Photosensitivity is reported to occur in approximately 40% of patients with juvenile myoclonic epilepsy. Our experience suggests that the prevalence is higher and may be related to both the duration of intermittent photic stimulation and also the age at which the procedure is undertaken. A two-year retrospective review of all EEGs was undertaken on all children attending a paediatric EEG department to identify those with juvenile myoclonic epilepsy. Photosensitivity was defined as a generalized spike or spike-wave paroxysm occurring at least twice during intermittent photic stimulation. Sixty-one children with a diagnosis of juvenile myoclonic epilepsy with a median age of 13 (range 7-16) years were identified, 55 (90%) of whom were photosensitive. Eighteen of these 55 patients showed photosensitivity only after four minutes of continuous photic stimulation. The prevalence of photosensitivity in juvenile myoclonic epilepsy is likely to be higher than previously reported. When a diagnosis of juvenile myoclonic epilepsy is being considered, the initial diagnostic EEG should include intermittent photic stimulation for up to five minutes, or less if the patient shows evidence of photosensitivity. The identification of photosensitivity may have important management implications.
A persistent focal abnormality was observed in 157 (16%) electroencephalograms undertaken in 964 consecutive children with epileptic and non-epileptic seizures seen over one year. CT head scans were performed in 121 (77%) of the 157 children with a focus on the EEG; 26 (21%) showed an abnormality, and 21 (81%) of the abnormalities were localised. There was no difference in the proportion of abnormal scans associated with a delta or slow wave focus compared with a spike or sharp wave focus. An abnormal scan was uncommon after a single seizure. In only two patients (1.7% of all scans) did the findings on CT alter or greatly influence subsequent management. ( Neurol Neurosurg Psychiatry 1993;56:369-37 Scans were performed with a third generation Siemens Somatrom 2 scanner before and after intravenous contrast and with specific views of the temporal lobes. Records showing symmetric, posterior slow waves of youth, bilateral multifocal abnormalities, and asymmetry of background rhythmic activity (without any focal abnormality) were excluded from the study. Reactiveness of the focal slow wave abnormality was not assessed.Statistical analysis of the CT and EEG appearances used the X2 test. Repeat or follow up EEGs were undertaken in about a quarter of subjects but these data have not been analysed in this report. ResultsEEGs were recorded in 964 consecutive patients, aged 2 months to 17 years (mean 8 years). A total of 182 patients had had a single witnessed seizure; the remaining 782 patients had had at least two seizures. It was difficult to ascertain what proportion of these 782 patients had epilepsy as they were not all under the care of the authors and clinical information was therefore limited. However, at least 530 were considered to have epilepsy.The records showed a continuous, persistent, or recurring focal abnormality in 157 patients (16%), of which 83 were slow waves and 74 were spike or sharp wave foci. Three of the 157 patients showed both a slow wave and epileptiform focus. CT head scans were performed in 121 of the 157 patients (77%) with an EEG focus. CT was not recommend-369 on 12 May 2018 by guest. Protected by copyright.
This audit evaluated the role and usefulness of ambulatory cassette EEG recordings without simultaneous video monitoring in children with paroxysmal episodes including epilepsy. Fifty-four children underwent ambulatory EEG recordings for 48 hours over a 12 month period. Only 31 of the 54 children experienced one of their typical clinical episodes during their recordings. Fifteen of these 31 patients were considered to have epilepsy, only three of whom had a clinical episode at the time of their recording and in all three the EEG demonstrated abnormal (generalized spike and slow wave or focal, rhythmic slow wave) activity. All 10 patients who were considered to have non-epileptic episodes showed no electrical change during their EEG recordings. The results of the ambulatory cassette EEG recordings were considered to have been helpful and to have contributed to the management of only 17 (31%) of the 54 patients in this audit. Stricter clinical criteria for undertaking ambulatory recordings and improved technology are likely to increase the role and usefulness of this procedure.
The practical value or usefulness of any investigation is dependent upon the clinical information provided and subsequent interpretation; this is particularly important in the investigation and classification of the epilepsies. For two months the histories from clinicians and EEG technicians were prospectively evaluated from 255 consecutive patients. The histories were interpreted by a single paediatric neurologist who was blinded to their origin. The histories were reported as "adequate' or "inadequate', and "diagnostic' or "non-diagnostic' (of epilepsy). Overall 92% and 40% of technicians' and 41% and 13% of clinicians' histories were considered to have been "adequate' and "diagnostic', respectively. These results have implications for the electro-clinical interpretation of the EEG.
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