Atypical evolution of Panayiotopoulos syndrome: a case report

Panayiotopoulos syndrome is a relatively common condition with susceptibility to early onset benign childhood seizures, which manifests primarily with autonomic and mainly emetic symptoms. It predominantly affects children of 3-6 years of age (13% of those with one or more non-febrile seizures). EEG shows great variability, with occipital, extra-occipital spikes or brief generalised discharges alone or in combination; it may also be consistently normal. Occipital spikes do not occur in one third of children. Despite the high prevalence of autonomic status epilepticus, the prognosis of Panayiotopoulos syndrome is usually excellent. Remission usually occurs within 1-2 years from onset, one third have a single seizure but 5-10% may have more than 10 seizures or a more prolonged course. Atypical evolutions with absences, atonic seizures and intellectual deterioration are exceptional; only two cases have been previously reported. We present a girl who initially had a prolonged autonomic status epilepticus typical of Panayiotopoulos syndrome, followed by seizures, with concurrent symptoms of Rolandic epilepsy. She then had an atypical evolution with atypical absences, absence status epilepticus, atonic seizures and mild impairment of scholastic performance. The case emphasises the close links between Panayiotopoulos syndrome and Rolandic epilepsy, both of which probably represent different clinical phenotypes of a maturational-related benign childhood seizure susceptibility syndrome [published with videosequences].

Treatment of typical absence seizures and related epileptic syndromes

Typical absences are brief (seconds) generalised seizures of sudden onset and termination. They have 2 essential components: clinically, the impairment of consciousness (absence) and, generalised 3 to 4Hz spike/polyspike and slow wave discharges on electroencephalogram (EEG). They differ fundamentally from other seizures and are pharmacologically unique. Their clinical and EEG manifestations are syndrome-related. Impairment of consciousness may be severe, moderate, mild or inconspicuous. This is often associated with motor manifestations, automatisms and autonomic disturbances. Clonic, tonic and atonic components alone or in combination are motor symptoms; myoclonia, mainly of facial muscles, is the most common. The ictal EEG discharge may be consistently brief (2 to 5 seconds) or long (15 to 30 seconds), continuous or fragmented, with single or multiple spikes associated with the slow wave. The intradischarge frequency may be constant or may vary (2.5 to 5Hz). Typical absences are easily precipitated by hyperventilation in about 90% of untreated patients. They are usually spontaneous, but can be triggered by photic, pattern, video games stimuli, and mental or emotional factors. Typical absences usually start in childhood or adolescence. They occur in around 10 to 15% of adults with epilepsies, often combined with other generalised seizures. They may remit with age or be lifelong. Syndromic diagnosis is important for treatment strategies and prognosis. Absences may be severe and the only seizure type, as in childhood absence epilepsy. They may predominate in other syndromes or be mild and nonpredominant in syndromes such as juvenile myoclonic epilepsy where myoclonic jerks and generalised tonic clonic seizures are the main concern. Typical absence status epilepticus occurs in about 30% of patients and is more common in certain syndromes, e.g. idiopathic generalised epilepsy with perioral myoclonia or phantom absences. Typical absence seizures are often easy to diagnose and treat. Valproic acid, ethosuximide and lamotrigine, alone or in combination, are first-line therapy. Valproic acid controls absences in 75% of patients and also GTCS (70%) and myoclonic jerks (75%); however, it may be undesirable for some women. Similarly, lamotrigine may control absences and GTCS in possibly 50 to 60% of patients, but may worsen myoclonic jerks; skin rashes are common. Ethosuximide controls 70% of absences, but it is unsuitable as monotherapy if other generalised seizures coexist. A combination of any of these 3 drugs may be needed for resistant cases. Low dosages of lamotrigine added to valproic acid may have a dramatic beneficial effect. Clonazepam, particularly in absences with myoclonic components, and acetazolamide may be useful adjunctive drugs.

Idiopathic generalised epilepsy with phantom absences and absence status in a child

A syndrome of idiopathic generalised epilepsy with phantom absences of undetermined onset has been recently described. This syndrome clinically becomes apparent in adulthood with generalised tonic clonic seizures and frequently absence status epilepticus. We report an 11 year-old normal girl with frequent episodes of absence status and no other overt clinical manifestations. However, appropriate video-EEG recordings documented that she had frequent absence seizures that were so mild as to escape recognition by her and the parents. These consisted of mild impairment of cognition and eyelid fluttering during brief generalised discharges of spike/multiple spike and slow waves. No further seizures occurred and the EEG normalised after appropriate drug treatment. Thus, it appears that this syndrome of phantom absences and absence status may start much earlier, in late childhood. Appropriate video-EEG documentation is needed for the recognition of these patients that may be more common than it appears from the few published cases (with Video).

Tooth brushing-induced seizures: a case report

We report a 28-year-old woman of normal intellect, who had three late-onset seizures with unusual ictal features and secondary generalization during prolonged and vigorous tooth brushing. Neurologic examination and brain magnetic resonance imaging (MRI) were normal, but interictal EEG showed left frontal epileptiform activity. Reasonable precautions (regular but briefer and less vigorous brushing of her teeth) combined with a moderate dose of carbamazepine effectively prevented seizure recurrence. This case may be an example of cryptogenic form of reflex epilepsy with seizures induced exclusively by tooth brushing.

Primary diffuse leptomeningeal gliomatosis simulating tuberculous meningitis

Three patients are reported on who presented with communicating hydrocephalus due to presumed tuberculous meningitis. Subsequent clinical deterioration despite antituberculous chemotherapy prompted reassessment with FDG-PET scanning and meningeal biopsy in one case and repeat CSF cytology with special staining in the second. The third patient died and postmortem confirmed a diagnosis of primary diffuse leptomeningeal gliomatosis. In the first two patients, MRI of the entire neuraxis showed no evidence of a primary intraparenchymal tumour. These cases emphasise the need for repeated reassessment in patients with culture negative lymphocytic meningitis. In addition, this is the first report of FDG-PET scanning in leptomeningeal gliomatosis.

Clinical, genetic, and expression studies of mutations in the potassium channel gene KCNA1 reveal new phenotypic variability

Episodic ataxia type 1 (EA1) is an autosomal dominant central nervous system potassium channelopathy characterized by brief attacks of cerebellar ataxia and continuous interictal myokymia. Point mutations in the voltage-gated potassium channel gene KCNA1 on chromosome 12p associate with EA1. We have studied 4 families and identified three new and one previously reported heterozygous point mutations in this gene. Affected members in Family A (KCNA1 G724C) exhibit partial epilepsy and myokymia but no ataxic episodes, supporting the suggestion that there is an association between mutations of KCNA1 and epilepsy. Affected members in Family B (KCNA1 C731A) exhibit myokymia alone, suggesting a new phenotype of isolated myokymia. Family C harbors the first truncation to be reported in KCNA1 (C1249T) and exhibits remarkably drug-resistant EA1. Affected members in Family D (KCNA1 G1210A) exhibit attacks typical of EA1. This mutation has recently been reported in an apparently unrelated family, although no functional studies were attempted. Heterologous expression of the proteins encoded by the mutant KCNA1 genes suggest that the four point mutations impair delayed-rectifier type potassium currents by different mechanisms. Increased neuronal excitability is likely to be the common pathophysiological basis for the disease in these families. The degree and nature of the potassium channel dysfunction may be relevant to the new phenotypic observations reported in this study.

Chronic relapsing multifocal sensory-motor neuropathy with conduction block

A 47 years old man had 13 episodes of relapsing and remitting sensory-motor neuropathy involving the upper limbs over the last 20 years. All but the last episode resolved spontaneously within 2 months. Neurophysiology revealed multifocal motor and sensory conduction block in the upper limbs with normal terminal latencies. CSF analysis was normal and anti-GM1 antibodies were not detected. There was a dramatic clinical improvement after intravenous immunoglobulin treatment. This case represents an unusual multifocal variant of chronic inflammatory demyelinating neuropathy.

Benign childhood epileptic syndromes with occipital spikes: new classification proposed by the International League Against Epilepsy

In a recent proposal, the Commission on Classification and Terminology of the International League Against Epilepsy recognized early-onset childhood epilepsy with occipital spikes (Panayiotopoulos type), differentiating it from the only other type of childhood epilepsy with occipital spikes previously accepted: late-onset childhood epilepsy with occipital spikes (Gastaut type). The importance of this newly recognized syndrome of benign childhood partial seizures is that it is very common-only 2.4 times less frequent than benign rolandic epilepsy, and of equally excellent prognosis. It is characterized by a unique seizure type comprising a combination of autonomic and behavioral disturbances, vomiting, deviation of the eyes, and often with impairment of consciousness that can progress to convulsions. These commonly last for more than 3 minutes and in one quarter of cases for hours. One or more of these symptoms can predominate or be absent. Eyes can remain open without deviation, ictal vomiting might not occur, and autonomic and behavioral disturbances can predominate, particularly in the early stages of the ictus, and be missed in nocturnal seizures. Age at onset is 5 years, with a singular or a median of three seizures, which are predominantly nocturnal. Interictal electroencephalography (EEG) frequently shows occipital paroxysms or occipital spikes but one-fifth of the cases have only extraoccipital spikes on normal EEG. Treatment might not be needed. Panayiotopoulos syndrome, like rolandic epilepsy, needs recognition by the general pediatrician because of the invariably excellent prognosis and also because it can be misdiagnosed as an acute cerebral insult.

Visual phenomena and headache in occipital epilepsy: a review, a systematic study and differentiation from migraine

This is a systematic-prospective study of occipital seizures with elementary visual hallucinations in 18 patients with symptomatic occipital epilepsy. Qualitative and chronological analysis showed that visual seizures usually lasted for seconds to 1-3 minutes. Three patients also had longer visual seizures of 20-150 minutes. Elementary visual hallucinations mainly consisted of coloured and small circular patterns flashing or multiplying in a temporal hemifield. Flashing lights or non-circular patterns were rare. Three patients experienced achromatic flickering lights. None of the patients had the over 4 minute, linear, zigzag, and achromatic or black and white patterns characteristic of migraine visual aura. Blurring of vision could precede visual hallucinations. Visual seizures were usually frequent, often occurring in multiple clusters daily or weekly. They usually occurred alone but they often advanced to other occipital and extra-occipital ictal symptoms. In 7 patients they progressed to temporal lobe seizure manifestations, and in 6 to motor partial seizures or ipsilateral hemiconvulsions. All but 2 had secondary generalised tonic clonic convulsions. Ictal blindness ab initio occurred in 2 and ictal, mainly orbital headache in another 2 patients. One patient had ictal vomiting as an occasional symptom. Postictal headache, often severe and indistinguishable from migraine, occurred in two thirds of the patients, even after brief visual seizures without convulsions. Despite relevant structural lesions in brain imaging, 10 patients had a normal mental and neurological state. In 8 patients, EEG was also normal or nonspecific. Misdiagnosis of visual seizures as visual aura of migraine was common and 3 patients were misdiagnosed as suffering from migraine. The differential diagnosis between migraine and the occipital epilepsies is reviewed. It is concluded that elementary visual hallucinations, blindness or both, alone or followed by headache and vomiting of symptomatic occipital epilepsy are identical to those of idiopathic occipital epilepsy. Progress to temporal lobe structures is different and consistent with symptomatic occipital lobe epilepsy. The clinical diagnosis of visual seizures is easy if individual elements of duration, colour, shape, size, location, movement, speed of development and progress are identified. They are markedly different from visual aura of migraine, although they often trigger migrainous headache, probably by activating trigeminovascular or brain stem mechanisms.

Interictal 18FDG PET findings in temporal lobe epilepsy with déjà vu

The authors studied the functional anatomy of the déjà vu (DV) experience in nonlesional temporal lobe epilepsy (TLE), using interictal fluorine-18 fluorodeoxyglucose PET in 14 patients with and 17 patients without DV. Several clinical conditions, such as age at PET study, side of ictal onset zone, and dominance for language, were no different between the two groups. The patients with DV showed significant relative reductions in glucose metabolism in the mesial temporal structures and the parietal cortex. The findings demonstrate that ictal DV is of no lateralizing value. They further suggest that temporal lobe dysfunction is necessary but not sufficient for the generation of DV. Extensive association cortical areas may be involved as part of the network that integrates this distinct experience.

Early-onset benign childhood occipital seizure susceptibility syndrome: a syndrome to recognize

Early-onset benign childhood occipital seizures (EBOS) described by Panayiotopoulos constitute the commoner after the rolandic phenotype of a childhood seizure susceptibility syndrome. EBOS are the clinical representative of occipital spikes. Their cardinal features are infrequent (often single) partial seizures manifested with deviation of the eyes and vomiting, frequently evolving to hemi- or generalized convulsions. Ictal behavioral changes, irritability, pallor, and rarely cyanosis, and eyes wide open are frequent. Retching, coughing, aphemia, oropharyngolaryngeal movements, and incontinence may occur. Consciousness is usually impaired or lost, either from the onset or the course of the fits, but in a few children, it may be preserved. Duration varies from a few minutes to hours (partial status epilepticus). Seizures are usually nocturnal, but semiology is similar in nocturnal or diurnal fits. Onset is between 1 and 12 years with a peak at 5 years. One third of children have a single seizure, the median total number of fits is two to three, and the prognosis is invariably excellent, with remission usually occurring within 1 year from onset. A few children may later develop rolandic or other benign partial seizures. The likelihood to have seizures after age 12 years is exceptional and rarer than that of febrile convulsions. EEG shows occipital paroxysms demonstrating fixation-off sensitivity, but random occipital spikes, occipital spikes in sleep EEG alone, or normal EEG may occur. Centrotemporal and other spike foci may appear in the same or more frequently in subsequent EEGs. The EEG does not reflect clinical course and severity.

Elementary visual hallucinations, blindness, and headache in idiopathic occipital epilepsy: differentiation from migraine

This is a qualitative and chronological analysis of ictal and postictal symptoms, frequency of seizures, family history, response to treatment, and prognosis in nine patients with idiopathic occipital epilepsy and visual seizures. Ictal elementary visual hallucinations are stereotyped for each patient, usually lasting for seconds. They consist of mainly multiple, bright coloured, small circular spots, circles, or balls. Mostly, they appear in a temporal hemifield often moving contralaterally or in the centre where they may be flashing. They may multiply and increase in size in the course of the seizure and may progress to other non-visual occipital seizure symptoms and more rarely to extra-occipital manifestations and convulsions. Blindness occurs usually from the beginning and postictal headache, often indistinguishable from migraine, is common. It is concluded that elementary visual hallucinations in occipital seizures are entirely different from visual aura of migraine when individual elements of colour, shape, size, location, movement, speed of development, duration, and progress are synthesised together. Postictal headache does not show preference for those with a family history of migraine. Most of the patients are misdiagnosed as having migraine with aura, basilar migraine, acephalgic migraine, or migralepsy simply because physicians are not properly informed of differential diagnostic criteria. As a result, treatment may be delayed for years. Response to carbamazepine is excellent and seizures may remit.

F-chronodispersion in patients on thalidomide

OBJECTIVES

To describe abnormalities of F-chronodispersion in patients treated with thalidomide.

METHODS

We retrospectively studies F-wave latency, persistence and F-chronodispersion in 12 patients on thalidomide treatment and compared them with a control group of another 12 patients with similar dermatological conditions who did not receive thalidomide. Furthermore, we prospectively performed longitudinal neurophysiological studies in 4 patients before and during thalidomide treatment.

RESULTS

Seven of 12 patients in the retrospective study had abnormal F-chronodispersion while this was normal in all patients of the control group (P = 0.014). All other neurophysiological parameters were similar in the two groups. Two of the thalidomide patients with abnormal F-chronodispersion later developed sensory neuropathy. In all 4 patients in the prospective study though F-chronodispersion was normal before thalidomide it became markedly abnormal after exposure to this drug.

CONCLUSIONS

Thalidomide may affect smaller diameter motor nerve fibres even before changes in sural sensory nerve action potentials. F-waves and F-chronodispersion should be routinely monitored in patients on thalidomide treatment.

Extraoccipital benign childhood partial seizures with ictal vomiting and excellent prognosis

In a previous report of 900 patients with epileptic seizures, 24 children had ictal vomiting. Twelve had a previously unrecognised syndrome of early onset benign childhood occipital seizures (EBOS) and three had symptomatic epilepsy. The other nine children with extraoccipital EEG foci or normal EEG are described in this paper based on a prospective follow up for a median of 9 years after their first seizure. All had normal neurology, mental state, and development. All seizures of all but one patient occurred in sleep. Seizures manifested with ictal vomiting (nine), deviation of the eyes (four), speech arrest (three), hemiconvulsions (five), oropharyngolaryngeal symptoms, and hypersalivation (one) with or without impairment of consciousness. Median age at onset was 5 years, seizures were infrequent and remitted at a median age of 6. Four children had a single fit, four had two to three, and only one child had many seizures before the initiation of treatment. This study certifies that idiopathic childhood partial seizures with ictal vomiting may occur with EEG spike foci in other than the occipital regions or EEG may be normal. Despite some clinico-EEG differences from the EBOS, childhood seizures with ictal vomiting, and extraoccipital EEG foci are of equally excellent prognosis. Their existence on the border between rolandic and occipital seizures is consistent with a unified concept of a benign childhood partial seizure susceptibility syndrome.

Typical absence status in adults: diagnostic and syndromic considerations

PURPOSE

To study the electroclinical features of typical absence status (TAS) in adults with syndromes of idiopathic generalized epilepsies (IGEs).

METHODS

Twenty-one patients with one or more spells of TAS were identified among 136 consecutive adult patients with IGEs. All patients with TAS had comprehensive electroclinical investigations and EEG or video-EEG recorded absences.

RESULTS

TAS occurred in 24.4% of 86 patients who had IGEs with typical absences alone or in combination with other seizures presisting in adult life. The prevalence of TAS appeared to be syndrome related, ranging from as high as 57.1% in perioral myoclonia with absences and 46.2% in "phantom" absences with GTCS to as low as 6.7% in juvenile myoclonic epilepsy. A varying degree of impairment of cognition was the cardinal clinical symptom shared in all TAS, but corresponding syndromes of IGE were often betrayed by other symptoms such as eyelid or perioral myoclonia. In phantom absences with GTCS, TAS was more numerous (p < or = 0.05) and more frequently the first overt seizure type (p = 0.006) than in any other IGE. Only in the syndrome of eyelid myoclonia with absences, TAS was always situation related, mainly as a result of antiepileptic drug discontinuation.

CONCLUSIONS

The clinical EEG semiology and prevalence of TAS appear to be syndrome related with the highest prevalence in the syndromes of perioral myoclonia with absences and phantom absences with GTCS (p = 0.0024).

Positron emission tomography in partial epilepsies: the clinical point of view

Epilepsy research using positron emission tomography (PET) has advanced our understanding of the pathophysiology and neurochemical correlates of both focal and generalized epilepsies, but from the clinical viewpoint its major contribution has been in the presurgical evaluation of patients with medically intractable partial seizures. Depending on the tracer used, PET may provide information on regional cerebral blood flow and glucose metabolism, and the binding of specific ligands to receptors that are thought to be related to the genesis and propagation of epileptic activity. In this communication, we discuss the diagnostic yield, limitations and perspectives of 18F-fluorodeoxyglucose (FDG) and 11C-flumazenil (FMZ) PET in partial epilepsies. The current evidence regarding the pathophysiology of the focal changes is also presented, with an emphasis on issues which must be carefully addressed for effective and reliable clinical research.

Inappropriate use of carbamazepine and vigabatrin in typical absence seizures

Carbamazepine and vigabatrin are contraindicated in typical absence seizures. Of 18 consecutive referrals of children with resistant typical absences only, eight were erroneously treated with carbamazepine either as monotherapy or as an add-on. Vigabatrin was also used in the treatment of two children. Frequency of absences increased in four children treated with carbamazepine and two of these developed myoclonic jerks, which resolved on withdrawal of carbamazepine. Absences were aggravated in both cases where vigabatrin was added on to concurrent treatment. Optimal control of the absences was achieved with sodium valproate, lamotrigine, or ethosuximide alone or in combination.

Interictal regional slow activity in temporal lobe epilepsy correlates with lateral temporal hypometabolism as imaged with 18FDG PET: neurophysiological and metabolic implications

OBJECTIVES

The phenomenon of interictal regional slow activity (IRSA) in temporal lobe epilepsy and its relation with cerebral glucose metabolism, clinical data, MRI, and histopathological findings was studied.

METHODS

Interictal 18F-fluorodeoxyglucose positron emission tomography (FDG PET) was performed under continuous scalp EEG monitoring in 28 patients with temporal lobe epilepsy not associated with intracranial foreign tissue lesions, all of whom subsequently underwent resective surgery. Regions of interest (ROIs) were drawn according to a standard template. IRSA was considered lateralised when showing a 4:1 or greater ratio of predominance on one side.

RESULTS

Sixteen patients (57%) had lateralised IRSA which was always ipsilateral to the resection and of maximal amplitude over the temporal areas. Its presence was significantly related to the presence of hypometabolism in the lateral temporal neocortex (p=0.0009). Logistic regression of the asymmetry indices for all measured cerebral regions confirmed a strong association between IRSA and decreased metabolism of the posterior lateral temporal neocortex only (p=0.009). No significant relation could be shown between slow activity and age at onset, duration of the epilepsy, seizure frequency, and MRI evidence for hippocampal atrophy. Furthermore, IRSA was not specifically related to mesial temporal sclerosis or any other pathology.

CONCLUSIONS

Interictal regional slowing in patients with temporal lobe epilepsy not associated with a mass lesion is topographically related to the epileptogenic area and therefore has a reliable lateralising, and possibly localising, value. Its presence is irrelevant to the severity or chronicity of the epilepsy as well as to lateral deactivation secondary to neuronal loss in the mesial temporal structures. Although slow EEG activity is generally considered as a non-specific sign of functional disturbance, interictal regional slowing in temporal lobe epilepsy should be conceptualised as a distinct electrographic phenomenon which is directly related to the epileptogenic abnormality. The strong correlation between interictal regional slowing and lateral temporal hypometabolism suggests in turn that the second may delineate a field of reduced neuronal inhibition which can receive interictal and ictal propagation.

The variants of reading epilepsy. A clinical and video-EEG study of 17 patients with reading-induced seizures

We present the clinical and electrographic data of 17 patients with reading-induced seizures documented with ictal video-EEG studies during provocation with language related tasks. The median age at onset was 15 years (range 11-22 years) and the male:female ratio was 2.4. Fourteen patients had no spontaneous seizures of any type while the remaining three had infrequent generalized tonic-clonic seizures during nocturnal sleep. Two distinct electroclinical ictal patterns were confirmed on video-EEG analysis. (i) Fifteen patients had reading-induced jerks which invariably involved the region of the jaw but also included the upper limbs in five of them. Ictal EEG discharges were noted in 12 patients; these were brief but varied in terms of morphology and spatial distribution, with a clear tendency for left-sided predominance. All but one of these patients had similar myoclonic seizures induced by linguistic activities other than reading, the phenomenon probably justifying the term 'language-induced epilepsy'. Some patients had evidence of transient cognitive impairment associated with the reading-induced jaw or limb jerks. Three patients had a sibling with reading epilepsy but there was no other family history of epileptic seizures. (ii) Two patients had reading-provoked paroxysmal alexia without motor symptoms, associated with prolonged focal ictal EEG abnormalities. Reading provoked a subclinical, continuous and reproducible EEG activation over the left posterior temporal area. We propose that ictogenesis in reading or language-induced epilepsy is based on the reflex activation of a hyperexcitable network that subserves the function of speech and extends over multiple cerebral areas on both hemispheres. The parts of this network responding to the stimulus may, secondarily, drive the relative motor areas producing the typical regional myoclonus. This network hyperexcitability can be genetically determined and its clinical expression is age-related.

Clinical value of "ictal" FDG-positron emission tomography and the routine use of simultaneous scalp EEG studies in patients with intractable partial epilepsies

PURPOSE

EEG is widely used during positron emission tomography (PET) to confirm the interictal state of the patient and assist in scan interpretation when a seizure occurs. Ictal scans usually reflect mixed interictal-ictal-postictal metabolic activity as seizures are brief in comparison to the 30-min uptake period of the tracer. We wished to determine whether routine EEG is justified and if seizures commonly affect the diagnostic information of the PET scan.

METHODS

We examined the PET scans of 6 of 236 outpatients with intractable epilepsy with clinical and electrical evidence of a seizure during tracer uptake. We performed semi-quantitative analysis in 2 patients who had "ictal" and control interictal scans.

RESULTS

Patients with single seizures lasting 23 s to 4 min [four complex partial seizures (CPS) and one absence seizure (AS)] had focal hypometabolism concordant with results of other investigations. One patient with complex partial status had irregular cortical uptake and focal hypometabolism, but the site of the ictal focus could not be confirmed.

CONCLUSIONS

In this group of patients, seizures occurred infrequently during tracer uptake. The interpretation of the PET scan when single seizures occurred did not appear to be influenced by the continuous scalp EEG (CSEEG) recordings. The value of routine CSEEG in outpatients treated with medication should be reappraised, with potential cost savings. In rare circumstances in which a true ictal study occurs (complex partial status, epilepsia partialis continua, and repetitive CPS), PET scanning may be inconclusive and repeat interictal scanning should be pursued.

Fixation-off (Scoto) sensitivity combined with photosensitivity

A 16-year-old boy of normal intelligence had brief absence and myoclonic jerks since age 7 years. Video-EEG documented the unexpected combination of fixation-off sensitivity (scotosensitivity) with photosensitivity.

Fixation-off, scotosensitive, and other visual-related epilepsies

FOS is a relatively recently described specific mode of precipitation of seizures and paroxysmal EEG abnormalities. Elimination of central vision and fixation, even in the presence of light, induces high-amplitude occipital or generalized paroxysmal discharges. FOS is suggested on routine EEG by abnormalities that consistently occur as long as the patient's eyes are closed but not when the eyes are open. The model example of FOS is early-onset and late-onset BCEOP. Idiopathic and cryptogenic generalized epilepsies with FOS have been described. Scotosensitive epilepsy implies seizures and EEG abnormalities induced by the complete elimination of retinal light stimulation, and most cases described as scotosensitive are probably FOS. FOS has characteristics opposite to those of photosensitive epilepsies, but conversion from one to the other or co-existence may rarely occur. The underlying mechanisms of FOS are not known, but they may be related to an abnormality of the alpha-rhythm generators.