Isolated speech arrest associated with bilateral secondary synchrony on the EEG as electroclinical epileptic feature related to the involvement of the supplementary motor cortex: a case investigated with the EEG fMRI.

Purpose: Speech arrest is a rather uncommon seizure type usually related to the involvement of the supplementary motor area (SMA) on both emispheres. That is sometimes difficult to distinguish from the other more prominent clinical features. The bilateral secondary synchrony is an EEG pattern characterized by generalized spike and wave discharges resembling the idiopathic generalized epilepsies pattern. That is typically the result of epileptic foci on the mesial surface of the frontal cortex. Method: We describe the case of a 36 yrs old woman with drug resistant seizures since the age of 5 taking the form of sudden speech arrest episodes sometimes followed by clonic jerks over the right half of the face and arm. Those may last some minutes and the patient is able to read and write ictally. Conventional and 3T MRI were both normal. Interictal EEG showed theta activity on left frontal electrodes followed by general- ized spike and wave discharges. EEG-fMRI showed a clear cut prominent activation of the left SMA. The case was eventually considered for surgery. Conclusion: Speech arrest is not a very common epileptic feature sometimes difficult to recognize specially if associated to clear-cut motor phenomena such as bilateral tonic posturing, facial grimacing, violent vocalization, which are motor phenomena usually associated with SMA- seizures. Secondary bilateral synchrony is the typical EEG picture of mesial frontal epileptic foci. That does not provide on other hand clear localizing data. In conclusion the speech arrest even if isolated may be the result of SMA seizures. Given the often poor contribute of the scalp EEG in localizing both the area and the side of onset, the EEG f-MRI may provide reliable data about those especially in the context of surgical work-up.