Overintepretation of EEGs and Misdiagnosis of Epilepsy

Abstract

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). In the other 12 records, the overread patterns were simple fluctuations of sharply contoured background rhythms or fragmented alpha activity. Rather than well-described normal variants, the overinterpreted patterns tend to be normal fluctuations of background activity.

The tragedy of over-read EEGs and wrong diagnoses of epilepsy

“…Approximately 30% of patients seen at epilepsy centers for refractory seizures do not have seizures and have been misdiagnosed [1]. As illustrated here, many of them have histories not in the least suggestive of seizures, and have their diagnosis based largely (and sometimes solely) on an 'abnormal' EEG [2][3][4][5][6][7][8].…”

“…to order an EEG than to take a history. The combination of vague, nonspecific symptoms with an equivocal (weak) EEG abnormality is a common cause of inappropriate diagnoses of seizures [4][5][6][7][8]10].…”

“…The EEG patterns that can be over-read include well-known normal variants, but in reality these are relatively rare and the vast majority of over-read patterns are either wicket rhythms or 'nameless variants', that is, simple fluctuations of sharply contoured background rhythms or fragmented a activity that do not fit into a well-described EEG waveform [6,8]. These 'nameless' fluctuations of normal backgrounds have been described under different names and are found on most EEGs [11][12][13][14][15][16].…”

Correlation Analysis and Modeling of EEG – EMG Signal for Startle-Induced Seizures

“…A 12-24 h data is sufficient for reporting the event. Benbadis and Tatum (2003) future, we study the presence of epileptic form activities such as spikes, slow rhythm, and highfrequency epileptic form oscillations. By using epileptic form oscillation we can confirm the presence of epilepsy easily (Indiradevi et al, 2008).…”

MRI (Minimum Recommended Imaging) in Epilepsy

“…tions (2,3). Inter-rater reliability for some EEG features can be poor, and a recent supplement of Neurology ("How not to read an EEG" [4]) was devoted to examining the sources of this variability and potential solutions.…”