Psychotropic drugs, especially antidepressants and antipsychotics, may give rise to some concern in clinical practice because of their known ability to reduce seizure threshold and to provoke epileptic seizures. Although the phenomenon has been described with almost all the available compounds, neither its real magnitude nor the seizurogenic potential of individual drugs have been clearly established so far. In large investigations, seizure incidence rates have been reported to range from approximately 0.1 to approximately 1.5% in patients treated with therapeutic doses of most commonly used antidepressants and antipsychotics (incidence of the first unprovoked seizure in the general population is 0.07 to 0.09%). In patients who have taken an overdose, the seizure risk rises markedly, achieving values of approximately 4 to approximately 30%. This large variability, probably due to methodological differences among studies, makes data confusing and difficult to interpret. Agreement, however, converges on the following: seizures triggered by psychotropic drugs are a dose-dependent adverse effect; maprotiline and clomipramine among antidepressants and chlorpromazine and clozapine among antipsychotics that have a relatively high seizurogenic potential; phenelzine, tranylcypromine, fluoxetine, paroxetine, sertraline, venlafaxine and trazodone among antidepressants and fluphenazine, haloperidol, pimozide and risperidone among antipsychotics that exhibit a relatively low risk. Apart from drug-related factors, seizure precipitation during psychotropic drug medication is greatly influenced by the individual's inherited seizure threshold and, particularly, by the presence of seizurogenic conditions (such as history of epilepsy, brain damage, etc.). Pending identification of compounds with less or no effect on seizure threshold and formulation of definite therapeutic guidelines especially for patients at risk for seizures, the problem may be minimised through careful evaluation of the possible presence of seizurogenic conditions and simplification of the therapeutic scheme (low starting doses/slow dose escalation, maintenance of the minimal effective dose, avoidance of complex drug combinations, etc.). Although there is sufficient evidence that psychotropic drugs may lower seizure threshold, published literature data have also suggested that an appropriate psychotropic therapy may not only improve the mental state in patients with epilepsy, but also exert antiepileptic effects through a specific action. Further scientific research is warranted to clarify all aspects characterising the complex link between seizure threshold and psychotropic drugs.

Summary:Purpose: To assess the comparative therapeutic value of valproate (VPA), lamotrigine (LTG), and their combination in patients with complex partial seizures resistant to other established antiepileptic drugs (AEDs).Methods: After a 3-month prospective baseline, 20 adults with refractory complex partial seizures not exposed previously to VPA and LTG were scheduled to receive three consecutive add-on treatments with VPA, LTG, or their combination, according to an open, response-conditional, crossover design. Each period consisted of a 6-to 12-week dose optimization followed by 3-month evaluation at stabilized serum drug levels. Only patients not responding to one phase proceeded to the next.Results: A >50% reduction in seizure frequency was observed in three of 20 patients given VPA and in four of 17 patients given LTG. Of the remaining 13 patients, four became seizure free, and an additional four experienced seizure reductions of 62-78% when VPA and LTG were given in combination. Mild tremor was observed in three patients receiving VPA and in all patients taking the VPA-LTG combination. In patients responding to combination therapy, optimized dosages and peak serum levels of both VPA and LTG were lower than those during separate administration.Conclusions: A considerable proportion of patients who failed to respond to VPA and LTG separately improved when the two drugs were combined, although serum levels of both agents were lower during combination therapy. Despite methodologic limitations in the nonrandomized treatment sequence, these findings suggest that VPA and LTG exhibit a favorable phmacodynamic interaction in patients with refractory partial epilepsy. The dosage of both drugs, however, may need to be reduced to minimize the risk of intolerable side effects.

As part of a door-to-door neuroepidemiologic survey, we investigated the frequency and distribution of essential tremor (ET) in a Sicilian municipality. During phase 1, we administered a screening instrument for tremor to 7,653 persons residing in Terrasini (Palermo province). During phase 2, neurologists evaluated those subjects who had screened positive. The diagnoses, based on specified clinical criteria, were reviewed to increase reliability across neurologists. We found 31 subjects affected by ET (17 men, 14 women); 11 patients (35.5%) reported a familial aggregation. The prevalence of ET as of November 1, 1987, was 405.1 per 100,000 for the total population, and 1,074.9 per 100,000 for those 40 years old or older. The prevalence increased with advancing age for both sexes and was slightly but consistently higher in men. Comparison with other studies suggests striking geographic variation, which may reflect genetic differences.

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