Occipital Lobe Epilepsy Research Articles

Characteristics of Epilepsies in Patients with Hypoxic‐Ischemic Encephalopathy (HIE) During the Neonatal Periods

Purpose: The purpose of this study was to observe the characteristics of epilepsies in patients with a history of hypoxic‐ischemic encephalopathy (HIE) during the neonatal period, which is presumed to be etiologic. Patients and Methods: Clinical records of 1,295 outpatients, whose first visit to our hospital was between November 1989 and October 1994, and who were under our care at the time of this study, were reviewed. Patients were selected who satisfied all of the following criteria for possible incidence for HIE. (a) gestational age was >38 weeks; (b) at least one of the following: incidence of meconium aspiration, a low Apgar score (<5 at 1 min), a neonatal asphyxia manifested as prolonged insufficient respiration or cyanosis, or recurrent apneic attacks; and (c) medical treatment such as artificial ventilation or oxygen inhalation. Patients transferred to a neonatal intensive care unit or a pediatrician were included even if the details of the medical care were not available. Patients who had other causative disorders for their epilepsy, such as encephalitis and traumatic brain injury after the neonatal period, were excluded. The epilepsies were classified according to the criteria presented by the International League Against Epilepsy. Simultaneous video‐EEG recordings were available for 15 patients. Results: Twenty‐two (18 male and four female) patients, whose mean age was 18.0 years at the time of this study, satisfied the criteria described. Their mean age at the onset of epilepsy was 5.6 years, They had been diagnosed as having meconium aspiration syndrome in two patients, low Apgar score in five, neonatal asphyxia at birth in 14, and apneic attacks on the day after birth in one. For respiratory insufficiency, they received artificial respiration (four cases) or resuscitation other than artificial respiration (nine cases); nine patients were transferred to a neonatal intensive care unit or a pediatric unit. Convulsions were observed in seven patients during the neonatal period. At the time of their first visit, quadriplegia (four cases), hemiplegia (five cases), defects in the visual fields (two cases). and difficulty in hearing (one case) were observed. In 20 patients, their intellectual quotient was <70, and in four of them, it was <30. Based on neuroimaging, 21 patients had apparent abnormalities: bilateral and diffuse (five cases), bilateral but predominantly unilateral (three cases). bilateral parietooccipital (three cases). and unilateral parietooccipital (LO cases). Two (9%) patients were diagnosed as having symptomatic generalized epilepsy with tonic seizures and the remaining 20 (91%) as having symptomatic partial epilepsy. In the latter cases, 10 patients had visual symptoms and an additional one had conjugated eye deviation during the initial phase of the seizure. These 11 (55%) patients showed occipital spikes in their interictal EEGs and were diagnosed as having occipital lobe epilepsy (OLE). One patient who was diagnosed as having parietal lobe epilepsy had sensory symptoms in his right arm. The interictal EEGs revealed bilateral independent anterior temporal spikes. One patient had autonomic sensations with right anterior temporal interictal spikes and was diagnosed as having temporal lobe epilepsy. In six patients, the epileptogenic areas were not determined electroclinically. In 20 patients, seizures haw not been controlled. Sixteen of them have tonic, complex partial, or secondarily generalized tonic‐clonic seizures more than once a month. Conclusions: Most of our patients whose history suggested an incidence of HIE during the neonatal period have intractable symptomatic partial epilepsy. In SS% of patients, epileptogenic areas are believed to be located in the occipital lobe. In addition to our finding that patients with OLE have a greater incidence of perinatal difficulties than do those with temporal or frontal lobe epilepsy, this study suggests that the occipital lobe is more likely than the other lobes to become epileptogenic as a consequence of hypoxic insults.

Effects of Playing Videogames on Paroxysmal Activities in Patients with Localization‐Related Epilepsy

Purpose: Although several articles suggested that videogames can induce seizures, little is known about the mechanism of videogame‐induced seizures. We investigated the effects of playing videogames on paroxysmal activities in the patients who were undergoing invasive long‐term EEG/video monitoring for surgical treatment. Methods: Twenty patients (mean age, 23.8 years) with localization‐related epilepsy who were undergoing invasive long‐term EEG/video monitoring were investigated. Seven of them had frontal lobe epilepsy, 12 had temporal lobe epilepsy, and one had occipital lobe epilepsy. None of them had either photosensitivity or a history of videogame‐induced seizures. Subdural electrodes and depth electrodes were implanted (mean number of electrodes, 114.5) for surgical treatment. The recordings were made with a 64‐channel EEG. EEG was recorded while sitting with open eyes for 1 h (control) and while playing videogames for 1 h. The number of interictal discharges (IIDs) in every electrode for 1 h were counted (Nippon Koden, Monitor Spike Detection). We investigated whether playing videogames induced an increase of IIDs of >50% or a decrease of IIDs of <50% compared with the controls. Results: Frontal lobe epilepsy (seven patients): An increase in the IIDs was observed at the epileptic focus (one patient), surrounding the epileptic focus (five patients) and at the mesial frontal lobe (four patients). Temporal lobe epilepsy (12 patients): An increase in the IIDs was observed at the epileptic focus (four patients), surrounding the epileptic focus (10 patients), and a decrease in the IIDs was observed at the parietal lobe (seven patients). Almost all patients spent a lot of time playing videogames. Among the 20 patients, five patients (two patients with frontal lobe epilepsy and three patients with temporal lobe epilepsy) had seizures while playing videogames apart from their EEG recording for the IIDs study. Electroclinical observations indicated that these seizures were identical with their habitual seizures. These five patients did not show any difference in pattern of IIDs compared with the other patients. Considering these results and that all of the five patients had no history of videogame‐induced seizures, we thought that the seizures occurring while playing videogames were not induced by videogames. Conclusions: We investigated the effects of playing videogames on paroxysmal activities in patients who had no history of videogame‐induced seizures with intracranial EEG. Playing videogames induced an increase in the IIDs at the epileptic focus, surrounding epileptic focus, and mesial frontal lobe, whereas playing videogames induced a decrease in the IIDs at parietal lobe. These findings indicated that playing videogames had some effects on the cortical function. Because changes of IIDs were not related to the occurrence of seizures and the seizures occurring while playing videogames were identical to habitual seizures, we thought that playing videogames had little effects on epileptogenicity.

Awareness and responsiveness during partial seizures.

We examined the impairment of consciousness during partial seizures (PS) arising from various brain sites according to the operational definition of the international classification, i.e., altered awareness and/or responsiveness. The subjects were 142 patients who underwent intracranial EEG evaluation and subsequent resective surgery. First, the patients were examined to determine whether they usually had been partially or completely aware of their seizures. Second, spontaneous habitual seizures that had been videotaped with simultaneous intracranial EEG recording were reviewed to determine responsiveness and recall during ictal behavioral alterations. In all, 114 patients were partially or completely aware of their seizures. Patients who tended not to be aware of their seizures were those with frontal lobe epilepsy (FLE) with extensive epileptogenic regions on the language nondominant side and those with temporal lobe epilepsy (TLE) with seizure origin in the lateral cortex of the language dominant side. Of the 21 patients with FLE, 88 with TLE, and 4 with occipital lobe epilepsy, 7, 22, and 2 patients responded to stimuli during the seizure, respectively, but only 11 of the patients with FLE and none of the other patients could recall the stimuli applied during the behavioral alterations. Bilateralization of seizure discharges correlated with impaired responsiveness. According to the International Classification, about half of patients with FLE had only simple partial seizures (SPS) and the other patients had complex partial seizures (CPS). Altered awareness and/or responsiveness occurred in most habitual partial seizures in our subjects. The term "complex" appears to be useful in clinical practice, although the contents of ictal behavior and the site or side of seizure origin are not implied.

Symptomatic occipital lobe epilepsy.

Symptomatic occipital lobe epilepsy is increasingly recognized among patients with partial-onset seizures. Although traditional clinical and electroencephalographic criteria had defined occipital lobe epilepsy in the past, new neuroimaging techniques and the recognition of specific syndromes associated with occipital lobe epilepsy have improved the diagnosis and management of these patients. These syndromes include, among others, lesional occipital lobe epilepsy (congenital vs. acquired), MELAS, and epilepsy with bilateral occipital calcifications. The diagnosis of symptomatic occipital lobe epilepsy is improving as functional and structural neuroimaging techniques enable the detection of subtle abnormalities in such patients. This has had a direct impact on the correct classification of patients with benign occipital lobe epilepsy, basilar migraine, and symptomatic occipital lobe epilepsy. The common clinical symptoms, EEG patterns, and neuroimaging findings of these patients are discussed.

Coeliac disease and epilepsy.

Whether there is an association between coeliac disease and epilepsy is uncertain. Recently, a syndrome of coeliac disease, occipital lobe epilepsy and cerebral calcification has been described, mostly in Italy. We measured the prevalence of coeliac disease in patients attending a seizure clinic, and investigated whether cerebral calcification occurred in patients with both coeliac disease and epilepsy. Screening for coeliac disease was by IgA endomysial antibody, measured by indirect immunofluorescence using sections of human umbilical cord. Of 177 patients screened, four patients were positive. All had small-bowel histology typical of coeliac disease. The overall frequency of coeliac disease in this mixed patient sample was 1 in 44. In a control group of 488 pregnant patients, two serum samples were positive (1 in 244). Sixteen patients with both coeliac disease and epilepsy, who had previously attended this hospital, were identified. No patient had cerebral calcification on CT scanning. Coeliac disease appears to occur with increased frequency in patients with epilepsy, and a high index of suspicion should be maintained. Cerebral calcification is not a feature of our patients with epilepsy and coeliac disease, and may be an ethnically-or geographically-restricted finding.

Seizure semiology of occipital lobe epilepsy in children.

Occipital lobe epilepsy in children occurs as an idiopathic form, i.e., Benign Epilepsy with Occipital Paroxysms (BEOP), and a symptomatic form. This study attempted to determine whether seizure semiology could distinguish between the two forms. Fifty children (34 boys, 16 girls) with clinical seizures and interictal EEGs presenting occipital spikes were included consecutively in the study. Seizure onset was between the ages of 2 months and 15 years. Epilepsy was considered symptomatic when psychomotor retardation and/or abnormalities at neurological and/or neuroradiological examination were found: 17 children were classified as idiopathic, and the remaining 33 children were classified as symptomatic. Seizure semiology was assessed by means of a structured interview of the children and their parents, using a detailed questionnaire. Seizure semiology was determined to comprise motor (versive or other movements of the eyes, versive movements of the head, (hemiconvulsions), visual, other signs (e.g. vomiting and headache), and impairment of consciousness. There were no statistically significant differences in seizure semiology between the two groups. Seizure semiology cannot distinguish between different forms of occipital lobe epilepsy: Further clinical examination, clinical neurophysiological investigations, and neuroimaging studies are needed for a correct classification.

Occipital lobe developmental malformations and epilepsy: clinical spectrum, treatment, and outcome.

Cortical developmental malformations (CDM) are increasingly recognized in association with epilepsy. We describe 10 patients (age range 14-35 years) with symptomatic occipital lobe epilepsy and CDM. Neurologic, neuroophthalmologic and electrophysiologic studies were performed. Patients had MRI, SPECT, and in some cases intracranial EEG investigators. Mean age of seizure onset was 8 years. We noted strong correlations between the presence of visual auras, the scalp EEG pattern, and the subtype of underlying pathology. Magnetic resonance imaging (MRI) showed CDM in all patients, with polymicrogyria and focal dysplasia being the most frequent malformations. Despite the presence of occipital lobe structural malformations in all patients, visual field deficits were present in only 2. Those who underwent cortical resections were seizure-free or showed major improvement at a mean follow-up of 3.5 years. Intracranial stimulation studies and the low frequency of pre- and postoperative deficits suggest that some degree of cortical visual reorganization may occur in patients with occipital lobe malformations. Occipital lobe CDM should be sought as a cause of symptomatic occipital lobe epilepsy even though they may become symptomatic after childhood.

Ictal amaurosis

We studied seven consecutive patients who experienced amaurosis as a prominent feature of their seizures. The mean age of seizure onset was 4 years. Six patients had MRI abnormalities including ischemic, traumatic, and space-occupying lesions, with five limited to the parietal-occipital region. Six patients had unilateral, posterior interictal spike and slow wave complexes. Four patients experienced severe postictal headache and nausea. Absence of a family history of seizures distinguished the patients with MRI lesions from previously presented series of benign occipital lobe epilepsy. We conclude that the constellation of ictal amaurosis, occipital paroxysms, and postictal migrainous symptoms does not necessarily signify a benign, nonlesional epilepsy; MRI is recommended for such patients without a family history of similar seizures.

Occipitotemporal epilepsies: evaluation of selected patients requiring depth electrodes studies and rationale for surgical approaches.

In 8 patients in whom it was uncertain whether they had occipital or temporal lobe (TL) epilepsy, clinical, scalp EEG, and radiologic features were correlated with the sites of seizure onset as determined by depth EEG. The 8 patients were selected from > 40 with occipital epilepsy because they had (a) an aura considered to be of occipital lobe (OL) origin, (b) an occipital interictal epileptic focus, (c) an OL lesion, or (d) a combination of all of these. Scalp EEG and clinical patterns suggested temporal involvement in all, however. Extracranial EEG recordings were often misleading, showing multilobar interictal epileptic abnormalities, and seizure onset was of poor localizing value and did not clarify the problem sufficiently. Intracranial EEG recordings showed that seizure onset could be ordered along an occipitotemporal gradient. Consistent OL seizure onset was observed in patients who had only elementary visual auras. Those who had inconsistent aura or no aura, suggesting OL origin, had onset of most attacks in the TL. All patients had a seizure spread pattern suggesting early TL involvement. To prevent visual field defect, surgical approaches included temporal resection when temporal seizure origin or spread was demonstrated; although occasionally this produced excellent results, it was of limited benefit in most patients, even when some seizures were proven to originate in TL structures. In patients with malignant epilepsy and in those with an occipital lesion, occipital resection should be considered.

The results of the surgical treatment of occipital lobe epilepsy.

Out of 502 patients with surgically treated drug-resistant chronic epilepsy (tumour cases excluded) in 12 (2%) a clear occipital focus was found. The pattern of seizures was in most cases nonspecific and polymorphic. EEG examination and neuroradiological findings led to proper localization of the epileptogenic focus. Partial or total occipital lobectomy was performed. Follow-up from 4 to 20 years revealed a satisfactory result in 11 of the surgical cases. One patient was lost to follow-up. Brain scarring was found in the histological examination of specimens in 9 out of 12 patients. The results of the surgical treatment of occipital lobe epilepsy are much better than in other localizations of epileptogenic foci.

Ellen R. Grass Guest Lecture: Epileptic Syndromes: A Remarkable Contribution of EEG to Epileptology

ABSTRACT.Epileptic syndromes represent a new way of looking at epileptological diagnostic entities. These syndromes transcend the realm of seizure types and constitute special clinical conditions which depend largely on age and genetic predisposition (notwithstanding the frequent occurrence of associated structural lesions). Epileptic syndromes without structural pathology tend to be benign: primary generalized epilepsy, benign rolandic epilepsy, benign occipital lobe epilepsy, and others. West syndrome and especially the Lennox-Gastaut syndrome exemplify severe forms of epileptic seizure disorder.Diagnosis and differential diagnosis of epileptic syndromes depend heavily on the correct interpretation of the EEG findings. Thus, this modern segment of epileptology is not thinkable without solid EEG diagnosis. The differentiation of these syndromes is highly pragmatic (and by no means merely academic): these differentiations result in much better understanding of benign and severe seizure disorders and permi...

Occipital lobe epilepsy: electroclinical manifestations, electrocorticography, cortical stimulation and outcome in 42 patients treated between 1930 and 1991. Surgery of occipital lobe epilepsy.

Our study documents the clinical and electrographic findings in 42 patients with medically refractory occipital lobe epilepsy, who underwent surgery at the Montreal Neurological Institute between 1930 and 1991, and the evolving manner in which those patients were studied by successive generations of investigators. In more than two-thirds of the patients the clinical manifestations indicated the occipital onset of the seizures. Seventy-three percent experienced visual aurae, of which elementary hallucinations were the most common and 12 also had ictal blindness. Other occipital manifestations included: contralateral eye deviation, blinking, a sensation of eye movement and nystagmoid eye movements. Intra-operative cortical stimulation elicited a habitual aura in 37% of 29 patients. Lateralizing clinical features were seen in almost two-thirds of patients: contralateral head deviation occurred in half, 59% had visual field defects contralateral to the epileptogenic area and 64% had abnormal imaging studies ipsilateral to the side of surgery. More than one-third of patients exhibited more than one seizure type, suggesting ictal spread to temporal or frontal lobe: 50% had typical temporal lobe automatisms, and 38% exhibited focal motor seizure activity. Surface electroencephalogram (EEG) recordings showed posterior temporal-occipital epileptiform discharges in 46% of patients. Only 18% had electronegative spiking limited to 01 or 02. Large epileptogenic areas were often found on intracranial recording with depth electrodes and on electrocorticography. Pre-excision electrocorticography spiking was restricted to the occipital lobe in only 13 out of 34 patients. More often spiking also involved the posterior temporal and posterior parietal regions. Twenty-three patients underwent only occipital resections; five had only temporal resections, so as to preserve the visual fields, and the remaining 14 patients had extensive resections, which included the posterior temporal or posterior parietal regions. A follow-up period of 1 to 46 yrs (mean 17 yrs) was available for 37 patients. Forty-six percent became seizure free and 21% had a significant reduction in seizure frequency. A better outcome was observed in those patients in whom there was no post-resection electrocorticographic or surface EEG epileptiform discharge, or who exhibited an occipital lobe lesion.

Occipital lobe epilepsy: clinical characteristics, seizure spread patterns, and results of surgery.

Twenty-five patients with occipital lobe seizure origin were retrospectively evaluated to determine clinical seizure characteristics and electroencephalographic manifestations. Certain symptoms and signs served to identify occipital lobe origin in 22 (88%). These included elementary visual hallucinations, ictal amaurosis, eye movement sensations, early forced blinking or eyelid flutter, and visual field deficits. Eye or head deviation, or both, was observed frequently and was contralateral to the side of seizure origin in 13, but 3 patients exhibited ipsilateral deviation in some or all their seizures. After the initial signs and symptoms, clinical seizure characteristics resembled those of seizures originating elsewhere. Seizures typical of temporal lobe origin with loss of contact and various types of automatic, semipurposeful activity occurred in 11 patients. Seizures in 3 patients exhibited asymmetrical tonic or focal clonic motor patterns characteristic of frontal lobe seizures. Eleven of the 25 patients had, on two occasions, two or more distinctly different seizure types. Scalp electroencephalographic findings were seldom helpful for occipital lobe localization and were frequently misleading. Intracranial electroencephalographic recording correctly identified occipital lobe seizure origin in most, but not all, patients who had such studies. Intracranial electroencephalic recording also proved the variability in clinical seizure characteristics was related to different seizure spread patterns, medially or laterally above and below the sylvian fissure, both ipsilateral and contralateral to the occipital lobe of seizure origin. Eighteen patients had occipital lobe lesions detected with computed tomographic or magnetic resonance imaging scans or both. Resection of the lesions in 16 patients produced excellent results in 14 (88%). Five patients had temporal lobectomies, with good results in 3, but poor results in 2. Two patients with unlocalized seizures had complete section of the corpus callosum, 1 with a good result and the other with a poor result.

Imaging of Propagated Sites of Epileptic Discharges in Repeated <sup>123</sup>I-IMP SPECT Scans

Single-photon emission computed tomographic (SPECT) brain scans with N-isopropyl-(iodine-123-p-iodoamphetamine (123I-IMP) were performed twice at an interval of about 2.5 years in the interictal period in an adult patient with occipital-lobe epilepsy. The first SPECT scan showed an abnormal image of decreased 123I-IMP uptake in the right occipital lobe. This abnormal image was regarded as the primary focus of his epilepsy on the basis of its regional agreement with right-occipital spikes consistently seen in interictal electroencephalographic recordings throughout his clinical history. In the second scan, he showed multiple abnormal images of decreased uptake in the right frontotemporal lobes and left occipital lobe together with the right occipital lobe. These additional abnormal images were considered to be propagated sites of epileptic discharges.

Epileptic activity of the occipital lobe. Clinico-electroencephalographic contribution

Our analysis of the course of illness in 14 patients, whose common electroencephalographic characteristic was epileptogenic activity in the occipital area, showed very different clinical symptoms. The first group comprised patients who presented bilateral amaurosis. In four of these cases, the occipital hypersynchronous EEG activity was merely a secondary symptom of either ischaemic hypoxia or of a degenerative process in the occipital visual cortex and was not responsible for the genesis of the actual blindness. In two further cases of monosymptomatic temporary loss of vision, it was difficult to make a differential diagnosis between ictal blindness, respectively status epilepticus amauroticus occurring in a occipital lobe epilepsy and a migraine attack involving the basilar territory. The second group comprised five patients with paroxysmal visual hallucinations respectively illusions. Three of them suffered from hallucinations of the elementary type, respectively flickering fits in the hemianopic field, symptoms which are based on discharges in the visual cortex of the occipital lobe. In a case of one patient with complex visual hallucinations as well as in a further case with visual illusions, it was not possible to find out with certainty their place of origin. A study of these cases shows that the cortical or sub-cortical functional disturbance within the visual system causing the various optical deformations and visual hallucinations, form an inhomogeneous group with different etiology. In the only patient belonging to the third group, whose seizures were i.a. characterized through motor phenomena in the field of the ocular organs and the tonic lateral turning movement of the bulbi of the eyes and of the head, an occipital epileptic crisis with spread of discharges from the occipital pole to the frontomesial surface should be assumed. The occurrence of complex partial seizures, respectively generalized tonic-clonic attacks in two patients of the fourth group who have definite epileptogenic EEG-activity in the occipital area, can be explained by a propagation of paroxysmal activity to the temporal lobe or to the motor cortex. Because of the marked tendency to propagation of the hypersynchronous activity originating in the occipital lobe, many combinations of sensory and/or motor symptoms can occur within the frame-work of occipital epileptic seizures. On the basis of one scalp EEG finding, no final localizing conclusions may be drawn here.

Benign occipital lobe epilepsy

Benign occipital lobe epilepsy (BOLE) represents a recently delineated form of epileptic seizure disorder. It occurs in children, adolescents, and young adults. The seizures are mostly of visual character with elementary or complex hallucinations, but nonvisual seizures also occur. The EEG usually shows runs of posterior slow spike-wave complexes interictally or during ictal episodes. Migrainelike headache may occur after the seizures and there are certain relationships between BOLE and migraine, but a line must be drawn separating these two conditions. Six typical cases are presented; diagnostic features, differential diagnosis, and possible underlying mechanisms are discussed.