SEIZURE CHARACTERISTICS AND THERAPEUTIC EFFICIENCY IN ELECTROCONVULSIVE THERAPY

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Abstract
There is a variability of seizure duration in electroconvulsive therapy(ect),and at the same time a varia-bility of the efficiency of the therapy. A statistical analysis was performed of the relationship between duration of the seizures and the therapeutic efficiency of the therapy in endogenous depression. The relationship has been examined for 2 types of seizure activity, the grand mal self-limited seizure and the lidocaine-modified seizure, the latter with a pattern resembling that in petit mal epilepsy; both types were recorded electroencephalographically under conditions of light narcosis and complete muscular relaxation. Therapeutic efficiency has been defined as the outcome after 4 treatments, as rated by a rating scale, and the total number of treatments required. The duration of a grand mal seizure has no significant relationship to therapeutic efficiency. It seems, therefore, to be of no importance whether a person develops long or short grand mal seizures, the essential thing being that they are grand mal self-limited seizures. The duration of a lidocaine-modified seizure has a significant relationship with therapeutic efficiency, i. e., the longer the petit-mal-like seizure activity the higher the therapeutic efficiency. Lidocaine seems, therefore, to have isolated a therapeuti-cally valuable component of the grand mal seizure. However, since the lidocaine-modified seizure has a lower therapeutic effect than the grand mal seizure, lidocaine has also eliminated some therapeutically valuable components,, Since the therapeutic effect of the lidocaine-modified, petit-mal-like seizure is related to the duration of this type of activity, it seems probable that the therapeutic effect of a grand mal seizure is not associated with the fast spike activity but rather with its component of wave-and-spike activity. On the basis of the interpretation of the eeg pattern in petit mal epilepsy given by Penfield and Jasper, it is suggested that the lidocaine-modified seizure discharge signals seizure activity which takes place mainly in the brain stem. According to that interpretation the depression-relieving effect of ect should be associated with the amount of seizure activity in the brain stem, possibly in structures belonging to the ascending reticular system. This view is in agreement with various kinds of indirect evidence that diencephalic structures are important for mood swings and that a diencephalic influence is relevant for the curative effect of ect. The lidocaine-modified seizure seems to contain therapeutically valuable components in a more pure form than the unmodified global seizure. However, lidocaine-modified therapy is less effective, and since its side-effects in the form of memory disturbances are only slightly less, there is no reason to prefer lidocaine-modified therapy to unmodified therapy.

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