Nonconvulsive status epilepticus with an unusual EEG: a fresh look at lateralities of motor control and awareness.

This article is an account of a patient with nonconvulsive status epilepticus associated with an unusual EEG. The importance of recording speed in lateralizing the hemisphere of onset of epilepsy is emphasized, on the basis of one-way callosal traffic theory. From this vantage point, the following were deemed responsible for the currently divergent views on the lateralizing significance of various signs and symptoms in epilepsy: (1) the dichotomous nature of laterality of motor control, which is the same as that of seizure onset; (2) the probabilistic nature of the availability of the callosal channel for transfer of epileptiform discharges from the major to the minor hemisphere (i.e., the random variability of synaptic transfer); (3) the dynamic (varying) expanse of the epileptic region within the major hemisphere. Other data reviewed indicated that measuring the reaction time of two symmetrically located effectors is the most robust way of determining the laterality of the major hemisphere, with the side of shorter reaction time being opposite to the major hemisphere. Clinical presentations of seizures reflect the probabilistic involvement of different regions of the major hemisphere by the epileptic process and the spread of the epilepsy to the minor hemisphere via the callosum. Termination of seizure activity with diazepam was associated with simultaneous recovery of awareness and speech in this case.