Age of appearence and disappearence of rolandic spikes of 160 children: an actuarial study

This study aims to determine the age at which the rolandic spikes (RS) appear and disappear in routine EEGs. Method: It has been carried out a hospital based prospective study of 412 EEGs records of 160 children who had been assisted at the neuropediatric out-patient department during the period between March, 1989 and March, 1998. Recordings were made on 8-channel instruments and 10/20 system has been to place the electrodes. The children have been divided into 4 groups, according to their age (1 to 4; 5 to 8; 9 to 16; 1 to 16), and the actuarial curve method has been used to show the disappearance of the rolandic spikes. Results: RS distribution between boys and girls has been 64/36 ratio. RS have been found at average age of 7 years (boys, 7.2 and girls, 6.6). In a small group of children with normal EEGs previous to the RS appearance, the average age has been 6.8 years old. After this 7-year follow up period, the percentage of patients free from RSs was 60% for 1 to 4 year old group at admission; 84% for the 5 to 8 year old group and for the 9 to 16 year old group. For the total group (I to 16 year old), the percentage of those free from RSs after this 7 year follow up period was 78%. Conclusion: This study shows that RSs appear at the average age of 7 years old, and are likely to disappear up to the end of a 7-year follow up period, independently on the appearance age.