Pattern-sensitive Epilepsy Research Articles

From working memory to epilepsy: Dynamics of facilitation and inhibition in a cortical network

Persistent states are believed to be the correlate for short-term or working memory. Using a previously derived model for working memory, we show that disruption of the lateral inhibition can lead to a variety of pathological states. These states are analogs of reflex or pattern-sensitive epilepsy. Simulations, numerical bifurcation analysis, and fast-slow decomposition are used to explore the dynamics of this network.

Do tinted spectacle lens wearers have a different personality?

The wearing of tinted spectacle lenses is considered by some health care workers to be a marker of psychopathology or a hypochondriacal personality type. The purpose of this study was to determine whether there is a relationship between the wearing of tinted spectacle lenses and personality type in physically healthy subjects. The Sixteen Personality Factor Questionnaire 5th Edition, a multidimensional standardized self-report inventory, was used to determine the personality type of 98 participants. Twenty currently wore tinted spectacle lenses for reasons other than ocular disease, sun protection, outdoor or indoor glare reduction, pattern sensitive epilepsy, migraines, reading difficulties or fashion. The remainder did not wear tinted spectacle lenses for any purpose other than sun protection. Tinted lens wear and no tinted lens wear groups were age and gender matched. There was no statistically significant difference in five global personality factors between the no-tint and tint groups: extraversion (p = 0.31), anxiety (p = 0.75), tough-mindedness (p = 0.96), independence (p = 0.63), and self-control (p = 0.87). This suggests that the use of tinted lenses by physically healthy people is unlikely to be an indicator of personality type.

Long‐Term Outcome of Pattern‐Sensitive Epilepsy

To evaluate the long-term outcome of patients with pattern-sensitive epilepsy. We prospectively studied 35 patients (21 females and 14 males) with pattern-sensitive epilepsy (follow up > or = 5 years; mean 13.9; range 6.4 - 27.6). All cases had regular clinical examinations and serial electroencephalographic (EEG) recordings. Photosensitivity and pattern sensitivity were ascertained neurophysiologically in all cases. Outcome was evaluated according to the following variables: duration of photosensitivity, rate of remission (seizure-free period > or = 2 years), withdrawal of therapy, and recurrence after drug discontinuation. The epilepsy was generalized in 18 cases (17 idiopathic, one symptomatic) and partial in 17 (13 idiopathic, four symptomatic). Sixteen patients (46%) had a family history of seizures. The mean age at the last examination was 21.4 years (range 11.2-35.5 years). Five patients (14%) had only reflex seizures. The most common type of spontaneous seizures was generalized (60%), whereas reflex seizures were more frequently partial (74%). Mean epilepsy duration was 8.7 +/- 6.3 years. Patients with only reflex seizures were instructed to avoid precipitating stimuli and were not treated with antiepileptic drugs. Treatment was gradually withdrawn in 10 out of 30 treated patients, with relapse in only two cases. At the end of follow up, 28 patients (80%) were seizure-free. The long-term outcome of patients with pattern-sensitive epilepsy indicates a good prognosis with a favorable course for both spontaneous and reflex seizures.

Pattern-Sensitive Epilepsy

The clinical and electroencephalographic (EEG) findings of 73 (43 female and 30 male) patients diagnosed with pattern-sensitive epilepsy between 1950 and 1999 were evaluated at the Mayo Clinic, Rochester, MN.

Pattern‐sensitive Epilepsy: Electroclinical Characteristics, Natural History, and Delineation of the Epileptic Syndrome

To elucidate the electroclinical features and long-term outcome of patients with pattern-sensitive epilepsy. We reviewed the clinical and electroencephalographic (EEG) findings of 73 (43 female and 30 male) patients in whom pattern-sensitive epilepsy was diagnosed at Mayo Clinic (Rochester, Minnesota, U.S.A.) from 1950 through 1999. We contacted patients and their relatives by letter or telephone to obtain the latest seizure and quality-of-life outcomes. The median age at onset of seizures was 12.8 years (range, 0.6-32.9 years). Most patients had absence, myoclonic, or generalized tonic-clonic seizures. Interictal epileptiform discharges in the EEG were detected in 61 (83.6%) patients and were generalized in 54 (74%). Paroxysmal epileptiform discharges in the EEG elicited with standard patterns were all generalized in two thirds of patients but were restricted to the posterior head region in one-third. Eight (11%) patients did not exhibit photosensitivity. Television was the most common precipitant [30 patients (41%)]. Twenty-nine patients gave a clear history of one or more seizures precipitated while viewing environmental patterns such as window screens, garments, tablecloths, and ceiling tiles; the rest of the patients admitted that they preferred to avoid looking at patterned objects because these objects made them uncomfortable. The electroclinical features suggested juvenile myoclonic epilepsy in 14 patients, progressive myoclonus epilepsy in three, progressive familial cerebellar ataxia with myoclonus in two, and severe myoclonic epilepsy of infancy in one. During a median follow-up period of 15.7 years, 25 (45.5%) of 55 patients who were followed up for > or =5 years achieved complete seizure remission. The median age at remission was 24.4 years. The absence of progressive neurologic disease was correlated significantly with remission; a family history of seizures showed a trend in favor of remission. More than two thirds of the patients did not consider the seizures an impediment to their family life or to educational and occupational achievements. Although pattern sensitivity as a trait occurs in various epileptic syndromes, pattern-sensitive epilepsy is a readily distinguishable subtype of the visually provoked reflex epilepsies. In our opinion, the location and extent of the excitable region or regions within the visual cortex concerned with different attributes of visual function dictate susceptibility to a specific trigger (intermittent light, pattern, or color) or closely related multiple triggers and the resultant electroclinical phenomenon.

Half a Century of Visual Pattern-Sensitive Epilepsy

Half a Century of Visual Pattern-Sensitive Epilepsy

The Effect of Television Frame Rate on EEG Abnormalities in Photosensitive and Pattern‐Sensitive Epilepsy

EpilepsiaVolume 39, Issue 4 p. 453-453 Free Access The Effect of Television Frame Rate on EEG Abnormalities in Photosensitive and Pattern-Sensitive Epilepsy F. Fylan, F. FylanSearch for more papers by this authorG. F. A. Harding, G. F. A. HardingSearch for more papers by this authorTimothy A. Pedley M.D., Timothy A. Pedley M.D. Editor-in- Chief Search for more papers by this author F. Fylan, F. FylanSearch for more papers by this authorG. F. A. Harding, G. F. A. HardingSearch for more papers by this authorTimothy A. Pedley M.D., Timothy A. Pedley M.D. Editor-in- Chief Search for more papers by this author First published: 03 August 2005 https://doi.org/10.1111/j.1528-1157.1998.tb01403.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume39, Issue4April 1998Pages 453-453 RelatedInformation

The relationship between television frame rate and EEG abnormalities in patients with photo and pattern sensitive epilepsy

The relationship between television frame rate and EEG abnormalities in patients with photo and pattern sensitive epilepsy

Pattern‐Sensitive Epilepsy: Genetic Aspects in Two Families

We report two families in which five members (three in one and two in the other) suffer from pattern-sensitive epilepsy. In all affected members seizures were induced by environmental visual patterned stimuli. Diagnosis was confirmed by neurophysiological studies, including EEG with pattern and intermittent light stimulation and visual evoked potentials. The role of genetic aspects and the relationship between this form of reflex seizures and photosensitive epilepsy are emphasized.

Self‐Induced Pattern‐Sensitive Epilepsy in Childhood

We studied five children (1 boy and 4 girls) with self-induced pattern-sensitive epilepsy. All patients had refractory epilepsy with multiform, though mainly myoclonic, seizures and medium grade to severe mental retardation. Spontaneously self-induced seizures were documented in all cases by EEG. All the patients underwent full neurophysiological assessment (baseline EEG recording, with activation: eyelid closed, hyperventilation, ILS, EEG during the randomized presentation of 3 types of spatial structured stimuli, VEP-F and VEP-PR). The pattern that triggered the EEG anomalies was highly specific and selective for each patient. Clinical seizures were reproduced by the same patterns as the ones used by the patients to bring on the seizures at will. Authors stress the importance of identifying such peculiar type of epilepsy and of attempting adequate treatment.

Dopamine agonist treatment of self-induced pattern-sensitive epilepsy. a case report

Abusing his own pattern sensitivity, a mentally retarded boy displayed frequent self-induced seizures resistant to conventional anticonvulsive treatment. Bromocriptine and fenfluramine have been successful in terminating self-induced seizures by means of blocking the photosensitive triggering mechanism. Secondary to this effect, the pathological drive toward seizures diminished. The possible mechanism of action has been discussed briefly.

EEG characteristics of epileptic pattern sensitivity and their relation to the nature of pattern stimulation and the effects of sodium valproate

Seven patients with pattern-sensitive epilepsy were examined repeatedly over a period of 4–12 months during which the dose of sodium valproate was adjusted. Patterns were presented in series in which the size of successive patterns was progressively increased until paroxysmal activity appeared, or until the largest pattern (radius 24° visual angle) had been presented. As valproate dose increased, paroxysmal activity was less likely to occur. When it did occur it was less likely to include a spike; it had a lower voltage, involved fewer electrodes, and lasted a shorter time. The size of the pattern just sufficient to induce paroxysmal activity showed relatively little change with valproate dose. The degree to which the various electrodes were involved in the discharges showed considerable stability. The paroxysmal response to patterns presented in one visual half-field was almost invariably maximal over the contralateral posterior quadrant, usually at the posterior temporal electrode.

Seizures induced by thinking

A patient with generalized convulsions noted that seizures were reliably precipitated by mental arithmetic. The interictal electroencephalogram revealed only a mild, diffuse, nonspecific disturbance, but bursts of generalized epileptiform activity with no obvious clinical expression accompanied efforts at mental arithmetic with a significantly high incidence. Tasks involving multiplication, division, and manipulation of spatial information were significantly associated with discharges, but few, if any, discharges appeared when addition and subtraction tasks of equivalent difficulty were performed. Tasks involving the retention of numerical information in short-term memory (e.g., immediate repetition of a series of 8 digits) were never associated with paroxysmal EEG activity. It is argued that generalized epilepsy of this kind may be related to focal dysfunction in a manner analogous to the involvement of the occipital lobe in cases of pattern-sensitive epilepsy.

Pattern‐Sensitive Epilepsy. I: A Demonstration of a Spatial Frequency Selective Epileptic Response to Gratings

Rare individuals suffer epileptic seizures when they view certain images, particularly stripes. Contrast-threshold functions (the ability to see faint stripes of various widths) were determined for two pattern-sensitive brothers, and the epileptogenicity of various patterns was assessed for one of them. Sine wave grating contrast-detection thresholds for the two subjects were essentially normal, with lowest thresholds at approximately 2 cycles/degree (c/deg). Epileptiform discharges occurred maximally at 5 c/deg with a 1-octave 50% bandwidth. Pattern epileptogenicity was increased by the addition of a third harmonic sine wave grating to its fundamental, but was unaffected by the phase relation of the two gratings. The frequency selectivity of epileptic responsiveness was quantitatively similar to a "spatial frequency channel." Inhibitory interaction were not present. The findings suggest relations between the phenomena of pattern-sensitive epilepsy and hypothesized spatial frequency channels which merit further exploration.

Case report: responses to stripe width changes and to complex gratings of a patient with pattern-sensitive epilepsy

A pattern-sensitive subject's ability to see faint gratings of several different stripe widths (spatial frequencies) was essentially normal, with the greatest sensitivity occurring for gratings with 2 cycles of light and dark stripes per degree of visual arc (c/deg). Epileptiform discharges, however, occurred maximally at a narrower stripe width, 5 c/deg. The 50% bandwidth of the epileptic response was approximately one octave, which is similar to postulated ‘spatial frequency channels’ in the visual system. Hypothesized inhibitory interactions between the 5 c/deg grating and a 15 c/deg grating were not observed.

Self-induced Pattern-Sensitive Epilepsy

A case of self-induced pattern-sensitive epilepsy was observed in a 13-year-old girl. This case resembles those of patients who induce seizures in themselves by light stimulation. The close relationship between photosensitive and pattern-sensitive epilepsy is emphasized.