Errors in EEG interpretation and misdiagnosis of epilepsy. Which EEG patterns are overread?

Comprehensive Epilepsy Program, Department of Neurology, University of South Florida and Tampa General Hospital, Tampa, FL, USA.
European Neurology (Impact Factor: 1.36). 02/2008; 59(5):267-71. DOI: 10.1159/000115641
Source: PubMed

ABSTRACT The overinterpretation of EEGs is common and is an important contributor to the misdiagnosis of epilepsy. We reviewed our experience in order to clarify which EEG patterns are commonly overread as epileptiform.
We identified patients who were seen at our epilepsy clinic and were ultimately diagnosed as having conditions other than epilepsy. We selected those who had previously had an EEG read as showing epileptiform discharges and whose EEG was available for our own re-review.
37 patients met the above criteria. Eventual diagnoses were psychogenic nonepileptic seizures (10), syncope (7), other miscellaneous diagnoses (5) and unexplained nonspecific symptoms (15). None of the EEGs had epileptiform discharges. The descriptions of the abnormalities included 'temporal sharp waves' in 30, 'frontal sharp waves' in 2 and 'generalized spike-wave complexes' in 2. Three had no reports available to identify the alleged abnormality. The benign patterns mistaken for temporal (30) and frontal (2) sharp waves were simple fluctuations of background activity with temporal phase reversals.
By far the most common patterns overread as epileptiform are nonspecific fluctuations of background in the temporal regions, which are misread as temporal sharp waves.

1 Bookmark
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The common diagnosis of loss of consciousness and clonic movements in children is seizure or epilepsy, but in a number of patients these symptoms could also be due to syncope. Over interpreted electroencephalography is misleading in a number of patients; therefore, in addition to a detailed and thorough history, a reliable test is needed to differentiate between these conditions. The aim of the study was to evaluate the utility of the head upright tilt test to differentiate between seizure-like events and syncope in children. A chart review descriptive study was conducted in a tertiary medical center in Ahvaz, Iran. We selected sixteen children (nine boys and seven girls) with convulsions of any type who were first diagnosed as epileptic based on the event description by their parents or caregivers to undergo the head upright tilt test. The main findings were the reproduction of previously presyncopal or syncopal symptoms in the tilted position. Fourteen children showed positive results after conducting the head upright tilt test, and their heart rates were significantly decreased compared to baseline at the onset of the syncopal or presyncopal manifestations. Systolic and diastolic blood pressures were significantly reduced in patients with positive results. In three children who initially had negative head upright tilt tests, intravenous isoproterenol was administered, and all three showed presyncopal and syncopal symptoms. The results indicate that the head upright tilt test could differentiate presyncopal and syncopal events in children who present with seizure-like movements but their history has clues for conclusive syncope.
    Acta neurologica Belgica 01/2015; DOI:10.1007/s13760-015-0433-0 · 0.60 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Objectives and Background: In patients with medically refractory seizures 20–30% do not have epilepsy, and the majority are diagnosed with psychogenic non-epileptic seizures (PNES). Almost one-third of this group has a prolonged episode that is termed as PNES status epilepticus (PNES-SE). The aim of this study was to describe the characteristics of patients with (1) PNES-SE only and (2) PNES-SE with concurrent epileptic seizures.Methods: We screened retrospectively all patients who underwent video-electroencephalogram (video-EEG) long-term monitoring at our institution between 1996 and 2009. Patients with PNES were identified by typical clinical features with no ictal EEG changes. Patients with continuous episodes for at least 30 min that led to intubation were identified as PNES-SE. They were divided into two groups: group 1, pure PNES-SE and group 2, PNES-SE with concurrent epilepsy. Group characteristics were defined with respect to demographic, clinical, electroencephalographic, neuroimaging and psychiatric variables.Results: PNES were recorded in 88/916 patients (10%) of whom 6 (7%) were treated intensively due to misdiagnosis of status epilepticus (SE), with two having coexistent epileptic seizures. All patients had concurrent psychiatric disorder(s), diagnosed by a psychiatrist. Duration of time until correct diagnosis was lengthy in all cases, and particularly for patients with PNES-SE with coexisting epileptic seizures (more than 10 years).Conclusion: To avoid iatrogenic complications and to treat the underlying psychiatric conditions, early diagnosis of PNES is necessary. Understanding the clinical characteristics of PNES-SE leads to early diagnoses, which may avoid iatrogenesis and economic burden.
    12/2012; 13(03). DOI:10.1017/BrImp.2012.30
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Delayed diagnosis of early onset epilepsy is a potentially important and avoidable complication in epilepsy care. We examined the frequency of diagnostic delays in young children with newly presenting epilepsy, their developmental impact, and reasons for delays. Children who developed epilepsy before their third birthday were identified in a prospective community-based cohort. An interval ≥1 month from second seizure to diagnosis was considered a delay. Testing of development at baseline and for up to 3 years after and of intelligence quotient (IQ) 8-9 years later was performed. Detailed parental baseline interview accounts and medical records were reviewed to identify potential reasons for delays. Factors associated with delays included the parent, child, pediatrician, neurologist, and scheduling. Diagnostic delays occurred in 70 (41%) of 172 children. Delays occurred less often if children had received medical attention for the first seizure (p < 0.0001), previously had neonatal or febrile seizures (p = 0.02), had only convulsions before diagnosis (p = 0.005), or had a college-educated parent (p = 0.01). A ≥1 month diagnostic delay was associated with an average 7.4 point drop (p = 0.02) in the Vineland Scales of Adaptive Behavior motor score. The effect was present at diagnosis, persisted for at least 3 years, and was also apparent in IQ scores 8-9 years later, which were lower in association with a diagnostic delay by 8.4 points (p = 0.06) for processing speed up to 14.5 points (p = 0.004) for full scale IQ, after adjustment for parental education and other epilepsy-related clinical factors. Factors associated with delayed diagnosis included parents not recognizing events as seizures (N = 47), pediatricians missing or deferring diagnosis (N = 15), neurologists deferring diagnosis (N = 7), and scheduling problems (N = 11). Diagnostic delays occur in many young children with epilepsy. They are associated with substantial decrements in development and IQ later in childhood. Several factors influence diagnostic delays and may represent opportunities for intervention and improved care.
    Epilepsia 12/2013; 55(1). DOI:10.1111/epi.12479 · 4.58 Impact Factor


Available from
May 21, 2014