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Idiopathic occipital and absence epilepsies appearing in the same children
Idiopathic Occipital and Absence Epilepsies Appearing in the Same Children Roberto H. Caraballo, MD*, Ariel Sologuestua, MD*, Nora Gran˜ana, MD†, Javier N. Adi, MD‡, Ricardo O. Cerso´simo, MD*, Edgardo Mazza, MD*, Owen Foster, MD†, and Natalio Fejerman, MD* Our aim is to report the association between idiopathic occipital epilepsy and childhood absence epilepsy in the same children. Six children met the diagnostic criteria for both idiopathic occipital epilepsy and childhood absence epilepsy, five patients with idiopathic occipital epilepsy Gastaut type and another with Panayiotopoulos type. All patients were monitored for 2 to 10 years with repeated electroencephalograms when awake and during sleep. Age at onset of seizures ranged from 4.6 to 8 years. Five patients had focal sensory visual seizures, all with migrainelike episodes. One patient presented ictal vomiting followed by oculocephalic deviation. All patients presented typical absences, with onset at least 1 year after having had idiopathic occipital epilepsy Gastaut type in three patients. In the other two patients with idiopathic occipital epilepsy Gastaut type and the patient with idiopathic occipital epilepsy Panayiotopoulos type, both types of epilepsy appeared at the same time. The electroencephalograms documented occipital paroxysms in all cases, with positive reactivity to the eye closure in five patients. All children presented spike-wave discharges at 3 cycles per second activated by hyperventilation. More genetic information would be necessary to demonstrate either a close genetic relationship between these syndromes or common markers with variable phenotypes. © 2004 by Elsevier Inc. All rights reserved. Caraballo RH, Sologuestua A, Gran˜ana N, Adi JN, Cerso´simo RO, Mazza E, Foster O, Fejerman N. Idiopathic occipital and absence epilepsies appearing in the same children. Pediatr Neurol 2004;30:24-28.
From the *Servicio de Neurologı´a, Hospital Nacional de Pediatrı´a Juan P. Garrahan, Buenos Aires, Argentina; †Servicio de Neurologı´a Infantil, Hospital San Bernardino, Hurlingham, Buenos Aires, Argentina; and ‡Servicio de Neurologı´a, Hospital de Pediatrı´a Dr. H. Notti, Mendoza, Argentina.
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Introduction The latest proposed diagnostic scheme for people with epilepsy, the Classification of Epilepsies and Epileptic Syndromes of the International League Against Epilepsy [1], includes among the idiopathic focal epilepsies in childhood: benign childhood epilepsy with centro-temporal spikes, early-onset benign childhood occipital epilepsy (“Panayiotopoulos type”), and late-onset childhood occipital epilepsy (“Gastaut type”). Childhood occipital epilepsy, as described by Gastaut, [2,3] is rare, of uncertain boundaries, and often of unpredictable prognosis [4]. This Gastaut type of childhood occipital epilepsy is characterized by brief seizures with mainly visual symptoms such as elementary visual hallucinations, illusions, or amaurosis, followed by hemiclonic seizures. Postictal migraine headache occurs in half of the patients [2-4], and age at onset is 8.9 years. The electroencephalograms reveal occipital spike-wave paroxysms that attenuate when the eyes are opened [2-4]. Panayiotopoulos described another, more common, and likely more benign clinical phenotype with occipital spikes [5-7]. The Panayiotopoulos type of benign childhood occipital epilepsy is characterized by uniform clinical and electroencephalographic features, high prevalence, and an excellent prognosis [5-7]. It is defined by a clustering of unusual ictal manifestations and confirmed by the finding of functional occipital spikes on the electroencephalogram in approximately 65%. Thus extraoccipital multifocal epileptiform activity is not rare. The semiology mainly consists of ictal vomiting, deviation of the head and eyes, often with impairment of consciousness and progression into generalized tonic-clonic seizures. Seizures are infrequent and often single. In two-thirds of the cases seizures appear during sleep.
Communications should be addressed to: Dr. Caraballo; Combate de los Pozos 1881.C.P.; 1245, Buenos Aires, Argentina. Received March 13, 2003; accepted June 6, 2003.
© 2004 by Elsevier Inc. All rights reserved. doi:10.1016/S0887-8994(03)00409-0 ● 0887-8994/04/$—see front matter
Childhood absence epilepsy is characterized by an electroclinical pattern of frequent typical absences with bilateral, synchronous and symmetrical spike-wave discharges at a frequency of 3 Hz on the electroencephalogram. Typical absences have also been described associated with epilepsy with myoclonic absences, juvenile absence epilepsy, and juvenile myoclonic epilepsy. We describe the electroclinical features of six patients who presented two types of idiopathic epilepsies (childhood occipital epilepsy and childhood absence epilepsy) either at different times or concomitantly.
Materials and Methods Between February 1990 and December 2001, we undertook a follow-up study of 160 patients with early-onset benign childhood occipital epilepsy Panayiotopoulos type and 35 patients with late-onset childhood occipital epilepsy Gastaut type. In the course of their disease, one patient of the first group and five of the second group also presented typical absences compatible with the diagnosis of childhood absence epilepsy. At the same time, we saw 80 patients with childhood absence epilepsy at our service. Our patients were monitored for 2 to 10 years (mean 6.5 years) with repeated clinical examinations and electroencephalograms during sleep and while awake. Morphology and topography of interictal spikes, and reactivity of spikes or spike-wave paroxysms to eye opening, hyperventilation, and photosensivity were specially looked for. Family and personal histories of epilepsy, febrile seizures, and migraine were analyzed, as well as age at onset, semiology, duration and frequency of the seizures. Brain computed tomographic scans and magnetic resonance imaging were obtained in all cases.
Results Clinical and electroencephalographic features of the six patients with both occipital childhood epilepsy and childhood absence epilepsy were as follows: age at onset of seizures ranged from 4.5 years to 8 years (mean: 5.5 years). There was a family history of epilepsy in three of the cases (two of them were sisters). One of them presented febrile seizures and migraine in one case. One of the patients presented febrile seizures before the onset of childhood occipital epilepsy and childhood absence epilepsy. The patients with Gastaut type childhood occipital epilepsy presented the following ictal manifestations: focal sensory visual seizures in all five children, with positive symptomatology in three and negative in two, followed by hemiclonic seizures in four patients and versive tonic deviation of the eyes in one patient. All of them presented migrainelike episodes. Duration of seizures was between 5 and 15 minutes while awake in five patients, with a frequency of one seizure in 6 months in four patients and one per week in one patient. Two of the cases presented secondary generalized tonic-clonic seizures. The patient with childhood occipital epilepsy of the Panayiotopoulos type had brief and sporadic ictal vomiting followed by oculocephalic deviation during sleep.
The ictal events in childhood absence epilepsy were characterized by typical absences with rhythmic clonic eyelid clonic seizures in four cases, automatisms and atonic components with autonomic signs in two. In three of the six patients, the onset of typical absences was after at least 1 year having had electroclinical characteristics of Gastaut type childhood occipital epilepsy. In the other two patients with Gastaut type childhood occipital epilepsy and in the patient with Panayiotopoulos type childhood occipital epilepsy, both types of epilepsy began at the same time. We did not find any case of childhood occipital epilepsy appearing in children previously having childhood absence epilepsy. The ictal electroencephalographic recordings of the absences were typical in all patients. Ictal occipital seizures were recorded in only two patients. The interictal electroencephalogram while awake indicated bilateral occipital paroxysms with positive reactivity to eye closure in five patients with Gastaut type childhood occipital epilepsy and left occipital spikes in the patient with Panayiotopoulos type childhood occipital epilepsy. All six electroencephalograms indicated activation of occipital paroxysms during sleep. In all cases, typical absences were associated with bilateral synchronous and symmetrical discharges of spike and waves at 3 cycles per second, spontaneously and during hyperventilation. Highest amplitude was focal in the frontal and central regions. The interictal electroencephalogram documented spike and polyspike waves while awake and in stages 1 and 2 of slow sleep. Two children exhibited a posterior symmetrical delta rhythm, sinusoidal activity at 3 cycles per second, blocked by eye opening. Photoparoxysmal response on the electroencephalogram was normal in all patients, and closing of the eyes did not activate absences in any of the children. Neurologic and neuropsychologic examination, brain computed tomographic scans, and magnetic resonance imaging were normal in all cases. The electroclinical features of one patient in our series were remarkable. In this female the onset of seizures was at 6.5 years of age, with visual symptoms followed by migrainelike episodes. At 8 years of age, she continued having the same type of seizures, and typical absences appeared. At that moment, the electroencephalogram indicated ictal activity characterized by irregular bilateral occipital spike and waves during simple visual hallucinations (phosphenes) and oculocephalic deviation followed by diffuse spike-wave activities during typical absences (Fig 1A,B). The same electroencephalographic recording revealed asymmetrical occipital spikes and waves that attenuated when the eyes were opened (Fig 2) and generalized spike and waves discharges during typical absences. Discussion All six patients presented electroclinical features compatible with childhood occipital epilepsy, of Gastaut type in five and of Panayiotopoulos type in one, as well as
Caraballo et al: Idiopathic Epilepsies 25
Figure 1. (A) The ictal electroencephalogram is characterized by irregular bilateral occipital spike-wave discharges during simple visual hallucinations (phosphenes).
childhood absence epilepsy. Three of the children presented both syndromes at the same time, whereas the other three had typical absences after having had seizures and electroencephalograms that were compatible with the diagnosis of childhood occipital epilepsy. Similar isolated cases in series of patients with Gastaut type childhood occipital epilepsy have been reported [3,8]. On the other hand, patients with benign childhood focal epilepsy with centro-temporal spikes may simultaneously display electroencephalographic recordings and clinical phenomena typical of idiopathic generalized epilepsy, such as generalized spike and waves associated with clinical absences [9]. Patients with childhood absence epilepsy with functional benign focal spikes without clinical manifestations have also been described [10]. The concurrence of a clinical or electroencephalographic pattern of two different types of partial idiopathic epilepsies in the same person is well-known [6,11,12]. The occurrence of typical generalized 3 Hz spike-and-wave discharges has led to speculation about a neurobiologic and genetic continuum between childhood absence seizures and benign focal epilepsies [13]. To date, it is still unknown if childhood absence seizures and idiopathic focal epilepsies are distinct in etiology [13]. Heijbel et al. [14] suggested that a common genetic factor may be expressed in different ways as a result of a
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variation in maturation of different parts of the brain. The appearance of posterior delta rhythm, usually as long bursts of high sinusoidal activity at 3 cycles per second, either symmetrical or more often asymmetrical in occipital and occipital-parietal areas, has been reported in patients with childhood absence epilepsy. This electroencephalographic activity is blocked by eye opening. The interictal electroencephalogram in patients with childhood occipital epilepsy demonstrates repetitive occipital paroxysms that are reactive to eye opening. In routine electroencephalograms in an illuminated room, occipital spikes are mainly or exclusively observed when the eyes are closed and are inhibited when the eyes are opened. If occipital spikes or paroxysms persist with eyes opened, these can be eliminated by asking the child to fixate on a visual target (the tip of a pencil will do). In 1998, Panayiotopoulos [15] documented that the effect of eye closing on occipital spikes is caused by the elimination of central vision and fixation, a phenomenon for which he coined the term “fixation-off sensitivity.” Activation and inhibition of the occipital paroxysms is usually immediately or within a second after closing or opening of the eyes. The underlying mechanisms of fixation-off sensitivity are not known. However, they may be related to an abnormality of alpha rhythm generators. In our patients, these electroencephalographic findings sug-
Figure 1. (B) Thirty seconds later, the ictal electroencephalogram reveals bilateral occipital discharges followed by generalized spike-wave activityduring typical absences
gest a possible genetic connection between the two electroencephalographic traits. According to Gastaut [3], in 38% of cases occipital paroxysms are associated with generalized bilaterally synchronous spike and waves or polyspike and waves, characteristic of idiopathic generalized epilepsy or with central or midtemporal spikes characteristic of other types of idiopathic focal epilepsy. In an earlier study, we reported two patients who initially presented with typical clinical and electroencephalographic features of Panayiotopoulos type childhood occipital epilepsy that evolved atypically. This atypical evolution was characterized by negative myoclonus seizures and absences in both patients and behavioral disturbances and aphasia in one of them. The electroencephalogram recorded continuous spike and waves during slow sleep in both patients [16]. An atypical evolution in another patient with Panayiotopoulos type childhood occipital epilepsy has recently been described [17]. Exceptionally, in Gastaut type childhood occipital epilepsy, children may develop status epilepticus and continuous spike and waves during slow sleep [18,19]. This atypical evolution may be due to a secondary bilateral synchrony mechanism, and the electroclinical picture is different from the one presented here. Ictal single-photon emission computed tomography in
absence seizure may reveal the neuronal mechanisms involved, indicating a different origin [20]. The focal seizures and absences may be combined so that when the basal ganglia are activated, focal or generalized seizures may arise, and when the thalami are activated, absence seizures may be triggered [20]. It is noteworthy that in our group of patients with Gastaut type childhood occipital epilepsy, 14% presented typical absences compared with only 0.6% (only one case) in the much larger group with Panayiotopoulos type childhood occipital epilepsy. This finding suggests that childhood absence epilepsy has a closer genetic relationship to Gastaut type childhood occipital epilepsy than to the Panayiotopoulos type. Conclusion Clinical and electroencephalographic findings in our series suggest either a close genetic relationship between Gastaut type childhood occipital epilepsy and childhood absence epilepsy or the existence of a unique marker with variable phenotypes. On the other hand, the appearance of typical childhood absence epilepsy features in 1 of 160 children with childhood occipital epilepsy of the Panayiotopoulos type may be merely coincidental.
Caraballo et al: Idiopathic Epilepsies 27
Figure 2. The interictal electroencephalogram when awake reveals bilateral occipital paroxysms that disappear when eyes are opened. Four seconds later, the electroencephalogram indicates left asymmetric, irregular occipital activity when the patient closes his eyes. References [1] International League Against Epilepsy. A proposed diagnostic scheme for people with epileptic seizures and with epilepsy. Report of the ILAE Task Force on Classification and Terminology. Epilepsia 2001;42:796-803. [2] Gastaut H. A new type of epilepsy: Benign partial epilepsy of childhood with occipital spikes-waves. Clin Electroencephalogr 1982;13: 13-22. [3] Gastaut H. Benign epilepsy of childhood with occipital paroxysms. In: Roger J, Bureau M, Dravet CH, Dreifuss F, Perret A, Wolf P, eds. Epileptic syndromes in infancy, childhood and adolescence, 2nd ed. London, Paris, Sidney: John Libbey, 1992:201-17. [4] Caraballo RH, Cerso´ simo RO, Medina C, Tenembaum S, Fejerman N. Epilepsias parciales idiopa´ ticas con paroxismos occipitales. Rev Neurol (Barc) 1997;25:1052-8. [5] Panayiotopoulos CP. Benign nocturnal childhood occipital epilepsy: A new syndrome with nocturnal seizures, tonic deviation of the eyes, and vomiting. J Child Neurol 1989;4:43-8. [6] Panayiotopoulos CP. Benign childhood partial epilepsies: Benign childhood seizure susceptibility syndrome. J Neurol Neurosurg Psychiatry 1993;56:2-5. [7] Caraballo R, Cerso´ simo R, Medina C, Fejerman N. Panayiotopoulos-type benign childhood occipital epilepsy. A prospective study. Neurology 2000;55:1096-100. [8] Caraballo RH, Cerso´ simo RO, Medina C, Tenembaum SN, Fejerman N. Epilepsias occipitales idiopa´ ticas. Arch Arg Pediatr 1998; 96:169-76. [9] Gambardella A, Aguglia U, Guerrini RM, Morelli F, Le Piane E, Quattrone A. Benign partial epilepsy evolved into absence epilepsy: Report of three cases [Abstract]. Epilepsia 1995;36(Suppl. 3):S200. [10] Dalla Bernardina B, Fontana E, Zullini F, et al. PM absences and rolandic spikes: An occasional association or a genetic relationship? [Abstract]. Epilepsia 1995;36(Suppl. 3):S200. [11] Guerrini R, Bonanni P, Parmeggiani L, Belmonte A. Adoles-
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cent onset of idiopathic photosensitive occipital epilepsy after remission of benign rolandic epilepsy. Epilepsia 1997;38:777-81. [12] Caraballo RH, Cerso´ simo RO, Fejerman N. Idiopathic partial epilepsies with rolandic and occipital spikes appearing in the same children. J Epilepsy 1998;11:261-4. [13] Gelisse P, Genton P, Bureau M, et al. Are there generalised spike waves and typical absences in benign rolandic epilepsy? Brain Dev 1999;21:390-6. [14] Heijbel J, Blom S, Rasmuson M. Benign epilepsy of childhood with centro-temporal EEG foci: A genetic study. Epilepsia 1975;16:28593. [15] Panayiotopoulos CP. Occipital spikes, occipital paroxysms and other EEG findings in children with benign childhood occipital seizures. Occipital spikes in normal children and those without seizures. In: Panayiotopoulos C, ed. Current problems in epilepsy: Vol 15. Benign childhood partial seizures and related epileptic syndromes. London, Paris, Sidney: John Libbey, 1999:173-202. [16] Caraballo RH, Astorino F, Cerso´ simo RO, Soprano AM, Fejerman N. Atypical evolution in childhood epilepsy with occipital paroxysms (Panayiotopoulos type). Epileptic Disord 2001;3:157-62. [17] Ferrie C, Koutroumanidis M, Rowlinson S, Sanders S, Panayiotopoulos C. Atypical evolution of Panayiotopoulos type: A case report. Epileptic Disord 2002;4:35-42. [18] Fejerman N, Tenembaum S, Medina C, Caraballo R, Soprano AM. Continuous spike-waves during slow-wave sleep and awake in a case of childhood epilepsy with occipital paroxysms [Abstract]. Epilepsia 1991;32:16. [19] Tenembaum S, Deonna TW, Fejerman N, Medina C, IngvarMaeder M, Gubser-Mercati D. Continuous spike-waves and dementia in childhood epilepsy with occipital paroxysms. J Epilepsy 1991;10:139-45. [20] Iannetti P, Spalice A, De Luca F, et al. Ictal single photon emission computed tomography in absence seizures: Apparent implication of different neuronal mechanisms. J Child Neurol 2001;16:339-44.
From the *Servicio de Neurologı´a, Hospital Nacional de Pediatrı´a Juan P. Garrahan, Buenos Aires, Argentina; †Servicio de Neurologı´a Infantil, Hospital San Bernardino, Hurlingham, Buenos Aires, Argentina; and ‡Servicio de Neurologı´a, Hospital de Pediatrı´a Dr. H. Notti, Mendoza, Argentina.
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Introduction The latest proposed diagnostic scheme for people with epilepsy, the Classification of Epilepsies and Epileptic Syndromes of the International League Against Epilepsy [1], includes among the idiopathic focal epilepsies in childhood: benign childhood epilepsy with centro-temporal spikes, early-onset benign childhood occipital epilepsy (“Panayiotopoulos type”), and late-onset childhood occipital epilepsy (“Gastaut type”). Childhood occipital epilepsy, as described by Gastaut, [2,3] is rare, of uncertain boundaries, and often of unpredictable prognosis [4]. This Gastaut type of childhood occipital epilepsy is characterized by brief seizures with mainly visual symptoms such as elementary visual hallucinations, illusions, or amaurosis, followed by hemiclonic seizures. Postictal migraine headache occurs in half of the patients [2-4], and age at onset is 8.9 years. The electroencephalograms reveal occipital spike-wave paroxysms that attenuate when the eyes are opened [2-4]. Panayiotopoulos described another, more common, and likely more benign clinical phenotype with occipital spikes [5-7]. The Panayiotopoulos type of benign childhood occipital epilepsy is characterized by uniform clinical and electroencephalographic features, high prevalence, and an excellent prognosis [5-7]. It is defined by a clustering of unusual ictal manifestations and confirmed by the finding of functional occipital spikes on the electroencephalogram in approximately 65%. Thus extraoccipital multifocal epileptiform activity is not rare. The semiology mainly consists of ictal vomiting, deviation of the head and eyes, often with impairment of consciousness and progression into generalized tonic-clonic seizures. Seizures are infrequent and often single. In two-thirds of the cases seizures appear during sleep.
Communications should be addressed to: Dr. Caraballo; Combate de los Pozos 1881.C.P.; 1245, Buenos Aires, Argentina. Received March 13, 2003; accepted June 6, 2003.
© 2004 by Elsevier Inc. All rights reserved. doi:10.1016/S0887-8994(03)00409-0 ● 0887-8994/04/$—see front matter
Childhood absence epilepsy is characterized by an electroclinical pattern of frequent typical absences with bilateral, synchronous and symmetrical spike-wave discharges at a frequency of 3 Hz on the electroencephalogram. Typical absences have also been described associated with epilepsy with myoclonic absences, juvenile absence epilepsy, and juvenile myoclonic epilepsy. We describe the electroclinical features of six patients who presented two types of idiopathic epilepsies (childhood occipital epilepsy and childhood absence epilepsy) either at different times or concomitantly.
Materials and Methods Between February 1990 and December 2001, we undertook a follow-up study of 160 patients with early-onset benign childhood occipital epilepsy Panayiotopoulos type and 35 patients with late-onset childhood occipital epilepsy Gastaut type. In the course of their disease, one patient of the first group and five of the second group also presented typical absences compatible with the diagnosis of childhood absence epilepsy. At the same time, we saw 80 patients with childhood absence epilepsy at our service. Our patients were monitored for 2 to 10 years (mean 6.5 years) with repeated clinical examinations and electroencephalograms during sleep and while awake. Morphology and topography of interictal spikes, and reactivity of spikes or spike-wave paroxysms to eye opening, hyperventilation, and photosensivity were specially looked for. Family and personal histories of epilepsy, febrile seizures, and migraine were analyzed, as well as age at onset, semiology, duration and frequency of the seizures. Brain computed tomographic scans and magnetic resonance imaging were obtained in all cases.
Results Clinical and electroencephalographic features of the six patients with both occipital childhood epilepsy and childhood absence epilepsy were as follows: age at onset of seizures ranged from 4.5 years to 8 years (mean: 5.5 years). There was a family history of epilepsy in three of the cases (two of them were sisters). One of them presented febrile seizures and migraine in one case. One of the patients presented febrile seizures before the onset of childhood occipital epilepsy and childhood absence epilepsy. The patients with Gastaut type childhood occipital epilepsy presented the following ictal manifestations: focal sensory visual seizures in all five children, with positive symptomatology in three and negative in two, followed by hemiclonic seizures in four patients and versive tonic deviation of the eyes in one patient. All of them presented migrainelike episodes. Duration of seizures was between 5 and 15 minutes while awake in five patients, with a frequency of one seizure in 6 months in four patients and one per week in one patient. Two of the cases presented secondary generalized tonic-clonic seizures. The patient with childhood occipital epilepsy of the Panayiotopoulos type had brief and sporadic ictal vomiting followed by oculocephalic deviation during sleep.
The ictal events in childhood absence epilepsy were characterized by typical absences with rhythmic clonic eyelid clonic seizures in four cases, automatisms and atonic components with autonomic signs in two. In three of the six patients, the onset of typical absences was after at least 1 year having had electroclinical characteristics of Gastaut type childhood occipital epilepsy. In the other two patients with Gastaut type childhood occipital epilepsy and in the patient with Panayiotopoulos type childhood occipital epilepsy, both types of epilepsy began at the same time. We did not find any case of childhood occipital epilepsy appearing in children previously having childhood absence epilepsy. The ictal electroencephalographic recordings of the absences were typical in all patients. Ictal occipital seizures were recorded in only two patients. The interictal electroencephalogram while awake indicated bilateral occipital paroxysms with positive reactivity to eye closure in five patients with Gastaut type childhood occipital epilepsy and left occipital spikes in the patient with Panayiotopoulos type childhood occipital epilepsy. All six electroencephalograms indicated activation of occipital paroxysms during sleep. In all cases, typical absences were associated with bilateral synchronous and symmetrical discharges of spike and waves at 3 cycles per second, spontaneously and during hyperventilation. Highest amplitude was focal in the frontal and central regions. The interictal electroencephalogram documented spike and polyspike waves while awake and in stages 1 and 2 of slow sleep. Two children exhibited a posterior symmetrical delta rhythm, sinusoidal activity at 3 cycles per second, blocked by eye opening. Photoparoxysmal response on the electroencephalogram was normal in all patients, and closing of the eyes did not activate absences in any of the children. Neurologic and neuropsychologic examination, brain computed tomographic scans, and magnetic resonance imaging were normal in all cases. The electroclinical features of one patient in our series were remarkable. In this female the onset of seizures was at 6.5 years of age, with visual symptoms followed by migrainelike episodes. At 8 years of age, she continued having the same type of seizures, and typical absences appeared. At that moment, the electroencephalogram indicated ictal activity characterized by irregular bilateral occipital spike and waves during simple visual hallucinations (phosphenes) and oculocephalic deviation followed by diffuse spike-wave activities during typical absences (Fig 1A,B). The same electroencephalographic recording revealed asymmetrical occipital spikes and waves that attenuated when the eyes were opened (Fig 2) and generalized spike and waves discharges during typical absences. Discussion All six patients presented electroclinical features compatible with childhood occipital epilepsy, of Gastaut type in five and of Panayiotopoulos type in one, as well as
Caraballo et al: Idiopathic Epilepsies 25
Figure 1. (A) The ictal electroencephalogram is characterized by irregular bilateral occipital spike-wave discharges during simple visual hallucinations (phosphenes).
childhood absence epilepsy. Three of the children presented both syndromes at the same time, whereas the other three had typical absences after having had seizures and electroencephalograms that were compatible with the diagnosis of childhood occipital epilepsy. Similar isolated cases in series of patients with Gastaut type childhood occipital epilepsy have been reported [3,8]. On the other hand, patients with benign childhood focal epilepsy with centro-temporal spikes may simultaneously display electroencephalographic recordings and clinical phenomena typical of idiopathic generalized epilepsy, such as generalized spike and waves associated with clinical absences [9]. Patients with childhood absence epilepsy with functional benign focal spikes without clinical manifestations have also been described [10]. The concurrence of a clinical or electroencephalographic pattern of two different types of partial idiopathic epilepsies in the same person is well-known [6,11,12]. The occurrence of typical generalized 3 Hz spike-and-wave discharges has led to speculation about a neurobiologic and genetic continuum between childhood absence seizures and benign focal epilepsies [13]. To date, it is still unknown if childhood absence seizures and idiopathic focal epilepsies are distinct in etiology [13]. Heijbel et al. [14] suggested that a common genetic factor may be expressed in different ways as a result of a
26
PEDIATRIC NEUROLOGY
Vol. 30 No. 1
variation in maturation of different parts of the brain. The appearance of posterior delta rhythm, usually as long bursts of high sinusoidal activity at 3 cycles per second, either symmetrical or more often asymmetrical in occipital and occipital-parietal areas, has been reported in patients with childhood absence epilepsy. This electroencephalographic activity is blocked by eye opening. The interictal electroencephalogram in patients with childhood occipital epilepsy demonstrates repetitive occipital paroxysms that are reactive to eye opening. In routine electroencephalograms in an illuminated room, occipital spikes are mainly or exclusively observed when the eyes are closed and are inhibited when the eyes are opened. If occipital spikes or paroxysms persist with eyes opened, these can be eliminated by asking the child to fixate on a visual target (the tip of a pencil will do). In 1998, Panayiotopoulos [15] documented that the effect of eye closing on occipital spikes is caused by the elimination of central vision and fixation, a phenomenon for which he coined the term “fixation-off sensitivity.” Activation and inhibition of the occipital paroxysms is usually immediately or within a second after closing or opening of the eyes. The underlying mechanisms of fixation-off sensitivity are not known. However, they may be related to an abnormality of alpha rhythm generators. In our patients, these electroencephalographic findings sug-
Figure 1. (B) Thirty seconds later, the ictal electroencephalogram reveals bilateral occipital discharges followed by generalized spike-wave activityduring typical absences
gest a possible genetic connection between the two electroencephalographic traits. According to Gastaut [3], in 38% of cases occipital paroxysms are associated with generalized bilaterally synchronous spike and waves or polyspike and waves, characteristic of idiopathic generalized epilepsy or with central or midtemporal spikes characteristic of other types of idiopathic focal epilepsy. In an earlier study, we reported two patients who initially presented with typical clinical and electroencephalographic features of Panayiotopoulos type childhood occipital epilepsy that evolved atypically. This atypical evolution was characterized by negative myoclonus seizures and absences in both patients and behavioral disturbances and aphasia in one of them. The electroencephalogram recorded continuous spike and waves during slow sleep in both patients [16]. An atypical evolution in another patient with Panayiotopoulos type childhood occipital epilepsy has recently been described [17]. Exceptionally, in Gastaut type childhood occipital epilepsy, children may develop status epilepticus and continuous spike and waves during slow sleep [18,19]. This atypical evolution may be due to a secondary bilateral synchrony mechanism, and the electroclinical picture is different from the one presented here. Ictal single-photon emission computed tomography in
absence seizure may reveal the neuronal mechanisms involved, indicating a different origin [20]. The focal seizures and absences may be combined so that when the basal ganglia are activated, focal or generalized seizures may arise, and when the thalami are activated, absence seizures may be triggered [20]. It is noteworthy that in our group of patients with Gastaut type childhood occipital epilepsy, 14% presented typical absences compared with only 0.6% (only one case) in the much larger group with Panayiotopoulos type childhood occipital epilepsy. This finding suggests that childhood absence epilepsy has a closer genetic relationship to Gastaut type childhood occipital epilepsy than to the Panayiotopoulos type. Conclusion Clinical and electroencephalographic findings in our series suggest either a close genetic relationship between Gastaut type childhood occipital epilepsy and childhood absence epilepsy or the existence of a unique marker with variable phenotypes. On the other hand, the appearance of typical childhood absence epilepsy features in 1 of 160 children with childhood occipital epilepsy of the Panayiotopoulos type may be merely coincidental.
Caraballo et al: Idiopathic Epilepsies 27
Figure 2. The interictal electroencephalogram when awake reveals bilateral occipital paroxysms that disappear when eyes are opened. Four seconds later, the electroencephalogram indicates left asymmetric, irregular occipital activity when the patient closes his eyes. References [1] International League Against Epilepsy. A proposed diagnostic scheme for people with epileptic seizures and with epilepsy. Report of the ILAE Task Force on Classification and Terminology. Epilepsia 2001;42:796-803. [2] Gastaut H. A new type of epilepsy: Benign partial epilepsy of childhood with occipital spikes-waves. Clin Electroencephalogr 1982;13: 13-22. [3] Gastaut H. Benign epilepsy of childhood with occipital paroxysms. In: Roger J, Bureau M, Dravet CH, Dreifuss F, Perret A, Wolf P, eds. Epileptic syndromes in infancy, childhood and adolescence, 2nd ed. London, Paris, Sidney: John Libbey, 1992:201-17. [4] Caraballo RH, Cerso´ simo RO, Medina C, Tenembaum S, Fejerman N. Epilepsias parciales idiopa´ ticas con paroxismos occipitales. Rev Neurol (Barc) 1997;25:1052-8. [5] Panayiotopoulos CP. Benign nocturnal childhood occipital epilepsy: A new syndrome with nocturnal seizures, tonic deviation of the eyes, and vomiting. J Child Neurol 1989;4:43-8. [6] Panayiotopoulos CP. Benign childhood partial epilepsies: Benign childhood seizure susceptibility syndrome. J Neurol Neurosurg Psychiatry 1993;56:2-5. [7] Caraballo R, Cerso´ simo R, Medina C, Fejerman N. Panayiotopoulos-type benign childhood occipital epilepsy. A prospective study. Neurology 2000;55:1096-100. [8] Caraballo RH, Cerso´ simo RO, Medina C, Tenembaum SN, Fejerman N. Epilepsias occipitales idiopa´ ticas. Arch Arg Pediatr 1998; 96:169-76. [9] Gambardella A, Aguglia U, Guerrini RM, Morelli F, Le Piane E, Quattrone A. Benign partial epilepsy evolved into absence epilepsy: Report of three cases [Abstract]. Epilepsia 1995;36(Suppl. 3):S200. [10] Dalla Bernardina B, Fontana E, Zullini F, et al. PM absences and rolandic spikes: An occasional association or a genetic relationship? [Abstract]. Epilepsia 1995;36(Suppl. 3):S200. [11] Guerrini R, Bonanni P, Parmeggiani L, Belmonte A. Adoles-
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