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Oommen KJ, Kopel J. Optimum duration of hyperventilation during electroencephalography. Proc AMIA Symp 2023; 36:325-328. [PMID: 37091767 PMCID: PMC10120555 DOI: 10.1080/08998280.2023.2177439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023] Open
Abstract
Hyperventilation (HV) is carried out for 3 minutes as a standard activation procedure in most routine electroencephalographic (EEG) procedures. The cerebral blood flow (CBF) reduction and the accompanying cerebral vasoconstriction caused by HV is believed to be the mechanism of EEG activation during HV. Some advocate for 5 minutes of HV, although the optimum duration is unknown. In this study, we measured the CBF continuously over the anterior temporal lobes using subdural probes, which use thermal diffusion flowmetry to measure CBF directly from the cerebral cortex. We sought to determine the duration of HV that produces the maximum reduction in CBF during routine HV in our epilepsy monitoring unit and prolonged the procedure for an additional 2 minutes for this study. Flowtronics® CBF probes were placed over the anterior temporal lobes in addition to the standard subdural strip placement for localization of their seizure focus in six patients who were candidates for epilepsy surgery. CBF was measured continuously for 2 minutes before and 5 minutes during HV for each patient. Time to reach maximum reduction of CBF for each attempt (11 temporal lobes) was computed. At 3 minutes, CBF reduction ranged from 11.6% to 40.0% from the pre-HV CBF level (mean 23.9%). At 5 minutes, CBF ranged from 14.3% to 42.0% (mean 25.7%). Six of the 11 measurements were steady or decreased slightly, and in the five other measurements, CBF showed a reverse trend after 3 minutes. A significant CBF reduction was attained in 3 minutes of HV in all trials. Continued HV after 3 minutes resulted in only a marginal (mean 1.8%) additional CBF reduction after 3 minutes. Thus, we propose that 3 minutes of HV is sufficient for EEG activation by the CBF criterion.
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Affiliation(s)
- Kalarickal J. Oommen
- Jay & Virginia Crofoot Epilepsy Monitoring Unit, Covenant Hospital, and Epilepsy Clinics, Covenant Medical Group, Lubbock, Texas
| | - Jonathan Kopel
- Texas Tech University Health Sciences Center, Lubbock, Texas
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Miraglia F, Pappalettera C, Guglielmi V, Cacciotti A, Manenti R, Judica E, Vecchio F, Rossini PM. The combination of hyperventilation test and graph theory parameters to characterize EEG changes in mild cognitive impairment (MCI) condition. GeroScience 2023:10.1007/s11357-023-00733-5. [PMID: 36692591 PMCID: PMC10400506 DOI: 10.1007/s11357-023-00733-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 01/10/2023] [Indexed: 01/25/2023] Open
Abstract
Hyperventilation (HV) is a voluntary activity that causes changes in the neuronal firing characteristics noticeable in the electroencephalogram (EEG) signals. HV-related changes have been scribed to modulation of pO2/pCO2 blood contents. Therefore, an HV test is routinely used for highlighting brain abnormalities including those depending to neurobiological mechanisms at the basis of neurodegenerative disorders. The main aim of the present paper is to study the effectiveness of HV test in modifying the functional connectivity from the EEG signals that can be typical of a prodromal state of Alzheimer's disease (AD), the Mild Cognitive Impairment prodromal to Alzheimer condition. MCI subjects and a group of age-matched healthy elderly (Ctrl) were enrolled and subjected to EEG recording during HV, eyes-closed (EC), and eyes-open (EO) conditions. Since the cognitive decline in MCI seems to be a progressive disconnection syndrome, the approach we used in the present study is the graph theory, which allows to describe brain networks with a series of different parameters. Small world (SW), modularity (M), and global efficiency (GE) indexes were computed among the EC, EO, and HV conditions comparing the MCI group to the Ctrl one. All the three graph parameters, computed in the typical EEG frequency bands, showed significant changes among the three conditions, and more interestingly, a significant difference in the GE values between the MCI group and the Ctrl one was obtained, suggesting that the combination of HV test and graph theory parameters should be a powerful tool for the detection of possible cerebral dysfunction and alteration.
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Affiliation(s)
- Francesca Miraglia
- Brain Connectivity Laboratory, Department of Neuroscience and Neurorehabilitation, IRCCS San Raffaele Roma, Rome, Italy.
- Department of Theoretical and Applied Sciences, eCampus University, Novedrate (Como), Italy.
| | - Chiara Pappalettera
- Brain Connectivity Laboratory, Department of Neuroscience and Neurorehabilitation, IRCCS San Raffaele Roma, Rome, Italy
- Department of Theoretical and Applied Sciences, eCampus University, Novedrate (Como), Italy
| | - Valeria Guglielmi
- Dipartimento Neuroscienze, Organi di Senso e Torace, Fondazione Policlinico Universitario A. Gemelli IRCCS, Rome, Italy
| | - Alessia Cacciotti
- Brain Connectivity Laboratory, Department of Neuroscience and Neurorehabilitation, IRCCS San Raffaele Roma, Rome, Italy
- Department of Theoretical and Applied Sciences, eCampus University, Novedrate (Como), Italy
| | - Rosa Manenti
- Neuropsychology Unit, IRCCS Istituto Centro San Giovanni di Dio Fatebenefratelli, Brescia, Italy
| | - Elda Judica
- Department of Neurorehabilitation Sciences, Casa di Cura IGEA, Milano, Italy
| | - Fabrizio Vecchio
- Brain Connectivity Laboratory, Department of Neuroscience and Neurorehabilitation, IRCCS San Raffaele Roma, Rome, Italy
- Department of Theoretical and Applied Sciences, eCampus University, Novedrate (Como), Italy
| | - Paolo Maria Rossini
- Brain Connectivity Laboratory, Department of Neuroscience and Neurorehabilitation, IRCCS San Raffaele Roma, Rome, Italy
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Bullock T, Giesbrecht B, Beaudin AE, Goodyear BG, Poulin MJ. Effects of changes in end-tidal PO 2 and PCO 2 on neural responses during rest and sustained attention. Physiol Rep 2021; 9:e15106. [PMID: 34755481 PMCID: PMC8578925 DOI: 10.14814/phy2.15106] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Revised: 10/08/2021] [Accepted: 10/10/2021] [Indexed: 01/23/2023] Open
Abstract
Impairments of cognitive function during alterations in arterial blood gases (e.g., high-altitude hypoxia) may result from the disruption of neurovascular coupling; however, the link between changes in arterial blood gases, cognition, and cerebral blood flow (CBF) is poorly understood. To interrogate this link, we developed a multimodal empirical strategy capable of monitoring neural correlates of cognition and CBF simultaneously. Human participants performed a sustained attention task during hypoxia, hypercapnia, hypocapnia, and normoxia while electroencephalographic (EEG) activity and CBF (middle and posterior cerebral arteries; transcranial Doppler ultrasound) were simultaneously measured. The protocol alternated between rest and engaging in a visual target detection task that required participants to monitor a sequence of brief-duration colored circles and detect infrequent, longer duration circles (targets). The target detection task was overlaid on a large, circular checkerboard that provided robust visual stimulation. Spectral decomposition and event-related potential (ERP) analyses were applied to the EEG data to investigate spontaneous and task-specific fluctuations in neural activity. There were three main sets of findings: (1) spontaneous alpha oscillatory activity was modulated as a function of arterial CO2 (hypocapnia and hypercapnia), (2) task-related neurovascular coupling was disrupted by all arterial blood gas manipulations, and (3) changes in task-related alpha and theta band activity and attenuation of the P3 ERP component amplitude were observed during hypocapnia. Since alpha and theta are linked with suppression of visual processing and executive control and P3 amplitude with task difficulty, these data suggest that transient arterial blood gas changes can modulate multiple stages of cognitive information processing.
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Affiliation(s)
- Tom Bullock
- Department of Psychological and Brain SciencesUniversity of CaliforniaSanta BarbaraCaliforniaUSA
- Institute for Collaborative BiotechnologiesUniversity of CaliforniaSanta BarbaraCaliforniaUSA
| | - Barry Giesbrecht
- Department of Psychological and Brain SciencesUniversity of CaliforniaSanta BarbaraCaliforniaUSA
- Institute for Collaborative BiotechnologiesUniversity of CaliforniaSanta BarbaraCaliforniaUSA
- Interdepartmental Graduate Program in Dynamical NeuroscienceUniversity of CaliforniaSanta BarbaraCaliforniaUSA
| | - Andrew E. Beaudin
- Department of Physiology & PharmacologyUniversity of CalgaryCalgaryAlbertaCanada
- Hotchkiss Brain InstituteCumming School of MedicineUniversity of CalgaryCalgaryAlbertaCanada
| | - Bradley G. Goodyear
- Hotchkiss Brain InstituteCumming School of MedicineUniversity of CalgaryCalgaryAlbertaCanada
- Department of Clinical NeurosciencesUniversity of CalgaryCalgaryAlbertaCanada
- Department of RadiologyUniversity of CalgaryCalgaryAlbertaCanada
| | - Marc J. Poulin
- Department of Physiology & PharmacologyUniversity of CalgaryCalgaryAlbertaCanada
- Hotchkiss Brain InstituteCumming School of MedicineUniversity of CalgaryCalgaryAlbertaCanada
- Department of Clinical NeurosciencesUniversity of CalgaryCalgaryAlbertaCanada
- O’Brien Institute for Public HealthUniversity of CalgaryCalgaryAlbertaCanada
- Libin Cardiovascular Institute of AlbertaUniversity of CalgaryCalgaryAlbertaCanada
- Faculty of KinesiologyUniversity of CalgaryCalgaryAlbertaCanada
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Korit Áková E, Doležalová I, Chládek J, Jurková T, Chrastina J, Plešinger F, Roman R, Pail M, Jurák P, Shaw DJ, Brázdil M. A Novel Statistical Model for Predicting the Efficacy of Vagal Nerve Stimulation in Patients With Epilepsy (Pre-X-Stim) Is Applicable to Different EEG Systems. Front Neurosci 2021; 15:635787. [PMID: 34045942 PMCID: PMC8144700 DOI: 10.3389/fnins.2021.635787] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 03/22/2021] [Indexed: 11/13/2022] Open
Abstract
Background: Identifying patients with intractable epilepsy who would benefit from therapeutic chronic vagal nerve stimulation (VNS) preoperatively remains a major clinical challenge. We have developed a statistical model for predicting VNS efficacy using only routine preimplantation electroencephalogram (EEG) recorded with the TruScan EEG device (Brazdil et al., 2019). It remains to be seen, however, if this model can be applied in different clinical settings. Objective: To validate our model using EEG data acquired with a different recording system. Methods: We identified a validation cohort of eight patients implanted with VNS, whose preimplantation EEG was recorded on the BrainScope device and who underwent the EEG recording according to the protocol. The classifier developed in our earlier work, named Pre-X-Stim, was then employed to classify these patients as predicted responders or non-responders based on the dynamics in EEG power spectra. Predicted and real-world outcomes were compared to establish the applicability of this classifier. In total, two validation experiments were performed using two different validation approaches (single classifier or classifier voting). Results: The classifier achieved 75% accuracy, 67% sensitivity, and 100% specificity. Only two patients, both real-life responders, were classified incorrectly in both validation experiments. Conclusion: We have validated the Pre-X-Stim model on EEGs from a different recording system, which indicates its application under different technical conditions. Our approach, based on preoperative EEG, is easily applied and financially undemanding and presents great potential for real-world clinical use.
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Affiliation(s)
- Eva Korit Áková
- Institute of Biostatistics and Analyses, Faculty of Medicine, Masaryk University, Brno, Czechia
| | - Irena Doležalová
- Brno Epilepsy Center, Department of Neurology and Neurosurgery, St. Anne's University Hospital and Medical Faculty of Masaryk University, Brno, Czechia
| | - Jan Chládek
- Behavioral and Social Neuroscience Research Group, Central European Institute of Technology, Masaryk University, Brno, Czechia.,Institute of Scientific Instruments of the Czech Academy of Sciences, Brno, Czechia
| | - Tereza Jurková
- Brno Epilepsy Center, Department of Neurology and Neurosurgery, St. Anne's University Hospital and Medical Faculty of Masaryk University, Brno, Czechia
| | - Jan Chrastina
- Brno Epilepsy Center, Department of Neurology and Neurosurgery, St. Anne's University Hospital and Medical Faculty of Masaryk University, Brno, Czechia
| | - Filip Plešinger
- Institute of Scientific Instruments of the Czech Academy of Sciences, Brno, Czechia
| | - Robert Roman
- Behavioral and Social Neuroscience Research Group, Central European Institute of Technology, Masaryk University, Brno, Czechia
| | - Martin Pail
- Brno Epilepsy Center, Department of Neurology and Neurosurgery, St. Anne's University Hospital and Medical Faculty of Masaryk University, Brno, Czechia
| | - Pavel Jurák
- Institute of Scientific Instruments of the Czech Academy of Sciences, Brno, Czechia
| | - Daniel J Shaw
- Behavioral and Social Neuroscience Research Group, Central European Institute of Technology, Masaryk University, Brno, Czechia
| | - Milan Brázdil
- Brno Epilepsy Center, Department of Neurology and Neurosurgery, St. Anne's University Hospital and Medical Faculty of Masaryk University, Brno, Czechia.,Behavioral and Social Neuroscience Research Group, Central European Institute of Technology, Masaryk University, Brno, Czechia
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Henkin RI, Potolicchio SJ, Levy LM. Olfactory Hallucinations without Clinical Motor Activity: A Comparison of Unirhinal with Birhinal Phantosmia. Brain Sci 2013; 3:1483-553. [PMID: 24961619 PMCID: PMC4061890 DOI: 10.3390/brainsci3041483] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 10/11/2013] [Accepted: 10/12/2013] [Indexed: 01/14/2023] Open
Abstract
Olfactory hallucinations without subsequent myoclonic activity have not been well characterized or understood. Herein we describe, in a retrospective study, two major forms of olfactory hallucinations labeled phantosmias: one, unirhinal, the other, birhinal. To describe these disorders we performed several procedures to elucidate similarities and differences between these processes. From 1272, patients evaluated for taste and smell dysfunction at The Taste and Smell Clinic, Washington, DC with clinical history, neurological and otolaryngological examinations, evaluations of taste and smell function, EEG and neuroradiological studies 40 exhibited cyclic unirhinal phantosmia (CUP) usually without hyposmia whereas 88 exhibited non-cyclic birhinal phantosmia with associated symptomology (BPAS) with hyposmia. Patients with CUP developed phantosmia spontaneously or after laughing, coughing or shouting initially with spontaneous inhibition and subsequently with Valsalva maneuvers, sleep or nasal water inhalation; they had frequent EEG changes usually ipsilateral sharp waves. Patients with BPAS developed phantosmia secondary to several clinical events usually after hyposmia onset with few EEG changes; their phantosmia could not be initiated or inhibited by any physiological maneuver. CUP is uncommonly encountered and represents a newly defined clinical syndrome. BPAS is commonly encountered, has been observed previously but has not been clearly defined. Mechanisms responsible for phantosmia in each group were related to decreased gamma-aminobutyric acid (GABA) activity in specific brain regions. Treatment which activated brain GABA inhibited phantosmia in both groups.
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Affiliation(s)
- Robert I Henkin
- Center for Molecular Nutrition and Sensory Disorders, The Taste and Smell Clinic, 5125 MacArthur Blvd, NW, Suite 20, Washington, DC 20016, USA.
| | - Samuel J Potolicchio
- Department of Neurology, The George Washington University Medical Center, 2150 Pennsylvania Avenue, NW, 7th Floor, Washington, DC 20037, USA.
| | - Lucien M Levy
- Department of Radiology, The George Washington University Medical Center, 900 23rd Street, NW, Washington, DC 20037, USA.
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Ponomareva NV, Goltsov AY, Kunijeva SS, Scheglova NS, Malina DD, Mitrofanov AA, Boikova TI, Rogaev EI. Age- and genotype-related neurophysiologic reactivity to oxidative stress in healthy adults. Neurobiol Aging 2011; 33:839.e11-21. [PMID: 22206848 DOI: 10.1016/j.neurobiolaging.2011.11.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 07/15/2011] [Accepted: 11/08/2011] [Indexed: 10/14/2022]
Abstract
The epsilon4 allele of the apolipoprotein E gene (ApoE), as well as aging increase the risk of Alzheimer's and vascular diseases. Electroencephalogram (EEG) reactivity to hyperventilation (HV) depends on hypocapnia-induced cerebral vasoconstriction, which may be impaired in subjects with subclinical cerebrovascular disease. Quantitative EEG at rest and under 3-minute HV was examined in 125 healthy subjects divided into younger (age range 28-50) and older (age range 51-82) cohorts and stratified by ApoE genotype. The younger ApoE-epsilon4 carriers had excessive EEG reactivity to HV characterized by the manifestation of high-voltage delta, theta activity and sharp waves, and larger HV-induced changes in EEG relative powers than in the younger ApoE-epsilon4 noncarriers. EEG reactivity to HV decreased with aging, and in the ApoE-epsilon4 carriers the decrease was more pronounced than in the ApoE-epsilon4 noncarriers. The older ApoE-epsilon4 carriers had smaller HV-induced changes in EEG relative powers than the older ApoE-epsilon4 noncarriers. A marked decline of EEG reactivity to HV in the older ApoE-epsilon4 carriers suggests the possible impact of vascular factors on the pathogenesis of ApoE-induced Alzheimer disease.
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Ponomareva NV, Korovaitseva GI, Rogaev EI. EEG alterations in non-demented individuals related to apolipoprotein E genotype and to risk of Alzheimer disease. Neurobiol Aging 2007; 29:819-27. [PMID: 17293007 DOI: 10.1016/j.neurobiolaging.2006.12.019] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2006] [Revised: 12/06/2006] [Accepted: 12/29/2006] [Indexed: 11/25/2022]
Abstract
Identification of preclinical markers is required for early diagnosis of Alzheimer's disease (AD) and cognitive dysfunction in advancing age. Quantitative EEG was examined in 145 individuals with AD, their unaffected relatives and unrelated individuals. The AD patients and their relatives were stratified by ApoE genotype. The resting EEG parameters were severely changed in AD patients, and in patients carrying the ApoE epsilon4 allele the decrease in alpha power was higher than in epsilon4 non-carriers. The resting EEG parameters were indistinguishable in AD relatives with different ApoE genotypes and similar to EEG pattern in common population. Under hyperventilation the presence of the epsilon4 allele in AD relatives was associated with the manifestation of synchronous high-voltage delta-, theta-activity and sharp-waves, pronounced decrease in alpha and increase in delta and theta relative powers. The data suggest that neurophysiological endophenotype of non-demented individuals at genetic risk for AD, characterized by increased excitability and dysfunction of deep brain and alpha rhythm-generating structures, may be revealed decades before the first clinical symptoms of presumable dementia.
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Affiliation(s)
- N V Ponomareva
- Institute of Neurology, Brain Research Department, Russian Academy of Medical Sciences, Moscow, Russia.
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Guaranha MSB, Garzon E, Buchpiguel CA, Tazima S, Yacubian EMT, Sakamoto AC. Hyperventilation revisited: physiological effects and efficacy on focal seizure activation in the era of video-EEG monitoring. Epilepsia 2005; 46:69-75. [PMID: 15660770 DOI: 10.1111/j.0013-9580.2005.11104.x] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE Hyperventilation is an activation method that provokes physiological slowing of brain rhythms, interictal discharges, and seizures, especially in generalized idiopathic epilepsies. In this study we assessed its effectiveness in inducing focal seizures during video-EEG monitoring. METHODS We analyzed the effects of hyperventilation (HV) during video-EEG monitoring (video-EEG) of patients with medically intractable focal epilepsies. We excluded children younger than 10 years, mentally retarded patients, and individuals with frequent seizures. RESULTS We analyzed 97 patients; 24 had positive seizure activation (PSA), and 73 had negative seizure activation (NSA). No differences were found between groups regarding sex, age, age at epilepsy onset, duration of epilepsy, frequency of seizures, and etiology. Temporal lobe epilepsies were significantly more activated than frontal lobe epilepsies. Spontaneous and activated seizures did not differ in terms of their clinical characteristics, and the activation did not affect the performance of ictal single-photon emission computed tomography (SPECT). CONCLUSIONS HV is a safe and effective method of seizure activation during monitoring. It does not modify any of the characteristics of the seizures and allows the obtaining of valuable ictal SPECTs. This observation is clinically relevant and suggests the effectiveness and the potential of HV in shortening the presurgical evaluation, especially of temporal lobe epilepsy patients, consequently reducing its costs and increasing the number of candidates for epilepsy surgery.
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Levy LM, Henkin RI. Physiologically initiated and inhibited phantosmia: cyclic unirhinal, episodic, recurrent phantosmia revealed by brain fMRI. J Comput Assist Tomogr 2000; 24:501-20. [PMID: 10966179 DOI: 10.1097/00004728-200007000-00001] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE Our goal was to use functional magnetic resonance imaging (fMRI) to demonstrate brain activation in patients with unirhinal, episodic, recurrent phantosmia who induced their phantosmia by coughing, sneezing, laughing or vigorous nasal inhalation and expiration, and inhibited it by sleep or performance of a Valsalva type maneuver. METHODS Three patients with unirhinal phantosmia without change in taste or smell acuity were studied by fast low angle shot (FLASH) MRI and by echo planar imaging (EPI). Brain activation was measured following memory of two tastants (salt, sweet), memory of two odorants (banana and peppermint), actual smell of three odors (amyl acetate, menthone, pyridine), memory of phantosmia (and phantageusia, where applicable), phantosmia initiated spontaneously or by vigorous nasal inhalation and exhalation, phantosmia after inhibition by Valsalva, and these stimuli before and after treatment with the neuroleptic thioridazine. Activation images were derived using correlation analysis and ratios of areas of brain activated to total brain areas were calculated. Total activated pixel cluster counts were also used to quantitative total and regional brain activation. RESULTS Sensory-specific brain activation was present in each section in each patient following memory of tastants and odorants, actual smell of each odor and memory, and initiation of and inhibition of phantosmia. Activation to odor memory after phantosmia initiation was very robust, whereas after phantosmia inhibition it was similar to that in normal subjects. Brain activation to unirhinal phantosmia was bihemispheric, independent of whether it was left or right sided or patient handedness. While phantosmia memory (in the absence of initiated phantosmia) produced extremely robust brain activation, after initiation and inhibition of phantosmia apparent brain activation decreased. These changes need to be related to shifting state of baseline brain activation and should be interpreted to reflect increased rather than decreased brain activation over that of phantosmia memory alone. Treatment with thioridazine inhibited brain activation to all stimuli including phantosmia and phantageusia memory, as it did previously in patients with birhinal phantosmia. CONCLUSIONS 1) Unirhinal phantosmia can be demonstrated by brain fMRI as can birhinal phantosmia; 2) unirhinal phantosmia can be initiated and inhibited by physiological maneuvers reflected by changes in fMRI brain activation; 3) fMRI brain activation of unirhinal phantosmia is bihemispheric and independent of peripheral side of phantosmia or patient handedness; 4) anterior frontal brain region plays a significant role in both phantosmia initiation and inhibition as, to some extent, do temporal brain regions; 5) activation of brain GABAergic systems appears to play a role in inhibition of unirhinal phantosmia; and 6) unirhinal phantosmia, similar to birhinal phantosmia, may reflect a type of maladaptive brain plasticity similar to that hypothesized to be responsible for phantom limb pain.
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Affiliation(s)
- L M Levy
- Department of Radiology, Georgetown University Medical Center, Washington, DC, USA
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Hoshi Y, Okuhara H, Nakane S, Hayakawa K, Kobayashi N, Kajii N. Re-evaluation of the hypoxia theory as the mechanism of hyperventilation-induced EEG slowing. Pediatr Neurol 1999; 21:638-43. [PMID: 10513691 DOI: 10.1016/s0887-8994(99)00063-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
To determine whether the well-accepted hypoxia theory accounts for hyperventilation-induced electroencephalogram (EEG) slowing, the authors monitored changes in cerebral oxygenation and end-tidal concentrations of carbon dioxide in 67 patients with epilepsy (age range = 5-12 years) during the hyperventilation activation test in a routine EEG examination. Relative concentration changes in cerebral oxygenated, deoxygenated, total hemoglobin, and oxidized cytochrome oxidase were measured by near-infrared spectroscopy in the frontal region. In all patients, except one who demonstrated EEG slowing, total and oxygenated hemoglobin decreased, and cytochrome oxidase was not reduced. EEG slowing occurred intermittently in 22 patients and was not synchronous with changes in either the cerebral oxygenation or end-tidal concentration of carbon dioxide. The degree of EEG slowing was diminished or the slow waves disappeared abruptly within 1 second after the cessation of hyperventilation in 22 patients when both the cerebral oxygenation and end-tidal concentration of carbon dioxide were still at low levels. The findings during the recovery periods do not confirm the hypoxia theory. It is thus supposed that more subtle mechanisms are the cause of EEG slowing.
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Affiliation(s)
- Y Hoshi
- Biophysics Group, Research Institute for Electronic Science, Hokkaido University, Sapporo, Japan
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Kaplan A, Kochetova A, Nezavibathko V, Rjasina T, Ashmarin I. Synthetic acth analogue semax displays nootropic-like activity in humans. ACTA ACUST UNITED AC 1999. [DOI: 10.1002/(sici)1520-6769(199609)19:2<115::aid-nrc171>3.0.co;2-b] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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12
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Goel V, Brambrink AM, Baykal A, Koehler RC, Hanley DF, Thakor NV. Dominant frequency analysis of EEG reveals brain's response during injury and recovery. IEEE Trans Biomed Eng 1996; 43:1083-92. [PMID: 9214826 DOI: 10.1109/10.541250] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A new method of monitoring an analyzing electroencephalogram (EEG) signals during brain injury is presented. EEG signals are modeled using the autoregressive (AR) technique to obtain the frequencies where there are peaks in the spectrum. The powers at these dominant frequencies are analyzed to reveal the state of brain injury during an experimental study involving progressive hypoxia, asphyxia, and recovery. Neonatal piglets (n = 8) were exposed to a sequence of 30 min of hypoxia (10% oxygen), 5 min of room air, and 7 min of asphyxia. They then received cardiopulmonary resuscitation and were subsequently monitored for 4 h. An optimal AR model order of six was obtained for these data, resulting in three dominant frequencies. These dominant frequencies, referred to as the low, medium, and high frequency components, fell in the bands 1.0-5.5 Hz, 9.0-14.0 Hz, and 18.0-21.0 Hz, respectively. A remarkable feature of our data is the spectral dispersion, or diverging trends in the three frequency bands. During hypoxia, the relative powers of the medium and high-frequency components of EEG increased up to 160% and 176%, from their respective baseline values. During the first minute of asphyxia the medium- and high-frequency powers (relative to baseline) increased by 280-400%. The power in three frequency components went down to nearly zero within 40-80 s of asphyxia. During recovery, the phenomenon of burst-suppression was clearly exhibited in the low-frequency component. A new index, called mean normalized separation, representing the degree of disproportionality in the recovery of powers of the three dominant components relative to their mean recovered power, is presented as a possible single indicator of electrical function recovery. In conclusion, dominant frequency analysis helps reveal the brain's graded electrical response to injury and recovery.
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Affiliation(s)
- V Goel
- Department of Biomedical Engineering, Johns Hopkins University, School of Medicine, Baltimore, MD 21205, USA
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Wirrell EC, Camfield PR, Gordon KE, Camfield CS, Dooley JM, Hanna BD. Will a critical level of hyperventilation-induced hypocapnia always induce an absence seizure? Epilepsia 1996; 37:459-62. [PMID: 8617175 DOI: 10.1111/j.1528-1157.1996.tb00592.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
We wished to determine if the degree of hypocapnia correlates with increased frequency of absence seizures and if there is a critical pCO2 at which absence seizures are reliably provoked. Twelve untreated children with newly diagnosed absence epilepsy were continuously monitored by EEG and end-expiratory CO2 recording during quiet respiration and hyperventilation (to absence seizure or exhaustion) while breathing four gas mixtures: (a) room air, (b) 100% O2, (c) 4% CO2 in room air, or (d) 4% CO2 + 96% O2). In quiet respiration, a reduction in number of spike and wave bursts and total seconds of spike and wave was noted in children breathing supplemental CO2 (gases c and d vs. gases a and b), p < 0.05. Supplemental O2 had no effect. Eight subjects had absence seizures elicited with each trial of hyperventilation. All subjects had their own critical pCO2, ranging from 19 to 28 mmHg. Three children had no seizures, two despite hypocapnia to pCO2 of 19 and 21 and 1 who achieved a pCO2 of only 25. In 1, absence seizures were provoked in only six of nine hyperventilation trials to pCO2 of 17-23. In 67% of subjects, absence seizures were reliably provoked by hypocapnia. Critical pCO2 varied among children with absence. Determination of whether variation in sensitivity to hypocapnia may be helpful in determining response to antiepileptic drugs (AEDs) or remission of seizures will require further study.
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Affiliation(s)
- E C Wirrell
- Department of Paediatrics, Dalhousie University Medical School, Izaak Walton Killam Hospital for Children, Halifax, Nova Scotia, Canada
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14
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Abstract
In 20 patients with epilepsy, electroencephalography (EEG) slowing was quantitatively characterized during standardized hyperventilation activation (respiratory rate: 30/min, threefold elevation of total expiratory volume, duration: 4 min) and changes in cerebral blood flow and velocity in the right common carotid artery were monitored with the Doppler ultrasonic method. Thirteen age-matched normal children served as controls. The results were as follows: (1) EEG slowing in the epilepsy group was greater compared with controls. (2) There was a significant decrease in mean frequency (decrease in alpha power and increase in delta power) during hyperventilation in the epilepsy group, but no significant change in the controls. (3) The decrease in cerebral blood flow (CBF) was greater in the epilepsy group at the beginning of hyperventilation, possibly related to the greater EEG slowing. (4) The percentage of CBF at the end of hyperventilation was similar in the epilepsy and control groups. The difference in EEG response to hyperventilation between the 2 groups may be due to differences in the decrease in CBF volume and the sensitivity of the change in CBF.
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Affiliation(s)
- M Yamatani
- Department of Pediatrics, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Japan
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15
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Abstract
In 66 children with no neurologic symptoms, we analyzed EEG slowing quantitatively during standardized hyperventilation (HV) activation [respiration rate (RR) of 30/min, threefold increase of VE, and 4-min duration]. Changes in cerebral blood flow (CBF) and velocity were also monitored in right common carotid artery by Doppler ultrasonic method. Decreases in PCO2 and CBF were the fundamental factors producing EEG slowing during HV. The degree of EEG slowing was greater in younger children and well proportional to age with such standardized HV. The decrease in CBF was much greater in younger children at the beginning of HV and may be related to the significant EEG slowing. EEG slowing was not related to the degree of decrease in CBF. The age difference in EEG response to HV in children and adults may be due to the differences in the decrease in the CBF volume and sensitivity of the CNS to the change in CBF.
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Affiliation(s)
- M Yamatani
- Department of Pediatrics, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Japan
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16
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Akeson J, Messeter K, Rosén I, Björkman S. Cerebral haemodynamic and electrocortical CO2 reactivity in pigs anaesthetized with fentanyl, nitrous oxide and pancuronium. Acta Anaesthesiol Scand 1993; 37:85-91. [PMID: 8424303 DOI: 10.1111/j.1399-6576.1993.tb03605.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Cerebral haemodynamic, metabolic and electrocortical reactivity to alterations in arterial CO2 tension (PaCO2) was assessed in seven mechanically ventilated juvenile pigs to test an experimental model designed for cerebral pharmacodynamic and pharmacokinetic studies. The animals were anaesthetized with fentanyl, nitrous oxide and pancuronium and sequentially normo- and hyperventilated over a 100-min period. Five measurements were made at 25-min intervals. The cerebral blood flow (CBF) was measured with the intra-arterial 133Xe technique and the cerebral metabolic rate for oxygen (CMRO2) determined from CBF and the cerebral arteriovenous oxygen content difference. A linear correlation (r = 0.845) was found between CBF and PaCO2. The cerebrovascular reactivity to hypocapnia (delta CBF/delta PaCO2) was maintained throughout the experimental period and amounted to (95% confidence interval) 9.1 (7.1-11.1) ml x 100 g-1 x min-1 x kPa-1 within the PaCO2 range 3.3-6.3 kPa. The CMRO2 was not influenced by hyperventilation. The baseline electroencephalographic (EEG) pattern was stable at normocapnia (mean PaCO2 5.6 kPa), whereas spectral values for delta and total average voltage increased significantly (P < 0.05) at extensive hypocapnia (3.5 kPa). Maintenance of cerebral CO2 reactivity and spectral EEG voltage at a stable plasma level of fentanyl is complementary to the cerebral haemodynamic and metabolic stability previously found at sustained normocapnia in this model.
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Affiliation(s)
- J Akeson
- Department of Anaesthesia and Intensive Care, Malmö General Hospital, Lund University, Sweden
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17
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Gravenstein MA, Sasse F, Hogan K. Effects of hypocapnia on canine spinal, subcortical, and cortical somatosensory-evoked potentials during isoflurane anesthesia. J Clin Monit Comput 1992; 8:126-30. [PMID: 1583548 DOI: 10.1007/bf01617431] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Although hyperventilation with hypocapnia is frequently used in the management of neurosurgical patients in whom sensory-evoked potentials may be monitored, the effects of hypocapnia on evoked potentials have not been described with precision. In the present experiment, the effects of randomized arterial carbon dioxide tensions of 20, 25, 30, and 35 mm Hg on spinal, subcortical, and cortical somatosensory-evoked potentials (SEPs) were measured in dogs anesthetized with 1.40% isoflurane. Other variables known to affect the SEP (temperature, blood pressure, and arterial oxygen tension) were stable throughout the experiment. Hypocapnia caused reductions in the latencies of the early peaks of the spinal and subcortical SEPs. These differences were small, consisting of a 2% shortening of latency at 20 mm Hg carbon dioxide tension when compared with 35 mm Hg. No changes were detected in the later subcortical and cortical latencies. SEP amplitudes were also unchanged. These results in a controlled animal study corroborate the direction and magnitude of changes due to hypocapnia observed by other investigators in surgical patients. The magnitude of the changes indicates that SEP monitoring sensitivity is not compromised by clinically useful levels of induced hypocapnia during isoflurane anesthesia. Because hypocapnia may produce small SEP changes, baseline recordings should be acquired prior to initiation of hyperventilation. It is not warranted, however, to impute a severe deterioration of the SEP to hypocapnia alone, and causes must be sought elsewhere in a patient's status and management.
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Affiliation(s)
- M A Gravenstein
- Department of Anesthesiology, Clinical Sciences Center, University of Wisconsin, Madison 53792
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18
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Balzamo E, Gayan-Ramirez G, Jammes Y. Quantitative EEG changes under various conditions of hyperventilation in the sensorimotor cortex of the anaesthetized cat. ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY 1991; 78:159-65. [PMID: 1704839 DOI: 10.1016/0013-4694(91)90116-l] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The effects on the EEG rhythms recorded from the sensorimotor cortex (post-sigmoid gyrus) of anaesthetized cats were studied under 4 conditions of artificial mechanical hyperventilation (HV) before and after cervical bilateral vagotomy. In animals with intact vagus nerves, using visual examination, EEG changes were only observed within the 2nd min during HV produced by increased stroke volume (delta V) with associated hypocapnia. Quantitative EEG (qEEG) showed that, for the same increase in minute ventilation and the same degree of hypocapnia, delta V induced a greater and earlier relative decrease (2nd min) in the power density of delta, theta and alpha bands, than increased pump frequency (delta F). The delta F tests produced a fall only in the theta band and within the 3rd min. With constant paCO2, transient modifications occurred only with delta V and were limited to the first 30 sec. In bivagotomized cats, moderate EEG responses to delta V plus associated hypocapnia persisted partly in the alpha band. Finally, no changes appeared with delta V or delta F when the vagus nerves were cut and paCO2 was maintained constant. The present data suggest strongly that, in anaesthetized cats, peripheral vagal afferents from the respiratory system play a major role in the EEG changes caused by artificial hyperventilation.
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Affiliation(s)
- E Balzamo
- Laboratoires de Biologie des Hautes Pressions (URA 1330 CNRS), Faculté de Médecine, Marseilles, France
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Adler G. Hyperventilation as a model for acute ischaemic hypoxia of the brain: effects on cortical auditory evoked potentials. Eur Arch Psychiatry Clin Neurosci 1991; 240:367-9. [PMID: 1831669 DOI: 10.1007/bf02279768] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Controlled hyperventilation (HV) may be used as an experimental procedure to produce transient ischaemic hypoxia of the brain. The effect of HV on the cortical auditory evoked potential (AEP) components N1 and P2 was studied in ten healthy adult subjects. AEP were recorded before HV, during 3 min of controlled HV, and 1 min and 5 min after the end of HV. The P2 amplitude was significantly reduced by HV and regained its initial value 1 min after the end of HV. The P2 amplitude decrease probably reflects an impairment of synaptic function produced by cerebral hypoxia. Thus, the investigation of cortical AEP components may provide a useful parameter in the study of anti-ischaemic or anti-hypoxic therapies.
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Affiliation(s)
- G Adler
- Neurologische Universitätsklinik Göttingen, Federal Republic of Germany
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Kraaier V, van Huffelen AC, Wieneke GH. Changes in quantitative EEG and blood flow velocity due to standardized hyperventilation; a model of transient ischaemia in young human subjects. ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY 1988; 70:377-87. [PMID: 2460311 DOI: 10.1016/0013-4694(88)90015-6] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A standardized hyperventilation (HV) procedure has been developed in which the end-tidal pCO2 was decreased to 2 kpa. In 24 young male subjects blood flow velocity and qEEG were studied before, during and after HV. This standardized hyperventilation procedure gave rise to a decrease in blood flow velocity to 40% of baseline value and highly significant qEEG changes in 3 derivations. Both relative and absolute band power estimates showed an increase in slow activity and a decrease in alpha and beta activity. The use of subtraction spectra led to a more precise and detailed presentation of these changes than the use of classical qEEG parameters. These changes were reproducible after 1 week. The effects found in the presented model of HV-induced ischaemia appeared to be twice as large as those found in a model of hypobaric hypoxia. The present model might be used to test the efficacy of anti-ischaemic drugs in young human subjects.
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Affiliation(s)
- V Kraaier
- Dept. of Clinical Neurophysiology, University Hospital Utrecht, The Netherlands
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