Bilateral synchrony

This article needs significant updating in light of recent advances in this field^(LIST).

~~AUTHORS:off~~

The term “bilateral synchrony” was introduced by Wilder Penfield. According to Penfield and Jasper “An epileptogenic lesion of the mesial or inferior aspect of a frontal lobe, although it is one-sided, may produce bifrontal synchronous discharges”. The mechanisms by which seizures that become secondarily generalised are not yet known fully.

The wave and spike of petit mal is a primary bilateral synchronous discharge . . . ; it appears not to be related to a unilateral cortical focus, but may be of subcortical origin …. On the other hand, a bilateral synchronous discharge which can be shown to arise from a unilateral cortical focus we shall call secondary bilateral synchrony - Tükel and Jasper^[1]

it is important to differentiate between primary and secondary bilateral synchrony when bilaterally synchronous spike and wave discharges are seen on EEG
Estimation of interhemispheric small time differences (TDs) during spike-wave bursts in the EEG by coherence and phase analysis is useful for differentiation between primary bilateral synchrony (PBS) and secondary bilateral synchrony (SBS) in epilepsy^[2].

http://www.neurology-asia.org/articles/20071_029.pdf

1. ^a Tukel K, Jasper H. The electroencephalogram in parasagittal lesions. Electroencephalogr Clin Neurophysiol. 1952 Nov;4(4):481-94. doi: 10.1016/0013-4694(52)90079-5.

2. ^a Kobayashi K, Ohtsuka Y, Oka E, Ohtahara S. Primary and secondary bilateral synchrony in epilepsy: differentiation by estimation of interhemispheric small time differences during short spike-wave activity. Electroencephalogr Clin Neurophysiol. 1992 Aug;83(2):93-103. doi: 10.1016/0013-4694(92)90022-a.