Magnetoencephalographic Findings in Two Cases of Juvenile Myoclonus Epilepsy

Abstract

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.

The Use of Magnetoencephalography to Evaluate Febrile Seizures and Epilepsy in Children

“…Right anterior temporal lobectomy resulted in cessation of status epilepticus. Anninos et al (2010) studied 15 children within the age range of 2 -7 years who experienced febrile seizures. Eight children showed ECDs located at the left-temporal, right-temporal, occipital, and frontal lobe, as active regions responsible for febrile seizures.…”

“…Informed consent for the methodology and the aim of the study was obtained from their parents prior to the procedure. The MEG recordings were carried out in a magnetically shielded room with a whole head 122-channel-biomagnetometer (Neuromag-122, Helsinki, Finland) (Anninos et al, 2010;Kotini et al, 2010;2008;2004;2002;Tonoike et al, 1998;Antoniou et al, 2004) (Figure 1). All studies performed precisely 10 days after fever subsided for the purpose of comparison.…”

“…The magnetic field generated by a single neuron is almost negligible. When several thousands of nearby cells are synchronously active, the summated extracranial magnetic field typically achieves a magnitude of a few hundred femto-Tesla (1fT=10 -15 ) where the strongest neuromagnetic signals like those associated with epileptic spikes are a few thousands femto-Tesla (Rose et al, 1987, Anninos et al, 19871989a,b;1999a,b;2000a-c;2003;2010;Anastasiadis et al, 1997, Kotini et al, 2007a. The magnetic activity of the brain is produced by cellular micro-currents, which emerge from ionic movements, due to the dynamical variations of the membrane potentials (Anninos and Raman, 1975;Anninos 1973).…”

“…The magnetic fields, are less distorted than electrical fields, because of the blurring effect of the skull, which acts as a low-pass filter for electrical potentials, providing, in this way, better conditions for the recording of fast activity. Moreover, inaccuracies in estimating the conductivities of the skull and other tissues of the head affect much more the interpretation of electrical than magnetic sources (Sobel et al, 2000;Wilson et al 2007;Ramantani et al,2006;RamachandranNai et al, 2007;Anninos et al, 2010;Kylliäinen et al,2006;Elger et al, 1989) . The MEG offers functional mapping information and measurement of brain activity in real time, unlike CT, MRI and functional magnetic resonance imaging (fMRI) which provide anatomical, structural and metabolic information.…”

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

“…The magnetoencephalography (MEG) produced by such¯elds is exclusively created by a°ow of electric currents tangential to the skull surface and therefore the signal will originate maximally from the cerebral sulci and only minimally from the gyri surface where their orientation is less favorable. The magnetic¯eld generated by a single neuron is weak; when several thousands of nearby cells are synchronously active, the summated extracranial magnetic¯eld typically achieves a magnitude of only a few hundred femto-Tesla Kotini et al, 2010).…”