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Biomedical subjects

J R Ives

Publications and source records attributed to J R Ives.

At least 19 recordsLinked to original sources
PubMed1991

128-channel cable-telemetry EEG recording system for long-term invasive monitoring.

A 128-channel cable-telemetry EEG monitoring system has been developed for use on patients undergoing intensive neurodiagnostic monitoring with invasive intracranial electrodes. A unique head mounted preamplifier/multiplexor design allows continuous recording from any combination of intracerebral, subdural, epidural or surface electrodes. A computer is used to delay or buffer all 128 channels by 2 min or more. This computer is connected to a fileserver via a local area network and is used exclusively for data acquisition. Seizure files created by the activation of the seizure/event push button or detected by a second computer containing on-line seizure/spike detection algorithms are written directly on to the fileserver by the acquisition computer. The 128 channels of EEG recorded on the fileserver can then be remotely reviewed on a high resolution graphics terminal, printed out on a laser jet printer, archived or played out on paper, 16 channels at a time on any EEG machine. A time of day signal is also generated by the computer to permit time correlation with a continuous audio/video VCR unit which permits comparison of the EEG and clinical events. This system allows continuous EEG monitoring of extensive multichannel arrays not previously possible with conventional 16-, 32- or even 64-channel systems.

Electroencephalography↗
PubMed1991

High resolution EEG output using a laser printer.

With increasing computerization, digitization and complexity of 64- to 128-channel long-term monitoring (LTM), new problems have arisen with data presentation. We describe customized software that allows for high resolution EEG output on a standard laser printer. This system can display from 1 to 128 channels of EEG on standard or legal size paper with freedom to alter both time and amplitude scales as desired. This technique is inexpensive and provides a high resolution rectilinear paper record of selected EEG events that is convenient for review and storage.

Computers↗
PubMed1990

Entry into practice.

Explore the source record for details and available documents.

Education, Nursing, Baccalaureate↗
PubMed1988

A 6-pole filter for improving the readability of muscle contaminated EEGs.

A multi-channel switched-capacitor 6-pole filter for significantly reducing the EMG artifact present during seizures recorded by long-term monitoring procedures has been implemented for routine use. This permits repeated replay of the seizures with different filter settings. All of the channels can be simultaneously dialed to any cut-off frequency (3 dB down) between 8 Hz and 70 Hz and the event replayed for filtering and write-out onto any standard EEG machine. The advantage of the 6-pole switched-capacitor filter is that it does not require a complex design with high precision RC components. The cut-off frequency is determined by the frequency of a simple clock that is used to select the same cut-off point for all 16 channels. By changing the clock frequency, the operator moves the cut-off point linearly. The dramatic improvement obtained by off-line digital filtering that was recently reported (Gotman et al. 1981) indicates that more efficient filtering of EMG contaminated seizures is diagnostically significant in selected cases. This approach is limited by the availability and expense of not only the computer's hardware but also the dedicated software. Specially designed 4-pole analog filters (Barlow 1984) are less expensive than digital filtering, but are difficult to design even at specific frequencies and do not allow for a range of frequencies. The switched-capacitor 6-pole filters have all the advantages of the above but are even more efficient in reducing EMG artifact. They also do not have any of the above disadvantages and cost only a few dollars per channel.

Adult↗
PubMed1985

Monitoring at the Montreal Neurological Institute.

Long-term monitoring of epileptic patients who are candidates for surgical therapy has developed at the Montreal Neurological Institute and Hospital over the last 15 years. Given the large number of patients being investigated, we had to develop procedures which were not labor-intensive. Our monitoring sessions require only the regular supervision of nursing staff. This allows monitoring to take place 7 days a week and 24 h a day on 2 or 3 patients, with minimal personnel requirement. The work of the EEGer is greatly simplified by the fact that the EEG tracing is reduced to the 'interesting' sections only. This was originally possible because of the concept developed by Ives et al. (1976) of delaying the EEG so that activity prior to perceptible clinical signs were always retained. The automatic detection of interictal spikes and seizures in the EEG complemented very effectively this original method of seizure recording. Video recording plays a critical role in the evaluation of seizure disorders. In order to have the maximum quality of EEG and behavior, we record them on their most appropriate medium, paper and video tape respectively; the two are synchronized by a common clock. EEGs are also recorded on a computer tape or disk and can be further analyzed for clinical and research purposes.

Canada↗
PubMed1985

Recording media for the EEG.

Long-term EEG monitoring usually implies the continuous recording (or the continuous monitoring of the EEG coupled with periodic or event recording) of the data on some medium other than paper. This involves a variety of technologies and methodologies and can become fairly complicated depending on the amount of data reduction, data analysis and type of replay used.

Data Display↗
PubMed1985

Recording the time of day.

The recording of the time-of-day (TOD) information (e.g., hours, minutes, and seconds) is an important part of a prolonged EEG and video study. The transcribing techniques for this information on paper (chart recorders), video tape, analog tape, and by digital computers are reviewed.

Computers↗
PubMed1979

Automatic recognition of inter-ictal epileptic activity in prolonged EEG recordings.

A method of automatic recognition and quantification of inter-ictal epileptic activity in the human EEG had previously been developed and tested using short recordings from awake subjects. This paper describes the adaptation of the method for use during overnight recordings in free-moving unattended patients, in combination with the already existing seizure monitoring system. EEG s were recorded from scalp and sphenoidal electrodes, using cable telemetry and a PDP-12 computer. The spike and sharp wave recognition method allowed the on-line analysis of 16 channels. A section of the 16-channel EEG including 1 sec before and 1 sec after each detected spike was saved on digital magnetic tape. Upon completion of the monitoring session, the tape was played back on the EEG machine, giving a discontinuous tracing of spike sections; this constituted a highly concentrated view of the inter-ictal epileptic activity, in traditional paper form. The spike sections were further analyzed by computer to determine and display on the computer terminal the spatial and temporal distributions of the epileptic activity, providing a complete synopsis of the recording. Several examples of the type of information available from this anslysis are discussed in detail. False detection rates are given for 34 six hour recordings, indicating a high vari ability in the performance, mainly because of artefacts. It is concluded that the final computer displays could only be trusted after visual inspection of the EEG sections provided on paper. The variety of morphologies of artefacts appeared to preclude a total automatic elimination.

Electroencephalography↗
PubMed1978

A long term time-lapse video system to document the patients spontaneous clinical seizure synchronized with the EEG.

A long term audio/video clinical seizure monitoring system is described which is complementary to a previously described EEG seizure monitoring system. The video unit is mobile and based on time-lapsed video recording techniques to extend the unattended continuous video recording of the patient to many days if necessary. The simultaneous coverage of the EEG and behavior of the patient particularly during his seizure has been very useful in the workup of intractable epileptic patients being considered for neurosurgical treatment.

Electroencephalography↗
PubMed1978

Update: chronic sphenoidal electrodes.

A technical modification in the type of material used in the chronic sphenoidal electrode previously described (Ives and Gloor 1977) has further improved their clinical use and benefit of the EEG work-up of epileptic patients. This procedure has become a routine investigation for all patients with suspected temporal lobe epilepsy at the Montreal Neurological Hospital.

Electrodes, Implanted↗
PubMed1977

Automatic noctural sleep sampling: a useful method in clinical electroencephalography.

The clinical usefulness of obtaining a sleep record in epileptic patients is well established. However, in many clinical EEG laboratories, it is difficult to obtain records at night during the patient's natural sleep. Thus, most sleep EEGs are recorded in the EEG laboratory during daytime and are induced by drugs. A 16 channel cable-telemetry system is described which automatically samples throughout the night the EEG of patients while sleeping in their room or ward without the aid of any medication. The electrodes and the cable-telemetry unit are applied to the patient in the afternoon and the system is checked. The patient is then instructed to plug the system into a wall box upon retiring and to disconnect it when he wakes up in the morning. The EEG samples are automatically written out during the night on one of the EEG machines located in the EEG laboratory to which the system is connected via spectral intra-hospital wiring. The duration of the samples and of the intervals separating them can be varied according to the circumstances. We have found this method to be very helpful in the investigation of epileptic patients, especially those considered for surgical treatment.

Electroencephalography↗
PubMed1977

New sphenoidal electrode assembly to permit long-term monitoring of the patient's ictal or interictal EEG.

A new sphenoidal wire electrode is described which greatly increases the clinical and diagnostic usefulness of sphenoidal electrode recordings. These very fine wire electrodes are easy to insert; they are comfortable and acceptable to the patient. In contrast to sphenoidal needle electrodes they expose the patient to no risk should he have a seizure during recording. These electrodes also allow one to extend the recording time to several days, thus increasing the chances of recording a spontaneous seizure, for instance while the patient's EEG is being recorded with a telemetry system. The extended recording time also allows for continuous automatic sampling of the interictal EEG over a period of several days. The quality and the reliability of the EEG record are also enhanced. The new sphenoidal electrodes have been used on over 100 patients and are now being used routinely on suspected temporal lobe epileptics recorded with conventional techniques, while 50 of the patients have also been recorded with a cable-telemetry seizure monitoring system which has captured 65 spontaneous seizures.

Electrodes, Implanted↗
PubMed1976

Seizure moitoring: a new tool in electroencephalography.

A seizure monitoring system, based on telemetry and computer techniques, has been developed to provide a reliable means of recording the patient's spontaneous seizures. It allows a patient's EEG to be monitored for hours or days with 16 channels of EEG from surface, sphenoidal or stereotaxically implanted depth electrodes, from any ward or room within the hospital. The EGG is delayed in time by up to 4 min by a mini-computer so that either the patient can push a button when he experiences his aura or others can push the button when they observe his seizure. Since the delayed EEG is written out, the preictal, ictal and postictal are recorded on paper, without many pages of uneventful interictal information. During the past 16 months, the seizure monitoring system has been used as a clinical service to examine patients with surface electrodes (42), sphenoidal wires (25) and depth electrodes (7) during 146 recording sessions for over 3200 h of monitoring time while over 200 seizures have been recorded.

Amplifiers, Electronic↗
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↗