Partial Seizures in Children: Clinical Features, Medical Treatment, and Surgical Considerations

Seizure Disorders

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Partial Seizures in Children: Clinical Features, Medical Treatment, and Surgical Considerations

Elaine Wyllie, MD, * A. David Rothner, MD, t and Hans Lilders, MD, PhD+

Partial seizures are not infrequent in children. In fact, the most frequent childhood epilepsy of all is probably benign childhood epilepsy with centrotemporal spikes 63 (also called benign rolandic epilepsy, or benign focal epilepsy of childhood). One half of all adults with complex partial seizures had the onset of their problem before the age of 20 years 25 ; and among children with epilepsy, the seizure type is simple or complex partial in approximately 23 to 66 per cent of patients. 10. 93. 102 Many children with partial seizures may need aggressive medical treatment, or even epilepsy surgery. Early intervention can make a critical difference in providing for a normal adult life. For this reason, it is important that these seizure types be familiar to physicians who care for children.

DEFINITIONS Types of Partial Seizures Partial seizures have been classified into two types: simple partial and complex partial. II The hallmark of both types is focal epileptiform discharges starting in a portion of one cerebral hemisphere. In addition, complex partial seizures involve impaired consciousness, but simple partial seizures do not. The impairment of consciousness during complex partial seizures may occur at the onset of the seizure, or after an initial simple partial phase From the Section of Pediatric Neurology and Section of Epilepsy and Clinical Neurophysiology, Cleveland Clinic Foundation, Cleveland, Ohio *Section of Pediatric Neurology, and Section of Epilepsy and Clinical Neurophysiology tChief, Section of Pediatric Neurology :j:Head, Section of Epilepsy and Clinical Neurophysiology

Pediatric Clinics of North America-Vol. 36, No.2, April 1989

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with preserved consciousness. When the simple partial seizure is sensory, it is sometimes called an aura. With the current classification, simple and complex partial seizures are differentiated solely on the basis of preservation or impairment of consciousness, regardless of the coinplexity of other symptoms. Therefore, in this usage, "complex" does not mean "complicated." This variance from the colloquial meaning of the word has caused some confusion over the years, especially because in the First International Classification of Seizures in 1970,29 the term complex did in fact mean "with complicated symptoms," with or without alteration of consciousness. The current distinction between simple and complex partial seizures, based on the presence or absence of impaired consciousness, has posed another problem because the ictal level of consciousness is not always easily assessed. By current convention, ictal unconsciousness is defined by ictal unresponsiveness and postictal amnesia, but these features may be difficult to determine, especially in young children. Obviously, there are still imperfections in the classification system, and it may sometimes be difficult to determine whether the seizure should be called simple or complex partial. Fortunately, for treatment purposes, this exact distinction is usually not important. Complex partial seizures sometimes have also been called psychomotor or temporal lobe seizures. These terms are not interchangeable, however. Psychomotor symptoms, or automatisms, also may occur during generalized absence ("petit mal") seizures, especially if the seizures last longer than several seconds. In addition, not all complex partial seizures arise from the temporal lobe; some may come from frontal, parietal, or occipital areas. The terms psychomotor seizures and temporal lobe seizures are not part of the current classification from the International League Against Epilepsy, so for purposes of communication, the term complex partial seizures is preferable. Types of Partial ("Localization-Related") Epilepsy Describing a child's seizures just as simple or complex partial does not communicate much clinical information about treatment or prognosis. For this reason, it is helpful to think not just about types of seizures, but also about types of epilepsy. With this classification, patients are grouped not just because of similar seizure type, but because of similar clinical, electrographic, radiographic, and pathologic findings; therefore, certain types of epilepsy may include one or more different types of seizures. In the current International Classification,12 the partial or focal epilepsies are called localization-related epilepsies. This classification is quite complex, and for this discussion we will use a simplified version. Patients with temporal lobe epilepsy have seizures arising from the temporal lobe, with epileptiform discharges from that region on EEG. Usually the seizures are complex partial, but some patients also may have seizures with more than one phase, so that the event starts out as a simple partial seizure and then evolves into a complex partial seizure, or as a complex partial seizure that evolves into a secondary generalized tonicclonic seizure. Regardless of the seizure type, this epilepsy may be difficult

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to control; temporal lobe epilepsy is the most common indication for epilepsy surgery in children and adults. The epilepsy may be due to a structural lesion in the temporal lobe or a previous insult to that area, but frequently no cause is found. Patients with extratemporal epilepsy have seizures arising from frontal, parietal, or occipital areas. The seizures may be simple partial, with focal motor, somatosensory, or special sensory phenomena, or they may be complex partial, especially if they arise from the occipital lobe or from nonrolandic areas of the frontal or parietal lobe. In any event, the partial seizures of extratemporal epilepsy, like those of temporal lobe epilepsy, also may have more than one phase. Extratemporal and temporal lobe epilepsy are similar in some other respects: they both may be due to focal pathology, they may both be difficult to treat, and they both may eventually lead to the need for epilepsy surgery. One special type of extratemporal epilepsy is benign childhood epilepsy with centrotemporal spikes. This epilepsy has features that are specific enough to warrant its designation as an epileptic syndrome. It occurs in children between 2 and 16 years of age, with a peak age of onset at 6 to 10 years old. The EEG sharp waves are identified by a typical morphology, typical location in centrotemporal (or occipital) regions, and significant activation during sleep.63 The affected cortical areas are usually rolandic motor regions. The usual seizure type is secondary generalized tonicclonic, simple partial with motor involvement of the face, or simple partial with motor involvement of areas other than the face. 63 The epilepsy is usually idiopathic, with no underlying structural lesions nor other identifiable cause. The prognosis is excellent: the seizures usually are easily controlled by antiepileptic medication, and resolve completely by age 16 years. It is clear that if a patient's signs and symptoms are typical of an epileptic syndrome, such as benign childhood epilepsy with centrotemporal spikes, then he can be given very specific information about the most likely etiology, course, and outcome. For this reason, it is worthwhile to make the most specific diagnosis possible.

CLINICAL MANIFESTATIONS Simple Partial Seizures Simple partial seizures may include a wide variety of clinical manifestations. 58 Possible symptoms include focal motor or somatosensory phenomena of any part of the body, with or without a march; special sensory phenomena including visual, auditory, olfactory, or gustatory hallucinations; autonomic symptoms such as pallor, Bushing, vomiting, sweating, piloerection, tachycardia, or pupillary dilatation; or complicated psychic symptoms such as deja vu (a feeling that something is familiar, even though it is not), jamais vu (a feeling that something is unfamiliar, even though it should be familiar), or other affective phenomena such as feelings of unreality, fear, dread, or pleasure. Although the symptoms vary greatly between patients,

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they tend to be stereotyped from seizure to seizure for each individual child. Simple partial seizures with focal motor phenomena sometimes have been called focal motor seizures. The focal motor phenomena may be clonic jerking or twitching of any part of the body: one typical pattern, for example, is jerking of one hand or arm plus the same side of the face. Different patterns of clonic jerking may occur depending on the cortical areas affected by the ictal epileptiform discharge. If the jerking spreads from one part of the body to another, to parts controlled by contiguous regions of the motor cortex, then it is said that the seizures have a jacksonian march. An example of simple partial seizures with a different type of focal motor phenomena is the seizure type seen in patients with benign childhood epilepsy with centrotemporal spikes focal motor phenomena, with prominent involvement of muscles of the face and head. During these seizures, the children often lose control of pharyngeal muscles and the tongue, resulting in drooling and speech arrest or dysarthria, without alteration of consciousness. There may also be tonic or clonic contractions of one side of the face, or clonic jerking, dystonic posturing, or even just clumsiness of one hand. These seizures usually do not closely resemble classic jacksonian marching seizures, but they also are classified as simple partial with focal motor phenomena. Simple partial seizures with focal motor phenomena also may occur as a form of status epilepticus, sometimes called epilepsia partialis continua. This may involve clonic jerking or twitching of a limited part of the body for hours, days, or even years: in one study, the epilepsia partialis continua lasted from 4 hours to 76 years, with a mean of 25 months. 101 The twitching may affect just a small group of muscles, or it may involve larger areas of an entire hemibody. These seizures typically respond poorly to antiepileptic medication, and the treatment may be quite difficult. Simple partial seizures with somatosensory phenomena may include symptoms such as tingling, deadness, burning, cold, pain, or a sense of movement in any part of the body. Like simple partial seizures with focal motor phenomena, these seizures with somatosensory phenomena also may involve a march, with the sensations spreading from one part of the body to another. Other types of simple partial seizures may include special sensory symptoms such as sensations of light, darkness, or color; distortions of vision; or complex visual, olfactory, auditory, or gustatory hallucinations. Sometimes the symptoms of a simple partial seizure give a clue about where in the brain it may have started. This is more so for some symptoms than for others: for example, seizures beginning with a jacksonian march of sensory or motor symptoms may be suspected of arising in or near the contralateral rolandic strip, but seizures beginning with psychic symptoms could arise from various areas of either hemisphere. Visual symptoms are reported most often by patients with occipital or parietal lobe epilepsy, and olfactory or auditory hallucinations are often reported by patients with temporal lobe epilepsy, but these symptoms may occur in other types of epilepsy as well. It must be remembered that no symptom will mean the same thing universally in every patient, and any localization implied by the

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symptoms of a simple partial seizure should be interpreted in the context of findings on EEG, imaging studies, and physical examination. Complex Partial Seizures A complex partial seizure may be preceded by a simple partial seizure; this is reported for 50 per cent to 83 per cent of adults with complex partial seizures l6 . 38, 48 but for less than 50 per cent of children. 40, 41 It is possible that more children actually start with a simple partial seizure but cannot describe the feeling. Sometimes an initial simple partial seizure can be suspected because the child always comes to a parent for help just before the development of altered awareness. If an initial simple partial seizure can be identified, then it may be helpful in the following ways: (1) it identifies the seizure as having partial onset, thus clearly distinguishing the later seizure as complex partial and not generalized absence ("petit mal"); (2) it may warn the patient that a complex seizure is about to occur, so that he can prepare himself; (3) it may be the only part that the patient remembers, so it may be his only clue afterwards that he recently had a seizure; and (4) it may provide some lateralizing or localizing information to the physician about the site of onset. For these reasons, it is worthwhile to ask the child and the parent specifically about any possible symptoms that might precede impairment of consciousness. The impairment of consciousness in complex partial seizures may simply be manifested by an arrest of ongoing activity with decreased responsiveness and a blank empty stare, or there also may be automatisms. Automatisms are most common during the seizures of temporal lobe epilepsy, but they may also be seen in frontal, parietal, or occipital lobe epilepsy, or in childhood generalized absence epilepsy ("petit mal").81 Because automatisms occur after consciousness has been lost, the children do not remember them. In one study based on videotape observation, automatisms occurred at some time or another during complex partial seizures in 87 per cent of 38 children who were 5 to 19 years of age. 41 Most of these children had temporal lobe epilepsy. In these children, the first clinical manifestations of the seizures were either (1) automatisms right from the start of the seizure, seen in 37 per cent of the children; (2) quiet motionless staring, followed later by automatisms, in 47 per cent; (3) sudden loss of body tone, followed by automatisms, in 4 per cent; or (4) motor phenomena, such as tonic extension of one or both arms, clonic movements of the extremities, or eye blinking, without automatisms, in 13 per cent. The automatisms in these children, occurring initially or later in the seizure, consisted of a wide range of poorly coordinated semipurposeful activity (Table 1). The automatisms during complex partial seizures vary widely between patients but tend to be stereotyped from one seizure to another for individual children. Automatisms may be perseverative, with confused and ineffective persistence of activities that were in progress prior to the seizure, or de novo, with new activities begun after the onset of the seizure. Automatisms have also been broadly claSSified, according to the type of automatic behavior, as gestural (including fumbling with nearby objects or

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Table 1. Ictal Events That Were Thought to Be Automatisms During Videotaped Complex Partial Seizures in 38 Children AUTOMATIC BEHAVIOR SEEN DURING SEIZURE*

FIRST SEIZURE

ALL SEIZURES

7

II II 10 16 9 7

Thrashing Chewing, lip smacking Resisting restraint Sitting/standing up Fumbling with helmet, belt Crying, yelling, groaning Decreased body tone Rocking Dropping object Eating Gesturing Hands over eyes Snapping fingers Scratching face Facial grimacing Walking around Tongue movements Laughing Grabbing arm

7

7 5 3 4 2

7

2

14

2

2 I

I 2 I

2 I

3 I 3 I I

3 6 6 2 24 I

5 I 4

*Some patients had more than one automatism. From Holmes GL: Partial seizures in children. Pediatrics 77:725, 1986; with permission.

picking at clothes or bedsheets), alimentary (chewing, swallowing, or lip smacking), mimicking (facial expressions suggesting an emotion such as fear), verbal (yelling, laughing, or repetitive speech), or ambulatory (walking or running). Holmes 41 found that the automatisms during complex partial seizures in a group of 5- to 19-year-old children were similar to those in adults. This may be because older children and adults with complex partial seizures most often have the same underlying problem of temporal lobe epilepsy, but infants with complex partial seizures may have a different type of epilepsy. In infants, the automatisms during complex partial seizures may be different from those in older children. Recent reports have included babies who had videotaped seizures with arrest of activity and apparent loss of contact with the environment, accompanied by a focal or lateralized seizure pattern on EEG 21 . 114; in these babies, the automatisms were more often alimentary than gestural. For example, Duchownr1 noted that 66 per cent of babies 0 to 2 years old had grimacing, lip smacking, chewing, or eyelid fluttering during complex partial seizures, but none had automatisms. Automatisms also may occur during the postictal phase of partial seizures, while the child is still significantly confused. If the child is physically restrained dUring that time, he may react with aggressive behavior against the restraining person, but if he is left alone except for maneuvers to protect his safety, there will most likely be no directed violence. 17 Patients also may have autonomic or motor symptoms during the

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complex partial phase of seizures. These symptoms may include any of those described above in the section about simple partial seizures. Rarely patients may have complex partial status epilepticus. 18 The symptoms may be similar to those seen in generalized absence status epilepticus, ranging from confusion, disorientation, and a dazed look, to deep stupor. EEG is critical to differentiate focal nonconvulsive status epilepticus from generalized nonconvulsive status epilepticus, and from other causes of acute encephalopathy. 71 Secondary Spreadirig and Generalization Partial seizures may end without any later symptoms of secondary generalization of the ictal discharge. If the ictal discharge spreads to involve widespread areas of the ipsilateral hemisphere, however, then there may be additional late symptoms. Secondary generalization during the complex partial seizures of temporal lobe epilepsy may typically include posturing or clonic jerking of the contralateral face or limbs, or versive turning of the head to the contralateral side. III In many patients, this leads to a full generalized tonic-clonic convulsion. In the child who has generalized tonic-clonic seizures, it is important to consider whether the seizure was primary or secondary generalized, because the treatment and prognosis may be very different. The key to the diagnosis of secondary generalized seizure is the history of a preceding simple or complex partial seizure.

ELECTROENCEPHALOGRAPHIC MANIFESTATIONS Interictal EEG BEG may be extremely helpful in the diagnosis of simple or complex partial seizures and should be performed in any child who is suspected of having this problem. The hallmark of a focal-onset seizure disorder is focal spikes or sharp waves; and if these are present, then there is strong supportive evidence for a diagnosis of partial seizures in the proper clinical setting. Different types of localization-related epilepsies have epileptiform discharges with a typical location or waveform, so that certain EEG findings may be highly suggestive of certain forms of epilepsy. For example, if there are interictal spikes or sharp waves in the temporal region (Figs. 1 to 3), theri there is strong supportive evidence for complex partial seizures and temporal lobe epilepsy. Not every patient with partial seizures will have spikes or sharp waves during an initial routine EEG, however. Factors shown to increase the yield of interictal epileptiform discharges include longer recording time, recording during sleep, and use of nasopharyngeal, sphenoidal, or extra scalp electrodes. It should be remembered that a significant proportion of the patients with partial seizures have normal routine interictal EEGs, and this may be especially true for inflints1l4 and children. 40 Therefore, a normal interictal EEG cannot be used to "rule out" a diagnosis of epilepsy in patients who have episodes that sound like simple or complex partial

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FPI-F7

F7-T3

T5-01

•

lse..

I

I70uv

Figure 1. Left anterior temporal sharp wave (arrow) on EEG, recorded from a 9-yearold girl with complex partial seizures for several years. (See also Figs. 2 and 3.)

Figure 2. Schematic illustration of the montage used for the EEG recording in Fig. 1. Each line of EEG in Fig. 1 corresponds to a numbered electrode pair in Fig. 2 (e.g., the first line of EEG is from the electrode pair FP 1 connected to F 7 , in the left frontal region). The first four lines of EEG in Fig. 1 are from the left, and the second four lines are from the right.

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Figure 3. Schematic illustration of the distribution of the left anterior temporal sharp wave in Fig. L The focal discharge is essentially limited to the left frontotemporal area beneath electrodes F, and T 3 • This is a common distribution ofleft anterior temporal discharges.

seizures. If the history is suggestive of partial seizures, then it may be appropriate to consider additional prolonged recordings to confirm the diagnosis. If necessary, the chance of actually recording a seizure may be increased by weaning the antiepileptic medication. Interictal EEG findings that support a diagnosis specifically of complex partial seizures include sharp waves from one temporal lobe, sharp waves independently from both temporal lobes (seen in one fourth to one third of patients), or sharp waves from unilateral frontaF 6 or occipital66 areas. Simple partial seizures also may arise from various cortical areas, but especially from regions with motor, somatosensory, or special sensory function. In any event, it is important to avoid misinterpretation of nonspecific findings such as small sharp spikes, psychomotor variant, 14and 6-per-second positive spikes, or slowing of background rhythms. 49. 91 It also should be remembered that children 2 to 16 years old frequently have a type of interictal sharp wave that does not support a diagnosis of complex partial seizures: the centrotemporal spikes of benign childhood epilepsy. These sharp waves are identified by a typical morphology on EEG, typical location in centrotemporal (or occipital) regions, and significant activation during sleep. 63 Although these discharges are clearly epileptiform, they frequently occur in normal children: it has been estimated that only 8.8 per cent of children with these EEG discharges actually ever have a seizure. 63 In the children with these centrotemporal spikes or sharp waves who do have seizures, the type usually is generalized tonic-clonic, or simple partial with focal motor phenomena. 63 It is likely that complex partial seizures do not occur in children with benign childhood epilepsy with centrotemporal spikes. This means that in a child who presents with a complaint of staring spells, the centrotemporal spikes may just be an incidental finding.

Ictal EEG During a simple partial seizure or the simple partial phase of a complex partial seizure, there may be no EEG seizure pattern detected at the scalp in at least 30 per cent of cases. 91 However, during a complex partial phase, an EEG seizure pattern is almost always identifiable. 19, 49 The ictal EEG pattern most commonly includes attenuation of the interictal pattern followed by focal paroxysmal rhythmic discharges that mayor may not have distinct spikes or sharp waves (Figs. 4 and 5). Usually ictal EEG discharges

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FPI-F7 F7-T3

T3-T5 T5-01 FP2-FB

F8-T4

T4-TS

TS-02 I'50p.V

Figure 4. EEG recording during a complex partial seizure in a 6-month-old baby. The recording used the same electrode montage illustrated in Fig. 2. The paroxysmal slowing is maximal in the left posterior temporal region (Fig. 5), although there is a widespread distribution throughout the left hemisphere. The clinical seizure consisted of body stiffening, staring, drooling, tearing, and decreased responsiveness.

are less well localized on scalp EEG than are the interictal discharges, but ictal recording may add important information by confirming that the episodes are truly epileptic, and that the interictal sharp waves are in fact from an area of the brain that generates seizures. . After a partial seizure that did not become secondarily generalized, the EEG may show focal slowing on the side of seizure onset. If recorded in isolation, this postictal finding may provide some helpful localizing information, but it does not prove that the preceding event was epileptic.

ETIOLOGY

The exact percentage of children with partial epilepsy who have identifiable causes is unknown. In a population study including adults, Hauser and Kurland39 found a plausible cause in 28 per cent of patients

Figure 5. Schematic illustration of the distribution of the EEG seizure pattern in Fig. 4.

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Figure 6. Computed tomography scan without injection of contrast material in a 21-month-old baby with complex partial seizures since 3 months old. Seizures consisted of staring with a frightened look and decreased responsiveness. The calcified lesion had not changed from previous CT scans at 3 and 16 months of age. The exact nature of the lesion was unknown.

with simple or complex seizures. In a longitudinal study of 100 children with partial seizures, however, Ounsted et a}.79. 80 reported a plausible cause for 67 per cent; and in a review of temporal lobe specimens from 857 patients who had epilepsy surgery, Mathieson 70 found a pathologic abnormality in 80 per cent. Several population studies are flawed because they lump together different types of seizures, and reports from surgical series are limited because they involve highly selected cases. It appears, however, that in essentially every series, the major etiologic factors are birth asphyxia, later anoxic episodes, head trauma, neoplasms (usually slow-growing gliomas), and infection. Less common etiologies include neurocutaneous syndromes, arteriovenous malformations, or old infarction. Because of the significant chance of a structural cerebral lesion, an imaging procedure is indicated in essentially every child with partial seizures. Magnetic resonance imaging (MRI), especially, may give important information. 8. 45. 52-54. 56. 72. 78. 90 This technique has significant advantages over computed tomography (CT) because of higher sensitivity, superior image quality, lack of radiation exposure, and ability for multiplanar display. In some cases, MRI has disclosed a lesion not seen on CT. The most frequent location for CT or MRI abnormalities in patients with complex partial seizures is the temporal lobe (Fig. 6). Febrile convulsions in infancy also have been identified as an etiology of temporal lobe epilepsy in a few surgical series70 • 85 and in one population series. 88 However, in a prospective population study that followed children until the age of 7 years old, it was found that epilepsy followed simple febrile seizures in only 1.1 per cent of children, but followed complicated

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febrile seizures in 9.2 per cent of children. 77 Complicated febrile seizures had one or more of the following: duration longer than 15 minutes, occurrence more than once in 24 hours, focal clinical features, or occurrence in a child with preceding brain damage or an abnormal EEG. Simple febrile seizures had none of these features. Most of the children in the population study by Rocca et al. 88 who had complex partial seizures following febrile seizures had at least one febrile seizure with one of these complicating factors. It appears that simple febrile seizures most probably do not predispose to later epilepsy. The above-mentioned etiologies are all factors that may be identified clinically by history, physical examination, or imaging procedures. In addition, patients may have pathologically identified etiologies that are only discovered at necropsy or after epilepsy surgery. These pathologic findings include lesions such as small tumors or vascular malformations that did not show up preoperatively on CT or MRI, mesial temporal sclerosis, or neuronal heterotopias. 4 The exact etiologic significance of some of these findings is still controversial, but in any event they are findings that are not generally available to the clinician during medical treatment.

TREATMENT Medical Management The primary drugs used for partial seizures are carbamazepine, phenytoin, phenobarbital, and primidone. Each of these medications has similar efficacy for control of partial seizures in children, but they differ in frequency of side effects, and because of undesirable effects on cognitive function and behavior, carbamazepine and phenytoin are usually preferable to phenobarbital or primidone. 43 , 100 Our personal first choice is carbamazepine, although we feel that phenytoin should certainly be tried if carbamazepine is ineffective or not tolerated. Second-line drugs include valproic acid, clonazepam, and clorazepate. The principles for anti epileptic therapy in children are similar to those in adults (Table 2). The general approach is to begin with one drug in low doses; in our schema, this is carbamazepine. If this first medication fails to control seizures, then it is used in progressively increased dosages as needed until the seizures are completely controlled or the child develops intolerable dose-related side effects. With this approach, the optimal dose of medication will often result in a serum drug concentration that is either above or below the usual therapeutic range. For this reason, the relationship between the patient's actual serum drug concentration and the usual therapeutic range should not be used as the sole criterion for raising or lowering the dose of medication. 55, 91 If seizures remain uncontrolled even at the maximal tolerated dosage of carbamazepine, then the medication is changed to phenytoin, again to be used singly. If phenytoin is also ineffective or not tolerated, then a change is made to phenobarbital or primidone. If this third medication is ineffective, then the next step is to use together the two best of the

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Table 2. Strategy of Treatment of Partial Seizures in Children U sed to maximally tolerated doses, if needed

If carbamazepine has failed:

If the diagnosis is clearly epilepsy, then try single drugs:

Carbamazepine

Consider pediatric neurologic consultation. If the diagnosis is uncertain, then consider prolonged EEG recording.

Phenytoin

Primidone or phenobarbital

If single-drug therapy has failed:

Combine the two best-working of the drugs already tried: carbamazepine or phenytoin, plus primidone Or phenobarbital.

If these two-drug regimens have failed:

Combine the one best-working of the above drugs, plus valproic acid, clonazepam, or clorazepate.

If these two-drug regimens have failed:

Return to the regimen that gave best results, and consider epilepsy surgery.

previously used medications. If this is also ineffective or not tolerated, then the next step is to try the one best drug so far in combination with valproic acid, clonazepam, or clorazepate. Except during brief changeover periods, the child should generally be on only one or two drugs at a time. Throughout these trials, it is important to document the patient's seizure frequency and side effects clearly so that later he can identifY and return to the single best regimen. Within the guidelines described above, it is our impression that there are certain two-drug combinations that may work better than others. In general, it makes sense to combine drugs with different mechanisms of action, to maximize potential benefits and minimize side effects. Such combinations include carbamazepine plus valproic acid, carbamazepine plus phenobarbital or primidone, phenytoin plus valproic acid, or phenytoin plus phenobarbital or primidone. For the same reasons, less desirable combinations include phenobarbital plus primidone, or carbamazepine plus phenytoin. Surgical Treatment The exact percentage of patients with partial epilepsy who are refractory to medication is not known. In patients who are refractory, however, it

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may be appropriate to consider epilepsy surgery, either temporal lobectomy or other focal cortical resection. A concern about early surgery in children is that until adulthood, it may be difficult to be sure that the child will not grow out of the seizures. It has not been clearly demonstrated that childhood-onset partial seizures have higher rates of spontaneous remission than adult-onset seizures, however. Reported remission rates in children with partial seizures have ranged from 6 to 65 per cent,3, 13, 20, 28, 33, 50, 61, 62, 89, 92, 93, 102 but most reports have had limitations. Several were based on clinical criteria only, or included patients with benign childhood epilepsy with centrotemporal spikes; some of these reported pediatric patients may have had other milder forms of epilepsy instead of the temporal lobe epilepsy seen in adults. One recent study included only children with complex partial seizures and temporal lobe sharp waves on EEG, excluding centro temporal spikes; in this report, the remission rate was only 18 per cent. 50 These data from Kotagal et al. 50 suggest that temporal lobe epilepsy is frequently intractable in children as well as adults, and that spontaneous remission is unlikely. In selected pediatric patients, epilepsy surgery may offer an improved chance for seizure control and development of educational, social, and vocational potential. The criteria for epilepsy surgery include the following: (1) a clearly established diagnosis of partial epilepsy; (2) intractable, handicapping seizures for at least two or three years; and (3) location of seizure onset in a relatively "silent" area of the brain that could be removed with a low risk of subsequent neurologic deficit. The most common operation is temporal lobectomy, followed by frontal lobectomy, but occasional patients may benefit from other types of extratemporal resections. Most children identified as candidates for epilepsy surgery are referred to specialized centers for further presurgical evaluation. The most important tool for localizing the epileptogenic area is intensive ictal and interictal video-EEG, usually with special electrodes and decrease or discontinuation of antiepileptic medication. 55 Patients also routinely have imaging studies such as CT scan, MRI, and positron emission tomography (PET). 1, 22, 54, 99 Further presurgical testing that generally has less localizing value, but that serves as baseline for later comparison with postsurgical results, includes psychometric testing, speech, and visual field evaluation. Patients also may need intracarotid amobarbital testing to determine the hemisphere dominant for speech and memory. 74, 104 If the presurgical evaluation yields consistent information that the epileptogenic area is in the anterior portion of one temporal lobe, then some centers will proceed directly to anterior temporal lobectomy, usually with a somewhat larger resection from the nondominant hemisphere. However, a significant number of patients have complicating features that necessitate further investigation, such as large structural lesions, multiple independent epileptogenic foci, or foci near functionally important cortical areas. Invasive recording from depth, 5, 9, 59, 67, 94. 95, 105 epidural, 34, 35 or subdural64, 68, 112, 113 electrodes may provide critical localizing information so that the epileptogenic area can be most completely removed, but most reports have been based on adult patients, and fe~4, 35, 113 have emphasized

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extraoperative invasive EEG in children. Cortical electrical stimulation may be done intraoperatively or extraoperatively to identifY functionally important areas that must be avoided at surge~' 57, 64, 65, 68, 112; again, there are few reports of results in pediatric patients. 34, 35, 84, !l3 In one recent report of patients who had extraoperative subdural EEG and cortical stimulation studies, however, it was found that the invasive techniques were as effective and as well tolerated in the children and adults. 113 These results suggested that certain types of invasive neurophysiologic techniques may be helpful in patients, regardless of age. Good outcome has been reported to be as frequent after epilepsy surgery in children as in adults. The definition of good outcome has varied between reports, but in general it includes being seizure-free, with auras only, or with a greater than 90 per cent decrease in seizure frequency. In one recent study, 76 per cent of children and adolescents had good outcome after temporal lobectomy, compared to 63 per cent of adults l13; these figures are within the 47 to 83 per cent range of good outcome reported for children in other operative series. 15, 23, 24, 34, 35, 37, 46, 47, 50, 73, 82-84, 106 More specific comparisons between series are difficult because of differences in patient selection, operations, and definitions of good outcome. It has become clear, however, that children as well as adults may benefit from early epilepsy surgery.

OTHER TYPES OF EPILEPSY SURGERY IN CHILDREN Hemispherectomy Hemispherectomy is a very effective form of epilepsy surgery in selected patients, because it involves essentially complete removal of all epileptogenic tissue. The operation has had a checkered history, however. In recent years, there has been a resurgence of interest in the procedure. Hemispherectomy first became an established type of epilepsy surgery after the report of 12 patients by Krynauw. 51 Between 1950 and 1968, there were many reports of excellent results, including one review of 420 cases. 44 The standard operation was complete hemispherectomy, with sparing only of basal ganglia. Candidates were patients with the following features: (1) intractable seizures arising only from widespread areas of one damaged hemisphere; (2) hemiplegia since before 4 years of age; (3) no functional hand use on the weak side of the body; and (4) homonymous hemianopia. Dramatic improvement in seizure control and behavior was reported for 70 to 100 per cent of patients, with rare worsening of preoperative neurologic deficits. By the late 1960s, however, it became clear that a significant number of patients had serious late complications after hemispherectomy. 78, 86, 109 The overall incidence of late complications appeared to be 17 to 35 per cent, but among patients who developed these problems, the mortality was 44 per cent. 86 Problems appeared 1 to 20 years postoperatively: patients had an initial problem-free period followed by a progressive slow deterioration, often ending in death. Signs and symptoms included increased

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intracranial pressure, ataxia, dementia, brain stem dysfunction, and blood or protein in the cerebrospinal fluid, but the exact cause of these problems is unknown. One theory is that they are caused by repeated low-grade bleeding into the huge subdural hemispherectomy cavity, resulting in cerebral, cerebellar, and brain stem hemosiderosis, and in obstructive hydrocephalus due to proliferative ependymitis. 86. 109 In an attempt to reduce these late complications without sacrificing the benefits of hemispherectomy, there have been modifications of the original operative technique. 2.36.86 Current operations include the following: (1) subtotal hemispherectomy, with sectioning of the remaining white matter; (2) hemicorticectomy, with removal only of cortical grey matter in one hemisphere; (3) complete hemispherectomy, but with placement of a subdural-ventriculoperitoneal shunt at the time of operation; and (4) complete hemispherectomy, but with suturing of the dura to reduce the size of the subdural space. In addition, some centers still perform the traditional complete hemispherectomy, with the expectation that late complications could now be more easily identified and treated with the help of CT and MRI. Long-term results from these operations are not yet available, but so far it appears that the incidence of late complications may be much reduced. The indications for hemispherectomy now are essentially the same as they were in the 1960s, with the addition that some centers now also include patients who are not totally hemiplegic but who have progressive devastating illness such as Rasmussen's chronic focal encephalitis. 14 Corpus Callosotomy In recent years, corpus callosotomy has gained recognition as a safe and effective treatment for selected patients with intractable, debilitating, generalized seizures. This operation is not appropriate for patients whose predominant seizure type is partial, but it is considered here as part of the discussion of epilepsy surgery. Results from recent operative series have been encouraging: 62 to 100 per cent of patients have had significant improvement in the frequency of generalized seizures, and serious complications have been rare. 7. 30-32, 69, 76, 87, 97, 107 Division of all or part of the corpus callosum is thought to give its resultant benefit by interfering with the spread of epileptic discharges from one cerebral hemisphere to the other. 6,96 As with hemispherectomy, the early more radical corpus callosotomy operations were found to have serious complications, resulting in the development of modified, safer techniques, Corpus callosotomy was first introduced as a form of epilepsy surgery by Van Wagenen and Herren in 1940,103 but it did not become popular until the 1960s and 1970s. Early operations included section not only of the complete corpus callosum, but also of deeper commissures, including the massa intermedia of the thalamus, anterior commissure, hippocampal commissure, and one fornix. In a report from Wilson et al. in 1977108 however, it was found that patients had an unacceptably high rate of complications, including aseptic meningitis, hydrocephalus, and even death, This experience resulted in the development of less extensive operations, so that modern series involve section only of all or part of the corpus callosum, with sparing of deeper commis-

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sures. With these newer techniques, there have been few serious operative complications. Patient selection criteria for corpus callosotomy are still being refined. 110 Important features include the following: (1) at least a 3-year duration of daily or weekly intractable, debilitating primary or secondary generalized tonic-clonic, atonic, tonic, or myoclonic seizures; (2) specific identifiable social or vocational goals for surgery based on realistic hopes for an improved lifestyle; and (3) EEG findings that rule out a single resectable epileptogenic focus. Good prognostic features have included unilateral cerebral damage, atonic or myoclonic falling attacks as the most debilitating seizure type, and relatively intact intellect, but favorable results also have been reported for mentally retarded patients. There are no specific age restrictions: most patients have been teens or young adults, but recent series have also included children as young as 5 and 6 years old. Some neuropsychologic deficits have been reported after corpus callosotomy, but in general they have not been disabling. In many cases, the deficits were actually asymptomatic and discovered only during special testing, and it should be remembered that there have also been reports of improvement in neuropsychologic function after corpus callosotomy.27 Reported series also have included patients who had an acute but transient "disconnection syndrome" with mutism and apraxia of the nondominant hand. For most patients, however, these problems have been clearly outweighed by the benefits of decreased seizures.

SUMMARY

Partial seizures are not uncommon in children. They are classified into two types: simple partial, without impairment of consciousness, and complex partial, with impaired consciousness. For both types, the hallmark is onset of the seizure from a portion of one cerebral hemisphere, as indicated by focal spikes or sharp waves on EEG. The symptoms of simple partial seizures may include focal motor or somatosensory phenomena, special sensory phenomena, autonomic symptoms, or psychic symptoms, and these symptoms may occur alone or they may progress into a complex partial seizure with alteration of consciousness. The complex partial phase may include simply an arrest of ongoing activity with altered awareness and a blank empty stare, or there may also be automatisms, including movements which are gestural, alimentary, mimicking, verbal, or ambulatory. Automatisms are predominantly seen in complex partial seizures arising from temporal areas, but they also may be seen in seizures with extratemporal onset. If the epileptic discharge spreads throughout both cerebral hemispheres, the child will have a secondarily generalized tonic-clonic convulsion. EEG should be performed in any child who is suspected of having partial seizures. If there are focal spikes or sharp waves, then there is strong supportive evidence for a diagnosis of partial seizures in the proper clinical setting. It should be remembered, however, that a normal routine

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EEG cannot be used to "rule out" a diagnosis of epilepsy in patients who have episodes that sound like simple or complex partial seizures. An underlying etiology may be found in a significant percentage of children with partial seizures. Most of these etiologies are static, and the seizures are the result of a previous cerebral insult, but some patients may have slow-growing gliomas or other mass lesions. MRI or CT is indicated in essentially any child with partial seizures. Medical treatment is based on the idea of using single drugs to maximally tolerated doses, if needed, before beginning with two-drug regimens. If the child continues to have seizures despite aggressive trials of medication, then it is important to consider epilepsy surgery, either temporal lobectomy or other cortical resection. When children are identified as candidates for epilepsy surgery, they should be referred to specialized centers for further testing. The success rate of epilepsy surgery has been equally good in children and adults, and it is likely that earlier surgery could result in improved chances for normal social and vocational adjustment. Other types of epilepsy surgery, besides focal cortical resection, include hemispherectomy and corpus callosotomy.

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