Jaime Parra

Methodology of photic stimulation revisited: Updated European algorithm for visual stimulation in the EEG laboratory

Intermittent photic stimulation (IPS) is a common procedure performed in the electroencephalography (EEG) laboratory in children and adults to detect abnormal epileptogenic sensitivity to flickering light (i.e., photosensitivity). In practice, substantial variability in outcome is anecdotally found due to the many different methods used per laboratory and country. We believe that standardization of procedure, based on scientific and clinical data, should permit reproducible identification and quantification of photosensitivity. We hope that the use of our new algorithm will help in standardizing the IPS procedure, which in turn may more clearly identify and assist monitoring of patients with epilepsy and photosensitivity. Our algorithm goes far beyond that published in 1999 (Epilepsia, 1999a, 40, 75; Neurophysiol Clin, 1999b, 29, 318): it has substantially increased content, detailing technical and logistical aspects of IPS testing and the rationale for many of the steps in the IPS procedure. Furthermore, our latest algorithm incorporates the consensus of repeated scientific meetings of European experts in this field over a period of 6 years with feedback from general neurologists and epileptologists to improve its validity and utility. Accordingly, our European group has provided herein updated algorithms for two different levels of methodology: (1) requirements for defining photosensitivity in patients and in family members of known photosensitive patients and (2) requirements for tailored studies in patients with a clear history of visually induced seizures or complaints, and in those already known to be photosensitive.

The Added Value of [18F]-Fluoro-D-deoxyglucose Positron Emission Tomography in Screening for Temporal Lobe Epilepsy Surgery

Purpose:[18F]‐Fluoro‐d‐deoxyglucose positron emission tomography (FDG‐PET) is an expensive, invasive, and not widely available technique used in the presurgical evaluation of temporal lobe epilepsy. We assessed its added value to the decision‐making process in relation to other commonly used tests.

Prognosis after temporal lobe epilepsy surgery: The value of combining predictors

Purpose: Although several independent predictors of seizure freedom after temporal lobe epilepsy surgery have been identified, their combined predictive value is largely unknown. Using a large database of operated patients, we assessed the combined predictive value of previously reported predictors included in a single multivariable model.

Are we overusing the diagnosis of psychogenic non-epileptic events?

In order to determine how often results of video/EEG (V-EEG) studies may change the clinical diagnosis of paroxysmal events, we prospectively studied 100 consecutive patients (75 females, 25 males) admitted for diagnosis of recurrent paroxysmal spells. The presumed diagnosis of the referring physician was obtained. Episodes were classified as epileptic seizures (ES), psychogenic non-epileptic events (PNEE), or physiologic non-epileptic events (PhysNEE). Eighty-seven patients had diagnostic events. A final diagnosis of ES was made in 21 patients, PNEE in 39, PNEE + ES in 20, and PhysNEE in seven. All PhysNEE were unsuspected. ES were misdiagnosed as PNEE more frequently than the reverse (57% vs. 12%, P < 0.001). Among the 64 patients with recorded events who had been suspected of having PNEE, 14 (21.9%) were misdiagnosed: two had PhysNEE and 12 (18.75%) had ES. Among the 23 patients with recorded events who were thought to have ES, 12 (39.1%) were misdiagnosed: seven had PNEE, five PhysNEE. V-EEG changed the clinical diagnosis in 29.8% of the patients with recorded events. Our data suggests that clinicians have become more aware of PNEE since the advent of V-EEG and have little problem recognizing them. However, they may be more prone to make a false-positive diagnosis of PNEE in ES with some atypical features. At this point, efforts should be channeled to better training in the proper recognition of ES that mimic PNEE.

When should induction protocols be used in the diagnostic evaluation of patients with paroxysmal events

Summary: Purpose: To determine the timing of spontaneous psychogenic nonepileptic events (PNEE) during video‐EEG telemetry (VEEG), and the need to use induction protocols (IP).

De novo psychogenic nonepileptic seizures after epilepsy surgery

Summary: Purpose: The occurrence of de novo nonepileptic seizures (NES) after epilepsy surgery have been reported only twice in the literature (one article and one abstract).

Decision-making in temporal lobe epilepsy surgery: The contribution of basic non-invasive tests

PURPOSE We studied the extent to which the widely used diagnostic tests contribute to the decision whether or not to perform temporal lobe epilepsy (TLE) surgery in The Netherlands. METHODS This nation-wide, retrospective study included 201 consecutive patients referred for TLE surgery screening. The individual and combined contribution of nine index tests to the consensus decision to perform surgery was investigated. The contribution of each test was quantified using multivariable logistic regression and ROC curves. RESULTS Surgery was performed in 119 patients (59%). Patient history and routine EEG findings were hardly contributory to decision-making, whereas a convergence of MRI with long-term interictal and ictal EEG findings correctly identified the candidates considered eligible for surgery (25% of total). Videotaped seizure semiology contributed less to the results. The area under the ROC curve of the combination of basic tests was 0.75. Ineligibility was never accurately predicted with any test combination. CONCLUSIONS In the Dutch presurgical work-up, when MRI and long-term EEG findings were concordant, a decision for TLE surgery could be reached without further ancillary tests. Videotaped seizure semiology contributed less than expected to the final clinical decision. In our study, basic test findings alone were insufficient to exclude patients from surgery.

What is the current evidence on decision-making after referral for temporal lobe epilepsy surgery?: A review of the literature

OBJECTIVES Many patients thought to have temporal lobe epilepsy, are evaluated for surgical treatment. Decision-making in epilepsy surgery is a multidisciplinary, phased process involving complex diagnostic tests. This study reviews the literature on the value of different tests to decide on whether to operate. METHODS Articles were selected when based on the consensus decision whether to perform temporal lobe surgery, or on the consensus localization or lateralization of the epileptic focus. The articles were scrutinized for sources of bias as formulated in methodological guidelines for diagnostic studies (STARD). RESULTS Most studies did not fulfill the criteria, largely because they addressed prognostic factors in operated patients only. Ten articles met our inclusion criteria. In most articles, a single test was studied; SPECT accounted for five papers. Unbiased comparison of the results was not possible. CONCLUSION Surprisingly little research in epilepsy surgery has focused on the decision-making process as a whole. Future studies of the added value of consecutive tests are needed to avoid redundant testing, enable future cost-efficiency analyses, and provide guidelines for diagnostic strategies after referral for temporal lobe epilepsy surgery.

Monozygous Twin Brothers Discordant for Photosensitive Epilepsy: First Report of Possible Visual Priming in Humans

Summary:  Purpose: The interaction of genetic predisposition and the environment in the development of epilepsy is often discussed, but, aside from some animal reflex epilepsies, little evidence supports such interaction in the development of reflex epilepsy in humans.

The "forgotten" cross-tolerance between phenobarbital and primidone: it can prevent acute primidone-related toxicity.

Purpose: We report on the effect that pretreating patients with phenobarbital has on averting adverse events when primidone is introduced.