Drug-associated delirium in cancer patients

1. Delirium definition and clinical characteristics Delirium is a disorder of consciousness and attention; it is one of the most common neurological complications seen in general in the medically ill hospitalised patient, and is also common in the medical oncology ward [1,2]. Delirium seen in different settings contributes to defining the diagnoses of diverse specificities: postoperative delirium, delirium in the ICU, withdrawal delirium or delirium tremens, terminal rest-lessness and others. Before considering specific clinical contexts or diagnoses it is necessary to recognise the general characteristics of delirium as a syndrome and its clinical implications. There is now almost universal agreement on the definition of delirium , or acute confusional state, according to the DSM. However , acute confusional state is a synonym of delirium and is still a useful clinical definition, particularly in non-English-speaking countries. Delirium is a syndrome and not a disease, and its pathophysiology has not been fully elucidated. Different theories have favoured alternatively the failure of a common final pathway – mainly regulating the cholinergic projection to the cerebral cortex – or a more diffused or multifocal impairment of different areas in the CNS which contribute to maintaining the normal level of vigilance and attention. Clinically, delirium is an altered state of consciousness with reduced awareness of self and of the environment, which may present with inability to think and talk clearly and rationally; at times there are hallucinations, delusions, disorientation with respect to time and space, altered sleep– wakefulness cycle and cognitive impairment. Psychomotor agitation can be present in the hyperactive deliria, but hypo-active deliria will show psychomotor retardation and somno-lence. One extremely important clinical aspect of delirium is fluctuation of the clinical presentation; symptoms can change suddenly, often under repetitive conditions (such as in the classic nocturnal worsening often described in the elderly with cognitive impairment and called in the past 'sun-downing'). These sudden changes from a near-to-normal mental state to frank delirium often surprise nursing and medical staff and find them unprepared in front of the patient and a distressed family. The clinical presentation of delirium varies, and no defined association of symptoms and signs can be considered specific [3]. For the purposes of diagnosis and clinical evaluation it is easier to use the DSM criteria as they give a systematic approach to the core clinical elements [4]. All four of the following criteria have to be fulfilled to make a diagnosis. Disturbance of …