Magnetoencephalography and normal pressure hydrocephalus: A case report.

A 82-year-old male experiencing headaches, dementia, urinary incontinence and gait instability was diagnosed with normal pressure hydrocephalus (NPH) and underwent a resting state magnetoencephalography (MEG) examination. MEG data were recorded in a magnetically shielded room with a whole-head 122 channel biomagnetometer. Following MEG, a ventriculoperitoneal (VP) shunt was placed in his head and greatly improved his symptomatology. Spontaneous MEG recordings revealed lower magnetic fields at frontal and frontotemporal regions compared to central and posterior regions. This finding correlated well with the significant ventricular distention, and specifically the enlargement of the frontal horns of the lateral ventricles, observed in presurgical CT. The regional pattern of MEG signal decrease in NPH seems to be quite different from that encountered in brain atrophy. In the latter case, a more generalized distribution of low magnetic fields is observed, possibly reflecting the high sensitivity of MEG to activity originating in sulci. Acquired data suggest that MEG may be able to differentiate between NPH and brain atrophy. Furthermore, MEG could potentially constitute a non-invasive, non-imaging tool, useful in the selection of patients with NPH to undergo shunt surgery. The findings of this study warrant further research in patient groups before firm conclusions can be drawn.

A comparative immunohistochemical investigation of the consequences of chorioamnionitis on the developing human fetal spleen.

INTRODUCTION: The objective of this study was to determine the effects of chorioamnionitis on the extracellular matrix (ECM) structural glycoproteins of the developing human fetal spleen, and their influence on the haematopoiesis and spleen immune system compared to controls. MATERIALS AND METHODS: After elective induced pregnancy termination due to chorioamnionitis or voluntary abortion, paraffin-embedded specimens from the spleen and respective fetal membranes of 90 fetuses were investigated by immunohistochemistry for presence of ECM structural glycoproteins, haematopoietic, and lymphoid cells. Conventional histological examination of the relative fetal membranes was performed. RESULTS: The present results showed no quantitative variations in the expression of the ECM glycoproteins and haematopoietic lineages of the fetal spleen parenchyma at the end of first trimester (in both groups). At the second and third trimesters, acute chorioamnionitis showed a decreased number of the aforementioned proteins, with an increase of granulopoiesis and CD34 progenitor/stem haematopoietic cells. The immune system of the spleen during the third trimester demonstrated a decrease of both B and T lymphocytes, in comparison with controls. CONCLUSIONS: These results suggest that toxins and cytokines generated during chorioamnionitis, seem to influence ECM structural glycoproteins synthesis and release in fetal splenic parenchyma by reducing them, and probably cause further disorders of haematopoiesis and lymphopoiesis.

MEG evaluation of pico-Tesla external TMS on multiple sclerosis patients.

Magnetoencephalographic (MEG) recordings of 10 multiple sclerosis (MS) patients (2 men, 8 women, mean 41.3±9.5 years, mean disease duration 12.7±7.2 years) were obtained using a whole-head 122 - channel MEG system in a magnetically shielded room of low magnetic noise. Our experimental design was double-blind in order to look for possible effect of external pico - Tesla Transcranial Magnetic Stimulation (pT-TMS). The external pT-TMS was applied on the MS patients with proper field characteristics (magnetic field amplitude: 1-7.5pT, frequency: the alpha-rhythm of the patient 8-13Hz) which were obtained prior to the application of pT-TMS. Each MS patient had two separate recording sessions consisting of 3 runs in between where were given real or sham pT-TMS. It was then tried to predict the real and sham stimulation sessions based on the changes in the mean peak frequency difference (MPFD) observed in the brain of the patients in the 2-7Hz frequency band. After unblinding it was found a significant effect of an increase of frequencies in the range of 2-7Hz across the subjects followed by an improvement and normalization of the MEG.

Biomagnetic activity and non linear analysis in obstetrics and gynecology in a Greek population.

This article reports the application of non-linear analysis to biomagnetic signals recorded from fetal growth restriction, fetal brain activity, ovarian lesions, breast lesions, umbilical arteries, uterine myomas, and uterine arteries in a Greek population. The results were correlated with clinical findings. The biomagnetic measurements and the application of non-linear analysis are promising procedures in Obstetrics and Gynecology.

Alpha, delta and theta rhythms in a neural net model. Comparison with MEG data.

The aim of this study is to provide information regarding the comparison of a neural model to MEG measurements. Our study population consisted of 10 epileptic patients and 10 normal subjects. The epileptic patients had high MEG amplitudes characterized with θ (4-7 Hz) or δ (2-3 Hz) rhythms and absence of α-rhythm (8-13 Hz). The statistical analysis of such activities corresponded to Poisson distribution. Conversely, the MEG from normal subjects had low amplitudes, higher frequencies and presence of α-rhythm (8-13 Hz). Such activities were not synchronized and their distributions were Gauss. These findings were in agreement with our theoretical neural model. The comparison of the neural network with MEG data provides information about the status of brain function in epileptic and normal states.

MEG localization of spike sources in human patients with brain tumors.

The purpose of this study was to use magnetoencephalography (MEG) to identify epileptic zones in patients with brain tumors before undergoing tumor surgery. The MEG data were recorded with a 122-channel biomagnetometer. Equivalent current dipoles (ECD) were calculated for epileptic spikes on MEG recordings according to the single dipole model. Eight patients (five males and three females) within the age range (43-73 years; mean ± SD = 55.12 ± 9.77) were examined by MEG before neurosurgery operation. Four patients had meningioma grade I, three had glioblastoma grade IV and one had astrocytoma grade II. All the patients showed ECD at their MEG's before surgical operation except a female one with meningioma who showed no ECD. Tumors observed in the frontal areas show posteriorly located ECD. We conclude that the MEG is a valuable clinical tool for the localization of epileptic foci in patients with brain tumors before surgical tumor operation.

A study on the age dependency of gustatory states: low-frequency spectral component in the resting-state MEG.

Magnetoencephalography (MEG) recordings were evaluated for 25 healthy female volunteers, in five different gustatory states: normal, sweet, bitter, sour and salty. The study population was divided in two groups according to age: group A (10-19 years old) and group B (20-30 years old). There was a higher count of low frequencies (2 Hz) and a lower count of high frequencies (7 Hz) with increasing age, in all studied states. We compared each state for the frequencies of 2 Hz and 7 Hz between the two groups. Statistically significant differences were found in the normal and sweet states for the frequencies of 2 Hz and 7 Hz and in the salty taste in the frequency of 7 Hz. We also intra-compared the five states in group A and the five states in group B for the 2 Hz and 7 Hz frequencies. The results were not statistically significant. A differentiation in the distribution of the frequencies with increasing age may provide new insights into the age-dependence of taste quality brain centers.

MEG evaluation of taste by gender difference.

Magnetoencephalographic recordings were evaluated in five different states: normal condition, sweet, bitter, sour, and salt taste. Twenty-eight healthy volunteers, 14 male and 14 female, ranging from 12 to 50 years of age, were included in the study. The results showed that, in the normal condition, as well as in the sweet and the bitter taste, the male volunteers exhibited a higher count of low-frequency than high-frequency channels compared to the femal ones; in the case of the sour taste, there was no clear differentiation between the genders; with the salt taste, the female volunteers exhibited a higher count of low-frequency channels whereas there was no clear differentiation in the number of high frequencies between the gender. A discrimination in the spatial distribution of the frequencies provides novel insights into the identification of gender-related taste sensation.

Magnetoencephalographic findings in two cases of juvenile myoclonus epilepsy.

The aim of this study is to investigate the electromagnetic sources of epileptic activity in two patients with juvenile myoclonus epilepsy (JME). The first patient was a 22-year old female with JME diagnosis by the age of 17 years old. Her initial EEG recording showed characteristic paroxysmal generalized activity with polyspike-wave complexes. She was on remission for 9 months. The second patient was a 29-year old male with JME diagnosis by the age 18 of years old. He showed an EEG recording with generalized spike-wave complexes of 3.5-4 Hz and presented a great improvement after therapeutic treatment. The MRI examinations for both patients did not disclose any focal lesions or areas of abnormal signal intensity or enhancement by contrast media. Magnetoencephalography (MEG) was recorded with a 122-channel whole-head system, 5 years after the disease onset for the first patient and 11 years for the second patient. For the first patient dipolar sources of MEG paroxysmal activity were localised at the vermis with extension up to the occipital region, whereas, for the second patient dipolar sources of MEG paroxysmal activity were localised at the cerebellar area (vermis and hemisphere). Implication of the cerebellum in JME, as suggested by MEG data in this study, is in accordance with previous reports employing functional MRI or cerebral blood flow evaluation in JME.

Biomagnetic activity in prostate cancer and BPH.

OBJECTIVE: The aim of this study was to investigate the role of biomagnetic activity measurements in detecting prostate malignancies, in differentiating cancerous from benign prostate lesions and in generally improving our understanding of prostate cancer biology. METHODS: Magnetic recordings were obtained from 47 patients with palpable prostate lesions. Twenty-four had prostate carcinoma and 23 benign prostatic hyperplasia (BPH). RESULTS: The magnetic field recorded in the 2-7 Hz frequency range was of high amplitude in most (95%) malignant lesions 248 +/- 82 Ft/Hz) and of low amplitude in most (95%) benign ones (166 +/-31 Ft/Hz). These findings displayed significant difference (p = 0.0021). CONCLUSIONS: Prostate cancer emits higher biomagnetic activity than BPH. This finding confirms the higher angiogenic activity of prostate cancer. The use of this method is safe and seems promising.

Meg recordings of patients with CNS disorders before and after external magnetic stimulation.

Magnetoencephalographic (MEG) recordings of patients with CNS disorders were obtained using a whole-head 122-channel magnetometer SQUID and analyzed using Fourier statistical analysis. External transcranial magnetic stimulation in the order of pico Tesla (pTMS) was applied to the above patients with proper characteristics (magnetic intensity 1-7.5 pT; frequency: 8-13 Hz) which were obtained with MEG recordings prior to pTMS. The MEG recordings after the application of pTMS showed a rapid attenuation of the high abnormal activity followed by an increase in the number of the low frequency components toward the patients alpha-rhythm. The possible mechanisms of the effects of external magnetic stimulation on the pineal gland in the brain are presented.

Meg evaluation of epileptic activity in the time and frequency domain.

We investigated the localization of current sources in the time and frequency domain from spontaneous MEG data recorded from nine epileptic patients (six females; three males) randomly selected, who had a mean age of 41 years old (range of 17-78 years old), with different types of epilepsy. The MEG data were recorded in a magnetically shielded room with a whole-head 122 channel biomagnetometer. For each MEG spike, we calculated the single Equivalent Current Dipole (ECD) sources at the initial spike peaks with a spherical model. MRI and EEG findings were available in patients' records. Prominent low frequencies can be seen in the majority of channels. For each patient there was an increase of the frequency range after the ECD in comparison with the frequency range before the ECD, in the whole study group due to epileptic discharge which is statistically significant (p=0.02). There was also a statistical significant difference in the increase of the frequency range in four patients with pathologic MRI (p=0.05), in five patients with normal MRI (p=0.02), in five patients with a high incidence of seizures (p=0.04) and in four patients with onset<10 years (p=0.04). The MEG analysis of neuromagnetic data gives information about the modification of the frequency range in the epileptic brains.

The process of learning in neural net models with Poisson and Gauss connectivities.

In this study we examined the dynamic behavior of isolated and non-isolated neural networks with chemical markers that follow a Poisson or Gauss distribution of connectivity. The Poisson distribution shows higher activity in comparison to the Gauss distribution although the latter has more connections that obliterated due to randomness. We examined 57 hematoxylin and eosin stained sections from an equal number of autopsy specimens with a diagnosis of "cerebral matter within normal limits". Neural counting was carried out in 5 continuous optic fields, with the use of a simple optical microscope connected to a computer (software programmer Nikon Act-1 vers-2). The number of neurons that corresponded to a surface was equal to 0.15 mm(2). There was a gradual reduction in the number of neurons as age increased. A mean value of 45.8 neurons /0.15 mm(2) was observed within the age range 21-25, 33 neurons /0.15 mm(2) within the age range 41-45, 19.3 neurons /0.15 mm(2) within the age range 56-60 years. After the age of 60 it was observed that the number of neurons per unit area stopped decreasing. A correlation was observed between these experimental findings and the theoretical neural model developed by professor Anninos and his colleagues. Equivalence between the mean numbers of neurons of the above mentioned age groups and the highest possible number of synaptic connections per neuron (highest number of synaptic connections corresponded to the age group 21-25) was created. We then used both inhibitory and excitatory post-synaptic potentials and applied these values to the Poisson and Gauss distributions, whereas the neuron threshold was varied between 3 and 5. According to the obtained phase diagrams, the hysteresis loops decrease as age increases. These findings were significant as the hysteresis loops can be regarded as the basis for short-term memory.

Evaluation of an intracranial arachnoid cyst with MEG after magnetic stimulation.

A 34-year-old male diagnosed of an intracranial arachnoid cyst arising in the left-sided temporal-parietal area, by computed tomography (CT), underwent evaluation by means of MEG. Biomagnetic waveform recordings were obtained from the target area and the Fourier analysis of these measurements was carried out. External magnetic stimulation in the order of pico Tesla was applied with proper field characteristics (intensity: 1-7.5 pT, frequency: 8-13 Hz), which were obtained prior to the application and the emitted MEG activity was recorded again. The cortical area adjacent to the borders of the arachnoid cyst emitted biomagnetic waveforms with high values. The application of magnetic stimulation resulted in a rapid attenuation of the high MEG activity in the target area. MEG may provide useful information in the diagnostic evaluation of arachnoid cyst patients and could be a supplement to other imaging modalities.

Differentiation of MEG activity in multiple sclerosis patients with the use of nonlinear analysis.

The aim of this study is to investigate if there is any nonlinearity in the magnetoencephalographic recordings of patients with multiple sclerosis in comparison with controls in order to find out the differences in the mechanisms underlying their brain waves. Five multiple sclerosis patients and five controls were included in this study. Chaotic activity of multiple sclerosis patients is lower than in the normal brain. Nonlinear analysis may offer fertile perspectives for understanding the features of patients with multiple sclerosis.

MEG evaluation of Parkinson's diseased patients after external magnetic stimulation.

Magnetoencephalographic (MEG) recordings of Parkinson's diseased (PD) patients were obtained using a whole-head 122-channel magnetometer and analyzed with Fourier statistical analysis. External transcranial magnetic stimulation (TMS) in the order of pico Tesla was applied on the above patients with proper field characteristics (magnetic amplitude : 1-7.5 pT, frequency : the alpha-rhythm of the patient: 8-13 Hz) which were obtained prior to TMS. The MEG recordings after the application of TMS showed a rapid attenuation of the high abnormal activity followed by an increase of the low frequency components toward the patients' alpha-rhythm. The patients responded to the TMS with a feeling of relaxation and partial or complete disappearance of tremor, muscular ache and levodopa induced dyskinesias as well as rapid reversed visuospatial impairment, which were followed by a corresponding improvement and normalization of the MEG.

Biomagnetism in perinatal medicine. Our experience in Greece.

This is a report on our experience in the application of biomagnetism in perinatal medicine. We provide a brief description of our research work in fetal magnetoencephalography and fetal magnetocardiography in normal, preeclamptic and IUGR pregnancies, together with hemodynamics of the umbilical cord and uterine arteries, providing a new approach to biomagnetism as a non invasive imaging modality in the investigation of perinatal complications.

Magnetic field profiles in normal human breast during the menstrual cycle.

OBJECTIVE: To investigate the subtle magnetic fields produced by living normal breast tissue during the menstrual cycle. METHODS: The magnetic activity of the breast was recorded in four young women, 26-28 years old; two had regular and two irregular menstrual cycles. The recordings were accomplished with a biomagnetometer and covered two complete menstrual cycles. The results were correlated with estrogen and progesterone levels on days 7, 14 and 21 of the menstrual cycle. RESULTS: The magnetic breast recordings in the two young women with the regular cycling endometrium showed a biphasic magnetic curve, apparently corresponding to the proliferative and secretory phase of the menstrual cycle. By contrast, the two young women with irregular menstrual cycles showed a monophasic magnetic curve. CONCLUSION: It is suggested that a biphasic, but not a monophasic, pattern of magnetic activity in the breast is indicative of an ovulatory endometrial cycle.

MEG mapping in multiple sclerosis patients.

AIM: The research over the past decade suggests that multiple sclerosis (MS) is a disease due to disorders of the immune system. Since the immune system is regulated by the pineal gland, which exerts immunomodulatory action with the secretion of melatonin and profound effects on electrical activity in the hippocampus, cerebellum and reticular formation structures, we have used magnetoencephalogram (MEG) recordings from MS patients in order to find any differentiation in brain activity in comparison with controls. METHODS: Ten MS patients and 10 controls were included in this study. The measurements were performed with a superconducting quantum interference device (SQUID) in an electrically shielded room. For each patient the magnetic activity was recorded from a total of 32 points of the skull as defined by a recording reference system, which is based on the International 10-20 Electrode Placement System. RESULTS: The biomagnetic signals (waveforms) were expressed in terms of magnetic power spectral amplitudes in the frequency range of 2-7 Hz. Some of the recorded points were observed to exhibit abnormal rhythmic activity, characterized by lower amplitudes and frequencies compared with controls. Using the MEG brain activity we were able to obtain a mapping technique characterized by the ISO-spectral amplitude of scalp distribution. CONCLUSION: This study, although preliminary, presents a novel approach for measuring brain biomagnetic activity from MS patients.

Transcranial magnetic stimulation. A case report and review of the literature.

OBJECTIVE: Transcranial magnetic stimulation (TMS) is a non-invasive tool for the electrical stimulation of neural tissue. TMS can be applied as single pulses of stimulation, pairs of stimuli separated by variable intervals to the same or different brain areas, or as trains of repetitive stimuli at various frequencies. CASE REPORT: A 2-years-old male infant was referred to our department with a history of Epstein-Barr virus (EBV) encephalitis, treated with foscarnet and steroids, for he developed mutism and ataxia and loss of the ability to eat, walk and talk. Brain imaging revealed loss of white matter around ventricles and progressive global brain atrophy, findings consistent with encephalopathy. Serology for antibodies against EBV infection was positive and the diagnosis of acute and prolonged EBV infection was made. There was an improvement of the clinical findings after the application of TMS with proper field characteristics (intensity: 1-7.5 pT, frequency: 8-13 Hz). CONCLUSIONS: Our case illustrates the possibility of therapeutic applications of TMS (in the order of pT) with proper field characteristics to normalize pathologically decreased levels of brain cortex activity. TMS might provide novel insights into the pathophysiology of the neural circuitry, be developed into clinically useful diagnostic and prognostic tests, and have therapeutic uses in various diseases.