IS MU A NORMAL RHYTHM?

Cristina Nombela

doi:10.4172/2161-0533.1000122

Abstract

Although it was first described more than 50 years ago, the physiological significance and the potential pathological features of the mu rhythm still remains unclear. In an attempt to clarify certain aspects of this activity, we studied the presence of mu rhythm in 100 healthy subjects with no family history of neurological disease. A 15 minute long resting EEG register was obtained from each subject using a 32 channel Nihon Kodem electroencephalography device, and from these recordings we localized and quantified the mu and alpha rhythms. Kulman´s criteria were used to differentiate the baseline alpha rhythm from mu rhythm within occipital alpha rhythm. Further graphoelements of interest were observed, what leds us to studied the relationship between the mu rhythm and abnormal graphoelements in temporal regions. Our results indicated abnormal graphoelements in 48% of the healthy participants studied here. Neither the mu nor the rolandic alpha rhythms displayed any significant differences between male and females during the appearance of the abnormal graphoelements. However, there was a strong correlation between the appearance of a bilateral mu rhythm and abnormal graphoelements. Despite this temporal association between abnormal graphoelements and rolandic mu rhythm, there is no clear evidence to consider the latter as a pathological sign (no epileptic clinical history within the sample). Nevertheless, the mu rhythm is not necessarily a normal element and further studies will be necessary to clearly define the physiological significance of mu rhythms.

Highlights

It was first described more than 50 years ago, the physiological significance and the potential pathological features of the mu rhythm still remains unclear
In an attempt to clarify the true significance of the rolandic mu rhythm in healthy population, we have carried out a large electroencephalographic study in which we unexpectedly found abnormal temporal epileptiform graphoelements
We believe there are two main reasons why there was a high frequency of mu rhythms found in our sample: 1) we didnt look for a specific morphology but rather, a specific reactive alpha rhythm located within the rolandic region; 2) Our electrode pattern was based on longer inter-electrode spaces than those used in previous studies, reflecting the relationship between “inter-electrode distance and trace amplitude”

Summary

Introduction

It was first described more than 50 years ago, the physiological significance and the potential pathological features of the mu rhythm still remains unclear. In terms of its pathological implications, the presence of mu rhythm was analyzed in a sample of more than 500 volunteers, 53 displaying clinical symptoms of epilepsy In this cohort, it appeared that the mu rhythm is more frequently located in the hemisphere of the epileptic focus, and it displays more severe characteristics in such participants [11]. In an attempt to clarify the true significance of the rolandic mu rhythm in healthy population, we have carried out a large electroencephalographic study in which we unexpectedly found abnormal temporal epileptiform graphoelements. These features were to some extent related with arch shaped rolandic waves, which were studied

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Conclusion