[Vagus nerve stimulation and psychosis. A single case report].

The appearance of behavioral disorders in the context of a decrease in the number of seizures in epileptic patients is a fact that was already described in Landolt's theory of forced normalization in the middle of the XX century. Through this clinical case, we propose several mechanisms that aim to give a general explanation to the physiopathology of this condition. Among them, the theory which suggests increased alertness as a result of inhibitory mechanisms secondary to a long lasting epileptic condition stands out. In addition, we consider the possibility that left vagus nerve stimulation (VNS), a procedure used as a second line treatment in epileptic patients refractory to multiple drug therapy, may cause an inhibitory reaction of similar characteristics as the previously described, and could therefore lead to different psychiatric disorders. Lastly, we bring up several alternatives that will try to throw some light on the physiopathological condition that leads to the chronification of this disease, the theory regarding a cognitive deterioration associated to the appearance of negative symptoms in patients with temporal lobe epilepsy standing out.