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Atypical evolution in childhood epilepsy with occipital paroxysms (Panayiotopoulos type) Volume 3, issue 3, September 2001

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Benign epilepsy of childhood with rolandic spikes (BECRS), and childhood epilepsy with occipital paroxysms were the only benign, childhood, partial epilepsies recognized in the 1989 ILAE's Commission on classification and terminology [1].

Childhood epilepsy with occipital paroxysms (CEOP), 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, illusion or amaurosis, followed by hemiclonic convulsions. Postictal migraine headache occurs in half of the patients [1-4]. Age at onset is around 8-9 years. EEG shows occipital spike-wave paroxysms that attenuate when the eyes are opened [1-4]. Panayiotopoulos described another, more common and probably more benign, clinical phenotype with occipital spikes [5, 6] confirmed in recent independent studies [7-19]. The "Panayiotopoulos type" of benign occipital epilepsy of childhood, is characterized by uniform clinical and EEG features, high prevalence and an excellent prognosis [5-19]. It is defined by a clustering of unusual ictal manifestations and often confirmed with the finding of occipital functional spikes at the EEG. The semeiology mainly consists of ictal vomiting, deviation of the head and eyes often with impairment of consciousness, and progression into generalized tonic-clonic convulsions. Seizures are infrequent and often solitary. Two thirds are nocturnal.

Partial status epilepticus occurs in more than one third of the children. Peak age at onset is 5 years, and seizures remit within one to two years.

Atypical evolution of BECRS has been frequently recognized [4, 11, 20, 21] and includes prolonged periods with atonic or inhibitory attacks [22], episodes of clinical and EEG status of BECRS [23] or evolution into two other recognized syndromes such as

Landau-Kleffner syndrome (LKS) and the syndrome of continuous spike-waves during slow sleep (CSWSS) [20, 24-26]. In fact, the two latter atypical evolutions may be severe enough to represent a high risk of persistent neuropsychological and language dysfunction.

Two patients with dementia associated with continuous spike-waves on the EEG during the course of the "Gastaut type" of CEOP have already been reported [27, 28], one of them with neuropsychological sequelae.

We present the first two cases with the "Panayiotopoulos type" of CEOP showing atypical evolution.

Case report 1

An 8 year-old, right-handed girl, whose parents were in good health and nonconsanguineous. Personal and family history were unremarkable. At age 2.5 years, she presented, during nocturnal sleep, a ten minute episode of eye and head deviation to the right, followed by vomiting. The EEG showed left occipital spikes during wakefulness and sleep. Physical and fundus examinations were normal, no focal neurological signs were found, and routine laboratory investigations, as well as brain CT scan and MRI were normal.

Phenobarbital (PB) was prescribed, at a dose of 45 mg/day, with a blood level within the so-called therapeutic range. At age 3 years, she had seizures with similar ictal symptomatology on awakening, followed by secondary generalization. Treatment with sodium valproate, 30 mg/kg/day, was started. Six months later the child began to have frequent atypical absences, myoclonus and "inhibitory" seizures with gait difficulties and frequent drops. EEG showed continuous spike-waves during slow sleep (CSWSS). She was given different antiepileptic drugs, but control of seizures was incomplete over the next 18 months.

At the age of 4.5 years, she developed aphasia, and behavioral disturbances. Interictal waking EEG showed frequent bilateral spike-waves and CSWSS during sleep (figure 1). AED were discontinued and she was admitted to hospital for steroid treatment (Prednisolone 1 mg/kg/day), associated with 0.5 mg/kg/day of diazepam. She was discharged on lamotrigine, and oral steroid treatment was maintained for the next three months. Following this she remained almost seizure-free. In the following months, a clear improvement in behavior and language was noted. At her last examination, at age 8 years, although seizure-free, she presented moderate mental retardation and dysphasia (figure 2).

Case report 2

A nine year old girl, whose sister had a history of febrile convulsions. Pregnancy and delivery were normal, as well as the child's early development. Two simple febrile convulsions occurred during her second year of life. At age 4 years, she presented an episode of ictal vomiting and left oculocephalic deviation, followed by a generalized tonic-clonic seizure during sleep. Interictal awake and sleep EEG showed bilateral occipital spikes with right predominance. Neurological examination and routine laboratory investigations were normal. Brain CT scan and MRI were normal. Carbamazepine (CBZ), 15 mg/kg/day was prescribed. Between the age of 4 and 7 years, the child presented similar types of seizures every three months. CBZ was discontinued. Firstly, phenobarbital and then sodium valproate was added, but control of seizures was incomplete. At age 7 years, the number of seizures increased, and frequent "inhibitory" seizures in the lower limbs, causing "pseudoataxic" gait, appeared. She also had behavioral disturbances. The interictal EEG showed frequent bilateral spikes predominating in the posterior regions during wakefulness and CSWSS (figure 3). These seizures were refractory to treatment with sodium valproate and clobazam despite blood levels within the so-called therapeutic range.

At age 7.5 years, the child presented with the same electro-clinical picture. Ethosuximide was added and 15 days later the seizures disappeared. Her EEG showed only bilateral occipital spikes. She is now 9 years old and has been seizure-free for 18 months. She is attending a normal school. The last EEG showed right occipital spikes.

Discussion

We report two patients who initially presented with typical clinical and EEG features of CEOP (Panayiotopoulos type). In the course of the disease, one child showed serious manifestations with impairment of motor, language and cognitive functions as well as behavioral disturbances. The other child showed mild impairment of motor functions and behavior that affected her quality of life. Our first case had electroclinical features similar to the cases described by Fejerman et al. [20] as mixed atypical evolution and epilepsy with CSWSS, while the second child showed electro-clinical features similar to the cases described by Aicardi and Chevrie [22] as atypical benign partial epilepsy of childhood.

Of 120 children with CEOP of the "Panayiotopoulos type" seen at our hospital, two had an atypical evolution. Panayiotopoulos-type CEOP may also manifest with symptoms of rolandic seizures simultaneously or after remission of occipital seizures [4, 5, 11, 13, 15, 29]. Centrotemporal spikes are frequently recorded with occipital spikes in the same or subsequent EEG. Such findings may favor the unifying concept of a benign childhood seizure susceptibility syndrome [4, 12, 30] and explain the possibility that patients with Panayiotopoulos type CEOP may also present with an atypical evolution.

Atypical evolutions of BECRS are well known [20, 31]. Exceptionally in the Gastaut type of CEOP, some children may develop status epilepticus manifested with severe behavioral problems, cognitive deterioration, and continuous spike-wave discharges during slow sleep [27, 28]. So far, a similar evolution has not been reported in patients with Panayiotopoulos-type CEOP.

The mechanisms underlying the phenomenon of electrical status epilepticus during sleep are yet not well understood. Because immature nervous systems have a tendency to develop status epilepticus, non-convulsive status could be induced by an epileptic focus during the age-related hypersynchronizing function of non-rapid eye movement sleep [32, 33].

Language, neuropsychological, and mental disturbances are considered as part of epilepsy with CSWSS and are thought to be related to the EEG activity [34]. Thus the recoveries observed when CSWSS stop, either spontaneously or as a response to treatment, have been interpreted as a demonstration of the strict relationship between the syndrome's particular EEG features and the clinical phenomena [35].

We may hypothesize then that whereas these evolutions may share certain common pathophysiological features, they differ on other key aspects, such as the localization of spikes. This "hereditary impairment of brain maturation", as it has been called by Doose and Baier [36], is quite similar to the concept of the "genetically determined, mild and reversible, functional derangement of the brain cortical maturational process" recently envisaged by Panayiotopoulos [4].

Several, electroclinically-atypical evolutions associated with benign focal epilepsies in childhood have been described (table I) [37, 38]. According to our experience, the morphology and distribution of interictal or ictal EEG paroxysms are similar in the different groups. Definite clues allowing prediction of atypical evolution are not available.

The syndrome of CSWSS is the best example of the relationship between epilepsy, behavior and cognitive dysfunction [22, 23, 39, 40]. Continuous epileptic discharges are not the only cause of deterioration of mental functions; short-lasting, subclinical epileptiform EEG discharges, can also influence cognitive performance in children [41, 42].

Continuous epileptic discharges may affect the brain due to chronic increased release of excitatory amino acids and activation of NMDA receptors resulting in the influx of calcium to the neuronal cytoplasm. This could lead to a neurochemical cascade of destructive events [43]. It must also be borne in mind that the occurrence of epilepsy during the period when the neuronal network is developing is likely to produce much greater disorganization than after the network has been organized [44].

Concerning our patients, the first girl was left with moderate mental retardation and dysphasia, as seen in patients with the syndrome of CSWSS or with the mixed evolutions described by Fejerman et al. [20]. Following control of seizures and improvement of EEG recordings, the second child showed restoration of behavior, motor and intellectual functions, thus presenting with an evolution similar to that which is observed in most cases of atypical benign partial epilepsy of childhood [22]. To our knowledge, no other case of typical childhood epilepsy with occipital spikes (Panayiotopoulos type), with an atypical evolution has been reported in the literature. Although the great majority of typical cases shows an excellent evolution, the cases reported here suggest that a less benign course may be rarely observed.

  Received May 10, 2001 - Accepted August 16, 2001