Ensayo el ruisenor y la rosa

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Ricardo Garcell, Josefina;Rueda Medina, Walfred Electroencefalograma y potenciales relacionados con eventos en el trastorno obsesivo compulsivo Salud Mental, Vol. 32, Núm. 2, marzo-abril, 2009, pp. 173-181 Instituto Nacional de Psiquiatría Ramón de la Fuente MéxicoDisponible en: http://redalyc.uaemex.mx/src/inicio/ArtPdfRed.jsp?iCve=58212275010

Salud Mental ISSN (Versión impresa): 0185-3325 perezrh@imp.edu.mx Instituto Nacional de Psiquiatría Ramón de la Fuente México

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www.redalyc.org Proyecto académico sin fines de lucro, desarrollado bajo la iniciativa de acceso abiertoSalud Mental 2009;31:173-181 Electroencefalograma y potenciales relacionados con en el trastorno obsesivo compulsivo

Electroencefalograma y potenciales relacionados con eventos en el trastorno obsesivo compulsivo
Josefina Ricardo Garcell,1,2 Walfred Rueda Medina2
Actualización por temas

SUMMARY
The obsessive compulsive disorder (OCD) is a diverse and multidimensional psychiatricsyndrome, characterized by obsessions and compulsions, where anxiety is considered to be a key clinical component. Imaging studies have shown brain abnormalities in patients with OCD involving mainly the frontotemporal circuits, the orbitofrontal and the anterior cingulate cortex. These techniques have a high spatial resolution to identify brain alterations in this disorder but have less timeresolution and are more expensive than electrophysiological studies. The electroencephalogram (EEG) and event-related potentials (ERPs) are the most common electrophysiological techniques used in the research of OCD. The EEG represents the electrical activity of the brain as recorded by electrodes placed on the scalp. The ERPs are voltage fluctuations that are temporarily linked to the presence of aphysical or mental event. The best-known type of EEG is the «traditional EEG» (analyzed by visual inspection), which is characterized by the presence and topographic distribution of four frequency bands: delta (δ), theta (θ), alfa (α), and beta (β). The δ and θ bands are identified as slow activities while the α and β bands are known as fast activities. The slow activity has been referred to as themost common abnormality in OCD, specially in the θ band. Moreover, the Broad Band Spectral Parameters (BBSPs) have contributed, for more than two decades, to the study of psychiatric patients and their values can be presented in a compact form as a topographic map on the scalp (Brain Mapping in the frequency domain). The Absolute Power (AP) and the Relative Power (RP) are the most common BBSPs used.Is difficult to determine if AP is abnormal at certain age due to the fact that AP values vary with age. To solve it, it is suggested to transform AP’s values, in every band, into Z values which indicate how close is the subject to the average values of normal individuals of the same age. Since abnormal increases and decreases have been described in the anterior brain regions by the slow bands (δand θ) and the fast bands (α and β), some authors have considered inconsistent the alterations that have been observed with the BBSPs. Nevertheless, in accordance with traditional EEG studies, other authors have confirmed the excess of theta activity in patients with OCD. Of special interest for the clinical practice is that some authors have demonstrated, using the BBSPs, the existence of two OCDpatients subgroups, which were homogeneous from the clinical point of view: one group with an excess of θ in the RP values, specially in the frontal and fronto-temporal regions, and a significative increase of α RP values for the other group. Eighty per cent of the patients of

the first subgroup did not improved with selective serotonine reuptake inhibitors treatment, whereas 82.4 % of the...