A delirium (especially if it concerns a hypoactive form) is often not recognised. It is estimated on the basis of research that of the cases of delirium in patients admitted to hospital, 22-50% go unrecognised.
Restlessness is often an important reason to consider a delirium. Other reasons for restlessness are a full bladder or full rectum, uncontrolled symptoms such as pain or shortness of breath, side effects of medication (including corticosteroids, metoclopramide, haloperidol(!), methylphenidate, paradoxical response to benzodiazepines) or fear. In these cases, consciousness remains intact and there are generally no cognitive functional disorders.
If there is apathy without restlessness however, a delirium should also be considered, certainly if this is accompanied by a reduction in consciousness and/or cognitive functional disorders.
Within the framework of early recognition and treatment of the delirium, it is important to actively search for prodromes (see below). The treating physician generally sees the patients during the day, while the prodromes usually occur at night. The required information can be gained from actively questioning the patient, family and/or health care professionals. For example, family members may mention that the patient had a strange look in their eyes the previous night or that something got under the patient's skin.
Prodromes The delirium is often preceded by one or more of the following prodromes:
a reversal of day and night rhythm
lively dreams or nightmares (or an increase in these)
temporary hallucinations, illusionary falsifications and delusions
difficulties concentrating and thinking clearly, easily distracted
oversensitive to stimuli such as light and sound
restlessness, fear, irritation or reservedness with apathy
Observation scales Several observation scales have been developed, which may increase the chance of early detection of a delirium.
The DOS scale (see appendix 1) is suited for use with patients who are able to communicate. The DOS scale is a measuring instrument designed in the Netherlands; the observations can be performed by a nurse. A total score of 3 or higher is indicative of a delirium.
The DOS scale has a sensitivity of 89-100% and a specificity of 68-88% (on the basis of 3 observations per 24 hours). The positive (score >3) predictive value is 47%, the negative (score <3) predictive valueis almost 100%. This means that the diagnosis of delirium is almost never missed (a negative result almost completely excludes a delirium), but the test does often give a false positive result. The latter is especially found with a high age, pre-existing ADL dependency, pre-existing cognitive disorders (e.g. dementia) and vision or hearing disorders. The DOS scale is a screening instrument and a positive result is no evidence for a delirium, but always a reason for a clinical evaluation.
The DOS scale may be used to recognise a delirium in a timely manner and may help to estimate the seriousness and duration of the delirium at the time of a delirium.
However, the diagnosis of delirium is never made using the score of the DOS scale, but using the most recent version of the criteria of the Diagnostic and Statistical Manual of Mental Disorders, the DSM-IV-TR.
Criteria for the diagnosis of delirium To classify a delirium according to the DSM-IV-TR, the following criteria must be met:
A. Disturbance of consciousness (i.e., reduced clarity of awareness of the environment) with reduced ability to focus, sustain or shift attention. The disorder represents a change in function.
B. A change in cognition (such as a memory deficit, disorientation, language disturbance) or the development of a perceptual disturbance that is not better accounted for by a pre-existing, established or evolving dementia.
C. The disturbance develops over a short period of time (usually hours to days) and tends to fluctuate during the course of the day.
D. There is evidence from the history, physical examination or laboratory findings that the disturbance is caused by the direct physiological consequences of a general medical condition.
The DSM-IV-TR subdivides delirium by aetiology, such as: delirium due to a general medical disorder; or delirium due to the use of substances.
Re A. With a delirium, a disturbance of consciousness is prominent. A normal state of consciousness is characterised by the patient being awake and clear, being able to focus on something, conduct a normal conversation, not being too easily distracted, being able to adjust to circumstances, achieve a goal, make choices and have a normal sense of the surroundings.
Re B. Patients often become disorientated about time, but also about their location and sometimes about the people around them. The patient's day and night rhythm becomes disturbed, they think they are in hospital instead of at home, and they do not recognise their carers. Perceptual disturbances and delusions may also occur:
Illusionary falsifications are incorrect interpretations of sensory perceptions, partly caused by expectations, fears and wishes. A 'new' face at their bed is wrongly connected with a fear or wish. For example, a son is seen as a gravedigger. These falsifications may occur, for example, when a patient is first given opioids or during a drastic increase in dose. The subsequent unavoidable reduction in consciousness increases the chance of illusionary falsifications. Fortunately, tolerance in relation to the sedative effect of opioids occurs within several days, which improves correct perception by the patient.
A hallucination is a sensory (especially visual) perception of something that is not there and that is experienced with a sense of real perception, such as seeing someone who is not there. Hallucinations come from within and are therefore not a wrong response to external stimuli. If opioids are the cause of hallucinations, which is fortunately a rare occurrence, then another opioid should be chosen (opioid rotation) or the dose should be reduced on a permanent basis, because tolerance for this effect does not occur. It often concerns compelling images that can be frightening (constantly seeing a funeral procession or eternal fires of hell). However, hallucinations resulting from opioids are not always frightening, they may be acceptable to the patient, certainly if there are no other signs of delirium. The patient may vary in their response to hallucinations, from substantial restlessness and anxiety (would like to attack the person that is not there, but that he/she does see) through to complete apathy and depression.
A delusion is an abnormality in the content of thought. A patient has a false belief and cannot be dissuaded from it.
An example is the convincing belief of being poisoned.
Re C. It is of great importance to realise that the clinical picture of a delirium varies throughout the course of the day(s). The symptoms are generally most pronounced at night and may vary strongly in subsequent days. As a result, the conclusion that there is no delirium or that an improvement is caused by a particular intervention should not be made too fast on the basis of a single evaluation. The DOS scale has three observation moments per 24 hours and often illustrates the fluctuating nature of the symptoms.
Associated signs Psychomotor behaviour is often disturbed.
The ability to formulate and legibly write an invented, coherent sentence already disappears in an early stage of the delirium. A change in day and night rhythm occurs early in the condition. Restlessness at night is often the first sign of an approaching delirium.
The psychomotor behaviour can be subdivided in the following manifestations:
hyperactivity and hyperalertness (e.g. during a withdrawal delirium)
hypoactivity and hypoalertness with apathy and reservedness, through to a stuporous condition (often seen with hepatic encephalopathy, for example); this silent delirium can easily be overlooked while it can cause serious suffering to the patient
mixed forms; these are most common; alternate periods of hyper- and hypoactivity.
A study with patients in a palliative care unit in a hospital found that 78% of patients suffered from a hypoactive or mixed delirium. A pure hyperactive delirium is therefore relative rare.
There often is also a disturbance in mood and affect:
anxiety and bewilderment
depression and apathy
excitement and crying fits
anger and aggression
Physical examination The physical examination focuses mainly on the treatable causes of a delirium. Firstly, the patient is examined for signs of drug intoxication. 'Pin-point' pupils, respiratory depression, constipation and urinary retention are indications of an opioid intoxication. A full bladder and/or full rectum are subsequently excluded. These can provoke a delirium, or worsen the restlessness during one.
At a minimum, the physical examination should consist of:
temperature, pulse, blood pressure, skin turgor and respiratory rate
pupil size, colour of the conjunctiva, skin and lips
examination of the thorax, especially auscultation and percussion of the lungs
percussion of the bladder (in order to exclude a full bladder as the cause of the restlessness); in case of doubt, catherisation or a bladder scan if required
if needed, a digital rectal toucher (in particular to exclude serious constipation as the cause of the restlessness)
limited neurological examination (consciousness, impairments in language ability, signs of meningeal irritation, loss of motor function, reflexes)
The suspected cause of the delirium (on the basis of the disease history, patient history and physical examination) provides direction for the additional testing to be conducted. The patient may be assessed for infections (airways, urine), metabolic disorders such as renal and liver function disorders, electrolyte disorders and signs of dehydration, lack of oxygen, anaemia or signs of cerebral metastases.
The consequence associated with the potential result of a test/examination is indicative of whether or not it should be performed. This depends on the wish of the patient and/or family, where the patient is staying, his physical condition and life expectancy. If treatment of a possible abnormality is not possible or desirable, the relevant test/examination should not be performed.
Further investigation can be extended on indication with:
Anxiety and despair There can be such an extent of anxiety and despair that a delirium is considered. Anxiety can be fed by denial of the disease and death, fear of death or fear of losing control. Unsolved conflicts from the past may also get the upper hand and result in immense anxiety. The patient may become increasingly restless on further deterioration. The distinction with a delirium is made by the absence of a reduction in consciousness, delusions and hallucinations.
Depression A depression develops over a longer period of time. The aversive behaviour, the lack of initiative and the subjective concentration problems of a depressive patient may sometimes be confused with behaviour corresponding to a hypoactive/hypoalert delirium. A depression develops more slowly, and together with a possible history of previous depressions may help to determine the correct diagnosis.
During a depression, there is a clear consciousness and there are no perception abnormalities.
The similarities between especially a quiet delirium and dementia are abnormalities in memory, thinking, judgment and orientation. There is a clear consciousness, a less acute onset and a less disturbed day and night rhythm with dementia. Distinction with a clinical picture of dementia should be made on the basis of the course and premorbid cognitive functioning. A dement patient is extra vulnerable to developing a delirium. A combination of dementia and delirium is therefore also possible.
During a psychosis, consciousness is clear and there are no abnormalities in memory or orientation. A psychosis is extremely rare with terminal patients without a history of, in particular, schizophrenia.