Side-to-side axial movements. Adding a new sign to the asymmetry of the clonic phase and asymmetric seizure termination in differentiating primary and secondarily generalised tonic-clonic seizures.

AIM: To study new semiological signs which help distinguish between primary and secondarily generalised tonic-clonic seizures (GTCS).

METHODS: We retrospectively studied 86 GTCS, 13 primary and 73 secondary, in 58 patients who underwent video-EEG (vEEG) evaluation in our epilepsy monitoring unit. Eleven patients had generalised epilepsy and 47 focal epilepsy. Two expert epileptologists, blinded to diagnosis, examined the vEEGs independently for the presence of five semiological signs.

RESULTS: Asymmetry of limb movements in clonic phase, side-to-side axial movements, and asymmetric seizure termination occurred more frequently (p<0.05) in secondary GTCS compared to primary GTCS. Combining asymmetry of limb movements in clonic phase and side-to-side axial movements provided the greatest value in differentiating secondary GTCS from primary GTCS.

CONCLUSION: Careful examination of GTCS seizure semiology can help differentiate primary from secondary GTCS. The semiological sign of side-to-side axial movements, which has not previously been studied in this context, may add to existing literature of semiological signs and be of value for the evaluation of surgical patients in the epilepsy monitoring unit. In the out-patient setting, a clear history of these signs may help guide drug treatment choices.