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Current thumbnail: Late onset childhood occipital epilepsy is an idiopathic form of epilepsy, which manifests with frequent visual seizures of elementary visual hallucinations, blindness or both. Interictal EEG commonly shows occipital spikes or occipital paroxysms that are activated by the elimination of fixation and central vision (fixation-off sensitivity). The syndrome is often misdiagnosed as basilar migraine or migraine with visual aura. Conversely, lesional epilepsies may imitate late onset childhood occipital epilepsy. Prognosis is usually good with remission of seizures and normalization of the EEG by late teens. In this update, C P Panayiotopoulos MD PhD FRCP, Consultant Emeritus, Department of Clinical Neurophysiology and Epilepsies, St. Thomas’ hospital, London details recent developments in late onset childhood occipital epilepsy and he provides clues for its proper differential diagnosis in relation to migraine and lesional occipital epilepsies.

HISTORICAL NOTE AND NONMENCLATURE
Gibbs and Gibbs documented that EEG “seizure foci in one or both occipital lobes are most commonly found in young children. Occipital foci tend to disappear in adult life, and the subsidence of the electroencephalographic abnormality is usually accompanied by a cessation of seizures” (Gibbs and Gibbs 1952). Peak age at first discovery of occipital foci was 4 years to 5 years, and they could occur in children without seizures. Gibbs and Gibbs also described an 8.5-year-old boy with “onset of attacks 2 months before the recording, consisting of blindness, followed by holding both hands to eyes, rolling up of eyes, and loss of consciousness. . . severe headache after attack. . . no convulsions at any time” (Gibbs and Gibbs 1952). EEG showed independent bilateral occipital spikes. Although similar cases were later reported by other authors, the recognition of late onset childhood occipital epilepsy was delayed. This was motivated by a report by Camfield and colleagues of 4 adolescents with EEG occipital paroxysms on closed eyes whose clinical features were interpreted as basilar migraine causing seizures (Camfield et al 1978). Panayiotopoulos questioned the diagnosis of basilar migraine and reported 4 children with occipital paroxysms activated by elimination of central vision and fixation (fixation-off sensitivity); 2 of them had what is now known as Panayiotopoulos syndrome, one had what is now known as Gastaut-type idiopathic occipital lobe epilepsy, and one had symptomatic occipital epilepsy (Panayiotopoulos 1980; 1981).|{video:CEOP3.avi}{caption:Occipital paroxysms activated by elimination of central vision and fixation}{label:Occipital paroxysms occur as soon and last as long as fixation and central vision are eliminated by any means. These are shown and may be (a) eyes closed in a lit room, (b) covering ordinary commercial underwater goggles with semitransparent tape, and (c) glasses with lenses that prohibit fixation.}||{diagram:CEOP1a.bmp}{caption:EEG of occipital paroxysms with eyes open and closed in a lit room}{label:Occipital paroxysms occur as long as fixation and central vision are eliminated by any means. Under these conditions, even in the presence of light, eyes open are not capable of inhibition. Symbols of eyes open and closed without glasses denote that fixation is possible.}||{diagram:CEOP1b.bmp}{caption:EEG of occipital paroxysms with eyes open and closed in total darkness}{label:Occipital paroxysms occur as long as fixation and central vision are eliminated by any means. Occipital paroxysms are totally inhibited by fixation and central vision. Symbols of eyes with glasses indicate elimination of central vision and fixation by complete darkness.}||{diagram:CEOP1c.bmp}{caption:EEG of occipital paroxysms with fixation on and off with eyes open}{label:Occipital paroxysms occur as long as fixation and central vision are eliminated by any means. Occipital paroxysms are totally inhibited by fixation and central vision. Symbols of eyes with glasses indicate elimination of central vision and fixation by means other than complete darkness.}|Subsequently, Gastaut retrospectively identified 36 patients with occipital paroxysms and widely reported them as “a new type of epilepsy: benign partial epilepsy of childhood with occipital spike-waves” (Gastaut 1982; Gastaut and Zifkin 1987). Fejerman and colleagues proposed to designate late onset childhood occipital epilepsy as the “Gastaut type of benign childhood occipital epilepsy” in order to distinguish it from the “Panayiotopoulos type of early onset benign childhood occipital epilepsy” (Fejerman 1996; Caraballo et al 1997). The latter is a variant of what is now known as “Panayiotopoulos syndrome” which includes children with occipital and extra-occipital spikes (Ferrie and Grunewald 2001; Koutroumanidis 2002; Lada et al 2003; Covanis et al 2003; Panayiotopoulos 2000; 2005b).

The new classification scheme of the ILAE Task Force recognizes this syndrome as “late onset childhood occipital epilepsy (Gastaut type)” (Engel 2001).

CLINICAL MANIFESTATIONS
Visual seizures are the cardinal symptoms of idiopathic childhood occipital epilepsy. They predominantly manifest with elementary visual hallucinations, blindness, or both. They are usually frequent and diurnal, and they usually last from seconds to 1 to 3 minutes. Elementary visual hallucinations are the most common and most characteristic ictal symptom. They are often the first, and frequently the only, seizure clinical manifestation, which may progress and coexist with other occipital symptoms such as sensory illusions of ocular movements and ocular pain, tonic deviation of the eyes, eyelid fluttering, or repetitive eye closures. Complex visual hallucinations, visual illusions, and other symptoms from more anterior ictal spreading rarely occur ab initio, or from seizure progress that may terminate with hemiconvulsions or generalized convulsions. Ictal blindness, appearing ab initio or, less commonly, after other occipital seizure manifestations, usually lasts for 3 minutes to 5 minutes. Spreading to symptoms of temporal lobe involvement is exceptional and may indicate a symptomatic cause. Consciousness is intact during the visual symptoms but may be disturbed or lost if the seizures progress to other symptoms and convulsions. Postictal headache, sometimes indistinguishable from migraine headache, often occurs in one-third of the patients. Headache, mainly orbital, may occasionally be ictal.

Visual seizures.

Visual hallucinations and blindness. Visual seizures are the most typical and usually the first ictal symptom (Panayiotopoulos 1980; 1981;1999; 2005a; Gastaut 1982; Gastaut and Zifkin 1987).
Elementary visual hallucinations occur as an initial seizure symptom in probably more than two-thirds of patients. They are mainly brief, developing fast, lasting for 5 seconds to 15 seconds, and seldom exceeding 1 minute to 2 minutes if they occur alone without other occipital or extra-occipital spreading. Rarely, they may last 15 minutes to 20 minutes or longer. The various components of the elementary visual hallucinations have been detailed by Panayiotopoulos in a prospective quantitative and qualitative analysis (Panayiotopoulos 1999). They are usually multicolored and circular, appearing either in the periphery of a hemifield or centrally; they may multiply in number or size, or both; they may move horizontally to the other side; and they may be flashing or static.|{picture:ceocp2.bmp}{caption:Elementary visual hallucinations in late onset childhood occipital epilepsy}{label:Elementary visual hallucinations as illustrated by three patients with the complete clinical and EEG features of late onset childhood occipital epilepsy. Note that the visual hallucinations are predominantly multicolored and circular.}|They may be the only ictal manifestations, or progress to other seizure symptoms. For every patient, in every seizure the elementary visual hallucinations have a fingerprint with a stereotypic appearance regarding morphology, colors, location, movement, and other specific features. Patients also know at what stage of their visual hallucinations progression to secondary generalization is likely to occur. This visual ictal symptomatology, considering all its components together, is markedly different from migraine visual aura (Panayiotopoulos 1999; 2005a; 2005b).

Complex visual hallucinations and visual illusions. Complex visual hallucinations are much rarer, probably occurring in less than 10% of the patients and usually emerging from elementary visual hallucinations. These patients usually see the form of a face or figures, which may have the same location and movement sequence as that of the elementary visual hallucinations. They do not have the same emotional or other characteristics as those associated with temporal lobe semiology.
Ictal visual illusions such as micropsia, metamorphopsia, and palinopsia are most likely generated from the nondominant parietal regions (Gastaut and Zifkin 1987; Panayiotopoulos 2005a; 2005b). They are extremely rare and are probably associated with symptomatic-only occipital seizures (Panayiotopoulos 1999; 2005b).

Blindness or partial visual loss. Blindness is probably as common an ictal symptom as elementary visual hallucinations. It can occur alone and can be the only ictal event in patients that may, in other times, have visual hallucinations without blindness (Panayiotopoulos 1980; 1981; 1999; 2005a; Gastaut 1982; Gastaut and Zifkin 1987; Shahar and Barak 2003). Blindness is sudden and total, and on average it lasts longer than the visual hallucinations, usually 2 minutes to 5 minutes, if alone. Post-ictal blindness, hemianopia, and other partial visual loss is well established after visual seizures, with or without secondarily generalization.

Sensory hallucinations of ocular movements and pain. A sensation of ocular movement in the absence of detectable motion is a rare occurrence and mainly occurs as a progression of elementary visual hallucinations (Panayiotopoulos 1999; 2002; 2005a; 2005b).

Nonvisual ictal symptoms.

Deviation of the eyes and oculoclonic seizures. Deviation of the eyes, usually following elementary visual hallucinations and often associated with ipsilateral turning of the head, is the most common (around 70%) nonvisual symptom (Gastaut 1982; Gastaut and Zifkin 1987; Panayiotopoulos 2005a; 2005b). This focal motor seizure usually starts after visual hallucinations, but may also occur while the hallucinations still persist. It may be mild, but more often it is severe and progresses to hemiconvulsions and generalized tonic clonic seizures (GTCS) (Panayiotopoulos 1999; 2005a; 2005b). That children with benign occipital seizures may have motor focal seizures ab initio is well established (Beaumanoir 1983). It is likely that these cases have a better prognosis and shorter seizure life span from those of Gastaut-type childhood occipital epilepsy, but this likelihood has not yet been properly examined.

Forced eyelid closure and eyelid blinking. Forced eyelid closure and eyelid blinking, an interesting ictal clinical symptom of occipital seizures, occur in approximately 10% of patients, usually at a stage in which consciousness is impaired. They signal impending secondarily generalized convulsions (Gastaut 1982; Gastaut and Zifkin 1987; Panayiotopoulos 1999; 2005a; 2005b).

Ictal clinical symptoms from occipital seizure propagation. Elementary visual hallucinations or other ictal symptoms may progress to hemiconvulsions or generalized convulsions. According to Gastaut and Zifkin, visual seizures are often followed by other nonvisual seizure symptoms such as hemiconvulsions (43%), complex focal seizures (14%), dysphasia, dysesthesia, aversive convulsions (25%), and generalized tonic-clonic seizures (13%) (Gastaut and Zifkin 1987). According to Panayiotopoulos, typical complex focal seizures of temporal lobe symptomatology is extremely rare and may indicate a symptomatic cause (Panayiotopoulos 1999; 2005a; 2005b).

Ictal vomiting (ictus emeticus) and ictal syncope. These are the most prominent symptoms in Panayiotopoulos syndrome and are scarce in late onset childhood occipital epilepsy (Ferrie and Grunewald 2001; Koutroumanidis 2002; Panayiotopoulos 2002; 2005b; Lada et al 2003).

Headache. Ictal headache, mainly orbital, is a rare occurrence. However, postictal headache is a consistent symptom in one-third of these children, even without preceding convulsions (Gibbs and Gibbs 1952; Panayiotopoulos 1980; 1999; 2005a; 2005b; Gastaut 1982; Gastaut and Zifkin 1987). This occurs immediately, or 5 minutes to 10 minutes after the end of the visual hallucinations. The duration and severity of the headache appears to be proportional to the duration and severity of the preceding seizures. The headache may be diffuse and of mild to moderate intensity, but in some patients it is strong and pulsating and may be associated with nausea, vomiting, photophobia, and phonophobia, which may make it indistinguishable from migraine. However, postictal headache is also common in other cryptogenic or symptomatic occipital seizures (Panayiotopoulos 1999; 2005a; 2005b).

Impairment of consciousness. Visual seizures, even the prolonged ones, are simple and are clearly described by the patients. Impairment of consciousness usually occurs at the onset of other manifestations following the visual hallucinations or blindness. In some cases, loss of consciousness associated with falls may occur independently and without convulsions (ictal syncope) (Panayiotopoulos 1999; 2005a; 2005b).

Circadian distribution. Visual seizures are predominantly diurnal and occur at any time of the day. Longer seizures, with or without secondarily hemiconvulsions or generalized convulsions tend to occur either during sleep, causing the patient to wake, or after awakening. Thus, some children may have numerous diurnal visual seizures and only a few exclusively nocturnal or on awakening secondarily GTCS.

Precipitating factors and idiopathic photosensitive occipital epilepsy. This is a matter of inclusion criteria. The new ILAE Diagnostic Scheme recognizes “idiopathic photosensitive occipital lobe epilepsy” as a new syndrome of reflex epilepsy with age-related onset (Engel 2001). However, its boundaries are uncertain: (a) Gastaut and Zifkin consider photosensitivity as part of the Gastaut type childhood occipital epilepsy (Gastaut and Zifkin 1987), (b) photosensitive occipital seizures may start in adulthood, develop later in children with Rolandic seizures (Panayiotopoulos 1999) or occur accidentally during intermittent photic stimulation of normal or migraine subjects (Panayiotopoulos 2002; 2005a; 2005b).

Occipital seizures may be induced by television, video games, and intermittent photic stimulation, and can manifest with multicolored circular visual hallucinations that are often associated with blindness (Aso et al 1987; Michelucci and Tassinari 1993; Guerrini et al 1995; 1998; Panayiotopoulos 1999; 2002; 2005c; Yalcin et al 2000). Tonic deviation of the eyes, epigastric discomfort and vomiting, headache, and generalized convulsions may follow. Duration varies from 2 minutes to 5 minutes or up to 2 hours. Prognosis is uncertain. Some children may have only 1 or 2 seizures, but others may not remit. Interictal EEG shows spontaneous and photically induced occipital spikes. Centrotemporal spikes may coexist. Ictal EEGs documented the occipital origin and the spreading of the discharges to the temporal regions (Guerrini et al 1995; 1998). By excluding patients with idiopathic photosensitive occipital seizures, there are no apparent precipitating factors in Gastaut type childhood occipital epilepsy. Despite EEG fixation-off sensitivity, only a few patients report that clinical seizures are precipitated by going from bright light to darkness or by darkness itself.

Age at onset and sex. Boys and girls are equally affected. The mean age at onset is 8 years of age with a range from 3 years to 16 years. Gastaut and Zifkin report age at onset from 15 months to 19 years, which is outside the boundaries of benign childhood seizure susceptibility syndrome (Gastaut 1982a; 1982b; 1982c; Gastaut and Zifkin 1987).

Frequency of seizures.

In untreated patients, brief visual seizures are frequent, occurring at a frequency of several per day or weekly. However, propagation to other seizure manifestations, such as focal or more generalized convulsions is much less frequent, occurring monthly, yearly, or exceptionally (Panayiotopoulos 1999; 2005a; 2005b).

CLINICAL VIGNETTE

Late onset childhood occipital epilepsy is often misdiagnosed as migraine with aura, acephalgic migraine, basilar migraine, and migralepsy. Case 1 was the first reported case questioning the diagnosis of basilar migraine in favor of occipital epilepsy (Panayiotopoulos 1980; 1981) prior to the reports of Gastaut (Gastaut 1982). However, this case is often erroneously cited as “basilar migraine with occipital paroxysms.”

Case 1. A 31-year-old man had 20 years of regular follow-up exams from age 11 when he first experienced visual seizures. These seizures consisted of brief, elementary visual hallucinations of "millions of small, very bright, colored mainly blue and green, circular spots of light, which appear on the left side and sometimes move to the right." They occurred about once a week, lasted no more than 1 minute, and were not accompanied by altered consciousness, headache, or vomiting. He also had 2 seizures at ages 10 and 11 where his “eyes turned to the right, right arm appeared rigid, and there was loss of consciousness for a few seconds." These were unrelated to any visual disturbances. EEG showed occipital paroxysms with fixation-off sensitivity (Panayiotopoulos 1980; 1981).

Despite phenobarbitone 90 mg daily, visual seizures continued, accompanied by postictal right-sided headaches, and vomiting for 1 or 2 hours. In 2 of these episodes, he was dysphasic, and may have been slightly confused, but could understand conversation. Three other episodes of complete blindness occurred immediately after diving into the sea: "Everything went suddenly black, I could not see and I had to ask other swimmers to show me the direction to the beach." The blindness cleared in 1 minute or 2 minutes and was followed by right-sided headache and vomiting. Only once visual hallucinations preceded blindness. He was treated with cyclohexyl-2-methylamino-propranol-phenylethyl barbiturate, 150 mg daily, and attacks ceased. Subsequently, he had only 3 visual seizures, and at age 16 he awoke from sleep with his habitual visual symptoms, fell asleep again, followed by a left motor focal seizure and a GTCS. The last ever visual seizure, at age 23, occurred during sleep. He awoke with familiar left-sided elementary visual hallucinations that lasted for 20 minutes with no other symptoms. He had unilateral headache and nausea the next morning. At last follow up at age 31, he was well, with no seizures or migraine headache.

Case 2. The next case with visual seizures had only a first EEG at age 10 years, with occipital paroxysms. All subsequent alert and sleep EEG, one 7 days later with no medication, and the others annually from 1990 to 1998, were normal. This indicates that occipital paroxysms may not be found in such cases of late onset childhood occipital epilepsy. This case is also interesting because of brief episodes of falls, with loss of consciousness without convulsions (ictal syncope). More importantly, he demonstrates excellent prognosis that may be related to early initiation of appropriate treatment with carbamazepine.

This 18-year-old normal man at age 10 years had:

(1) Frequent (1 to 3 per week) visual seizures lasting for 10 seconds to 30 seconds. He described them as follows: “It looked like a rectangle filled with colored small circles. This time I saw the colors. They were blue, green, red, and yellow. While I was reading, I started seeing the words stuck all together. I blink a lot to see more clearly. It is a familiar vision, sometimes bright or dark. It replaces, obscures the real images. They are large objects, probably people, which I cannot identify. They are always in my right eye and draw my right eye and my head to the right.”

(2) Brief infrequent seizures of complete blindness without warning or impairment of consciousness.

(3) Four brief (1 to 2 minute) episodes of falling down unresponsive without convulsions. A physician witnessed 1 episode and described him clumsy, vacant, and unresponsive. This type of ictal syncope is more common in Panayiotopoulos syndrome (Koutroumanidis 2002).
No further seizures of any type occurred after treatment with carbamazepine. The treatment was withdrawn 3 years later. At his last follow-up at age 18 years, he was well, had normal EEG and MRI, and was in no need of further treatment.
The next case is to illustrate that this syndrome of idiopathic childhood occipital epilepsy may occur without detectable EEG abnormalities, misdiagnosed as migraine and delayed treatment. Like case 1, visual seizures became longer at a later stage.

Case 3. A normal 18-year-old man had onset of weekly episodes of elementary visual hallucinations at age 8 years. These were brief, lasting 5 seconds to 15 seconds, and consisted of 3 to 4 concentric spherical rings of red and yellow moving from the left to the right visual field, and repeating the same course again after their disappearance on the right. On other occasions, there was only 1 colored ball moving continuously from left to right. The colors were faint at onset, becoming more intense and brilliant as the seizure progressed. There was no impairment of consciousness, convulsions, or headache. The diagnosis of acephalgic migraine was made.

Beginning at age 10 years, on 4 occasions, the same concentric rings were bigger (double in size), followed the same course from left to right, but the duration of the seizure was longer, lasting 1 minute. This is probably associated with left hemianopia. On 3 more occasions, visual seizures were longer, lasting 2 minutes to 3 minutes, followed by left sided deviation of the head, and left hemiconvulsions. At this stage, the diagnosis of occipital lobe seizures was suspected.

No further seizures occurred when carbamazepine 600 mg daily was initiated at age 11 years, except for infrequent, brief, elementary visual hallucinations like those mentioned above, which are more likely to occur after watching television or playing video games for long periods. The longer of the episodes are occasionally followed by diffuse headache of moderate intensity for 10 minutes to 15 minutes, and once he felt sick. At age 17 years, he had 3 visual seizures lasting for nearly an hour each (focal visual status epilepticus). They started with left sided blurring of vision, “whitish like a fog,” together with “small clouds of colors; mainly red,” and mixed with small colored circles. There was no progression to other symptoms, but when the blurring of vision and the visual hallucinations cleared, he had left sided throbbing headache, which started 5 minutes to 7 minutes after the cessation of the seizures, and lasted for half an hour. No further seizures of any type occurred the next year, after increasing carbamazepine to 800 mg daily. Three EEGs, alert and asleep, at the active stage of his seizures, were normal. A high resolution MRI was also normal.

ETIOLOGY

Usually, no family history of similar seizures exists, though in one report a boy and his sister had visual seizures and occipital paroxysms while another asymptomatic brother had centrotemporal spikes in EEG.

There may be an increased family history of epilepsies or migraine in late onset childhood occipital epilepsy. Thus, of 63 heterogeneous patients, 36.6% had a family history of epilepsy, 15.9% of migraine, and 14% of febrile seizures (Gastaut and Zifkin 1987).

PATHOGENESIS AND PATHOPHYSIOLOGY

Late onset childhood occipital epilepsy, and all other syndrome of benign childhood seizure susceptibility, are probably linked together due to a common, genetically determined, mild and reversible, functional derangement of the brain cortical maturational process, which Panayiotopoulos proposed to call “benign childhood seizure susceptibility syndrome” (Panayiotopoulos 2002; 2005a; 2005b). In more than 90% of patients, this is a clinically silent manifestation with EEG sharp and slow waves only. Others may have infrequent focal seizures. EEG and seizure manifestations often follow an age-related localization and prevalence. Thus, this cortical excitability is expressed from the occipital cortex of younger children (5 years old is the peak age of onset), while the centrogyral and neighboring cortex becomes active at a later age (7 years to 9 years old). Centrogyral location is 2.5 times more frequent than occipital location, whereas other cortical areas are less often actively involved. That occipital paroxysms may be bilateral and synchronous can be explained by cortical occipital hyperexcitability, which is driven simultaneously by fixation-off sensitivity (Panayiotopoulos 1981; 2002; 2005a). Conversely, Gastaut and Zifkin hypothesized that the occipital paroxysms are due to a subcortical, thalamocortical, mechanism “in order to explain the rhythmic spike and wave complexes seen with eye closure or intermittent photic stimulation over an intact occipital lobe" (Gastaut and Zifkin 1987).

An association between late onset childhood occipital epilepsy and typical absence seizures in 5 children has been recently reported. Typical absences appeared at the same time as visual seizures (2 patients) or after 1 year (3 patients). All patients had EEG occipital paroxysms and 3 Hz generalised spike-wave discharges (Caraballo et al 2004).

The mechanisms of postictal headache, common even after minor idiopathic or symptomatic visual seizures with or without a predisposition to migraine, are unknown. It is likely that the occipital seizure discharge triggers a genuine migraine headache through trigeminovascular or brain stem mechanisms. This epilepsy-migraine progression is most realistic rather than the popular theme of migraine-epilepsy sequence (Panayiotopoulos 1999; 2005a).

EPIDEMIOLOGY

Late onset childhood occipital epilepsy is rare, with a probable prevalence of 0.2% to 0.9% of all epilepsies and 2% to 7% of benign childhood focal seizures (Panayiotopoulos 1999; 2005a).

PREVENTION

Not applicable.

DIFFERENTIAL DIAGNOSIS

The differential diagnosis of late onset childhood occipital epilepsy is mainly from cryptogenic or symptomatic occipital epilepsy, celiac disease, and migraine with aura, basilar, or acephalgic migraine (Panayiotopoulos 1999; 2005a; 2005b). Symptomatic occipital epilepsy often imitates late onset childhood occipital epilepsy; neuro-ophthalmological examination and brain imaging may be normal requiring high resolution MRI for detection of subtle lesions. Occipital seizures of hyperglycemia, mitochondrial disorders, Lafora disease, and celiac disease should be considered (Panayiotopoulos 2005b).

The differential diagnosis of late onset childhood occipital epilepsy from Panayiotopoulos syndrome is remarkably easy, despite sometimes similar interictal EEG (Panayiotopoulos 2002; 2005a). In Panayiotopoulos syndrome, seizures are rare, usually only 1 to 3 occur, often nocturnally, have a long duration from 5 minutes to 10 minutes to hours, and cardinal ictal symptoms consisting of autonomic and behavioral disturbances, vomiting, and deviation of the eyes. Conversely, in late onset childhood occipital epilepsy, seizures are frequent, sometimes daily, primarily diurnal, have a brief duration from seconds up to 2 minutes, and cardinal ictal symptoms mainly consist of visual seizures. Ictal EEGs are different. Some patients with Panayiotopoulos syndrome may have visual hallucinations. Also, patients with late onset childhood occipital epilepsy often have deviation of the eyes following visual hallucinations. Overlapping ictal symptoms are common in epilepsies, requiring a synthetic quantitative and qualitative approach for their differentiation.

The most frequent misdiagnosis of visual seizures is with migraine with aura, and basilar and acephalgic migraine, but their epileptic nature can not escape clinical scrutiny (Panayiotopoulos 1999; 2005a; 2005b). The differential diagnosis of occipital seizures with elementary visual hallucinations from migraine with aura and basilar migraine have been extensively reported by Panayiotopoulos (Panayiotopoulos 1999; 2005a; 2005b).

DIAGNOSTIC WORKUP

By definition of an idiopathic syndrome, neurologic, mental, and high resolution MRI are normal, though Gastaut and Zifkin included patients with abnormal neurology and brain scans (Gastaut and Zifkin 1987). All patients should have high resolution MRI to exclude static or progressive occipital lesions (Panayiotopoulos 2005a; 2005b).
The EEG shows occipital spikes or occipital paroxysms, with or without fixation-off sensitivity. Occipital paroxysms, in routine recordings, occur when the eyes are closed, because of fixation-off sensitivity.|{video:CEOP3.avi}{caption:Occipital paroxysms activated by elimination of central vision and fixation}{label:Occipital paroxysms occur as soon and last as long as fixation and central vision are eliminated by any means. These are shown and may be (a) eyes closed in a lit room, (b) covering ordinary commercial underwater goggles with semitransparent tape, and (c) glasses with lenses that prohibit fixation.}||{diagram:CEOP1a.bmp}{caption:EEG of occipital paroxysms with eyes open and closed in a lit room}{label:Occipital paroxysms occur as long as fixation and central vision are eliminated by any means. Under these conditions, even in the presence of light, eyes open are not capable of inhibition. Symbols of eyes open and closed without glasses denote that fixation is possible.}||{diagram:CEOP1b.bmp}{caption:EEG of occipital paroxysms with eyes open and closed in total darkness}{label:Occipital paroxysms occur as long as fixation and central vision are eliminated by any means. Occipital paroxysms are totally inhibited by fixation and central vision. Symbols of eyes with glasses indicate elimination of central vision and fixation by complete darkness.}||{diagram:CEOP1c.bmp}{caption:EEG of occipital paroxysms with fixation on and off with eyes open}{label:Occipital paroxysms occur as long as fixation and central vision are eliminated by any means. Occipital paroxysms are totally inhibited by fixation and central vision. Symbols of eyes with glasses indicate elimination of central vision and fixation by means other than complete darkness.}|Random occipital spikes, sometimes occurring only during sleep and normal EEG, are frequent. EEG abnormalities may be disproportional to clinical severity. Age-dependent occipital spikes frequently occur in organic brain diseases with or without seizures, and in children with congenital and early onset visual deficits, or in normal, mainly pre-school age children.
The main contribution in the field of ictal EEG is from Beaumanoir (Beaumanoir 1983; 1993). Simple focal occipital seizures with positive signs are characterized by fast spike activities that, when slowing down, can reach neighboring regions of the scalp. While the amplitude of the ictal activity increases, the frequency of repetition lessens. In oculoclonic seizures, spikes and spike waves are typical of the last part of the discharge. There are usually no postictal abnormalities. Phosphenes are related to the fast spike activity, often quickly involving the two hemispheres; on the contrary, when the discharge is slower, complex hallucinations may take place. In oculoclonic seizures, a localized ictal fast spike rhythm may be observed before the deviation of the eyes (Beaumanoir 1993).

Similar are the results of more recently published ictal EEGs in Gastaut type childhood occipital epilepsy (Panayiotopoulos 2002; 2005a; Thomas et al 2003).

Furthermore, Beaumanoir also concluded that the ictal EEG, during “temporary blindness is characterized by pseudoperiodic slow waves and spikes, which is different from that of positive visual hallucinations.” Beaumanoir also stressed that postictal abnormalities of slow waves may be prolonged in migraine, whereas in occipital seizures, they frequently return quickly to the pre-ictal state.

PROGNOSIS AND COMPLICATION

Prognosis is unclear, though available data may indicate that remission occurs in more than 60% of patients (Gibbs and Gibbs 1952; Gibbs et al 1954; Gastaut and Zifkin 1987).

Uncertainty in prognosis is partly due to undefined boundaries of this syndrome, where symptomatic and generalized epilepsies have been included (Gastaut and Zifkin 1987) in what, by definition, is an idiopathic condition with focal occipital seizures. Furthermore, this syndrome is often misdiagnosed as migraine, resulting in the delay of appropriate antiepileptic medication sometimes for years. In a prospective study of patients with strictly defined idiopathic late onset childhood occipital epilepsy, frequent visual seizures stopped, or dramatically reduced with carbamazepine, which was needed for at least 3 years to 6 years before remission (Panayiotopoulos 1999; 2005a; 2005b). It is possible that delaying appropriate medication with carbamazepine may adversely affect prognosis.
Another concern is from 3 reported cases of late onset childhood occipital epilepsy that developed continuous spike-waves during slow-wave sleep with cognitive deterioration, which may be reversible with appropriate medication (Fejerman 1996; Tenembaum et al 1997).

Gulgonen and colleagues (Gulgonen et al 2000) tested intellectual functioning, attention, memory, academic achievement, visual-motor functioning, and executive functioning in 21 patients with Gastaut type idiopathic occipital lobe epilepsy. There were no significant differences in basic neurophysiological functions between the patient and control groups, although the case patients' performance scores were lower in attention (less than 0.01) and memory (less than 0.01), as well as in intellectual functioning (less than 0.05) (Gulgonen et al 2000).

MANAGEMENT

Unlike Rolandic epilepsy and Panayiotopoulos syndrome that often does not need treatment, Gastaut type childhood occipital epilepsy should be treated because seizures, though brief and mild, are frequent. Secondary generalization is probably unavoidable without medication. All seizures stopped or dramatically reduced within days after appropriate treatment with carbamazepine (Panayiotopoulos 1999; 2005b).

Slow reduction of medication 2 years to 3 years after the last visual or other minor or major seizure may be advised, but if visual seizures reappear, treatment should be restored.

PREGNANCY

Not applicable.

ANESTHESIA

Not applicable.

REFERENCES CITED

Beaumanoir A. Infantile epilepsy with occipital focus and good prognosis. Eur Neurol 1983;22:43-52.

Beaumanoir A. Semiology of occipital seizures in infants and children. In: Andermann F, Beaumanoir A, Mira L, Roger J, Tassinari CA, editors. Occipital seizures and epilepsies in children. London: John Libbey, 1993:71-86.

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ILAE.

ILAE Copyright Notice

ABBREVIATIONS

CT:computed tomography
EEG:electroencephalography
GTCS:generalized tonic clonic seizures
MRI:magnetic resonance imaging

SYNONYMS

Childhood epilepsy with occipital paroxysms
Gastaut type of benign childhood occipital epilepsy
Idiopathic childhood occipital lobe epilepsy
Late onset benign childhood epilepsy with occipital paroxysms
Late onset benign childhood occipital epilepsy

SUBTOPICS

Nonvisual ictal symptoms
Occipital spikes
Visual seizures

MAJOR KEYWORD DESCRIPTIONS

aversive convulsions
benign childhood seizure susceptibility syndrome
complex focal seizures
diurnal occipital seizures
dysesthesia
dysphasia
elementary visual hallucinations
eyelid fluttering
fixation-off sensitivity
Gastaut type
generalized tonic-clonic seizures
hemiconvulsions
nonvisual ictal symptoms
ocular pain
occipital epilepsy
occipital paroxysm
occipital seizures
occipital spikes
partial seizures
postictal migraine
repetitive eye closures
sensory illusions of ocular movements
tonic deviation of the eyes
tonic-clonic seizures
visual hallucinations
visual seizures

MINOR KEYWORD DESCRIPTORS

blindness
convulsions
epilepsy
headaches
impairment of consciousness
migraines
photosensitivity
seizures
spikes

AGE OF PRESENTATION

02-05 years
06-12 years
13-18 years

AGE OF TYPICAL PRESENTATION

06-12 years

POPULATION GROUP(S) PREFERENTIALLY AFFECTED

none selectively affected

OCCUPATION GROUP(S) PREFERENTIALLY AFFECTED

none selectively affected

SEX

male=female

FAMILY HISTORY

family history may be obtained

HEREDITY

heredity may be a factor

ILLUSTRATION CAPTIONS

Fig 1. Title: none
Legend: From video-EEG recording of patient presented in the video clip.
Occipital paroxysms occur as long as fixation and central vision are eliminated by any means (eyes closed, darkness, plus 10 spherical lenses, Ganzfeld stimulation). Under these conditions, even in the presence of light, eyes open are not capable for inhibition. Conversely, occipital paroxysms are totally inhibited by fixation and central vision.
Symbols of eyes open and close without glasses is to denote that fixation is possible (routine EEG recordings in a lit room).
Symbols of eyes with glasses indicate elimination of central vision and fixation, in the middle by complete darkness and in the bottom by other means.

Legend of Fig 2. Elementary visual hallucinations as illustrated by 3 patients with the complete clinical and EEG features of late onset childhood occipital epilepsy.

Left are the visual hallucinations as conceived by the patient detailed by Panayiotopoulos (1980;1981).

Middle are the visual hallucinations of a girl detailed in Panayiotopoulos’ studies (Panayiotopoulos 1989).

Right are the visual hallucinations of the boy presented in the video-clip and detailed as case 2 of clinical vignettes.
Note that the visual hallucinations are predominantly multicolored and circular.

Legend of video clip. Occipital paroxysms occur as soon and last as long as fixation and central vision are eliminated by any means. These are shown and may be (a) eyes closed in a lit room, (b) covering ordinary commercial underwater goggles with semitransparent tape, and (c) glasses with lenses that prohibit fixation.

New figure, LCEP2
Title: Ictal EEG of visual seizures
Caption: Brief visual seizure captured with video-EEG. Note the brief duration of the ictal discharge, which starts with small occipital spikes spreading with fast rhythmic activity.
From Panayiotopoulos 2002a with the permission of the publisher John Libbey

PERMUTATIONS, SYNONYMS, VARIANTS

Late onset childhood occipital epilepsy (Gastaut type)
onset childhood occipital epilepsy (Gastaut type), Late
childhood occipital epilepsy (Gastaut type), Late onset
occipital epilepsy (Gastaut type), Late onset childhood
epilepsy (Gastaut type), Late onset childhood occipital
(Gastaut type), Late onset childhood occipital epilepsy

RELATED TOPICS

Early onset benign childhood seizures with occipital spikes (Panayiotopoulos syndrome)
Idiopathic photosensitive occipital lobe epilepsy
Migraine aura without headache

DIFFERENTIAL DIAGNOSIS

symptomatic (cryptogenic) occipital epilepsy
symptomatic occipital epilepsy
celiac disease
migraine with aura
basilar migraine
acephalgic migraine
occipital seizures of hyperglycemia
mitochondrial disorders
Lafora disease

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