EEG source imaging concordance with intracranial EEG and epileptologist review in focal epilepsy.

EEG source imaging is becoming widely used for the evaluation of medically refractory focal epilepsy. The validity of EEG source imaging has been established in several studies comparing source imaging to the surgical resection cavity and subsequent seizure freedom. We present a cohort of 87 patients and compare EEG source imaging of both ictal and interictal scalp EEG to the seizure onset zone on intracranial EEG.

Frequent sleep-related bitemporal focal seizures in transient epileptic amnesia syndrome: Evidence from ictal video-EEG.

Two patients who shared similar presenting clinical features of anterograde and retrograde autobiographical amnesia typical of transient epileptic amnesia (TEA) underwent prolonged video electroencephalogram (VEEG) monitoring and were found to have sleep-activated epileptiform activity and frequent subclinical bitemporal seizures predominantly during sleep. Case 1 is a 59-year-old woman whose presenting complaint was memory impairment. Over 18 months, she had three distinct 8-h-long episodes of confusion and disorientation with persistent anterograde and retrograde autobiographical amnesia.

Routine vs extended outpatient EEG for the detection of interictal epileptiform discharges.

Objective: To compare the yield of epileptiform abnormalities on 30-minute recordings with those greater than 45 minutes.

Methods: We performed a prospective observational cross-sectional study of all outpatient routine EEGs comparing the rate of interictal epileptiform discharges (IEDs) and clinical events during the initial 30 minutes (routine) with those occurring in the remaining 30-60 minutes (extended). A relative increase of 10% was considered clinically significant.

Autoimmune epilepsy: clinical characteristics and response to immunotherapy.

Objective: To describe clinical characteristics and immunotherapy responses in patients with autoimmune epilepsy.

Design: Observational, retrospective case series.

Setting: Mayo Clinic Health System.

Influence of subtraction ictal SPECT on surgical management in focal epilepsy of indeterminate localization: a prospective study.

The impact of functional imaging tests on the decision-making and planning process for epilepsy surgery has never been prospectively assessed. We prospectively evaluated 50 consecutively eligible patients whose noninvasive evaluations showed nonlocalized findings and determined how their SISCOM (subtraction ictal SPECT [single photon emission computed tomography] co-registered to MRI [magnetic resonance imaging]) data altered consensus decisions for epilepsy surgery. At an epilepsy surgery conference where each patient was discussed, consensus decisions were documented after a standardized presentation of data from the noninvasive evaluation (SISCOM findings initially were excluded).

Ictal source analysis: localization and imaging of causal interactions in humans.

We propose a new integrative approach to characterize the structure of seizures in the space, time, and frequency domains. Such characterization leads to a new technical development of ictal source analysis for the presurgical evaluation of epilepsy patients. The present new ictal source analysis method consists of three parts.

3D source localization of interictal spikes in epilepsy patients with MRI lesions.

The present study aims to accurately localize epileptogenic regions which are responsible for epileptic activities in epilepsy patients by means of a new subspace source localization approach, i.e. first principle vectors (FINE), using scalp EEG recordings.

Use of principal component analysis in the frequency domain for mapping electroencephalographic activities: comparison with phase-encoded Fourier spectral analysis.

Principal component analysis (PCA) can separate multichannel electroencephalographic (EEG) epochs into linearly independent (temporally and spatially noncorrelated) components. Results of PCA include component time-series waveforms and factors representing the contribution of each component to each electrode; these factors may be displayed as contour maps representing the topographic distribution of each component. However, PCA often does not achieve the most useful separation of components.

Spectral analysis of slow modulation of EEG amplitude and cardiovascular variables in subjects with postural tachycardia syndrome.

Objective: Previous studies have reported slow (<0.5 Hz) modulation of electroencephalographic (EEG) background amplitude and suggested that this reflects periodic neuronal activity in the brainstem, such as may be recorded from cardiovascular and respiratory centers in animals. We searched for a relationship between EEG amplitude modulation and modulation of simultaneously recorded cardiovascular variables and attempted to determine whether this relationship was altered in subjects with postural tachycardia syndrome (POTS).

Abnormal corticomuscular coherence is associated with the small amplitude cortical myoclonus in Parkinson's disease.

Coherence is the degree of time-locked correlation between two signals as a function of frequency. The purpose of this study was to test the following hypotheses: (1) corticomuscular coherence is abnormally increased in those Parkinson's disease (PD) patients with small amplitude cortical myoclonus, and (2) corticomuscular coherence peaks around the time of the myoclonus electromyographic (EMG) discharge. We studied Parkinson's disease patients with and without myoclonus and controls.

A general method for remontaging based on a singular value decomposition algorithm.

The authors developed a general mathematic algorithm to convert any montage (referential, bipolar, or Laplacian) to any other by linear transformation. Input and output montages are described by matrices, and singular value decomposition is used to find the linear transformation. An error signal can be calculated from the input data to monitor remontaging validity.

Role and limitations of routine and ambulatory scalp electroencephalography in diagnosing and managing seizures.

The scalp electroencephalogram (EEG) is the cornerstone in the diagnosis and treatment of seizure disorders. The EEG, with its excellent temporal resolution, provides a direct measurement of cortical electrophysiology, revealing, for example, the presence of interictal epileptiform discharges that identify regions of an epileptogenic brain. We define the EEG characteristics of focal and generalized epileptiform discharges and provide evidence for their varying diagnostic importance in different patient populations.