A multichannel intracerebral EEG monitoring system for epilepsy presurgical evaluation

Salam, Muhammad Tariqus; Nguyen, Dang Khoa

doi:10.1109/ccece.2011.6030465

Cited by 5 publications

(4 citation statements)

References 7 publications

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“…Flicker noise is predominant in lower frequencies (<3 Hz) and higher frequency noise is primarily located at >40 Hz because of the sampling frequency limitations and thermal noise. 19 Therefore, recorded signals were divided into three main frequency bands (ie, noise 1 , icEEG, and noise 2 as shown in Figure 8D ). Figure 8D–F show comparative studies on impedance magnitude of commercial subdural electrodes (Ad-Tech Medical Instruments) and the proposed subdural electrodes.…”

Section: Resultsmentioning

confidence: 99%

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Subdural porous and notched mini-grid electrodes for wireless intracranial electroencephalographic recordings

Salam¹,

Gelinas²,

Desgent³

et al. 2014

JMDH

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BackgroundIntracranial electroencephalography (EEG) studies are widely used in the presurgical evaluation of drug-refractory patients with partial epilepsy. Because chronic implantation of intracranial electrodes carries a risk of infection, hemorrhage, and edema, it is best to limit the number of electrodes used without compromising the ability to localize the epileptogenic zone (EZ). There is always a risk that an intracranial study may fail to identify the EZ because of suboptimal coverage. We present a new subdural electrode design that will allow better sampling of suspected areas of epileptogenicity with lower risk to patients.MethodImpedance of the proposed electrodes was characterized in vitro using electrochemical impedance spectroscopy. The appearance of the novel electrodes on magnetic resonance imaging (MRI) was tested by placing the electrodes into a gel solution (0.9% NaCl with 14 g gelatin). In vivo neural recordings were performed in male Sprague Dawley rats. Performance comparisons were made using microelectrode recordings from rat cortex and subdural/depth recordings from epileptic patients. Histological examinations of rat brain after 3-week icEEG intracerebral electroencephalography (icEEG) recordings were performed.ResultsThe in vitro results showed minimum impedances for optimum choice of pure gold materials for electrode contacts and wire. Different attributes of the new electrodes were identified on MRI. The results of in vivo recordings demonstrated signal stability, 50% noise reduction, and up to 6 dB signal-to-noise ratio (SNR) improvement as compared to commercial electrodes. The wireless icEEG recording system demonstrated on average a 2% normalized root-mean-square (RMS) deviation. Following the long-term icEEG recording, brain histological results showed no abnormal tissue reaction in the underlying cortex.ConclusionThe proposed subdural electrode system features attributes that could potentially translate into better icEEG recordings and allow sampling of large of areas of epileptogenicity at lower risk to patients. Further validation for use in humans is required.

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Section: Resultsmentioning

confidence: 99%

“…We have previously demonstrated several front-end preamplifiers for noise reduction. 18 , 19 However, optimum SNR values can also be obtained by improving intracranial electrode contacts. 20 …”

Section: Introductionmentioning

confidence: 99%

Subdural porous and notched mini-grid electrodes for wireless intracranial electroencephalographic recordings

Salam¹,

Gelinas²,

Desgent³

et al. 2014

JMDH

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“…Careful analysis of recorded seizures allows a better delineation of the epileptogenic zone for subsequent surgery. Most studies on interictal or ictal icEEG data only report a limited frequency range (0.1-40Hz) [1], [2]. This may be due to the fact that oscillations with frequencies above ∼ 40Hz are of relatively low-amplitude, are obscured by lower frequency activity, and hence go undetected using common clinical EEG viewing parameters (10s/page, 0.5mA/mm).…”

Section: Introductionmentioning

confidence: 95%

“…The available instruments have relatively poor noise performance for the low-spectral neural signal amplification. We have previously demonstrated several front-end preamplifiers for noise reduction [1], [2].…”

Section: Introductionmentioning

confidence: 99%

New subdural electrode contacts for intracerebral electroencephalographic recordings: Comparative studies on neural signal recording in vivo

Salam

Desgent

Duss

et al. 2011

2011 IEEE Biomedical Circuits and Systems Conference (BioCAS)

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In this paper, we propose new subdural electrode contacts to improve signal-to-noise ratio (SNR) for intracerebral electroencephalographic (icEEG) recording. We describe the proposed electrodes material composition, fabrication process, electro-chemical impedance spectroscopy analyses, and in vitro comparative studies with commercial electrodes (microelectrodes -MRE, depth electrodes -DPE, and subdural electrodes -SDE). The proposed subdural electrode contacts are made of Platinum (Pt) or Gold (Au). Compared to the DPE/SDE and MRE, the proposed Pt or Au electrodes feature reduced impedances of ~116 kΩ and ~8.89 MΩ respectively. In vivo icEEG recordings for three weeks in an adult Sprague Dawley rat demonstrated signal stability, 50% noise reduction and up to 3 dB SNR improvement. Following the long-term icEEG recording, brain histological result showed no abnormal tissue reaction in underlying cortex.

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Wireless Recording Systems: From Noninvasive EEG-NIRS to Invasive EEG Devices

Sawan

Salam

Lan

et al. 2013

IEEE Trans. Biomed. Circuits Syst.

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In this paper, we present the design and implementation of a wireless wearable electronic system dedicated to remote data recording for brain monitoring. The reported wireless recording system is used for a) simultaneous near-infrared spectrometry (NIRS) and scalp electro-encephalography (EEG) for noninvasive monitoring and b) intracerebral EEG (icEEG) for invasive monitoring. Bluetooth and dual radio links were introduced for these recordings. The Bluetooth-based device was embedded in a noninvasive multichannel EEG-NIRS system for easy portability and long-term monitoring. On the other hand, the 32-channel implantable recording device offers 24-bit resolution, tunable features, and a sampling frequency up to 2 kHz per channel. The analog front-end preamplifier presents low input-referred noise of 5 μ VRMS and a signal-to-noise ratio of 112 dB. The communication link is implemented using a dual-band radio frequency transceiver offering a half-duplex 800 kb/s data rate, 16.5 mW power consumption and less than 10(-10) post-correction Bit-Error Rate (BER). The designed system can be accessed and controlled by a computer with a user-friendly graphical interface. The proposed wireless implantable recording device was tested in vitro using real icEEG signals from two patients with refractory epilepsy. The wirelessly recorded signals were compared to the original signals recorded using wired-connection, and measured normalized root-mean square deviation was under 2%.

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A multichannel intracerebral EEG monitoring system for epilepsy presurgical evaluation

Cited by 5 publications

References 7 publications

Subdural porous and notched mini-grid electrodes for wireless intracranial electroencephalographic recordings

Subdural porous and notched mini-grid electrodes for wireless intracranial electroencephalographic recordings

New subdural electrode contacts for intracerebral electroencephalographic recordings: Comparative studies on neural signal recording in vivo

Wireless Recording Systems: From Noninvasive EEG-NIRS to Invasive EEG Devices

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