Long-term or Extended MonitoringLong-term or Extended Monitoring

Long-term monitoring (LTM) with video EEG can be critical for the diagnosis of epilepsy, correlating the time of the physical manifestation of the seizure with abnormal electrical activity in the brain. Video EEG (vEEG) can also be used to detect epileptic activity not detectable in routine EEG.

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High spatial resolution

Diagnosing and treating epilepsy can be frustrating for physicians and patients alike. The Geodesic EEG product line offers a better way to provide LTM and vEEG for your patients. Compared to conventional EEG, EGI’s High Density EEG (HD EEG) systems provide greater coverage and have higher spatial resolution when detecting the electrical activity of the brain.

Using High Density EEG for long term monitoring


Publications using High Density EEG in Epilepsy Research

Over 70 papers have been published using HD EEG to study epilepsy. View.

Improved patient satisfaction

In order to make HD EEG practical for the clinic, the Geodesic EEG System uses the Geodesic Sensor Net, a gentle, painless electrode placement system that requires no scalp abrasion, glues, or sedation, and can be applied in about 30 minutes for long-term monitoring (LTM). The result is a major improvement in the response of patients and their families, to the EEG evaluation.

A practical clinical possibility

Although many epilepsy centers have considered it impossible, or at least impractical, to record HD EEG continuously over many days, advances in hardware and software provided by EGI’s Geodesic EEG make it now practical for EEG technologists, nurses, and physicians to integrate HD EEG into the daily workflow of the epilepsy monitoring unit.

At the University of Washington, Dr. Mark Holmes’ group is pioneering the use of dense array 128- and 256-channel EEG for long-term video EEG recordings. They have found that they can obtain a higher clinical yield from High Density EEG (HD EEG) compared to conventional EEG. For instance, using a conventional EEG system, ictal EEG discharges were localized to the left posterior quadrant in one patient showing a normal MRI (Holmes et al., (2008)). In contrast, using long-term video monitoring with 128-channel Geodesic EEG, applying a source analysis method and overlaying the data on an MRI model, they were able to localize the epileptic zone to the “left inferior posterior occipital cortex, followed by propagation to the right, and the left, posterior cerebral hemispheres, and finally to the left superior-medial parietal lobe”. The increase in information allowed them to understand the seizures in patients in much greater detail, contributing to successful treatment with surgery.

Holmes, M., Brown, M., Tucker, D., Saneto, R., Miller, K., Wig, G., & Ojemann, J. (2008). Localization of extratemporal seizure with noninvasive dense-array EEG. Pediatric Neurosurgery, 44 (6), 474-479.

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