Parathyroidectomy-pinealectomy-induced seizures: effects of intersurgical length.

Parathyroidectomized rats subjected to pinealectomy experience seizures characterized by wild running typically followed by clonic-tonic activity. By increasing the number of days between parathyroidectomy and pinealectomy an increase in seizure activity was observed. Increasing the length of time between the two surgical procedures resulted in significant increases in both the percentage of animals experiencing seizures and the mean number of seizures per convulsing animal. Conversely, a decrease in the average time to onset of the first seizure episode was observed with increasing intersurgical time intervals. The potential for exhibiting seizures developed between 8 and 24 h after parathyroidectomy. The highest incidence of seizures occurred after an intersurgical interval of 3 days and remained constant at approximately 75% thereafter.