[Use of event related potentials for the diagnosis and follow up of sub clinical disorders of sustained attention in ischemic cerebrovascular disease]. / Uso de potenciales relacionados con eventos para el diagn stico y seguimiento de los trastornos subcl nicos de la atenci n sostenida en la enfermedad cerebrovascular isqu mica.

INTRODUCTION: Ischemic cerebrovascular disease causes cognitive disorders among survivors, which may range from vascular dementia to alterations of a sub clinical nature. These are not easily detected using conventional diagnostic tools. Some of the most frequent disorders after a cerebral infarction are those affecting sustained attention or vigilance. The event related potential (ERP) P300 or P3 could be a valuable diagnostic indicator of this type of disorder and its evolution. AIMS. The evaluation and diagnosis of sub clinical disorders of sustained attention in patients with cerebral infarction by using ERP as a method of diagnosis and follow up. PATIENTS AND METHODS: We studied 13 patients with cerebral infarction located in the left parietal lobe, 13 with infarction in the right parietal lobe and 26 healthy control subjects, who were paired by gender, age and educational level. All subjects were submitted to a computerized continuous performance test, associated with the recording of electrical brain activity. RESULTS: Patients with right parietal lesions made more mistakes due to omission, answered fewer questions correctly and had a lower attention index than the rest of the patients and healthy controls. Although there were no significant differences in the P3 amplitude values, patients with right lesion presented significantly increased latencies in the F7, Fz and Cz derivations. After five months there was a significant improvement in performance in the attentional test. The value of the latency in the Cz derivation, nine days after the occurrence of the cerebral infarction, was related with the number of mistakes made by the subjects five months later in the attention test. CONCLUSIONS: Patients with an ischemic lesion in the right parietal lobe presented disorders in sustained attention, which were only diagnosed adequately by use of computerized tests associated with ERP recordings. This shows that evoked potentials are valuable in cognitive diagnosis, and also demonstrates the relation that exists between the capacity to hold the attention on a stimulus over a period of time and the structures of the right parietal lobe. Five months later, these disorders of a sub clinical nature can disappear. The value of the latency in Cz, nine days after the occurrence of the event, acts as a predictor of this recovery. Cognitive rehabilitation plans could benefit from the use of these diagnostic tools.