The cerebral hemodynamic response to electrically induced seizures in man

Saito, Shigeru; Yoshikawa, Daisuke; Nishihara, Fumio; Morita, Toshihiro; Kitani, Yasuharu; Amaya, Taro; Fujita, Tatsushi

doi:10.1016/0006-8993(94)01408-a

Cited by 60 publications

(33 citation statements)

References 33 publications

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“…This is consistent with the finding that the oxygenation state as measured using NIRS decreases with increasing mean flow velocity in transcranial Doppler ultrasonography in patients undergoing electroconvulsive therapy for depression. 45 While not involving a form of epilepsy, a study that used NIRS to monitor the hemodynamics responses in rat brains during transcranial direct current stimulation found that the HbO concentration increased almost linearly during this stimulation. 46 In a study of patients with periodic limb movements during sleep, the cerebral hemodynamics varied among the different sleep stages, and there were also changes in the phase differences between HbO and HbR during the different sleep stages in normal controls.…”

Section: Epilepsymentioning

confidence: 99%

Application of near-infrared spectroscopy in clinical neurology

Kim

Bae

2018

Ann Clin Neurophysiol

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Near-infrared spectroscopy (NIRS) monitoring has been used mainly to detect reduced perfusion of the brain during orthostatic stress in order to assess orthostatic intolerance (OI). Many studies have investigated the use of NIRS to reveal the pathophysiology of patients with OI. Research using NIRS in other neurological diseases (e.g., stroke, epilepsy, and migraine) is continuing. NIRS may play an important role in monitoring the regional distribution of the hemodynamic flow in real time and thereby reveal the underlying pathophysiology and facilitate the management of not only patients with OI symptoms but also those with various neurological diseases.Key words: Orthostatic intolerance; Near-infrared spectroscopy; Clinical neurology INTRODUCTIONMany studies have investigated the hemodynamics and functions of the brain in various fields.1 Several noninvasive methods have been introduced in recent decades for measuring neuronal activity in the brain. 2 Neurophysiological techniques such as electroencephalography, magnetoencephalography, and event-related potentials offer the ability to measure overall changes in the electromagnetic field with an excellent time resolution, but these methods have poor spatial resolution. On the other hand, brain imaging techniques such as positron-emission tomography (PET) and functional magnetic resonance imaging (fMRI) have greatly increased our knowledge about neural circuitry. However, PET is highly sensitive to motion artifacts, confines the patient, and involves the injection of radioactive materials. Although fMRI is noninvasive and has excellent spatial resolution, it is expensive, highly sensitive to motion artifacts, and difficult to integrate with other imaging modalities. 3,4 Near-infrared spectroscopy (NIRS) was introduced as a new neuroimaging modality for Principle of NIRSNIRS is a noninvasive optical imaging tool for observing changes in the hemodynamics in the prefrontal area that is based on measuring the concentrations of HbO and HbR in the blood. Since Franz Jöbsis first studied the oxygenation of living tissues, NIRS has been extensively applied in imaging studies of brain activation. 6 The physiological activation of neurons leads to an imbalance between oxygen supply and utilization, increasing the concentration of HbO and decreasing the concentration of HbR. Most tissues are relatively transparent to light in the near-infrared range from 700 to 900 nm, and photons interact with tissues via absorption and scattering. This means that near-infrared light is less absorbed and scattered by tissue than is light at other wavelengths. 7 This range of wavelengths is often called an optical window since the light can easily pass through most tissues; however, it is reflected by HbO and HbR, and hence the absorption and scattering of light used for NIRS can provide information relevant to neural activity. 8 This light penetrates several centimeters through tissue and can still be detected (Fig. 1). The NIRS system consists of a light source and a photodetector. The l...

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Section: Epilepsymentioning

confidence: 99%

Application of near-infrared spectroscopy in clinical neurology

Kim

Bae

2018

Ann Clin Neurophysiol

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“…There is evidence that during IEDs a compensatory increase in rCBV in the focus region could be expected, concomitantly with a decrease in local HbR and an increase in local HbO and HbT, to provide extra oxygen supply to the epileptic tissue (Penfield and Jasper, 1954;Saito et al, 1995;Suh et al, 2006;Geneslaw et al, 2011). Thus at each location on 2D maps, a hemodynamic response to IEDs was called "standard", or non-inverted, if the response at that location was a negative change for HbR, or a positive change for HbO/HbT.…”

Section: Coregistration and Contrastsmentioning

confidence: 99%

fNIRS-EEG study of focal interictal epileptiform discharges

et al. 2014

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Functional near-infrared spectroscopy (fNIRS) acquired with electroencephalography (EEG) is a relatively new non-invasive neuroimaging technique with potential for long term monitoring of the epileptic brain. Simultaneous EEG-fNIRS recording allows the spatio-temporal reconstruction of the hemodynamic response in terms of the concentration changes in oxyhemoglobin (HbO) and deoxy-hemoglobin (HbR) associated with recorded epileptic events such as interictal epileptic discharges (IEDs) or seizures. While most previous studies investigating fNIRS in epilepsy had limitations due to restricted spatial coverage and small sample sizes, this work includes a sufficiently large number of channels to provide an extensive bilateral coverage of the surface of the brain for a sample size of 40 patients with focal epilepsies. Topographic maps of significant activations due to each IED type were generated in four different views (dorsal, frontal, left and right) and were compared with the epileptic focus previously identified by an epileptologist.After excluding 5 patients due to the absence of IEDs and 6 more with mesial temporal foci too deep for fNIRS, we report that significant HbR (respectively HbO) concentration changes corresponding to IEDs were observed in 62% (resp. 38%) of patients with neocortical epilepsies. This HbR/HbO response was most significant in the epileptic focus region among all the activations in 28%/21% of patients. Keywords:Focal epilepsy, fNIRS, NIRS-SPM, EEG, interictal epileptic discharges

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“…In published studies to date, diffuse reflectance optical imaging has been used frequently to monitor the hemodynamics of an epileptic lesion in vivo in both animal models of epilepsy and humans. 3,8,14,17,28,37,40,41,44,49,52,53 Although these results support the idea that the investigation of intrinsic physiological characteristics, especially hemodynamics, may be a viable alternative or addition to the current methods of epileptic lesion demarcation, the impact of such an approach on the outcome of epilepsy surgery has not yet been determined. Furthermore, the feasibility of using optical spectroscopy to delineate the margins of neocortical epileptic lesions in children has not yet been proven.…”

Section: Optical Spectroscopymentioning

confidence: 74%

“…The fluorescence and diffuse reflectance spectral features depict unique, static, in vivo characteristics of the epileptic cortex during the interictal period, which should not be confused with the dynamic diffuse reflectance features reported by other groups. 3,8,14,17,28,37,40,41,44,49,52,53 These observations warrant further studies to ascertain the clinical utility of optical spectroscopy in pediatric epilepsy surgery.…”

Section: Discussionmentioning

confidence: 89%

The role of optical spectroscopy in epilepsy surgery in children

Bhatia

Ragheb

Johnson

et al. 2008

FOC

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Object Surgery is an important therapeutic modality for pediatric patients with intractable epilepsy. However, existing imaging and diagnostic technologies such as MR imaging and electrocochleography (ECoG) do not always effectively delineate the true resection margin of an epileptic cortical lesion because of limitations in their sensitivity. Optical spectroscopic techniques such as fluorescence and diffuse reflectance spectroscopy provide a nondestructive means of gauging the physiological features of the brain in vivo, including hemodynamics and metabolism. In this study, the authors investigate the feasibility of using combined fluorescence and diffuse reflectance spectroscopy to assist epilepsy surgery in children. Methods In vivo static fluorescence and diffuse reflectance spectra were acquired from the brain in children undergoing epilepsy surgery. Spectral measurements were obtained using a portable spectroscopic system in conjunction with a fiber optic probe. The optical investigations were conducted at the normal and abnormal cortex as defined by intraoperative ECoG and preoperative imaging studies. Biopsy samples were taken from the investigated sites located within the zone of resection. The optical spectra were classified into multiple subsets in accordance with the ECoG and histological study results. The authors used statistical comparisons between 2 given data subsets to identify unique spectral features. Empirical discrimination algorithms were developed using the identified spectral features to determine if the objective of the study was achieved. Results Fifteen pediatric patients were enrolled in this pilot study. Elevated diffuse reflectance signals between 500 and 600 nm and/or between 650 and 850 nm were observed commonly in the investigated sites with abnormal ECoG and/or histological features in 10 patients. The appearance of a fluorescent peak at 400 nm was observed in both normal and abnormal cortex of 5 patients. These spectral alterations were attributed to changes in morphological and/or biochemical characteristics of the epileptic cortex. The sensitivities and specificities of the empirical discrimination algorithms, which were constructed using the identified spectral features, were all > 90%. Conclusions The results of this study demonstrate the feasibility of using static fluorescence and diffuse reflectance spectroscopy to differentiate normal from abnormal cortex on the basis of intraoperative assessment of ECoG and histological features. It is therefore possible to use fluorescence and diffuse reflectance spectroscopy as an aid in epilepsy surgery.

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The cerebral hemodynamic response to electrically induced seizures in man

Cited by 60 publications

References 33 publications

Application of near-infrared spectroscopy in clinical neurology

Application of near-infrared spectroscopy in clinical neurology

fNIRS-EEG study of focal interictal epileptiform discharges

The role of optical spectroscopy in epilepsy surgery in children

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