularly as a part of pre-surgical assessment. MRI is the investigation of choice in epilepsy . How ever, as this may be a frightening experience, it is not routinely offered to people with learning disabilities. If it is deemed necessary, then sedation or even a general anaesthetic may have to be administered. Nowadays , functional imaging of the brain is also possible using radio isotope labelled chemical to study the function of parts of the brain. This is done by positron emission tomography ( PET ) or single photon emission tomograhy (SPECT). If surgical treatment is necessary , a referral to a specialist centre for  neuro-psychological tests and a full work up will be needed.  A specialist text book such as Engel (1993) should be consulted for further information on evaluation for surgery and surgical techniques.

MANAGEMENT

The management of epilepsy in people with learning disabilities involves and requires the co-operative and collaborative working of the multi-disciplinary team.  The person who has received the diagnosis will often have input from several professionals.  These may include teachers, day centre staff, respite care agencies, specialist nurses, physiotherapists, speech therapists, psychologists in addition to doctors specialising in epilepsy or learning disability psychiatry. 

The diagnosis of epilepsy may come as a considerable shock to carers and may result in a grief reaction.  Information on the condition may need to be repeated as carers may not be able to absorb information given at the first appointment.  Written and video material on epilepsy; such as that provided by voluntary epilepsy agencies is useful in this regard, particularly if supported by input from a specialist nurse.  The provision of appropriate information and advice at this time will help to avoid  overprotection which is often received by people with epilepsy and learning disability.

DRUG THERAPY

The majority of people with epilepsy will require the prescription of anti-epileptic drugs to prevent seizures from recurring.  In some, particularly where there is severe brain damage it may not be possible to completely eliminate seizures without causing excessive side effects and sedation and the prescribing doctor must balance the risks and benefits involved.  Selection of the anti-epileptic drugs depends on seizure type and syndromic classification. For details of drugs commonly in use in the UK refer to Table 4.

The vast majority of  people can be treated with one or two drugs.  Polytherapy should be avoided due to the likelihood of increased side effects. When starting drug therapy, the dose should be increased gradually, noting any adverse side effects.  Carbamazepine and Sodium Valproate remain the drugs most widely used in the UK.  Newer drugs are being used more frequently either in monotherapy (Lamotrigine) or as an adjunct (Vigabatrin, Gabapentin, Topiramate, Tiagabine).  Older drugs such as Phenytoin and Phenobarbitone are no longer drugs of first choice.

The major problem with phenobarbitone lies in its propensity to influence adverse behaviour, mood and cognition which is undesirable, particularly in people with learning disabilities.  Phenytoin can produce a range of dose related and idiosyncratic adverse effects.  Cosmetic changes such as hirsutism, acne and gum hyperplasia are troublesome and toxic serum levels can be reached with small minor increases in dose.  The benzodiazepines, clobazam and clonazepam are used as add on therapies with their usefulness being limited by the development of tolerance.  One exception is the use of clobazam as a prophylactic treatment for women who suffer a cluster of seizures in the pre-menstrual phase.

Diazepam is administered rectally to patients who suffer status epilepticus or serial seizures.  It is absorbed rapidly and has anti-convulsant, anxiolytic, sedative and muscle relaxant effects.  There is considerable controversy surrounding the use of this drug in settings outside of hospitals and family homes where it can be given by trained nurses or family carers.  Staff and managers in other residential, educational or day care settings are concerned about their legal status and the possibility of adverse effects and this results in some persons being taken to hospital following each seizure.  The situation at present is unsatisfactory and guidelines are required for training and accreditation of staff who will administer this drug.

Once started on drug therapy, it is important that seizures are recorded accurately.  This can be a problem, particularly when the person spends time in several settings and the use of a seizure diary can help overcome communication problems in this area.

In the general population, the majority of people will have their seizures adequately controlled using drug therapy and may not need specialist follow up.  However, in the learning disability population, people will continue to have intractable seizures and will need continued specialist support.  Primary health care teams may have limited experience of working with this client group and in addition, general neurology services may not adequately meet their needs either.  The learning disability team is,. therefore, well placed to provide a service to offer treatment and follow up given their expertise in the field.

Non-Drug Treatments

Surgical treatments should be considered where seizures are resistant to drug therapy and where a resectible lesion is believed to be the focus for epileptic activity.  Pre-surgical evaluation will be needed to document the precise location of the lesion and to weigh up the risks and benefits of surgery.  People with learning disabilities have been helped by surgery and referral for surgery should be considered as part of management.

Specific diets, including the ketogenic diet, have been used in the management of seizures that prove unresponsive to drug therapy, particularly in children.  The diet is rather unpalatable and parents will require support from a dietician to comply with the requirements exactly.

Non-pharmacological approaches to seizure control can be divided into measures aimed at reducing seizure frequency and those which focus on improving psychological adjustment to epilepsy. In reflex epilepsy where specific triggers for seizures exist, the person can be instructed to avoid these triggers, e.g. avoiding flickering lights which may bring on a fit: or can receive desensitisation therapy as there may be an emotional association with the stimulus.   Many people report an increase in seizures in association with anxiety and a variety of relaxation strategies have been used, with training to recognise and deal with anxiety symptoms before seizure onset.  The use of alternative therapies such as use of aromatherapy and reflexology have also been reported.

Lifestyle focused approaches including advice on exercise have been found to reduce seizure frequency (Ellertson et al,1993).  People with learning disabilities are often overprotected by carers and have little exercise.  Non-compliance with drug therapy for epilepsy is one of the main causes of poor seizure control and information on the disorder and the need for compliance can be included in educational programmes for carers and / or individuals or groups of people with epilepsy.

Living with Epilepsy:  

To avoid overprotection and an overly restricted existence, carers and people with epilepsy need advice and explanations on the disorder.  This advice should include guidance on management of seizures, sporting and leisure activities and safety in the home.  People with epilepsy face some legal restrictions, notably in the areas of driving and employment. They are prohibited from entering specific professions such as becoming an aircraft pilot, ambulance driver, soldier etc. Research in mainstream epilepsy has focused on the quality of life of the person with epilepsy and stress and adjustment in carers.  It can be difficult to assess the effect of seizures on quality of life in a person who is already disabled and further research is needed in this area.  Involvement in voluntary epilepsy agencies can be very useful in providing education and support for people with epilepsy and their carers.

Behavioural and Psychiatric Disorders:

Until the last century, epilepsy was considered to be a mental disorder and those affected by the condition were often residents in mental hospitals. Epilepsy is now accepted as a medical or neurological disorder and it is known that not all people with epilepsy ( or epilepsy and learning disability ) have a psychiatric disorder. Psychiatric symptoms occur in the prodromal phase ( hours or rarely days ) before a seizure, during seizures ( particularly simple or complex partial in type ) and post ictally  ( when confusion , aggression and dysthymic mood may be present ). These symptoms are most likely to respond to adjustments in antiepileptic drug treatment which improve seizure control.

Interictal psychiatric symptoms or disorders may be short lived or lengthy in duration. Aetiology is multifactorial, reflecting the interaction of personality, family relationships, societal responses to epilepsy and disability in addition to the epilepsy and its treatment. Rates of affective ( mood ) disorders and suicide are raised in people with normal intelligence and epilepsy, and a link to right hemispheric EEG abnormality has been suggested. In people with learning disabilities,  the diagnosis of psychiatric disorder can be difficult, particularly in those with a severe learning disability and a distinction between affective and non- affective psychosis may not be possible. Deb and Hunter (1991 ) did not find increased rates of affective disorder when they compared adults with learning disability with and with out epilepsy. Psychosis and depression have been seen in those taking vigabatrin( which in some one with a learning disability may present with behaviour disorder ) and have also been described with other antiepileptics. Cognitive deterioration may be seen in chronic epilepsy and may be due to repetitive seizure related head injuries and /or episodes of status epilepticus.

Behaviour disorders are common in people with learning disabilities and also must be considered to be multifactorial in aetiology. Carers are often most distressed by behavioural problems which can result in diminution in quality of life due to reduction in access to community facilities and services. Deb and Hunter ( 1991 ) in their study found a subgroup of people with epilepsy and mild learning disabilities and generalised EEG abnormality who had more challenging behaviours. A change of antiepileptic medication can result in a deterioration in behaviour despite improved seizure control. This may be short-lived, but if severe may prove unacceptable to carers. Behaviour disorders may be unrelated to the epilepsy and its treatment. After easily treated medical conditions such as ear infections are ruled out, a careful functional analysis based on detailed descriptions of the behaviour and / or observation by a professional skilled in working with people with learning disabilities is often necessary to achieve an understanding of the behaviour and to provide advice on management.          

CONCLUDING REMARKS

Epilepsy is a common additional disability in people with learning disabilities, with seizures continuing into adulthood and in a substantial proportion proving resistant to antiepileptic drug therapy. The accurate diagnosis of epilepsy is dependent on a good account of seizures from carers who also have an important role in follow up treatment. The selection of drug therapy should be based on a classification of seizures and /or epileptic syndrome according to international guidelines and must balance risks and benefits. Management should address the social and psychological aspects as well as the purely medical. Behavioural and psychiatric disorders are not always present in people with epilepsy and learning disabilities but when present merit a careful assessment to find the underlying causes. 

REFERENCES

Betts, T. Epilepsy, Psychiatry  and Learning Difficulty. Martin Dunitz.  London. 1998

Commission on Classification and Terminology of the International League Against Epilepsy (1981).  Proposal for Revised Clinical and Electroencephalographic Classification of epileptic Seizures.  Epilepsia 22: 489-501.

Commission on Classification and Terminology of the International League Against epilepsy (1989).  Proposal for Revised Classification of Epilepsies and Epileptic Syndromes.  Epilepsia 30: 389-399.

Commission on Epidemiology and Prognosis, International League Against Epilepsy (1993).  Guidelines for Epidemiologic Studies on epilepsy.  Epilepsia 34 (4): 592-596.

Corbett, J A, Harris, R & Robinson, R (1975) in Wortis J (Ed) Mental Retardation and Developmental Disabilities, Vol. VII 79-111.  New York: Ravens Press.

Coulter, D (1993) Epilepsy and Mental Retardation: An Overview.  American Journal on Mental Retardation 98 (Suppl) 27-33.

Deb, S & Hunter, D (1991) Psychopathology of People with Mental Handicap and Epilepsy I-III, British Journal of Psychiatry 59, 822-834.

Ellertson B, Eriksen H R, Mostofsky DI et al (1993) Exercise in Epilepsy In the Neurobehavioural Treatment of Epilepsy. (Editors: D I Mostofsky & Y Loyning) pp 107-122.  Lawrence Erlbaun Inc. New Jersey.

Engel, J (1993) Surgical Treatment of the Epilepsies. 2^nd Edition, Raven Press Network.

Hopkins, A., Shorvon,S. Definitions and epidemiology of epilepsy . In : Epilepsy. Ed A Hopkins, S Shorvon and F Cascino. Chapman & Hall. London. 1995. 

Jenkins, L K & Brown S W (1992).  Some issues in the Assessment of Epilepsy Occurring in the Context of Learning Disability in Adults Seizure 1, 49-55.

Kotagal, P & Rothner, A D (1993). Epilepsy in the Setting of the Neurocutaneous Syndromes.  Epilepsia 34 (Suppl 3) 571-578.

Lund, J (1985) Epilepsy and Psychiatric Disorder on the Mentally Retarded Adult. Acta Psychiatrica Scandinavica 72, 587-562.

Mariani, E, Ferini-Strambi L, Sala M, Erminio, C & Smirne, S. (1993) Epilepsy in Institutionalised Patients with Encephalopathy: Clinical Aspects and Nosological Considerations.  American Journal on Mental Retardation, 98 (Suppl) 27-33.

Ross, E. M. & Peckham, C.S. (1983) School Children with Epilepsy.  In Advances in Epileptology XIVth Epilepsy International Symposium, p 213-230.  Editors: Parsonage, M, Grant, RHE, Craig, AG, et al, NewYork: Ravens Press.

CLASSIFICATION OF SEIZURES AND EPILEPSIES

Table 2:  Classification of Seizures

PARTIAL SEIZURES (BEGINNING LOCALLY ) :

*          Simple partial seizures (without impairment of consciousness)

            -            with motor signs

            -            with somatosensory or special sensory symptoms

            -            with autonomic symptoms

            -            with psychic symptoms

*            Complex, partial seizures (with impairment of consciousness)

            -            beginning as simple partial and progressing to impairment of          consciousness

            -            with impairment of consciousness from onset.

*          Partial seizures evolving into secondarily generalised seizures

GENERALISED SEIZURES (WITHOUT LOCAL ONSET, SYMMETRICAL)

*            Absence seizures

*            Atypical absence seizures

*            Myoclonic seizures

*          Clonic seizures

*          Tonic seizures

*          Tonic-clonic seizures

*          Atonic seizures

UNCLASSIFIED EPILEPTIC SEIZURES

·      Inadequate or incomplete information to classify (ILAE, 1981)

Table 3:  Classification of Epilepsy and Epileptic Syndromes

LOCALISATION RELATED ( PARTIAL ) EPILEPSIES AND SYNDROMES

Idiopathic ( with age related onset ) e.g. Benign childhood epilepsy, Primary reading epilepsy

Symptomatic e.g. Chronic progressive epilepsia partialis continua of childhood

Cryptogenic

GENERALISED EPILEPSIES AND SYNDROMES  

Idiopathic e.g. Benign neonatal convulsions, Childhood absence epilepsy

Symptomatic e.g. Cerebral malformations, Inborn errors of metabolism

Crytogenic e.g. West syndrome, Lennox- Gastaut syndrome

EPILEPSIES AND SYNDROMES UNDETERMINED AS TO WHETHER FOCAL OR GENERALISED

  e.g. Severe myoclonic epilepsy in infancy

SPECIAL SYNDROMES

Situation related

e.g. Febrile convulsions, seizures due to toxins such as alcohol or drugs

( ILAE, 1989 )

Table 1:  PREVALENCE OF EPILEPSY (SEIZURES IN THE PAST YEAR)

Population                   CHILDREN             Prevalence

 MILD LEARNING DISABILITY               6%              (Ross and Peckham, 1983)      

 MODERATE LEARNING  DISABILITY            15%            (Corbett et al 1975)

 SEVERE LEARNING DISABILITY               26%            (Corbett et al 1975)  

 PROFOUND LEARNING  DISABILITY            27%            (Corbett et al 1975)

Population                   ADULTS                   Prevalence

 MILD LEARNING DISABILITY                     4%             (Lund, 1985)  

MODERATE LEARNING  DISABILITY          7%            (Lund, 1985)  

SEVERE LEARNING DISABILITY                 12%            (Lund, 1985)  

PROFOUND LEARNING  DISABILITY         28%            (Lund, 1985)

  Table 4: Antiepileptic drugs  

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