Background The aim of this randomized, parallel-arm trial was to study the effect of treating subsyndromal delirium with risperidone on the incidence of clinical delirium in elderly patients who underwent on-pump cardiac surgery. Methods One hundred one patients aged 65 yr or older who experienced subsyndromal delirium after on-pump cardiac surgery were randomized using a computer-generated list to receive 0.5 mg risperidone (n = 51) or placebo (n = 50) every 12 h by mouth. Patients were assessed at 8 h by a blinded observer using the Intensive Care Delirium Screening Checklist, and those scoring more than 3 were evaluated by a blinded psychiatrist to confirm delirium. Patients in either group who experienced delirium were treated according to the same algorithm. Initially, risperidone was administered and if symptoms were not controlled, haloperidol was administered. The primary outcome was the proportion of patients who experienced delirium in either group. Results Seven (13.7%) patients in the risperidone group experienced delirium versus 17 (34%) in the placebo group (P = 0.031) Competing-risks regression analysis showed that failure to treat subsyndromal delirium with risperidone was an independent risk factor for delirium (subhazard ratio, 3.83; 95% CI, 1.63-8.98; P = 0.002). Two (3.9%) patients in the risperidone group experienced extrapyramidal manifestations versus one (2%) in the placebo group (P = 1.0). Conclusion Administration of risperidone to elderly patients who experienced subsyndromal delirium after on-pump cardiac surgery was associated with significantly lower incidence of delirium. Larger studies are required to determine whether early administration of risperidone during the subsyndromal phase of delirium would influence the clinical course of such patients.

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Introduction In recent year deterioration in cognitive, learning, and memory become one of the significant problems in human life. Hippocampus is a pivotal part of the brain’s limbic system which serves a critical role in memory, learning process and regulating the emotions. In most regions of the brain, neurons are generated only at specific periods of early development, and not born in the adulthood. In contrast, hippocampal neurons are generated throughout development and adult life. The hippocampal dentate gyrus was reported to be one of the few regions of the mammalian brain where neurogenesis continue to occur throughout adulthood. The neurogenesis in the dentate gyrus was thought to play an important role in hippocampus-dependent learning and memory. The hippocampal formation is composed of the hippocampus proper, the dentate gyrus and the subiculum. The hippocampus proper is the largest part and is subdivided into fields designated as Cornu Ammonis or Ammon’s horn (CA) from CA1 to CA4. Ammon's horn is continuous with the subiculum, which acts as the main output source of the hippocampal formation. Aim of the Study To study the postnatal development of the hippocampal formation. Materials and Methods Five male albino rats from the following postnatal ages day 1, week 1, week 2, week3 and week 4 were studied by histological, immunohistochemical, and morphometric methods. Results The general architecture of the hippocampus proper with its polymorphic, pyramidal, and molecular layers was present at day1, whereas the details of the adult structure appeared at week 2. In the dentate gyrus, distinct lamination appeared at week 1 and its maturation continued with the production of neurons at the interhilar zone that peaked at week 2. The number and density of pyramidal axons and dendrites increase by age. Astrocytes increased in size and staining affinity for glial filaments, and acquired a stellate shape with age. Furthermore, the number of granule cell layers increased concomitantly with the increase in thickness of the molecular and polymorphic layers of both the hippocampus proper and the dentate gyrus. Conclusion The important sequences of events in the growth and maturation of the hippocampal formation in male albino rat occurred in the first 2 postnatal weeks.