Panayiotopoulos Syndrome Research Articles

Epilepsy classification and additional definitions in occipital lobe epilepsy.

To evaluate epileptic children with occipital lobe epilepsy (OLE) in the light of the characteristics of Panayiotopoulos syndrome and late-onset occipital lobe epilepsy of Gastaut (OLE-G). Patients were categorized into six groups: primary OLE with autonomic symptoms (Panayiotopoulos syndrome), primary OLE with visual symptoms (OLE-G), secondary OLE with autonomic symptoms (P-type sOLE), secondary OLE with visual symptoms (G-type sOLE), and non-categorized primary OLE and non-categorized secondary OLE according to characteristic ictal symptoms of both Panayiotopoulos syndrome and OLE-G, as well as aetiology (primary or secondary). Patients were compared with regards to seizure symptoms, aetiology, cranial imaging, EEG, treatment and outcome. Of 108 patients with OLE (6.4±3.9 years of age), 60 patients constituted primary groups (32 with Panayiotopoulos syndrome, 11 with OLE-G, and 17 with non-categorized primary OLE); the other 48 patients constituted secondary groups (eight with P-type sOLE, three with G-type sOLE, and 37 with non-categorized sOLE). Epileptiform activity was restricted to the occipital area in half of the patients. Generalized epileptiform activity was observed in three patients, including a patient with Panayiotopoulos syndrome (PS). Only one patient had refractory epilepsy in the primary groups while such patients made up 29% in the secondary groups. In OLE, typical autonomic or visual ictal symptoms of Panayiotopoulos syndrome and OLE-G do not necessarily indicate primary (i.e. genetic or idiopathic) aetiology. Moreover, primary OLE may not present with these symptoms. Since there are many patients with OLE who do not exhibit the characteristics of Panayiotopoulos syndrome or OLE-G, additional definitions and terminology appear to be necessary to differentiate between such patients in both clinical practice and studies.

From focal epilepsy to Dravet syndrome – Heterogeneity of the phenotype due to SCN1A mutations of the p.Arg1596 amino acid residue in the Nav1.1 subunit

ObjectiveThe aim of this study was to analyze the intra-/interfamilial phenotypic heterogeneity due to variants at the highly evolutionary conservative p.Arg1596 residue in the Nav1.1 subunit. Materials/participantsAmong patients referred for analysis of the SCN1A gene one recurrent, heritable mutation was found in families enrolled into the study. Probands from those families even clinically diagnosed with atypical Dravet syndrome (DS), generalized epilepsy with febrile seizures plus (GEFS+), and focal epilepsy, had heterozygous p.Arg1596 His/Cys missense substitutions, c.4787G>T and c.4786C>T in the SCN1A gene. MethodFull clinical evaluation, including cognitive development, neurological examination, EEGs, MRI was performed in probands and affected family members in developmental age. The whole SCN1A gene sequencing was performed for all probands. The exon 25, where the identified missense substitutions are localized, was directly analyzed for the other family members. ResultsMutation of the SCN1A p.1596Arg was identified in three families, in one case substitution p.Arg1596Cys and in two cases p.Arg1596His. Both mutations were previously described as pathogenic and causative for DS, GEFS+ and focal epilepsy. Spectrum of phenotypes among presented families with p.Arg1596 mutations shows heterogeneity ranged from asymptomatic cases, through FS and FS+ to GEFS+/Panayiotopoulos syndrome and epilepsies with and without febrile seizures, and epileptic encephalopathy such as DS. Phenotypes differ among patients displaying both focal and generalized epilepsies. Some patients demonstrated additionally Asperger syndrome and ataxia. ConclusionClinical picture heterogeneity of the patients carrying mutation of the same residue indicates the involvement of the other factors influencing the SCN1A gene mutations’ penetrance.

Panayiotopoulos syndrome and diffuse paroxysms as the first EEG manifestation at clinical onset: a study of nine patients.

To present a retrospective study of nine children with Panayiotopoulos syndrome associated with diffuse spikes and waves as the sole EEG manifestation at onset. Charts of children with typical clinical criteria of Panayiotopoulos syndrome, electroclinically followed between February2000 and February2012, were reviewed. Among 150 patients who met the electroclinical criteria of Panayiotopoulos syndrome, we identified nine children who presented with the typical clinical manifestations but who, on EEG, only had diffuse paroxysms at onset that continued along the course of the syndrome. In three, in addition to the diffuse paroxysms, focal spikes appeared later. From a clinical point of view, other features were otherwise unremarkable. Diffuse spike-and-wave discharges were observed in all patients when awake and during sleep (100%). Later, three children also had focal spikes during sleep, which were occipital in one, frontal in one, and temporo-occipital in the remaining patient. Spikes were activated by sleep in all three cases. During disease evolution, no particular electroclinical pattern was observed. Two patients who received clobazam and carbamazepine, respectively, did not respond well to the drugs and valproic acid was added with excellent seizure control. Outcome was good. We present evidence that patients with Panayiotopoulos syndrome may have diffuse discharges at onset as the sole EEG manifestation, which last throughout the course of the syndrome. In some, focal paroxysms developed later. The course was benign. In our group of patients, clinical features and evolution were similar to those of typical cases of Panayiotopoulos syndrome.

Sleep and epilepsy syndromes.

Sleep and epilepsy have a close relationship. About 20% of patients suffer seizures only during the night, approximately 40% only during the day and approximately 35% during the day and night. In certain epilepsy syndromes, the occurrence of seizures is strongly related to sleep or awakening. Infantile spasms appear predominately on awakening, and hypsarrhythmia is sometimes visible only in sleep. Children with Panayiotopoulos syndrome or benign epilepsy with centrotemporal spikes (BECTS) have seizures mostly when asleep, and in both syndromes interictal spike waves are markedly accentuated in slow wave sleep. Electrical status epilepticus during slow sleep/continuous spike wave discharges during sleep (ESES/CSWS), atypical benign partial epilepsy, and Landau-Kleffner syndrome are epileptic encephalopathies with substantial behavioral and cognitive deficits, various seizures, and continuous spike-wave activity during non-rapid eye movement (NREM) sleep. The hallmark of juvenile myoclonic epilepsy and grand mal seizures on awakening are seizure symptoms within 2 hours after awakening, often provoked by sleep deprivation. Nocturnal frontal lobe epilepsy is sometimes mistaken for parasomnia. Differentiation is possible when the clinical symptoms and the frequency of the paroxysmal events per night and month are carefully observed and nocturnal video electroencephalography (EEG) performed. Sleep EEG recordings may be helpful in patients with suspected epilepsy and nonconclusive awake EEG. Depending on the clinical question, sleep recordings should be performed during nap (natural sleep or drug induced), during the night, or after sleep deprivation.

1-A-D-10. A study on spike focus-dependence of high-frequency oscillations in benign childhood partial epilepsy

We analyzed spike-associated high-frequency oscillations (HFOs) and their relationship to spike foci in electroencephalograms (EEGs) of patients with benign epilepsy with centrotemporal spikes (BECTS) and Panayiotopoulos syndrome (PS). In 35 patients with BECTS and 29 with PS, focal spikes in scalp sleep EEGs were firstly classified into clusterings according to their characteristics including shapes and distributions. In each patient, the maximum of three spike clusters were investigated through time–frequency and single-dipole analyses to explore relationships between presence or absence of spike-associated HFOs and the distribution of estimated spike sources. A total of 159 spike clusters was analyzed (96 in BECTS and 63 in PS). HFOs were detected in 73 spike clusters (76.0%) in BECTS and 37 (58.7%) in PS with a statistically significant difference ( p = 0.024 by Fisher’s exact test). In BECTS, the spike sources had a close relationship with HFOs and were largely uniform irrespective of presence or absence of HFOs. In contrast in PS, the spikes tended to be dispersed and the rate of association with HFOs was significantly higher in occipito-parietal spikes (29/39) than the others (8/24; p = 0.002) suggesting that occipito-parietal spikes with a close link to HFOs were indicated to have a particular meaning in the epileptogenesis.

Early Onset Benign Occipital Epilepsy (Panayiotopoulos syndrome): a case Report & Literature Review

Panayiotopoulos syndrome is a type of benign childhood epilepsy syndrome characterized by episodic 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. Despite the high prevalence of autonomic status epilepticus, the prognosis of Panayiotopoulos syndrome is usually excellent and most do not require anti epileptic medications. 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. We present a 5 year old boy with this condition, who presented with episodes of severe vomiting, deviation of eyes, focal seizure, altered sensorium, characteristic EEG in the form of multiple occipital spikes and normal neuroimaging studies.J. Natl Inst. Neurosci Bangladesh 2015;1(1):27-30

EARLY ONSET BENIGN CHILDHOOD OCCIPITAL EPILEPSY (PANAYIOTOPOULOS SYNDROME). A CASE REPORT

The childhood epilepsy with occipital paroxysms and early onset or Panayiotopoulos syndrome is a benign focal epileptic syndrome, a benign disease, developing at infants. The disease has been described in 1989 by S. Panayiotopoulos on the basis of results of own observations, who has called this syndrome “benign night childhood occipital lobe epilepsy”. In 1996 N. Fejerman et al. offered the new name of the syndrome – benign childhood occipital lobe epilepsy, with earlier onset (Panayiotopoulos type), versus the childhood occipital lobe epilepsy, starting later in childhood (Gastaut type). The Panayiotopoulos syndrome occurs only at children, develops at healthy children without neurological disorders, the pick of disease falls on 4–5 years. The morbidity of boys and girls is almost the same. In most cases of the syndrome seizures take place during the sleep, 2 / 3 of patients report seizures only during sleep. As a rule, seizures last for more than 5 min, in 40 % of cases it last for more than 30 min, what corresponds (according to the consciousness level) to focal or generalized epileptic status criteria. To typical clinical syndromes at Panayiotopoulos syndrome are referred the ictal vomiting, as well as different vegetative symptoms. So, theictal vomiting, which, generally, is not typical for epilepsy, takes place in about 80 % of cases at Panaytopululos syndrome. Authors describe their own observation of the Panayiotopoulos syndrome at 5 years old girl.

Sequential prefrontal lobe volume changes and cognitive dysfunctions in children with Panayiotopoulos syndrome presenting with status epilepticus

Panayiotopoulos syndrome (PS) is usually not associated with neurodevelopmental problems. However, neuropsychological impairments may also be present in at least some of the patients with PS. On the other hand, several degrees of neuronal damage due to status epilepticus (SE) may occur in the cortex. We prospectively measured frontal and prefrontal lobe volumes using three-dimensional magnetic resonance imaging (3D-MRI)-based volumetry in patients with PS with and without SE. Moreover, the neuropsychological outcome in relation to the presence of SE in children with PS is also discussed. We studied six patients with a final diagnosis of PS, including three cases with SE and cognitive impairments/behavioral problems (SE group) and three cases without SE (non-SE group). Serial 3D-MRI studies were performed five times (at onset of clinical symptoms and 1-4 years after onset) in both the SE and non-SE patients. All patients were studied with a set of Wechsler Intelligence Scale for Children, version III (WISC-III) or Wechsler Preschool and Primary Scale of Intelligence tests and the Kaufman Assessment Battery for Children (K-ABC). Growth of the frontal and prefrontal lobes was slightly decreased for some time after SE episodes in the SE patients. Moreover, the prefrontal-to-frontal lobe volume ratio was stagnant for some time after SE in the SE patients. The scores on the neuropsychological tests were decreased in the SE patients. Moreover, the average WISC and K-ABC scores in the SE group remained low and did not reach the levels of the initial examinations. Occurrence of SE in patients with PS at least in some patients may be associated with retarded prefrontal lobe growth, which was related to neuropsychological problems and ultimately, neuropsychological outcomes. Treatment management may be required to prevent SE as much as possible to achieve optimal prognosis in PS at least in some patients.

Coexistence of fixation-off sensitivity and inverted fixation-off sensitivity in a female child with Panayiotopoulos syndrome: Video-electroencephalography documentation.

Fixation-off sensitivity (FOS) is a rare phenomenon elicited by elimination of central vision and fixation, which even in the presence of light induces occipital paroxysms or generalized paroxysmal discharges. It is most commonly encountered in patients with idiopathic childhood occipital epilepsies but may also be observed in cases of symptomatic focal and generalized epilepsies. We describe a female Emirati child with Panayiotopoulos syndrome who exhibited FOS in addition to the reverse phenomenon called “inverted fixation-off sensitivity,” in which the electroencephalographic discharges were suppressed by the absence of central vision or fixation and activated by central vision or fixation.

Panayiotopoulos Syndrome vs. GERDs

Investigators at Sapienza University of Rome, Italy, describe 12 children with Panayiotopoulos syndrome (PS) misdiagnosed as gastroesophageal reflux disease (GERD).

Syndromes with very low risk of acute prolonged seizures.

The provision of rescue medication is an important component in the treatment of epilepsy. An intervention within five to ten minutes in the case of an acute prolonged seizure may preserve the patient from status epilepticus (SE). However, the risk of convulsive SE (CSE) differs markedly between patients depending on individual factors. This report summarizes the literature on risk factors for CSE in children with epilepsy and adolescents, and discusses the hypothesis that some electroclinical syndromes engender a very low risk of CSE. The most important risk factor for SE is the history of a previous event. The longer a patient lives without SE, the lower the risk will be. CSE occurs significantly less frequently in idiopathic epilepsies compared to epilepsies with symptomatic or unknown aetiology. It is very rarely observed in patients with (non-encephalopathic) idiopathic generalised epilepsies, i.e. childhood absence epilepsy or juvenile myoclonic epilepsy. However, non-compliance or inappropriate treatment may trigger CSE in these syndromes. A very low risk can be assumed for children with Rolandic epilepsy, while CSE occurs in a considerable percentage of patients with Panayiotopoulos syndrome. Although the risk of CSE in otherwise normal children with cryptogenic focal epilepsy is uncertain, it is presumably low under successful continuous medication. In conclusion, the choice for or against the prescription of rescue medication remains an individual decision. Consequently, for several electroclinical syndromes, a per se provision of rescue medication does not appear justified.

Gastroesophageal reflux disease vs. Panayiotopoulos syndrome: An underestimated misdiagnosis in pediatric age?

Autonomic signs and symptoms could be of epileptic or nonepileptic origin, and the differential diagnosis depends on a number of factors which include the nature of the autonomic manifestations themselves, the occurrence of other nonictal autonomic signs/symptoms, and the age of the patient.Here, we describe twelve children (aged from ten months to six years at the onset of the symptoms) with Panayiotopoulos syndrome misdiagnosed as gastroesophageal reflux disease.Gastroesophageal reflux disease and Panayiotopoulos syndrome may represent an underestimated diagnostic challenge. When the signs/symptoms occur mainly during sleep, a sleep EEG or, if available, a polysomnographic evaluation may be the most useful investigation to make a differential diagnosis between autonomic epileptic and nonepileptic disorders. An early detection can reduce both the high morbidity related to mismanagement and the high costs to the national health service related to the incorrect diagnostic and therapeutic approaches. To decide if antiseizure therapy is required, one should take into account both the frequency and severity of epileptic seizures and the tendency to have potentially lethal autonomic cardiorespiratory involvement.In conclusion, we would emphasize the need to make a differential diagnosis between gastroesophageal reflux disease and Panayiotopoulos syndrome in patients with “an unusual” late-onset picture of GERD and acid therapy-resistant gastroesophageal reflux, especially if associated with other autonomic symptoms and signs.

B-34 * Neuropsychological Findings Associated with Panayiotopoulos Syndrome

B-34 * Neuropsychological Findings Associated with Panayiotopoulos Syndrome

Panayiotopoulos syndrome with convulsive status epilepticus at the onset: A long-term study

PurposeTo better define the convulsive status epilepticus (CSE) as a possible manifestation at the onset of Panayiotopoulos syndrome (PS) and to assess its prognostic value in these children. MethodsChildren with CSE and diagnostic criteria of PS were identified, followed clinically and compared with a group of patients with PS without CSE from 1993 to 2012. ResultsWe identified 37 patients with CSE at the onset of PS. During the same period we identified 72 children with autonomic symptoms of PS without CSE. The first episode of CSE occurred at a mean age of 6.5 years. Generalized clonic seizures were the most common ictal event and one-third of the patients required admission to Intensive Care Units. Interictal EEGs showed occipital spike activity in 31 (83.7%) subjects. Only 14 (37.8%) patients were treated with valproic acid and for two of them (5.40%) it was necessary to administer other drugs. There were no intractable cases. The overall prognosis was excellent. After the first event, 15 subjects (40.54%) experienced at least another typical PS seizure, but all patients were seizure free at the last follow-up. ConclusionCSE is not uncommon in PS and it may occur at the onset of benign childhood epilepsy, without leading to a poor prognosis.

Panayiotopoulos syndrome and symptomatic occipital lobe epilepsy of childhood: a clinical and EEG study.

Panayiotopoulos syndrome (PS) is an age-related seizure susceptibility syndrome that affects the central autonomic system. Although the majority of the few ictal recordings obtained so far suggest an occipital origin, semiological and interictal EEG data appear to favour more extensive involvement. In this study, the characteristics (including those based on semiology and EEG) of children with Panayiotopoulos syndrome (n=24) and those with lesion-related, symptomatic occipital lobe epilepsy (SOLE) (n=23) were compared. Detailed semiological information and EEG parameters including the localisation, distribution, density (n/sec), reactivity, and morphological characteristics of spike-wave foci and their relationship with different states of vigilance were compared between the two groups. The age at seizure onset was significantly younger in patients with symptomatic occipital lobe epilepsy than in those with PS (mean age at onset: 3.4 versus 5.6 years, respectively; p=0.044). Autonomic seizures (p=0.001) and ictal syncope (p=0.055) were more frequent in PS than in symptomatic occipital lobe epilepsy (87.5% and 37.5% versus 43.5% and 13%, respectively). The interictal spike-wave activity increased significantly during non-rapid eye movement (non-REM) sleep in both groups. The spike waves in non-REM seen in PS tended to spread mainly to central and centro-temporal regions. The results indicate that although common features do exist, Panayiotopoulos syndrome differs from symptomatic occipital lobe epilepsy and has a unique low epileptogenic threshold related to particular brain circuits.

Panayiotopoulos syndrome: A case series from Turkey

The aim of the study was to evaluate the demographic, clinical, and EEG characteristics of patients with Panayiotopoulos syndrome (PS) and the course of their illness.Thirty-eight patients followed up with a diagnosis of PS between January 2011 and December 2013 were evaluated.We found high rates of personal history of febrile convulsions, breath-holding spells, and family history of febrile convulsions, afebrile convulsion/epilepsy, migraine, and breath-holding spells. Seizures started before the age of eight in 87% of the patients, and the mean age at seizure onset was 4.6years. Seizures were sleep-related in 81.5%, and autonomic status was seen in a third of the patients. The number of seizures was between 2 and 10 in 66% of the patients. The most common symptoms were ictus emeticus, eye/head deviation, and altered consciousness. Rolandic features were seen in 26% of the patients, and visual symptoms in 5%. Multifocal epileptiform discharges on EEG were identified in 84% of the patients. Two or more antiepileptic drugs were required in only 13% of the patients. Evolution to electrical status epilepticus in sleep and Gastaut-type epilepsy were seen in patients with more than ten seizures.The high rates of febrile convulsions, afebrile convulsions/epilepsy, migraine, and breath-holding spells in the patients and families suggest the importance of genetic factors and, perhaps, a common pathogenesis. However, the high rates of febrile convulsions and breath-holding spells in patients can be related to a misdiagnosis because of the similar symptoms. Despite its disturbing symptoms, PS is a benign epileptic syndrome requiring multiple antiepileptic drug use only in a small proportion of patients.

Manifestation of both emetic seizures and sylvian seizures in the same patients with benign partial epilepsy

Benign childhood epilepsy with centro-temporal spikes (BECTS) and Panayiotopoulos syndrome (PS) have different pathophysiologies and show different types of seizures, yet they overlap in some important respects. In an attempt to understand the ways in which they differ from each other and overlap each other, we performed a detailed investigation on patients who had both characteristic types of seizure manifestations, namely, sylvian seizures and emetic seizures. We recruited consecutive subjects from the EEG database of outpatients who had visited our hospital between 2008 and 2010 and who had been diagnosed with BECTS or PS. As a result, 45 patients with BECTS and 50 patients with PS were selected from the database. Viewing the clinical records of these 95 patients, five patients were selected who had experienced both sylvian seizures and emetic seizures. Next, the clinical features and EEG findings of these five patients were retrospectively observed at the date of investigation: October 1, 2011. We found that all the patients showed rolandic spikes when they had sylvian seizures, and occipital spikes or multifocal spikes when they had emetic seizures. We also report in detail on one patient who showed two different types of ictal EEG patterns: one of which started in the occipital area and the other of which was located in the rolandic area. Based on these findings, we conclude that widespread cortical hyperexcitability that includes the occipital area is necessary to produce the autonomic seizure manifestations seen in PS.

Early classification of childhood focal idiopathic epilepsies: Is it possible at the first seizure?

PurposesTo evaluate the possibility of early syndrome classification of idiopathic partial epilepsies in children at the first seizure. Patients and methodsIn this observational study we prospectively evaluated 298 patients, aged between 1 month and 17 years and consecutively referred for the first unprovoked focal seizure. The whole cohort included 133 patients; the final analysis was carried out on 107 (59 males) individuals. Age at the first seizure ranged between 2.3 and 13.0 years. Clinical and EEG data of all patients were independently reviewed by two medical doctors. Patients were followed-up for at least 5 years, with a mean period of follow-up of 6.9 years. ResultsAfter the first seizure, a specific syndrome could be diagnosed in eighty (74.7%) children. In particular, Childhood Epilepsy with Centro-Temporal Spikes (CECTS) 42.9% of cases, Panayiotopoulos Syndrome (PS) 28.9%, idiopathic childhood occipital epilepsy of Gastaut (ICOE-G) 2.8%. Unclassified cases were 25.4%. At the end of the follow-up, the diagnosis was confirmed in 72 of 80 children (90%): BCECTS 89% of patients, PS 90% and ICOE-G 100%: among the unclassified cases, in 11 patients (40.7%) the diagnosis did not change, whereas 16 patients (59.3%) evolved into other syndromes or into atypical forms. ConclusionsAt the onset an initial diagnosis is possible in the majority of cases; epilepsy syndromes can be identified at the time of the initial diagnosis and at follow up this diagnosis has not to be revised in 90% of the cases.

Benign occipital epilepsy of childhood: panayiotopoulos syndrome in a 3 year old child

Panayiotopoulos syndrome (PS) is a relatively frequent and benign epileptic syndrome seen in children in the age group of 3-6 years and is characterised by predominantly autonomic symptoms and/or simple motor focal seizures followed or not by impairment of consciousness. Although multifocal spikes with high amplitude sharp-slow wave complexes at various locations can be present in the EEG, interictal electroencephalogram (EEG) in children with this particular type of epilepsy characteristically shows occipital spikes. This syndrome has known to be a masquerader and can imitate gastroenteritis, encephalitis, syncope, migraine, sleep disorders or metabolic diseases. In the absence of thorough knowledge of types of benign epilepsy syndromes and their various clinical presentations, epilepsy such as PS can be easily missed. The peculiar aspects of this type of epilepsy in children should be known not only by paediatricians but also by general doctors because a correct diagnosis would avoid aggressive interventions and concerns on account of its benign outcome. In this case study, we report a case of PS in a 3 year old child.

Neuropsychological abnormalities in children with the Panayiotopoulos syndrome point to parietal lobe dysfunction

Panayiotopoulos syndrome (PS) is a common epilepsy syndrome associated with rare clinical seizures and unknown localization of the epileptogenic area. Despite findings of normal development in patients with PS, recent neuropsychological studies point to subtle and diverse cognitive impairments. No well-outlined hypothesis about the localization of the brain dysfunction responsible for these impairments has been proposed. We further explored the cognitive dysfunctions in PS and made inferences on the most likely anatomical localization of brain impairment. A group of 19 patients (aged 6–12) with PS was rated according to spike activity and lateralization. The patients were submitted to a neuropsychological evaluation to assess general intelligence, memory, language, visual–perceptual abilities, attention, and executive functions. Using 35-channel scalp EEG recordings, the N170 face-evoked event-related potential (ERP) was obtained to assess the functional integrity of the ventral pathway. All patients with PS showed normal IQ but subtle and consistent neurocognitive impairments. Namely, we found abnormalities in the copy task of the Rey–Osterrieth Complex Figure and in the Narrative Memory Test. There was no correlation between neuropsychological impairments with spike activity and hemispheric spike lateralization. The N170 ERP was normal in all patients except for one. Our neuropsychological findings demonstrate impairments in visual–perceptual abilities and in semantic processing. These findings, paired with the absence of occipital lobe dysfunction in all neuropsychological studies of PS performed to this date, support the existence of parietal lobe dysfunction.