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Epilepsy Res 2021 Feb 5;170:106539. Epub 2021 Jan 5.

Department of Neurology, Smt. B. K. Shah Medical Institute and Research Center, Sumandeep Vidyapeeth, Vadodara, Gujarat, India.

Objective: To prospectively study the prevalence of benign epileptiform variants (BEVs) and their impact on epilepsy misdiagnosis.

Methods: Consecutive patients, older than one year, who underwent EEG from January 2016 to December 2019 were prospectively studied for the presence of BEVs. We used descriptions of Klass and Westmoreland (1985) to categorize the BEVs. Read More

J Clin Neurophysiol 2020 Nov;37(6):518-536

Epilepsy Center, Cleveland Clinic, Cleveland, Ohio, U.S.A.

Normal variants, although not occurring frequently, may appear similar to epileptic activity. Misinterpretation may lead to false diagnoses. In the context of presurgical evaluation, normal variants may lead to mislocalizations with severe impact on the viability and success of surgical therapy. Read More

Clin EEG Neurosci 2020 Sep 3:1550059420953735. Epub 2020 Sep 3.

Sree Chitra Tirunal Institute for Medical Sciences & Technology, Trivandrum, Kerala, India.

Purpose: Children with refractory focal to bilateral tonic-clonic seizures, despite normal high-resolution imaging, are often not subjected to genetic tests due to the costs involved and instead undergo multimodality presurgical evaluation targeted at delineating a focal onset. The objective of this study was to ascertain genotype-phenotype correlations in this group of patients.

Method: An online hospital database search was conducted for children who presented in 2019 with drug-resistant epilepsy dominated by nonlateralizing focal-onset/rapid generalized (bilateral) tonic-clonic seizures (GTCS), subjected to presurgical evaluation and subsequent genetic testing due to absence of a clear focus hypothesis. Read More

Ital J Pediatr 2020 Mar 27;46(1):36. Epub 2020 Mar 27.

Child Neuropsychiatric Unit - Epilepsy Center, San Paolo Hospital, Department of Health Sciences, Università degli Studi di Milano, Via di Rudinì 8, 20142, Milan, Italy.

Background: Seizures in individuals affected by tuberous sclerosis complex (TSC) commonly develop in the first year of life, are often preceded by a progressive deterioration of the electroencephalogram (EEG), and likely influence developmental outcome. Although early diagnosis of TSC has offered a tremendous opportunity to monitor affected patients before seizure onset, reports of the neurological manifestations of TSC in infants before seizure onset are still scarce. Here we describe early EEG activity, clinical and genetic data and developmental assessment in a group of TSC infants, with the aim of identifying possible prognostic factors for neurodevelopmental outcome. Read More

J Clin Neurophysiol 2020 Jan 2. Epub 2020 Jan 2.

Neurosciences and Mental Health Department, Hospital de Santa Maria, CHLN, Lisbon, Portugal.

Purpose: Periodic discharges (PDs) are common in acute structural or metabolic brain lesions, but their occurrence during follow-up of epileptic patients in an outpatient setting is rare. Aim of this article was to study whether PDs on the routine outpatient scalp EEG of patients with epilepsy, as compared with nonperiodic epileptiform discharges, are associated with drug refractoriness and the decompensation of epilepsy and particular etiologies.

Methods: A retrospective case-control study. Read More

Epilepsia 2019 12;60 Suppl 3:S77-S85

Danish Epilepsy Center, Dianalund, Denmark.

Pathogenic variants in SCN8A have originally been described in patients with developmental and epileptic encephalopathy (DEE). However, recent studies have shown that SCN8A variants can be associated with a broader phenotypic spectrum, including the following: (1) Patients with early onset, severe DEE, developing severe cognitive and motor regression, pyramidal/extrapyramidal signs, and cortical blindness. Severe SCN8A-DEE is characterized by intractable seizures beginning in the first months of life. Read More

Neurol Sci 2020 Mar 16;41(3):631-636. Epub 2019 Nov 16.

Department of Pediatric Metabolism, Faculty of Medicine, Mayıs University, Samsun, Turkey.

Objective: Methylenetetrahydrofolate reductase (MTHFR) is an important enzyme involved in folate metabolism. MTHFR C677T and A1298C polymorphisms are best-defined variants of MTHFR that were reported to be associated with epilepsy development. The aim of the study was to determine the incidence of interictal epileptiform discharges on electroencephalography (EEG) in asymptomatic children with C677T and A1298C polymorphisms who had no history of seizure. Read More

Clin Neurophysiol 2019 09 21;130(9):1570-1580. Epub 2019 Jun 21.

Department of Neurology, University of Pittsburgh, Pittsburgh, PA, USA; University of Pittsburgh Comprehensive Epilepsy Center, Pittsburgh, PA, USA.

Objective: To investigate the intracranial correlate of the 14&6/sec positive spikes normal variant of scalp EEG.

Methods: Out of 35 adult refractory focal epilepsy patients who underwent intracranial electrode implantation with simultaneous scalp EEG electrodes, the 14&6/sec positive spikes variant was found in 4. We used three methods to identify and quantify intracranial correlates to the variant: visual inspection, time-referenced waveform averaging and 3D brain volume spectrum-based statistical parametric mapping (SPM). Read More

Handb Clin Neurol 2019 ;160:143-160

Department of Neurology, Mayo Clinic College of Medicine and Health Sciences, Jacksonville, FL, United States. Electronic address:

Understanding common variations of normal EEG and benign variants of uncertain significance is essential to discern the boundary between normal and abnormal EEG. Wide variation and fluctuation can occur with normal signals generated by the brain, and these can be a pitfall for less-experienced electroencephalographers in accurately interpreting the EEG. Normal EEG variants are benign and do not portend specific pathological conditions. Read More

J Clin Neurophysiol 2019 Jul;36(4):257-263

Department of Neurology/Epilepsy Division, Johns Hopkins University School of Medicine, Baltimore, Maryland, U.S.A.

Electroencephalographers may misclassify benign variant EEG patterns as epileptiform discharges, resulting in delays in the diagnosis and appropriate treatment of other paroxysmal disorders, such as psychogenic nonepileptic seizures, anxiety/panic disorders, and near syncope. These benign variant patterns include wicket spikes, small sharp spikes, and rhythmic mid-temporal theta of drowsiness. Cautious interpretations of semi-rhythmic sharp transients, usually gradually rising from the EEG background in drowsiness, can help avoid misdiagnosing patients as having seizures. Read More

Epilepsy Behav 2018 12 3;89:94-98. Epub 2018 Nov 3.

F.M. Kirby Neurobiology Center, Translational Neuroscience Center, Department of Neurology, Boston Children's Hospital, Harvard Medical School, Boston, MA, United States of America. Electronic address:

High-voltage rhythmic electroencephalographic (EEG) spikes have been recorded in wildtype (WT) rats during periods of light slow-wave sleep and passive wakefulness. The source of this activity is unclear but has been attributed to either an inherent form of absence epilepsy or a normal feature of rodent sleep EEG. In contrast, little is known about epileptiform spikes in WT mice. Read More

Clin Neurophysiol 2018 09 28;129(9):1796-1803. Epub 2018 Jun 28.

Department of Neurology, University of Chicago, USA.

Objective: Mesial temporal lobe epilepsy (mTLE) is the most common type of focal epilepsy, but often lacks scalp EEG correlates. We ask if hippocampal epileptiform discharges that are characteristic of mTLE are associated with small sharp spikes (SSS) recorded on scalp EEG. SSS are considered benign waveforms, so are not currently used as markers of epilepsy. Read More

Neurophysiol Clin 2018 Jun 21;48(3):171-179. Epub 2018 Apr 21.

Service de neurophysiologie clinique, centre hospitalier Sainte-Anne, 1, rue Cabanis, 75014 Paris, France; Université Paris-Descartes, 12, rue de l'école de médecine, 75006 Paris, France; Inserm UMR S894, centre de psychiatrie et neurosciences, rue de la Santé, 75014 Paris, France.

Introduction: In France, a systematic EEG is performed during initial examination in military aircrew applicants, which may provide an estimation of the prevalence of benign epileptiform variants in healthy adults.

Methods: We analyzed standard EEG (21 scalp electrodes, 20minutes, 400Hz sampling rate) of military aircrew applicants examined in the French Main Aeromedical Center in 2016. EEGs were analyzed using both bipolar and referential montages. Read More

Clin Neurophysiol 2018 05 8;129(5):952-955. Epub 2018 Feb 8.

Epilepsy Center, Department of Neurology, Ludwig Maximilians University, Munich, Germany.

Objective: Positive interictal epileptiform discharges (IEDs) are rarely recorded from surface EEG, due to the orientation of the cortex and its neurons. Their frequency and significance in adults is unknown, and has only been studied as a phenomenon of the neonatal period and childhood. We aimed to evaluate the frequency and characteristics of positive epileptiform discharges in a large cohort of patients. Read More

Neurology 2013 Jan;80(1 Suppl 1):S4-11

Department of Neurology, Mayo College of Medicine, Mayo Clinic, Jacksonville, FL, USA.

The EEG is a unique measure of electrical brain function and is widely used in patients with seizures. Many normal variants and variations of normal EEG have a predilection for the temporal lobe and mimic epileptiform discharges. The high prevalence of temporal lobe epilepsy and the propensity for normal variants to occupy the temporal lobe may result in an undesired bias, leading to misidentification of normal waveforms. Read More

Neurology 2013 Jan;80(1 Suppl 1):S12-25

Department of Neurology, Mayo College of Medicine, Mayo Clinic, Jacksonville, FL, USA.

Potentials that do not conform to an expected electrical field generated by the brain characterize an extracerebral source or artifact. Artifact is present in virtually every EEG. It is an essential component for routine visual analysis, yet it may beguile the interpreter into falsely identifying waveforms that simulate epileptiform discharges (ED). Read More

Rev Neurol 2012 Apr;54(7):435-44

Instituto Nacional de Ciencias Medicas y de la Nutricion Salvador Zubiran, Tlalpan, Mexico.

Electroencephalography is an important tool in the diagnosis of primary or secondary disorders of central nervous system, epilepsy is one of the most important. Sometimes normal electroencephalographic activity simulates epileptiform activity. This activity does not have pathological value and is considered a variant of normal brain activity. Read More

Nervenarzt 2012 Feb;83(2):172-80

Epilepsie-Zentrum, Neurologische Klinik und Poliklinik, Klinikum der Universität München-Großhadern, Marchioninistr. 15, 81377, München, Deutschland.

The electroencephalogram (EEG) is a specific diagnostic method for the evaluation of patients with epilepsies. Interictal epileptiform discharges (IED) recorded in the seizure interval have a high association with the clinical diagnosis of epilepsy. IEDs have to be differentiated from normal variants that resemble IEDs. Read More

J Clin Neurophysiol 2011 Jun;28(3):308-10

Mayo College of Medicine, Mayo Clinic, Jacksonville, Florida, USA.

The misdiagnosis of epilepsy may occur from the misinterpretation of a routine scalp EEG. Typically, interictal epileptiform discharges are misidentified on EEGs because of the overinterpretation of normal variants or variations in normal electrocerebral activity. Most reports of misinterpretation have arisen from patients diagnosed with psychogenic nonepileptic attacks using in-patient video-EEG monitoring. Read More

J Clin Neurophysiol 2011 Apr;28(2):178-84

Department of Neurosciences, Medical University of South Carolina, 96 Jonathan Lucas Street, Charleston, SC 29425, USA.

Computerized detection of epileptiform transients (ETs), characterized by interictal spikes and sharp waves in the EEG, has been a research goal for the last 40 years. A reliable method for detecting ETs would assist physicians in interpretation and improve efficiency in reviewing long-term EEG recordings. Computer algorithms developed thus far for detecting ETs are not as reliable as human experts, primarily due to the large number of false-positive detections. Read More

Can J Neurol Sci 2010 Nov;37(6):819-25

Service de neurologie, Centre hospitalier de l'Université de Montréal - Hôpital Notre-Dame, Montréal, Québec, Canada.

Background: To ensure the overall quality of our electroencephalogram (EEG) laboratory, we decided to perform an audit of EEGs interpreted at our institution, focusing initially on EEGs reporting temporal abnormalities.

Methods: Reports of all EEGs performed between January 1st and June 30th, 2006 were reviewed in order to identify tracings mentioning abnormalities in the temporal regions. These records were then independently reviewed by two epileptologists on two distinct occasions, separated by an interval of at least six months. Read More

Zh Nevrol Psikhiatr Im S S Korsakova 2009 ;109(10):51-6

Based on the analysis of clinical and neurophysiological data with the use of up-to-date methods of EEG processing, the authors discuss a role of cerebral asymmetry (CA) in the pathogenesis of cervical dystonia (CD). Sixty-seven patients (31 male and 36 female) with CD have been studied. The pathological turn of the head to the right side (RT) was observed in 34 patients, to the left side (LT) - in 33 patients. Read More

J Clin Neurophysiol 2006 Jun;23(3):194-207

Department of Neurology, Tampa General Hospital, University of South Florida, Tampa, Florida 33613, USA.

A thorough understanding of a normal EEG is critical in defining those patterns that are abnormal. Because EEG is unique in the ability to support a clinical diagnosis of epilepsy, epileptiform patterns merit careful consideration. Certain benign patterns maybe epileptiform, yet can occur in healthy individuals without epilepsy. Read More

Zh Nevrol Psikhiatr Im S S Korsakova 2006 ;106(4):4-9

Fourteen patients, aged from 5 to 14 years, with syndrome of electrical status epilepticus during slow sleep (ESESS) have been studied. The absence of epileptic attacks was observed in 21.5% of patients and diagnosis was established by a combination of continuous diffuse epileptiform activity with marked cognitive disturbances. Read More

J Clin Neurophysiol 2003 Feb;20(1):42-4

Departments of Neurology and Neurosugery, University of South Florida and Tampa General Hospital, Florida 33606, USA.

The overinterpretation of EEGs is a known problem that has not been reported specifically. The authors report a series of EEGs on patients who were diagnosed eventually with psychogenic nonepileptic seizures and who had an EEG read as epileptiform. Of the 15 actual records available for review, the overread patterns were wicket spikes (n = 1), hypnagogic hypersynchrony (n = 1), and hyperventilation-induced slowing (n = 1). Read More

Epilepsia 1991 Jan-Feb;32(1):44-50

Clinical Neurophysiology Laboratory, SUNY Health Science Center, Syracuse.

Seventy-eight individuals with EEG records containing benign epileptiform transients of sleep (BETS) were identified among 7,400 records reviewed in our laboratory in a 6-year period. The records contained no other abnormality in 51 patients (65%). Genuine epileptiform discharges were found in the records of 19 patients; 14 had a history of epilepsy. Read More