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Biomedical subjects

J R Ives

Publications and source records attributed to J R Ives.

41 records · Page 3Linked to original sources
PubMed1975

4-channel 24 hour cassette recorder for long-term EEG monitoring of ambulatory patients.

A 4-channel cassette recorder capable of continuously recording the EEG for 24 h on a C-120 cassette is currently in use at the Montreal Neurological Institute. We have done a limited study on 20 patients with over 2000 h of recording to evaluate the recording system, its limitations and its capabilities, and to develop methodology for its operations. The use of preamplifiers enables one to record the background EEG with a noise level of 3-5 muVpp on 4 channels continuously for 1 day. The electrodes can be hidden in the hair and the preamplifier under the collar, to allow the patient to carry on his normal activities at home and at work. Since the cassette and the batteries can be easily changed, the patient himself can prolong the recording for several days. The cassette can be played back as fast as 60 times on a Minograf EEG machine for compressed analysis or 20 times for more detailed write-out, to obtain a record equivalent to standard EEG recordings. The system was not designed to replace or compete with standard EEG recordings but when used on well defined clinical problems, or in specific research projects, it can enhance the diagnostic or research value of the EEG.

Ambulatory Care↗
PubMedDate not supplied

New topographic mapping of temporal lobe seizures.

A unique topographic map has been developed based on EEG data of ictal events originating from the basal/mesiotemporal lobe regions. This technique involves a new mapping method of temporal lobe seizures as opposed to the interictal activity maps of most commercially available software. The map integrates data from sphenoidal electrodes as well as the standard 10-20 surface electrodes recorded with bipolar montages. A basal view is ideal for visualization of onset of temporal lobe ictal discharges recorded with chronic sphenoidal electrodes. We used the last 150 ictal events from 40 patients with basal/mediotemporal lobe epilepsy to develop this technique. Results indicate that a topographic view incorporating sphenoidal and scalp electrodes may provide a useful adjunct for interpretation of EEG recordings and a basis for comparison between and among patient groups for both ictal and interictal epileptic discharges.

Brain Mapping↗
PubMedDate not supplied

Echo-planar functional MR imaging of epilepsy with concurrent EEG monitoring.

BACKGROUND AND PURPOSE: The role of functional MR (fMR) imaging in the evaluation of patients with epilepsy has not been systematically studied. Our purpose was to identify the fMR correlates of interictal epileptiform discharges. METHODS: Twenty patients with epilepsy and frequent interictal discharges were studied with concurrent EEG monitoring on a 1.5-T echo-planar magnet to acquire blood-oxygenation-level-dependent (BOLD) images in the baseline (OFF) and immediate post-discharge (ON) states. Analysis was performed using subtraction of average ON and OFF data (method I); cross-correlation analysis between the ON and OFF states (method II); and individual spike analysis (ISA), with which signal intensity in the individual ON states was statistically analyzed using a weighted comparison with the mean and variance of the OFF states (method III). Agreement of fMR activation with EEG localization was determined. RESULTS: Eighteen of 20 patients had interictal discharges during the monitoring period. Method I yielded visually detectable sites of BOLD signal differences in only one patient. Method II resulted in two patients with sites of BOLD activation. Method III, ISA, resulted in regions of increased BOLD signal corresponding to the EEG focus in nine of 10 patients. CONCLUSION: fMR studies can often reveal sites of increased BOLD signal that correspond to sites of interictal EEG discharge activity. Because of variable intensity changes associated with discharge activity, ISA resulted in increased sensitivity.

Adult↗