[Predictive factors of response to electronarcosis]

There is an international consensus on the indications of electroconvulsive treatment (ECT): they result in particular from the limitations of antidepressant drug treatment. Even though the global effect of ECT is considered as satisfactory, 10 to 20% of depressed patients eligible for ECT are treatment refractory. This warrants a search for factors predicting efficacy or lack of efficacy of ECT. Predicting factors prior to ECT: Usual clinical criteria, such as the presence of delusional thoughts, are generally classified with endogenous signs of depression. Among biological criteria, EEG data, tests assessing reactivity of autonomous nervous system, plasma measures of catecholamines, calcium and cortisol do not seem relevant parameters. Dexamethasone suppression test and stimulation of TSH by TRH have no more predictive value. Predictive indices during treatment: Empirically clinicians identified a sequence in the response of depressive symptoms, although no conclusion can be drawn from these clinical impressions. Among biological factors some authors stress the importance of the epileptogenic threshold and of measuring plasma levels of peptides released by the posterior lobe of hypophysis. Such data have to be confirmed and their physiopathological value better understood. Actually some parameters representing good therapeutic practices are valued by physicians using ECT: sufficient duration of electrical crisis, total seizure time during the series of electroshocks. Those conceptions are close to the classical emphasis on the adequate number of ECTs and to the discussion on the comparative efficacy of unilateral and bilateral ECT. After ECT most authors shift to antidepressants, although data about medium and long term outcome prediction with this approach are also lacking.