Assessment of the Utility of Ictal Magnetoencephalography in the Localization of the Epileptic Seizure Onset Zone.

Authors: Alkawadri R, Burgess RC, Kakisaka Y, Mosher JC, Alexopoulos AV.

To read the full article please visit JAMA Neurology website

Key Points

Question  What is the chance of recording a seizure and the localizing yield of seizures recorded during routine magnetoencephalography (MEG) studies?

Findings  In this medical record analysis of 44 patients, MEG provided unique and more focal localization information, including in some electroencephalography and interictal MEG silent cases and in some cases that were nonlocalizable otherwise. Extended-source localization was more suitable for analysis of ictal rhythms than commonly used single-point solutions.

Meaning  If feasible, ictal MEG should be sought and considered in presurgical evaluation of drug-resistant epilepsy.

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Averaging in time-frequency domain reveals the temporal and spatial extent of seizures recorded by scalp EEG.

Authors: Alkawadri R, Gaspard N

To read the full article refer to Epileptic Disorders

To demonstrate the importance of averaging in time-frequency space and the added localizing value in time and space in a case of cortical myoclonus. One hundred myoclonic jerks were averaged in time series and in spectral domain. For the latter, we chose 100 (10-second) segments from interictal background and used the unpaired t-test for the jerk-related and control spectral data to obtain the t value and corresponding p value at each pixel. We corrected for multiple comparisons using false discovery rate procedure. We generated maps of spectral significance per electrode. All insignificant t-values were converted to 0 for easier visual analysis. Standard back-averaging of 100 jerks disclosed a single spike preceding EMG activity by 19-27 milliseconds. No other definite ictal patterns were discernible in the time domain. Statistical analysis of the same 100 epochs in the time-frequency domain disclosed a greater temporal extent of the seizure, as well as a more detailed rendering of rhythms and frequencies involved. Valproate was added and led to substantial improvement. Averaging in the spectral domain may reveal frequency-specific changes that may not be otherwise appreciated in the time domain. Future studies may elucidate the effect on the sensitivity of diagnosis of simple partial seizures and auras.

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Impairment of consciousness induced by bilateral electrical stimulation of the frontal convexity

We report a case of impairment of consciousness (IOC) induced by electrical cortical stimulation (ECS) of homologous regions within the lateral frontal convexities in a patient with medically intractable epilepsy. The patient had mixed features of idiopathic generalized and focal epilepsy. On intracranial EEG recording, interictal and ictal discharges showed a high degree of synchrony across widespread bilateral fronto-parietal areas. We identified regions in the lateral frontal lobes that reliably and produced loss of consciousness by ECS.

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Propagation of seizures in a case of lesional mid-cingulate gyrus epilepsy studied by stereo-EEG.

Authors: Alkawadri R, Gonzalez-Martinez J, Gaspard N, Alexopoulos AV

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We present a case of lesional mid-cingulate epilepsy confirmed by stereotactically implanted intracranial depth electrodes and subsequent surgical resection. Hypermotor symptomatology was seen during the first seven seconds of seizure onset while the seizure was still confined to the mid-cingulate gyrus contacts.

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Cingulate epilepsy: report of 3 electroclinical subtypes with surgical outcomes

Authors: Alkawadri R, So NK, Van Ness PC, Alexopoulos AV

Please visit JAMA Neurology to read the full article

Abstract

Importance  The literature on cingulate gyrus epilepsy in the magnetic resonance imaging era is limited to case reports and small case series. To our knowledge, this is the largest study of surgically confirmed epilepsy arising from the anterior or posterior cingulate region.

Objective  To characterize the clinical and electrophysiological findings of epilepsies arising from the anterior and posterior cingulate gyrus.

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