Archive for the ‘Epilepsy’ Category

SURGICAL APPROACHES TO EPILEPSY: SURGERY FOR PARTIAL (FOCAL) SEIZURES – MAKING THE FINAL DECISION

Monday, June 13th, 2011
While each step in the process of evaluation of a child for surgery requires careful thought, it is at this point, when all the available information has been collected, that reconsideration of the potential risks and benefits is necessary. We accomplish this with a meeting of the whole team that has been involved in the evaluation. This team includes the epilepsy specialist who has been your child’s primary physician, our group of monitoring specialists, those who have carefully assessed language and intellectual function, our counsellor who has been working closely with the child and the family, and the surgeon who will be performing the operation. At this conference we carefully assess where the seizures appear to be coming from, what surgery can be done to eliminate them, what normal functions might be damaged by the surgery, and the risks and the potential benefits of the surgery. At times we decide that, despite all our careful evaluation, surgery should not be performed. After the group reaches consensus, we then present our opinions to the patient and family, who must make their independent decision on whether or not to proceed with surgery, whether their perception of the risks and benefits is similar to ours.
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EPILEPSY AS A PSYCHO-SOCIAL DISEASE: THE CHILD’S SELF-PERCEPTION – WHAT SHOULD YOU DO?

Friday, February 11th, 2011
Age-appropriate discussion of epilepsy, of your child’s particular type of seizures, and of the reason for taking medication is an important first step in an understanding and an acceptance of his condition. In one study, many children still believed they could swallow their tongues during a seizure. They feared that they might die. Unfounded apprehensions seem to be more damaging than the reality. Shielding your child from the facts to prevent him “from being scared” is more likely to lead to worse, but unspoken, fears than an honest and open discussion.
Your attitude toward your child and his seizures will affect his own. If you are frightened, he may be too, even if he doesn’t understand why. If you are overprotective, he may respond by either becoming dependent or rebellious Understanding that he is normal most of the time and honest calmness on your part will allow your child to get on with the process of developing independence and competence.
It should be the job of your physician and the team to assure that issues of honesty, overprotection, and dependency have been discussed with you and your spouse, and that you have come to terms with them. The epilepsy team should also discuss the seizures, medication, and reasonable restrictions with your child and make sure that you also have discussed them with him in age-appropriate terms.
Remember, ultimately epilepsy is your child’s problem. If the seizures continue or if he must continue to take medication, then he will have to assume responsibility for his condition and its treatment. If your child is given a sense of control from the beginning, he will feel more responsible for his future life. We try to have these discussions with children when they are as young as five or six years of age. Responsibility clearly increases with age, but participation can rarely begin too early.
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EPILEPSY AS A PSYCHO-SOCIAL DISEASE: THE CHILD’S SELF-PERCEPTION – WHAT SHOULD YOU DO?Age-appropriate discussion of epilepsy, of your child’s particular type of seizures, and of the reason for taking medication is an important first step in an understanding and an acceptance of his condition. In one study, many children still believed they could swallow their tongues during a seizure. They feared that they might die. Unfounded apprehensions seem to be more damaging than the reality. Shielding your child from the facts to prevent him “from being scared” is more likely to lead to worse, but unspoken, fears than an honest and open discussion.Your attitude toward your child and his seizures will affect his own. If you are frightened, he may be too, even if he doesn’t understand why. If you are overprotective, he may respond by either becoming dependent or rebellious Understanding that he is normal most of the time and honest calmness on your part will allow your child to get on with the process of developing independence and competence.It should be the job of your physician and the team to assure that issues of honesty, overprotection, and dependency have been discussed with you and your spouse, and that you have come to terms with them. The epilepsy team should also discuss the seizures, medication, and reasonable restrictions with your child and make sure that you also have discussed them with him in age-appropriate terms.Remember, ultimately epilepsy is your child’s problem. If the seizures continue or if he must continue to take medication, then he will have to assume responsibility for his condition and its treatment. If your child is given a sense of control from the beginning, he will feel more responsible for his future life. We try to have these discussions with children when they are as young as five or six years of age. Responsibility clearly increases with age, but participation can rarely begin too early.*212\208\8*

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DRIVING AND EPILEPSY-PART 1

Tuesday, December 22nd, 2009

There are few aspects of having epilepsy in adult life that cause greater distress than the necessary legal restrictions on driving. For some people owning and using a car is a hobby in itself—albeit an expensive one. Others, particularly those living in rural areas where public transport is limited or non-existent, find car ownership and driving necessary for shopping and social contact, and for getting to work. There are jobs such as delivery van driver in which driving is the sole function of employment, and any restriction on driving will cause the employee to lose his job.

This book may well be read in a number of countries, and the legal requirements vary from place to place. As an example, however, we consider the UK eligibility to hold a private (Group 1) driving licence in the UK, as determined by the Motor Vehicles (Driving Licences) (Amendment) (No. 2) Regulations 1994 which came into force on 5th August 1994. Epilepsy is prescribed for the purposes of Sections [92 (4) (b)] of the 1988 Road Traffic Act. The 1994 Regulations amended the 1987 Regulations (which specified a seizure-free period of two years) as follows:

‘An applicant for a licence suffering from epilepsy shall satisfy the following conditions, namely that he shall:

a) have been free from any epileptic attack during the period of one year immediately preceding the date when the licence is granted; or

b) have had an epileptic attack whilst asleep more than three years before the date when the licence is granted and shall have had attacks only whilst asleep between the date of that attack and the date when the licence is granted; and that the driving of a vehicle by him in accordance with the licence is not likely to be a danger to the public.. The purpose of clause (b) is to allow someone to drive who has established a long history of seizures whilst asleep without ever having had any whilst awake. It allows someone with continuing seizures only whilst asleep to drive, without requiring a period of one year free from such a seizure.

These Regulations are, we believe, a reasonable attempt to protect the public from the chances of meeting a driver who is briefly incapable of controlling his car because of a seizure. The Regulations are also fair to those with epilepsy insofar as they clearly state the circumstances under which they can drive.

What actually happens in practice? Take the example of a woman who has held a licence for several years, and then has two grand mal seizures at work within a month. Her family doctor or neurologist will explain that she is no longer eligible to hold a driving licence. It is not the responsibility of either doctor to inform the licensing authority of this, but a doctor will record in their notes the fact that they have explained the position to the patient. It is the driver’s responsibility to take action. Inside each UK Driving Licence is the statement that the ‘Drivers Medical Branch, Swansea SA99 ITU MUST be told at once if: you NOW have any physical or mental disability which affects your fitness as a driver or which might do so IN THE FUTURE’. The patient should write a brief note to the Drivers and Vehicle Licensing Authority (DVLA) at Swansea (the address above being sufficient) explaining the details and enclosing the licence, which will be acknowledged. No further action is necessary.

If all goes well for this woman, and she has no further seizures after the first two, she becomes eligible to hold a driving licence one year after the date of the last attack. She then completes an application form as usual. In Section 6d, or in a covering letter if there is insufficient space on the form, she writes briefly exactly what has occurred, refers to her earlier letter, states the date of her last seizure, and gives the name and address of her family doctor or neurologist to whom reference can be made. After a short interval, she will receive her new licence.

All this seems entirely straightforward, but we know that many people with epilepsy find the Regulations hard to accept. Doctors appreciate the difficulties that may be caused by giving up driving. Driving is usually an essential part of their work, so they do not have to make great leaps of imagination to realize the difficulties that a ban on driving may cause. Unfortunately the law does not take hardship into account. Doctors should, however, not only advise their patients of the law, but also, from their experience, advise patients how to cope with their changed circumstances. Doctors are in a position to influence decisions of employers about the nature of their patients’ work. They can write to the employer, with the patient’s consent, supporting a request for a change of job within the same company. In such a letter, a doctor does not necessarily have to say that the person has epilepsy, only that they are not able to drive for medical reasons, and not likely to be able to drive for some time. Such letters may well influence company decisions. We have known many examples of this. A travelling salesman has become a successful office-bound sales manager; a busy surveyor has taken on increased training responsibilities; and a delivery van driver has been employed within the factory making the goods he was previously delivering. Obviously such changes are easier within large organizations with their greater variety of jobs.

We usually advise people living in rural areas not to move house just because of their new inability to drive. If it seems likely that the seizures can be easily controlled, then it is probably better to cope somehow for the time necessary, rather than disturb the whole family’s way of life. The people with epilepsy are the only ones who can decide whether to move, but their doctors should give them sufficient information about the probability of seizure control to allow an informed decision.

Sometimes people with epilepsy will say that they consider it safe to drive as they always get a warning of their attacks. Leaving aside the legal point—that they are ineligible, and unfortunately their opinion does not count—we explain that the warning is the start of the cerebral events which form the early part of the seizure itself. The fact that to date the progression of the seizure discharge has been sufficiently slow to allow the subject to stop his or her car safely does not mean that this will always be the case. Such a person with epilepsy may well have a sudden grand mal seizure without warning.

Again, people with epilepsy may indicate that they consider it safe to drive, as all their seizures are small ones—perhaps temporal lobe seizures in which consciousness is disturbed in only a minor way. We have to say that the law does not distinguish between the various types of seizures. We also have to say that the next seizure may unfortunately be a grand mal one, and that in any event catastrophe is as likely to be caused by a momentary reduction of conscious awareness as by a major fit.

It is useless for the patient to say to his or her doctor that seizures always occur in the evening, or sometimes even: ‘I’ve never had one whilst driving’, as the next seizure may well be when he or she is in the driving seat.

Sometimes a patient may feel that the events which have led him to the doctor are not epileptic in nature. All a doctor can do in such circumstances is to disagree, and advise that the patient seeks a further opinion. As noted above, it is not a doctor’s responsibility to inform the licensing authority of a person’s epilepsy. It may be, however, that if a doctor is convinced of the diagnosis, and believes that there is a real risk to the public, and if the patient refuses to seek a further opinion, he or she may feel that responsibility to the public at large overrides responsibility to the individual patient.

There are, however, circumstances in which the occurrence of epileptic seizures is not automatically associated with loss of eligibility to hold a driving licence. Clause (b) of the Regulations quoted states that an applicant shall ‘have had an epileptic attack whilst asleep more than three years before the date when the licence is granted and shall have had attacks only whilst asleep between the date of that attack and the date when the licence is granted’. There are some people, though not many, who only have fits during sleep; three years seems a reasonable period to allow one to see if that is the case. After that, even if attacks do occur in sleep and never whilst awake, a person can nevertheless drive.

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LIVING WITH EPILEPSY: EMPLOYMENT

Tuesday, December 22nd, 2009

It is not sensible to be a steeple-jack or scaffolder if one has many seizures. But just what restrictions on employment should be applied to those with epilepsy?

First of all, there are the legal restrictions on driving. This may stop employment as a travelling representative, for example, but these Regulations have a wider effect in making travel to a job more difficult, especially in rural areas, however suitable that job may be.

Driving is the most obvious way in which a person with epilepsy can harm others, as well as himself, during a seizure. But there are occupations of heavy personal responsibility to others which those with uncontrolled seizures must not do. Surgery and nursing are obvious examples from our own health professions. The occupations of airline pilot, and bus, train, mass transit and crane driver, railway signalman, and merchant navy sailor, are other examples. The Armed Forces, fire, and ambulance services and Police also exclude those with continuing seizures.

In other jobs, there is no real risk to bystanders during a seizure, but there is a substantial risk of injury or death to the person with continuing epilepsy. The operation of heavy moving machinery, including agricultural machinery, work near conveyor belts, work at heights, particularly in the construction or electric power industries, and work underground or underwater should all be avoided. However keen the subject may be to take his own life in his hands, it is not fair to burden employers if there is a substantial risk of a mutilating or fatal accident.

One of the agonizing questions that people with infrequent seizures must ask themselves is whether to tell a potential employer about them. Obviously it is best if they do because the employer can take into account any remote risks about which the applicant is unaware. Employers can make an occasional allowance for rare but unexpected absences from work, and they can, in an informed way, cope with occasional seizures at work. The truth of the matter is that many employers reject those with seizures which are few and far between, or those who have had no seizures for some years, for jobs which carry virtually no risk to the person with epilepsy or to others.

Surveys of public attitudes towards those with epilepsy are in our view meaningless, insofar as potential employers may well make favourable remarks about the employment of a hypothetical person with epilepsy in response to an interviewer, because this is the polite and modern thing to say. However, it is their actual behaviour in hiring and firing that counts. A truer measure of the amount of prejudice against employing people with epilepsy would be to send round two personable young people with equal qualifications in response to 100 advertisements for a post as a secretary, for example. In half the interviews each applicant would indicate that they suffered from mild, well-controlled epilepsy. The success rate with and without revealing this information would be a fair guide to current prejudice against the employment of those with epilepsy. Unfortunately such a study would be unethical, insofar as it would waste the time and resources of employers. Nevertheless, we would be fascinated to know the answer!

Those with epilepsy intuitively know the likely result from the results of their own interviews. One survey of people with epilepsy in London showed that over half those who had two or more full-time jobs after the onset of epilepsy had never disclosed their epilepsy to an employer, and only one in ten had always revealed it. Furthermore, if seizures were infrequent or nocturnal, so that applicants considered that they had a good chance of getting away with concealment, the employer was virtually never informed. Whilst not condoning or encouraging dishonesty, the relative success of this policy can be judged by the fact that 74 per cent of the men of employable age with epilepsy were employed at the time of the survey, compared with 81 per cent of male workers of the same age group in the UK as a whole.

Whatever the policy about disclosure, applicants for a job will be more successful if they follow the general rules of taking care with their written application, taking trouble to inform themselves about the responsibilities of the post and about the employer, presenting themselves well at interviews, selling their ability to do the job, and convincing the prospective employer that they have an enthusiastic desire to work. What is absolutely disastrous is for frequent rejections to lead to the development of a chip on the shoulder, so that a potential employer is confronted by the attitude ‘I have epilepsy; you haven’t; you have a duty to employ me’. We have helped look after patients with seizures who succeed in presenting themselves and their epilepsy in such an unfavourable light that we feel there can be no strong motivation to obtain work.

Obtaining a job is obviously only the first step. Most of us want promotion up to the limits of our energies and capabilities, and here again epilepsy, even if well controlled, often spoils chances in life. It is difficult to measure the frequency with which those well qualified for promotion are overlooked, but one study found that the rate of dismissal following the onset of epilepsy was increased approximately sixfold.

There is another more subtle way in which epilepsy can hinder employment and promotion. The fear of encountering rejection, or the fear of leaving an established position with a tolerant employer may cause the people with epilepsy to deny themselves chances for betterment. Just as the employer may be prejudiced against ‘epileptics’ so may the epileptic be prejudiced against ‘employers’, believing them all to be lacking in understanding.

There may be an advantage in young people with epilepsy seeking a career in small organizations, where regulations for employment, sick leave, insurance, and pensions are flexible compared with those of, for example, the Civil Service.

As might be expected, if seizures occur frequently, one study showed that it was much more difficult to hold down a job. The study showed that a third of the unemployed were having generalized seizures monthly or more frequently, whilst only 2 per cent of those in work were suffering equivalently. Roughly the same proportions held true for partial seizures. Apart from seizure frequency, the main barrier to employment is lack of any special skill. One survey found, as could have been foretold, that virtually all those with frequent seizures and no special skills were unemployed. It is here that specialist advice from employment agencies should be sought.

In the UK the Employment Service provides a wide range of services to help people with disabilities to get and keep suitable employment. Most disabled people helped by the Employment Service are helped by general services. There is also a network of 71 Placing, Assessment, and Counselling Teams (PACTs) to help those people with disabilities who cannot be helped properly by the general services. This may include some people with epilepsy. People in PACTs are called Disability Employment Advisers (DEAs). The DEA can be contacted at, or through, the local Employment Service Jobcentre. It is not necessary to be registered as disabled to use most of the services provided through the DEA, though they may recommend registration. The Disabled Persons Register is a voluntary register of people who want to work, and are able to do so, but who have difficulty in getting or keeping suitable work because of their long-term health problem or disability. The Register is run by the Employment Service through its DEAs. All employers who have 20 or more workers have a duty, under the Disabled Persons (Employment) Acts 1944 and 1958, to employ a quota of registered disabled people, usually three per cent of their total workforce. Consequently a big firm is keen to employ someone capable of good work if they happen to be on the Register. Before registration, the family doctor or neurologist will, with the person’s consent, fill in a special form which provides basic information about the type and frequency of seizures, and any other associated disability.

The DEA may consider that a person with epilepsy may benefit from a course of vocational training, to equip him or her with a special skill not already possessed. For example, a nurse with frequent seizures might no longer be suitable for nursing, until the seizures were controlled, and the DEA might well advise that she or he take a course to encourage the development of business skills. This could be arranged through, and at the expense of, the local Training and Enterprise Council (TEC) (Local Enterprise Company (LEC) in Scotland). Training allowances may be payable. The DEA could put the client in touch with the TEC (LEC).

For those with frequent seizures, possibly in association with learning disabilities, the DEA may advise a job in Supported Employment, in which severely handicapped people work in a supported environment—either in a Remploy factory, a supported workshop run by a local authority or voluntary body, or in a supported placement in ordinary employment.

The DEA can also advise on the wide range of help which is available, where appropriate, through the new Access to Work Programme. Individuals can get up to £21 000 worth of help, over a five year period, to pay for things such as extra costs of travel to work for those who cannot use public transport because of their disability; vehicle adaptations; special equipment needed at work; adaptations to the employer’s premises; communication support for blind or deaf people at work; or human support. The DEA can also offer a weekly grant to an employer who provides employment on a trial basis to give a disabled person the chance to demonstrate that they can do the job.

There will always be a nucleus of people with epilepsy who are unemployed either temporarily or more or less permanently. The person who is capable of work but unemployed may, as time passes, become progressively more unemployable if not given occupation and support. It is here that local authority social workers DEAs, and epilepsy associations can help.

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LIVING WITH EPILEPSY: EDUCATION

Tuesday, December 22nd, 2009

Most children with epilepsy attend normal mainstream schools and can participate fully in the schools’ curricular and extra-curricular activities. This is the case even in children in whom the epilepsy is not fully controlled. It is important for the teachers and for the school doctor and nurse to know that a child has epilepsy—even if the child’s seizures are at the current time controlled. Teachers will then know what to expect and what to do if the child has a seizure. The teacher may also involve children in the class in the care of the child after a seizure; this is important for two reasons. First, it teaches children how to help someone in a seizure, and secondly—and perhaps more importantly—it shows children that there is no need to be scared or upset when someone has a fit. Hopefully, such activities may reduce, in future generations, some of the misunderstanding and social prejudice which surround epilepsy.

About one fifth of children with epilepsy are not able to attend a normal school. This may simply be because of different and frequent seizure types which are not fully controlled. However, the more common reason for these children not being able to attend a normal school is that they have additional problems, such as moderate or severe learning difficulties or physical handicaps (or both), as well as their epilepsy. Most of these children will attend special schools, usually within the local neighbourhood. In this situation in the UK, under the terms of the Education Act, the child will have an assessment or ‘statement’ made of his or her educational needs so that the most appropriate school can be found. This statement is based on reports from doctors (including the hospital doctor), teachers, clinical psychologists, therapists, and any other specialist who may have been involved with the child. The ultimate decision as to which school the child should attend rests with the parent.

Perhaps 1-2 per cent of all children with epilepsy may need to attend a school specifically established for children with epilepsy. These schools are usually residential or boarding schools, and the staff have special expertise in teaching children with epilepsy, in coping with their seizures, and in generally supporting them. One of the additional benefits provided by these schools is that they allow separation from the family. The benefit of this lies in the

over-protective attitude of many parents who do not allow their child the opportunity to participate in normal social activities. This clearly may not be in the child’s best interest with regard to either control of seizures or enabling the child to ‘grow’ into adulthood and to develop a degree of independence. The environment provided by these schools encourages self-reliance.

Occasionally, a child with epilepsy, although not having frequent seizures, may be doing badly in school. Rarely this is due to the fact that the child is experiencing many more absences or complex partial seizures. These may actually be first picked up by the child’s teachers. In these situations, an EEG may help to confirm that the child is experiencing frequent seizures. Another rare possibility—but one that is often put forward—is that the child’s poor school work is due to the effect of the anti-epileptic drugs. However, if the child is not excessively sleepy or drowsy, then it is most unlikely that the drugs are interfering significantly with school work. Exceptions include phenobarbitone and phenytoin, which may affect a child’s concentration and therefore their learning potential. In these situations the amount of drug in the blood may need to be checked. The most common reason for learning problems in a child with epilepsy is that the intellectual difficulty and the epilepsy share a common cause due to abnormal development of the brain or brain damage (for example, after meningitis or a head injury). In these situations, an educational psychologist will assess the child’s strengths and weaknesses and advice on the most appropriate school. Sometimes the cause of the child’s learning difficulties may be familial—that is, other family members show similar educational problems which has nothing at all to do with the epilepsy.

Children up until the age of 16 years are well cared for by society, educationally and medically. The difficult time comes after the age of 16 years—the ‘adolescent’ period which, brings changes in social, family, and educational life. This is often a difficult time of life, even for those who do not have epilepsy.

Many changes occur at adolescence which need to be coped with.

• The seizures may change in type, particularly if the epilepsy started at a young age. These changes may include more complex partial and generalized tonic-clonic seizures, and a reduction in absence and myoclonic (jerk) seizures.

• The anti-epileptic medication may have to change in order to maintain control of the epileptic seizures. This may mean a change in dose or even the introduction of different drugs.

• Young people may find it difficult to take their anti-epileptic drug regularly, or they may deliberately decide not to do so. This is more likely to occur in teenagers who have recently been diagnosed and who may find it difficult to come to terms with the diagnosis and need for regular treatment. This may be just one part of a general rebelliousness—against the condition, the treatment, the doctor, family and friends, even life itself. The best way of dealing with these understandable reactions is for the young person to talk about their epilepsy and all its associated problems. Friends may or may not be the easiest to talk to, but hopefully the young person will discuss his or her feelings with the rest of the family and with an understanding doctor.

• There are a number of educational possibilities beyond the normal school leaving age. Many young people with epilepsy will obtain higher qualifications at school and then obtain a place at college or university. It is important that college or university tutors and examiners are told about students who have epilepsy as this promotes and encourages increased awareness and understanding. Those students who live away from home in halls of residence or in rented accommodation should tell friends and college or university tutors.

• Most paediatricians would not think it sensible to continue seeing patients over the age of 16 years. Teenagers of 17 or 18 years have questions and needs that reflect his transition to adult life. All too often transfer from paediatric to adult services in poorly planned. The family doctor will continue his or her support, but consideration of course should be given to transferring care to a neurologist who has a special interest in epilepsy. A special clinic for teenagers with epilepsy has been established in Liverpool to ensure that there is a smooth handover of care from a children’s epilepsy clinic to an adult clinic, and in which the specific issues and problems of teenagers can be dealt with satisfactorily.

• There are many changes in life style at adolescence, with different interests and activities and different sleeping patterns, and it is known that deprivation of sleep and alcohol may precipitate seizures. These activities are important in developing independence and self reliance. There are few activities which young people with epilepsy cannot undertake.

An occasional drink containing alcohol is unlikely to be harmful. However, alcohol can make anti-epileptic medication less effective and may, in excess, bring on a seizure. It is important to get the balance right—and this applies to the correct amount of sleep and appropriate diet, as well as the amount of alcohol that is drunk. Medical research suggests that drinking more than two units of alcohol in less than 12-15 hours may significantly increase the risk of seizures in patients who have epilepsy (2 units = one pint of beer, lager, or cider, or 2 glasses of wine, or two measures (‘shorts’) of spirits such as whisky, rum, vodka, or gin).

• Contraception will also begin to emerge as an important issue during this time. The most effective form of contraception is the pill. The oral contraceptive pill does not make epileptic seizures more or less likely to happen and there is no reason why women with epilepsy cannot take the pill. Certain anti-epileptic drugs (except sodium valproate and the newer ones including vigabatrin and gabapertin) may reduce the contraceptive efficacy of the pill, resulting in an unwanted pregnancy. A contraceptive pill with a high oestrogen content may need to be prescribed, but other forms of contraception (condom or cap plus spermicide) should be considered.

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THE TREATMENT OF EPILEPSY: SURGERY

Tuesday, December 22nd, 2009

The surgical treatment of epilepsy is becoming increasingly useful, particularly when the seizures are not controlled by anti-epileptic drugs. However, surgery must only be undertaken after a careful detailed assessment of the patient. This, and the operation, should only be carried out in recognized specialist centres. This is because both the assessment of the patient, and the operation itself involve expert and sophisticated procedures—and clearly surgery is an irreversible treatment.

Surgical treatment depends on two main principles or ideas. The first is that a local abnormal area of brain can be entirely removed, leaving behind only healthy, normal brain. The second is that the spread of the seizure discharge, can be prevented by cutting the nerve fibres which cause the discharge. Penfield and Rasmussen, two Canadian neurosurgeons, were the pioneers of surgery for epilepsy and much of the surgical assessment and treatment of patients today is based on their early work. One of the most important questions that must be answered before surgery can be considered is from where

precisely within the brain do the seizures originate. When the cause is a tumour or cyst, then this is relatively easy, but frequently the cause is an area of brain that developed abnormally in fetal life. The identification of the abnormal part of the brain relies upon magnetic resonance imaging, and the use of special electrodes to try and record or ‘capture’ the epileptic discharge. The scalp electrodes (used in a routine EEG) are not usually sensitive enough for this task, and so other electrodes, called depth electrodes, are frequently used. They are also called ‘sphenoidal’ or ‘foramen ovale, electrodes because this describes how they are placed close to the brain. Electrodes may even have to be placed directly on the surface of the brain, or, as fine silver needles, within its substance. Because these special electrodes are in very close contact with the brain, there is a much greater chance that they will pick up the epileptic discharge.

As well as these assessments, people being considered for surgery may also need detailed psychological evaluation, specifically to try and identify which side of the brain is responsible for language and memory, so that these areas are not damaged during the operation. Consideration must also be given to avoid operating in those parts of the brain responsible for movement—it would be unacceptable to stop the seizures at the expense of causing a paralysis on one side of the body (hemiplegia), which might result in losing the ability to walk or write.

Before a patient is considered for surgical treatment of their epilepsy, it must have been shown that the patient’s seizures could not be adequately controlled using anti-epileptic drugs. For how long a patient should not have been controlled is dependent on individual circumstances. It is unwise to operate too early, as the epilepsy might remit (stop) spontaneously, although this is unlikely in the difficult epilepsies. However, if surgery is delayed for too long, then this may limit the potential success of the operation, either because the patient has suffered irreversible educational and social consequences of repeated seizures, or because other parts of the brain which were previously normal may have developed abnormal foci of electrical activity as a result of the continuing activity of the primary focus. Generally speaking most patients with difficult, drug-resistant epilepsy are being considered for surgery too late; surgery can safely be undertaken in children—even young infants. Most specialists would now consider that if acceptable seizure control has not been achieved using optimal doses of anti-epileptic drugs after one to two years, then surgery should be considered as the next step in a patient’s treatment. It has been estimated that many patients in the UK might currently benefit from surgery, but only about 200 operations per year are at present being performed.

There are four types of surgical procedure that are currently undertaken:

• removing a large, identifiable lesion such as a tumour or cyst.

• removing an entire cerebral hemisphere. This is done when the whole of one side of the brain is abnormal, this being associated with a hemiplegia (weakness down one side of the body). The operation sounds dramatic, but is often successful leading to a complete resolution of seizures and, frequently, an improvement in the hemiplegia. Hemispherectomy is particularly useful in children with the Sturge-Weber syndrome.

• removing a small or large lesion which has been identified on the basis of detailed specialized EEG recording and imaging. This procedure is the one frequently used in temporal lobe epilepsy, where different parts and amounts of the temporal lobe are removed. Advances in imaging have led to the identification of subtle structural abnormalities in the temporal lobes, which are responsible for seizures.

• carrying out a disconnection procedure; this is to try and separate the focus (site of abnormal electrical activity) of origin of the seizure from other parts of the brain, by cutting the nerve fibres which allow the epileptic discharge to spread. Operations attempted have included division (cutting) of the corpus callosum. This is a large band of fibres which transmits electrical information from one hemisphere to another. A more sophisticated, technically difficult procedure (called subpial transection) appears to be more successful.

Overall, the results of epilepsy surgery are encouraging, as many as 60-70 per cent of people who have operations for epilepsy have no further seizures, whilst another 10-20 per cent are much improved. Patients undergoing a hemispherectomy or temporal lobectomy do better than patients who have a corpus callosotomy. For some patients who have had to live with uncontrolled seizures for many years, a cure of their epilepsy following surgery may come as something of a ‘shock’, requiring a major adjustment in their lives. These patients need careful and expert support and counselling.

It must be emphasized again that patients must be assessed carefully in specialist centres before undergoing surgical treatment of their epilepsy. No one person can have a guarantee that their seizures will stop.

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TESTS IN EPILEPSY: ELECTROENCEPHALOGRAPHY (EEG)

Tuesday, December 22nd, 2009

The EEG is the principal investigation used in epilepsy. Many patients with epilepsy will have an EEG performed, usually after a clinical diagnosis has been made, and before treatment is started. The EEG detects the brain’s electrical activity by sensitive sensors called ‘electrodes’ which are placed on the scalp; these electrodes detect the normal and abnormal electrical activity of the nerve cells within the brain. Most routine EEGs are recorded with the child or adult awake, but EEGs may be arranged after deprivation of sleep or during sleep (spontaneous or induced by drugs).

All hospitals with neurological or neurosurgical departments and some larger, non-specialized hospitals will have facilities for recording a routine EEG. The procedure is simple and painless and, in the case of a routine EEG takes only about 20-30 minutes to complete. The EEG detects and records the brain’s activity; at no time is there any electrical discharge passing from the equipment to the patient. The EEG should not be confused with electroconvulsive therapy or ECT, which is used to treat depressive illnesses, and has nothing to do with epilepsy.

The recording technician first measures the patient’s head for correct placement of the electrodes, which are then placed according to an international system based on the patient’s head size and on measurements taken from the bridge of the nose, and the bony protuberance at the back of the head. Silver electrodes are fastened to the head with a sticky substance called collodion. Alternative electrodes are gauze pads moistened with a salt solution and secured with a rubber cap. Sometimes the patient’s scalp is gently rubbed beneath the electrodes to reduce the electrical resistance of the skin which improves the recording. Twelve electrodes are used in small infants, 20 in older children and adults. Wires from each electrode are then connected to a junction box (head-box), connected in turn to the amplifiers of the EEG machine by a cable. After amplification, the EEG machine records the signals on tape or disc, or displays them directly by ink-jets, pens, or laser on to paper which moves at constant speed, usually 3 cm/second. It is this paper with the written waves that is known as ‘the EEG’ and which is examined and analysed by doctors. The advantage of recording the electrical signals from the different electrodes on to magnetic tape or disc is that they can be recombined in other ways for subsequent more detailed analysis. They can then of course be displayed on paper again at any subsequent time.

During an EEG the child or adult is asked to lie quite still. This is because movement of any part of the body may obscure, or make it difficult to detect the electrical activity of the brain. The technician also in the course of the recording will ask the patient to open and close the eyes (to look for normal patterns of activity which vary according to whether the eyes are opened or not), to breathe deeply for 3 minutes, and to look at a flashing light. Overbreathing (also called hyperventilation) and the flashing-light test (called photic stimulation) are useful ways of activating or provoking abnormal electrical activity from the brain, and are often important in helping to decide what type of seizure or what epilepsy syndrome a person has.

The appearance of the EEG is dependent upon the age of a patient because the brain is developing and maturing rapidly, particularly from birth to 7 or 8 years of age. Generally speaking, a normal adult EEG pattern is reached by the age of 10-12 years and there is then little change until the age of 60 or 70 years. Doctors who analyse EEGs must have some knowledge and understanding about EEG patterns (normal and abnormal) in infants and children, as well as in adults.

The hallmark or typical EEG finding in a patient with epilepsy between seizures is a ‘spike’ or ‘spike and slow wave’ or ‘sharp wave,. A ‘spike’ is a sudden change in voltage that shows up against the background activities. An example of a very abnormal EEG seen in infants with West syndrome. However, even in patients who have epilepsy these abnormalities are not always seen, and this is why the EEG must not be relied upon to make or exclude a diagnosis of epilepsy. The first 20 minute recording of an adult who has had an undoubted tonic-clonic seizure is normal in 40-50 per cent of cases.

For most people with epilepsy, a routine (20-30 minute) EEG is the only necessary test. However, this is only a short period to record the brain’s electrical activity, and it is unlikely that a clinical attack or seizure will occur in this time. If more information is required, then other types or systems of EEG recording may be performed.

(a) EEG after deprivation of sleep: In this situation a patient is asked to make sure they get only 4-5 hours sleep for two consecutive nights. This encourages the occurrence of seizure discharges. Deprivation of sleep may also lead the patient to drowse or to sleep during the recording, and again this encourages the appearance of abnormal EEG discharge.

(b) Drug-induced sleep EEG: A small dose of a sedative drug may encourage the patient to fall asleep during the recording, and again drowsiness and sleep may show abnormalities which may not be present whilst awake.

(c) Ambulatory EEG monitoring: This is a technique of recording an EEG for not just 20 or 30 minutes but for up to 24 or even 48 hours. The electrodes (six, eight or 12, rather than the twenty electrodes in a routine EEG) are wired up to a small tape recorder (like a Walkman cassette player) which is strapped to the waist. After this the child or adult can leave the EEG department, go home and carry on their normal activities, and then return to the EEG department after 24 hours to have the tape analysed or the tape replaced. This procedure is more likely, by the length of the recording alone, to pick up abnormal electrical activity, and is particularly valuable if the person has a fit or seizure during the 24 hours when the electrical activity is being recorded. The tape can be analysed in a special fast-pace display unit, so the doctor does not have to sit watching the EEG for 24-48 hours!

(d) Depth electrodes: On rare occasions, special depth electrodes are used. These are fine wires inserted under sterile conditions into areas of the brain thought possibly to be the site of origin of seizure discharge. This is an important test in those patients who are being considered for surgical treatment of their epilepsy.

(e) Video-telemetry: This is another way of obtaining an EEG over a longer period of time. In this technique the patient has to stay in a room in the hospital for 24 hours or longer. At the same time as the electrical activity is recorded on the EEG, a video camera records the activities of the patient. In this way it is possible to replay repeatedly both simultaneous video and EEG recordings and observe the pattern of the EEG during an attack or seizure. This provides valuable information on the type of epileptic seizure and from where within the brain the seizure may be starting. If no abnormalities are seen on the EEG during an ‘attack’, then almost certainly the attacks are not epileptic. Video-telemetry is really only of practical benefit if the patient is having frequent attacks, as it is otherwise impractical to keep the patient in hospital attached to expensive equipment on the remote chance that a seizure may occur.

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