Sequential Tonic Motor Phenomena of Generalized Seizures

Objective: To demonstrate that the semiology of human bilateral tonic motor seizures evolves intra-ictally and that their full description should comprise this evolution. Method: We scrutinized sequential tonic phenomena of bilateral motor seizures as recorded by video-EEG telemetry among 15 adult patients investigated because of intractable epilepsy. Seizures were divided into sequential stages, each defined as a tonic motor posture maintained for at least three seconds. As posture reflects joint involvement and its principally flexor or extension contour, results are expressed by joints as opposed to patients. Only the first seizure of each patient meeting all criteria are included. All four limbs had to be involved for three consecutive stages for inclusion. Two authors (SB, WB) each independently assessed ictal evolution, rare discordances (rare werer esolved by mutual review. Results: The tonic motor component of each of 15 seizures evolved intra-ictally. More joints were involved in seizure stages two and three than in stage one, except cephalic version, which occurred principally in, stage one. Involvement of joints became more bilaterally symmetrical as seizures evolved. Joint flexion evolved to extension far more commonly than conversely. Significance: Our data suggest that any study describing tonic motor semiology must indicate at what point in seizure evolution the observations were made. Its findings will sharpen ictal history taking: lay persons' observations may better reflect ictal evolution if sequence is emphasized. We interpret these findings as reflecting increasing reticulospinal tract involvement as the seizure proceeds.