Convulsive aspects of barbital sodium withdrawal in the cat

Abstract

Six cats received gradually increasing amounts of barbital sodium until final dose levels of 190 to 335 mg per kilogram were reached in 106 to 267 days. Extradural electrodes were implanted in the skull to monitor the EEG during intoxication and withdrawal. During intoxication fast frequencies of 18 to 34 c/sec, such as those observed in the human EEG during barbiturate use, were present when the animals demonstrated waking, but not sleeping, behavior. Following abrupt withdrawal, five of the cats developed interseizure paroxysmal EEG abnormalities. The interseizure EEG abnormalities occurred commonly during drowsing, and they were bilaterally symmetrical. Minor seizure behaviors were frequently observed during the occurrence of these transient EEG changes. Records were obtained on two animals at onset, and during major withdrawal convulsions. In both cases the associated EEG changes were abrupt, symmetrical, and generalized at seizure onset. The cerebral cortex appears to participate in the convulsive process, but its order of involvement may be secondary to that of the brain stem.