486

EPILEPSY OCTET Childhood epileptic syndromes SHEILA J. WALLACE

The International Classification of Epilepsies and Epileptic Syndromes (see S. Shorvon, this series) categorises these disorders on the basis of localised or generalised onset of the predominant seizure type. In childhood, such precision is often difficult. A workshop on childhood epileptologyl introduced a more helpful approach, in which the main seizure type, electroencephalographic (EEG) findings, age at onset, neurological examination, family history, response to antiepileptic drugs, aetiology, and prognosis contribute to the definition of childhood epileptic syndromes. Thus, although the main seizure type can be used as a starting point for classification of childhood epilepsies (see table), consideration of syndromes in relation to age at onset makes for easier categorisation.

Neonatal onset

Benign neonatal convulsionsZ are associated with a good neurodevelopmental outlook. Familial cases are dominantly inherited. Clonic seizures start on days 2-3, may be frequent up to day 7, and then remit; there are no specific EEG findings. In non-familial cases clonic, usually partial, seizures present on days 4-6 and are repeated frequently until status epilepticus supervenes; the EEG is dominated by discontinuous, unreactive theta activity. Early myoclonic encephalopathy.3,4 The seizures are fragmentary or massive myoclonias, partial motor or tonic. Periods of EEG suppression alternate with complex bursts of spikes and sharp and slow waves. The condition is characterised by severe neurological abnormality and early death. Non-ketotic hyperglycinaemia has been identified in some patients.5 Onset in infancy West

syndromeis

characterised by repetitive flexor, mixed spasms;7 developmental delay or regression; and a hypsarrhythmic EEG. Response to anticonvulsants is poor and subsequent neurological and intellectual handicaps are almost invariable. Benign myoclonic epilepsy in infancy.8 Bouts of repetitive myoclonic jerking occur in otherwise normal infants. Brief bursts of generalised spike-waves are recorded in early sleep. Valproate controls the seizures and the long-term outlook is good. Severe myoclonic epilepsy in infancy9 starts with unilateral or bilateral clonic seizures, usually with fever. Later, generalised myoclonic attacks, often precipitated by alterations in light intensity, supervene. Partial seizures with autonomic or atonic features and automatisms may occur. Early EEGs are normal but generalised spike-waves and extensor,

or

polyspike-waves, photosensitivity, and focal abnormalities appear

later.

developmental

Resistance to arrest are usual.

anticonvulsants

and

Onset in childhood

Myoclonic astatic epilepsy.10 Myoclonic, astatic, and myoclonic-astatic seizures are often accompanied by atypical absence, generalised tonic-clonic (GTCS), and tonic seizures. Bilaterally synchronous irregular and regular 2-3 Hz spike-waves are superimposed on a background of pronounced 4-7 Hz rhythms. The response to therapy and prognosis are very variable. Lennox-Gastaut syndrome. 11 Axial tonic seizures are the hallmark but atypical absences and atonic attacks also occur. Diffuse 2 Hz spike-waves dominate the waking interictal EEG, with bursts of 10 Hz activity during sleep. Mental development is slow and resistance to anticonvulsants is usual. Childhood absence epilepsy usually remits at puberty. Sudden onset and offset of loss of consciousness with, in 90% of cases, mild clonic, atonic, tonic, or autonomic components or automatisms12 characterise the seizures, which are very frequent and are associated with rare GTCS in 40% of cases. Regular 3 Hz spike-waves are recorded

during absences. The response to ethosuximide or valproate is usually complete. Epilepsy with myoclonic absences.13 Loss of awareness is accompanied by severe bilateral rhythmical myoclonus, sometimes with a tonic component. The ictal EEG shows 3 Hz spike-wave. Resistance to anticonvulsants and mental deterioration are common. Benign partial epilepsies. Neurological and intellectual findings are normal. A history of seizures in relatives is common and remission at puberty is usual. (a) Patients with benign epilepsy of childhood with centrotemporal spikes14 present with unilateral paraesthesias and/or tonic, clonic, or tonic-clonic contractions of the face, lips, tongue, pharynx, and larynx with consequent anarthria and drooling. Consciousness is preserved initially, but nocturnal attacks may become generalised. The interictal EEG is characterised by frequent centrotemporal spikes. (b) In benign epilepsy of childhood with occipital paroxysms15 there is distinctive repetitive occipital spiking on eye closure. Seizures include visual symptoms with variable other manifestations and postictal severe headache is common.

ADDRESS: Department of Paediatric Neurology, University Hospital of Wales, Heath Park, Cardiff CF4 4XW, UK (Dr S. J.

Wallace, FRCPE).

487

EPILEPTIC SYNDROMES ASSOCIATED WITH SPECIFIC SEIZURE TYPES

Myoclonic seizures or "spasms" Neonatal at onset

"Early myoclonic encephalopathy’" Onset 1-12 months

"Spasms" West syndrome6 Myoclonus

Benign partial seizures of adolescents-21 are usually simple in onset with motor or sensory symptoms. Loss of consciousness and secondary generalisation may supervene. Neurological and intellectual findings are normal. Interictally, the EEG may be normal or show only minor dysrhythmias. Onset throughout childhood

Benign myoclonic epilepsy" Severe myoclonic epilepsy9 Onset first 5 years

Myoclonic-astatic epilepsy’O (Lennox-Gastaut syndrome)" Onset 2-12 years Epilepsy with myoclonic absences" Adolesence

Juvenile myoclonic epilepsy’9 Associated with epilepsia partialis continua

Kojewnikow’s syndrome 22 Absence seizures

Typical/classical Childhood onset’2 Adolescent onset’8 With bilaterally synchronous myoclonic Epilepsy with myoclonic absences" Atypical with slow spike-wave

Kojewnikow’s syndrome22 consists of two electroclinical types. (a) In patients in whom a rolandic lesion has already been identified and a static neurological abnormality is present, partial motor seizures are followed by well-localised myoclonic jerks. The EEG shows a focal abnormality. (b) In previously normal children, partial motor seizures rapidly become associated with myoclonic jerks. The EEG shows background abnormalities and focal and diffuse spikes and/or spike-waves. Neurological deficits and intellectual impairment are progressive. Comment

jerking

Myoclonic-astatic epilepsy’O Lennox-Gastaut syndrome"I Landau-Kleffner syndrome’6 Epilepsy with continuous spikes and Waves during slow sleep" Partial seizures

Neurological findings normal, specific EEG changes Benign partial epilepsies of childhood"’1S

syndromic approach that I have outlined emphasises important differences within the epilepsies and can help with selection of therapy, discussion of prognosis, and genetic counselling. Nevertheless, it is important to recognise that not all epilepsies can be suitably classified. Inappropriate inclusion in a syndrome can lead to The

management that is less than ideal.

and adolescence21

Progressive neurological and intellectual deficit Kojewnikow’s syndrome Generalised tonic-clonic seizures With typical absences Childhood absence epilepsy" Juvenile absence epilepsy’8 With myoclonias

Juvenile myoclonic epilepsy’9 Occurring on awakening Epilepsy with GTCS on awakening"o

Landau-Kleffner syndrome 16 is characterised by acquired aphasia with multifocal spike and spike-wave discharges. Two-thirds of affected children have clinical seizures and a similar number have behavioural and intellectual difficulties. Epilepsy with continuous spikes and waves during slow sleep .17 Seizures are partial or generalised motor and are mainly nocturnal, although diurnal atypical absences may occur. Waking EEGs show focal or generalised spikes with or without slow waves; during slow-wave sleep continuous diffuse spike-wave activity is recorded. Seizures remit in adolescence.

Onset in adolescence Juvenile absence epilepsy.l8 Absences are infrequent and are associated with GTCS, usually on awakening, in 80% of cases. Ictal EEGs show regular 3-5-4 Hz spike-wave

activity. Juvenile myoclonic epilepsy.19 Myoclonic jerks present after awakening. Infrequent GTCS are almost invariable and absences may also occur. Sleep deprivation and alcohol are precipitants. Polyspike-wave at 4-6 Hz is found on the EEG and photosensitivity is common. Response to valproate is almost universal. Epilepsy with GTCS on awakening20 is one of the idiopathic generalised epilepsies with a strong genetic predisposition and a high incidence of photosensitivity.

soon

REFERENCES

(GTCS)

Roger J, Dravet C, Bureau M, et al, eds. Epileptic syndromes in infancy, childhood and adolescence. London: John Libbey Eurotext, 1985. 2. Plouin P. Benign neonatal convulsions (familial and non-familial). In: Roger J, Dravet C, Bureau M, et al, eds. Epileptic syndromes in infancy, childhood and adolescence. London: John Libbey Eurotext, 1.

1985: 2-9. 3. Aicardi J. Early myoclonic encephalopathy. In: Roger J, Dravet C, Bureau M, et al, eds. Epileptic syndromes in infancy, childhood and adolescence. London: John Libbey Eurotext, 1985: 12-21. 4. Ohtahara S, Ishida T, Oka E, et al. On the age-dependent epileptic syndromes: the early infantile encephalopathy with suppression-burst. Brain Dev 1976; 8: 270-88. 5. Brandt NJ, Brandt S, Rasmussen K, Schønheyder F. Hyperglycericacidaemia with hyperglycinaemia: a new inborn error of metabolism. Br Med J 1974; iv: 344. 6. West WJ. On a peculiar form of infantile convulsions. Lancet 1841; i: 724-25. 7. Kellaway P, Hrachovy R, Frost JD, Zion T. Precise characterization and quantification of infantile spasms. Ann Neurol 1979; 6: 214-18. 8. Dravet C, Bureau M. L’épilepsie myoclonique bénigne du nourrisson. Rev EEG Neurophysiol 1981; 11: 438-44. 9. Dravet C, Bureau M, Roger J. Severe myoclonic epilepsy in infants. In: Roger J, Dravet C, Bureau M, et al, eds. Epileptic syndromes in infancy, childhood and adolescence. London: John Libbey Eurotext, 1985: 58-67. 10. Doose H, Gerken H, Leonhardt R, et al. Centrencephalic myoclonicastatic petit mal. Neuropadiatrie 1970; 2: 59-78. 11. Niedermeyer E, Degen R, eds. The Lennox-Gastaut syndrome. Neurology and neurobiology, vol 45. New York: Alan R. Liss, 1988. 12. Penry JK, Porter RJ, Dreifuss FE. Simultaneous recording of absence seizures with videotape and electroencephalography: a study of 374 seizures in 48 patients. Brain 1975; 98: 427-40. 13. Tassinari CA, Bureau M. Epilepsy with myoclonic absences. In: Roger J, Dravet C, Bureau M, et al, eds. Epileptic syndromes in infancy, childhood and adolescence. London: John Libbey Eurotext, 1985: 121-29. 14. Loiseau P, Beaussart M. The seizures of benign childhood epilepsy with rolandic paroxysmal spikes. Epilepsia 1973; 14: 381-99. 15. Gastaut H. A new type of epilepsy: benign partial epilepsy of childhood with occipital spike-waves. Clin Electroencephalogr 1982; 13: 13-22. 16. Landau WM, Kleffner FR. Syndrome of acquired aphasia with convulsive disorder in children. Neurology 1957; 7: 523-30.

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17. Tassinari CA, Bureau M, Dravet C, et al. Epilepsy with continuous spikes and waves during slow sleep. In: Roger J, Dravet C, Bureau M, et al, eds. Epileptic syndromes in infancy, childhood and adolescence. London: John Libbey Eurotext, 1985: 194-204. 18. Wolf P. Juvenile absence epilepsy. In: Roger J, Dravet C, Bureau M, et al, eds. Epileptic syndromes in infancy, childhood and adolescence. London: John Libbey Eurotext, 1985: 242-46. 19. Dreifuss FE. Juvenile myoclonic epilepsy: characteristics of a primary generalized epilepsy. Epilepsia 1989; 30 (suppl 4): S1-S7.

20. Wolf P. Epilepsy with grand mal on awakening. In: Roger J, Dravet C, Bureau M, et al, eds. Epileptic syndromes in infancy, childhood and adolescence. London: John Libbey Eurotext, 1985: 259-70. 21. Loiseau P, Orgogozo JM. An unrecognised syndrome of benign focal epileptic seizures in teenagers. Lancet 1978; ii: 1070-71. 22. Bancaud J. Kojewnikow’s syndrome (epilepsia partialis continua) in children. In: Roger J, Dravet C, Bureau M, et al, eds. Epileptic syndromes in infancy, childhood and adolescence. London: John Libbey Eurotext, 1985: 286-98.

Treatment of epilepsy and febrile convulsions in children GEORGE W. RYLANCE

Starting treatment The risk of recurrence after a single afebrile seizure in children varies widely, but is probably about 50%.1 Most children with epilepsy (more than one afebrile seizure) will achieve long-term freedom from seizures with anticonvulsant therapy, but the adverse effects of these drugs cannot be discounted. Thus, there are good reasons for early treatment of unprovoked seizures, but probably not until two seizures have occurred. Other considerations are the interval between seizures (eg, a seizure-free interval of more than 12 months might militate against treatment) and the type of seizure disorder. The only seizure type for which drug treatment might not always be appropriate is benign partial epilepsy of childhood.

Selectifig the drug Although the type of seizure is the major determinant of drug choice, for most children the decision will be influenced by the frequency and nature of adverse effects and by the convenience of drug regimens based on kinetic factors and toxicity. Single-drug therapy should be used because this will achieve long-term remission in over 75 % of cases.3-6 Carbamazepine or sodium valproate is appropriate for most seizure disorders. Only in status epilepticus or childhood absence seizures is there a good reason for entertaining other agents. Management of status epilepticus in children is similar to that in adults, and ethosuximide can be used in children whose absences are not associated with generalised tonic-clonic seizures. First-choice drugs and other useful agents for the major epileptic disorders are listed in table I.

Using the drug Principle Drugs should

be prescribed alone and in deliberate sequence and the dose should be adjusted until seizures are controlled or until adverse effects prove intolerable and unacceptable. Only then should two drugs be given together; one should be maintained at a constant dose and others introduced one at a time. The possibility of interaction must be considered. It is doubtful whether three drugs together are ever more helpful than two.5,6

rapidly from the body; if this is not appreciated, suboptimum doses may be used. There is considerable variation in drug handling between children of the same age, possibly even as much as that between children of different ages. In tableI only the broad range of likely effective doses is shown; the lower value indicates the initial dose to aim for and on which the effect of the drug should be assessed. When rapid control of convulsions is indicated (eg, in a child with frequent fits or status epilepticus) loading doses are necessary, and, for the reasons stated above, seem large (eg, phenobarbitone 600 mg in a 5-year-old child-20 mg/kg). Otherwise, drugs should be introduced at low doses and built up gradually. In principle, the smallest effective dose should be used, but because this dose cannot be predicted and because any child might have a low fit frequency potential (as judged by the length of time between first and second fits), it is practicable to aim for the target dose or steady state plasma drug concentration as shown in the table. Dose increments and timing will depend on the drug being used; especially for carbamazepine, increments should be small and widely spaced to reduce the likelihood

of toxicity. Route of administration. Drugs should be given orally except when this route is inappropriate-eg, during

operative procedures, intercurrent illness with vomiting, or a long period of postictal drowsiness. Phenobarbitone (intramuscular or intravenous) and phenytoin (intravenous only) can be used as anticonvulsant cover for carbamazepine, which is available only as an oral formulation. Formulation. Although liquid preparations are widely prescribed for children, nearly all those above the age of 5 years can cope with tablets or capsules, so ensuring more certain dosing. Other disadvantages of liquid preparations include potentially damaging ingredients (eg, sucrose); the need for frequent renewal because of the short shelf-life; and fluctuating concentrations as a result of the more rapid absorption of drug molecules in suspension. Dose intervals. Dose frequency should approximate the elimination half-life of the drug if there is a relation between concentration and effect. There is no such relation for sodium valproate and a single daily dose is effective for most children.7 The elimination kinetics of phenobarbitone and phenytoin allow effective once daily dosing except at low

Dose

Especially in children between 3 months and 4 years, anticonvulsants are widely distributed and are cleared

Children’s Hospital, Ladywood Middleway, Birmingham B16 SET, UK (Dr G. W. Rylance, MRCP).

ADDRESS

Childhood epileptic syndromes.

486 EPILEPSY OCTET Childhood epileptic syndromes SHEILA J. WALLACE The International Classification of Epilepsies and Epileptic Syndromes (see S. Sh...
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