Psychiatric emergencies (part I): psychiatric disorders causing organic symptoms.

Psychiatric emergencies are conditions that mostly destabilize the already frenetic activity of the Emergency Department. Sometimes the emergency is clearly referable to primitive psychiatric illness. Other times, psychiatric and organic symptoms can independently coexist (comorbidity), or develop together in different conditions of substance abuse, including alcohol and prescription drugs. Differentiating between substance induced and pre-existing psychiatric disorder (dual diagnosis) may be difficult, other than controversial issue. Finally, an organic disease can hide behind a psychiatric disorder (pseudopsychiatric emergency). In this review (part I), psychiatric disorders that occur with organic symptoms are discussed. They include: (1) anxiety, conversion and psychosomatic disorders, and (2) simulated diseases. The physiologic mechanisms of the stress reaction, divided into a dual neuro-hormonal response, are reviewed in this section: (1) activation of the sympathetic nervous system and adrenal medulla with catecholamine production (rapid response), and (2) activation of the hypothalamic-pituitary-adrenal axis with cortisol production (slow response). The concept of the fight-or-flight response, its adaptive significance and the potential evolution in paralyzing response, well showing by Yerkes-Dodson curve, is explained. Abnormal short- and long-term reactions to stress evolving toward well codified cluster of trauma and stressor-related disorders, including acute stress disorder, adjustment disorder and post-traumatic stress disorder, are examined. A brief review of major psychiatric disorder and related behaviour abnormalities, vegetative symptoms and cognitive impairment, according to DMS IV-TR classification, are described. Finally, the reactive psychic symptoms and behavioral responses to acute or chronic organic disease, so called "somatopsychic disorders", commonly occurring in elderly and pediatric patients, are presented. The specific conditions of post-operative and intensive care unit patients, and cancer and HIV positive population are emphasized.