Electroencephalographic recording from the temporal lobes: A comparison of ear, anterior temporal, and nasopharyngeal electrodes

Abstract

A prospective study was performed to evaluate the usefulness of ear, anterior temporal, and nasopharyngeal electrodes for recognizing temporal lobe epileptic electroencephalographic (EEG) foci. One hundred and three EEGs were performed on patients suspected of having epilepsy who had a previous normal record. Nasopharyngeal electrodes were simultaneously compared with ear and anterior temporal electrodes to determine their relative abilities to detect pathological epileptiform transients from the temporal region. Epileptic discharges were detected in 22% of the recordings. Pathological discharges seen in nasopharyngeal electrode derivations invariably were seen in ear and anterior temporal electrode derivations using carefully designed montages, and EEG diagnosis was not altered by use of nasopharyngeal electrodes. We conclude that EEG recording with ear and anterior temporal electrodes is sufficient to detect pathological temporal epileptiform transients, and that the use of nasopharyngeal electrodes as a routine procedure offers no added benefit.

Routine EEG and Temporal Lobe Epilepsy: Relation to Long‐Term EEG Monitoring, Quantitative MRI, and Operative Outcome

“…The routine EEG almost invariably records only interictal epileptiform activity in patients with intractable epilepsy, and this identifies the irritative zone in patients with partial seizures (7,8,18). The irritative zone may correspond to the site of seizure onset, but it does not always approximate the size of the critical epileptogenic brain region (7,19,20). The relatively short duration of the routine EEG provides only a limited sample of interictal activity (7).…”

“…The consensus of previous studies suggests that interictal epileptiform alterations may be a good index of the epileptogenic temporal lobe (7-10, 12,15, [21][22][23][24]. Interictal discharges, however, may incorrectly lateralize the epileptic temporal lobe in -10-20% of patients (18)(19)(20). Persistent focal slowing has also been shown to correlate with the temporal lobe of seizure origin (25).…”

Temporal Lobe Epilepsy in Children

“…The value of scalp EEG is improved by ensuring a sleep recording during routine EEG. Furthermore, localization of seizure onset is improved through the use of additional EEG electrodes, either sphenoidal or inferolateral temporal, as well as closely placed electrodes [38–41]. …”

Role of Electroencephalography in Presurgical Evaluation of Temporal Lobe Epilepsy

“…NP recordings are cumbersome and provide little information over the well-tolerated routine anterior temporal and ear recordings especially with regard to anterior temporal IEDs [17, 18]. However, NP recordings have increased sensitivity for IEDs arising from mesiobasal temporal regions (increasing IEDs identification by 25%) [19].…”