Delirium has been described as 'An aetiologically non-specific syndrome characterized by concurrent disturbances of consciousness and attention, perception, thinking, memory, psychomotor behaviour, emotion, and the sleep-wake cycle' (World Health Organization, ICD-10).
Delirium was described in
European Psychiatry by Bonhoeffer (1909) as a syndrome consistently associated with brain failure. He regarded chaotic, incoherent thought as a central feature. Following further investigations Wolff and Curran (1935) confirmed the main features described by Bonhoeffer and others but added that the content of the syndrome had emanated to a considerable extent from previous experience and premorbid personality. Engel and Romano (1959) reported that the EEG showed abnormalities in the form of high-voltage discharges from rhythmic high-voltage delta waves which were in accord with the severity of the physical symptomatology.
At a later stage Lipowski (1990) described two main relatively distinct versions of the clinical picture. In the first, patients were restless, overactive, oversensitive, often with persecutory delusions. In the second the patients tended to be retarded, inactive, silent, and muddled in thought. Visual distortion and hallucinations often of a vivid and terrifying character were a common feature, mainly in the overactive subgroup.
Delirium is a common form of mental illness among aged persons. It is also manifest at earlier stages of the lifespan but its peak prevalence has been found to be at the latter end of life.
In recent decades extensive studies have been devoted to delineating its clinical features, formulating reliable criteria for its diagnosis from other mental disorders of late life, and identifying factors involved in its causation or predisposing individuals to its development. The importance of delirium is derived from a number of different features. In a high proportion of cases the disorder is life threatening, commonly caused by a serious and acute physical illness. The effect of terror and excitement that is manifest at the height of the illness in more than half of cases may cause death by a combination of exhaustion and the effects associated with physical illness. However, in cases where acute disease is benign and there is a response to treatment, the symptoms of delirium subside and recovery from the attack leaves no deficit.
The patient is grossly disoriented in respect of time, date, and place. All aspects of memory function, registration, retention, and recall are severely impaired. He is unable to perceive or to interpret his environment and is incapable of new learning. He cannot explain how and why he has been admitted to hospital. There is impaired awareness and inattention to the outside world. This is associated with disturbing inner experiences dominated by hallucinations and delusions. Speech tends to be more or less incoherent and the capacity to understand communications from others is impaired. Any statement that penetrates into consciousness is rapidly wiped off the slate of memory.
Anxiety and agitation, mounting often into severe and sustained bouts of distress, are the most common and prominent reactions to these symptoms. In the course of long attacks of delirium a strong depressive colouring enters. In other cases, psychotic, depressive illness, or bipolar disorders in a setting of physical illness form the starting point of the delirium and constitute a suicide risk. Treatment with antidepressants and psychotherapy has to be provided in association with management of any concomitant acute physical illness.
Delirium is a many-sided and serious illness particularly in aged persons. The patient has to be kept under close observation in disturbed episodes to provide reassurance and explanation and to protect him from the suicide risk which is manifest in a proportion of cases. However, within a few hours the clinical picture can be entirely transformed. It arises from the marked fluctuation over time in the severity and the clinical profile manifest in the disorder of consciousness suffered by the majority of those affected. A patient who was indubitably delirious during one evening may by noon on the following day appear to be free from symptoms and signs. These phenomena are more fully described below.
Lishman (1987) described the main features of impaired consciousness as slow deterioration of thinking, attending, perceiving, and remembering, a combination that suggests general deterioration of cognitive functions combined with reduced awareness of the environment. Impairment may be ill considered and it is difficult to establish, with confidence, whether or not consciousness is impaired. Abnormality of the
EEG, which is usual in a high proportion of cases, provides valuable information for the delirious state (Roth and Myers 1962) (Figs. 1 and 2).
The main clinical features have been lucidly and succinctly set out in the fourth edition of the
Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) of the American Psychiatric Association (1994). The diagnostic criteria are:
(a) Disturbance of consciousness (i.e. reduced clarity of awareness of the environment) with reduced ability to focus, sustain, or shift attention.
(b) A change in cognition (such as memory deficit, disorientation, language disturbance) or the development of a perceptual disturbance that is not better accounted for by pre-existing, established, or evolving dementia.
(c) Disturbance develops over a short period of time (usually hours) 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 consequence of the general medical condition.
1. Related disorders 2. Causation 3. Aspects of treatment 4. Some future perspectives
A severe delirium associated with broncho-pneumonia in a woman of 60 years of age. EEG shows bilaterally synchronous frontally predominant 2 c/s runs of delta activity. The EEG returned to normal after recovery.
Senile dementia in a woman of 80 years of age. EEG shows dominant posterior rhythm at 7–8 c/s associated with irregular theta components, and eye movement artefacts in anteriorly recording channels. Despite advanced dementia, the EEG abnormality is slight.
1. Related disorders
The stages of delirium in which the patient is disoriented, confused, incoherent in speech, deluded, and hallucinating are generally regarded as exhibiting the features of the unconscious phase of delirious phenomena.
There are two syndromes that show that this unconsciousness is unusual, in that it is characterized by perception usually associated with beliefs that have undergone some scrutiny and have been modified by ideas generally associated with consciousness rather than consistent and severe delirious states.
In most cases of anosognosia the patient has suffered hemiplegia and hemi-anaesthesia following a stroke, but in a minority the lesions are in the left, or non-dominant, hemisphere. Most of these patients are left-handed. On examination, if asked to lift his paralysed left arm, the patient will lift his right arm instead. When attention is drawn to his inappropriate response he makes excuses. The left arm has gone to sleep or has been overworked and is too painful to move. In some cases he will insist that the arm in question belongs to the man in the next bed. He may address it by a special name and refer to it in derisory terms. The patient's posture is characteristic. He lies in bed and is found to pay no attention to the left half of the space and turns towards the right. He is usually in a good, friendly mood and in conversation smiles a great deal in a childish way. The smile and his relative normality of speech in simple conversations may lead to his level of consciousness and mental state as a whole being regarded as normal. Detailed evaluation reveals subtle cognitive deficits.
There are defects of memory for recent events and misinterpretations of his environment, which he may describe as a railway station or as a prison cell, despite being apparently fully alert. Attempts to inform him of the true diagnosis of his condition may be swiftly rejected, sometimes in aggressive tones, and reveal features of dissociation and denial of obvious phenomena. The incongruous, unchanging, smiling face he displays led Paul Schilder (1935) to describe this condition as 'organic hysteria'. The reason is that in this condition a painful truth registered in consciousness is being repressed into the unconscious on account of the patient's inability to assimilate and face up to a threatening piece of reality which he inwardly recognizes as possibly a lasting hemiplegic paralysis and which resembles typical hysterical dissociation and affect.
This interesting hypothesis shows that the vigilance of normal consciousness is not entirely in abeyance even in states of organic separation from normal conscious mental life, and a small element of reality has managed to penetrate the mental curtain of delirium, so creating distortion of reality.
The second variant of consciousness is the phenomenon of double orientation, which is in certain respects similar to anosognosia. A brief account of a case with a typical disorder of this nature was a 58-year-old man with a left hemiparesis who was admitted to hospital in Chichester following a stroke that had supervened after a haemorrhage from an aneurysm on his cerebral artery. When asked to name the city where he was born he said he was born in Edinburgh and added that it was very near Chichester, just outside the walls. He wore a faint smile when he spoke on this subject. As his delirious attack began to improve, the location of his whereabouts began to move north. When questioned about orientation first he mentioned Chichester then London, Stamford, York, Durham, Newcastle, Berwick on Tweed, then Haddington, and finally Edinburgh, this last name when his recovery of his hemiparesis was virtually complete. He had worn the same incongruous smile as a patient with anosognosia and also resisted correction in the same way.
The development and reversal of such chinks of reality with a small part of the truth, which continues to survive in the records that sustain the correct picture of the outside world, are suppressed by intact emotional factors.
2. Causation
The main common causes of delirium are cardiac disorders, such as congestive cardiac failure or dysrhythmia, almost any infection in the elderly, drug intoxication (with benzodiazepines, barbiturates), alcohol (including abrupt withdrawal), anticholinergic drugs, antidepressants, cardiovascular drugs, anti-Parkinsonian agents, metabolic disorders, electrolyte disturbances, liver or renal failure, endocrine factors (myxoedema), sensory deprivation, e.g. with visual and auditory impairment, urinary retention or constipation, central-nervous-system (CNS) disorders, Alzheimer's or multi-infarct dementia, cerebrovascular disease and complications. Loss by death of a member of the family, interconnection with an organic factor, association with a near-threshold level of intoxication with a drug administered over a period may cause delirium of abrupt onset.
After depressive illness delirium is the second most highly prevalent form of mental disorder among aged persons, recorded as being responsible for 15–20 per cent of aged persons admitted to hospital geriatric departments. Early arrival at the correct diagnosis is important for a number of reasons.
In a high proportion the condition is caused by organic factors in the brain or in some non-cerebral organ. The recovery rate following treatment is high and in treatable cases the delirious state is abolished.
A mistaken diagnosis of dementia in severe cases delays prompt treatment. An accurate history helps to establish the correct diagnosis. An important clue is provided by the abrupt development, onset having begun days or weeks previously in dementia, where the history usually extends back months or even years. EEG helps discrimination in difficult cases; high-voltage discharges from rhythmic high-voltage delta waves are characteristic (Engel and Romano 1959).
Symptomatology is abolished in a high proportion of persons but may end in grave illness in a pre-terminal stage. After the first few days of treatment, a fluctuating course is manifest in the patient's mental state and the findings on clinical examination of the mental state have been supported and can receive a definite diagnosis.
Clinical and psychological evaluation shows the patient disoriented, unable to comprehend that he is in hospital and the reasons for his admission. All categories of memory function are impaired and in severe cases in complete abeyance. He is fearful, agitated, and usually deluded and hallucinated. Visual hallucinations are characteristic. The nurse a few yards away is a prison warder or guard in a concentration camp. Irregular cracks in the paintwork are interpreted as writhing snakes. He fails to recognize members of his family paying him a visit and they may be dismissed as impostors. His mood is fearful, agitated to the point of panic, and he may attempt to escape. The consciousness of such a patient in this phase is clouded and impaired in all respects. He is awake but can be regarded as enacting a nightmare, with all mental factors in abeyance, or severely distorted and inadequate so as to falsify his perceptions of the world around him.
There are, however, fluctuations which take the form of intervals of mental lucidity in the mental state lasting a few hours to 1–2 days, during which the features of the phases of impaired consciousness remain in abeyance and a relatively normal mental state is manifest. These phases are the lucid interludes of delirious states. The main features are due to the re-entry of consciousness to mental functioning and the simultaneous elimination of hallucinations, cognitive failure, anxiety, and depression and the revival of speech. That the 'state of impaired consciousness' results essentially from the extinction of the main cognitive, affective, and perceptual abnormalities of limitation of consciousness is confirmed by renewed observations in the late afternoon and evening the same day reveals that the sequence of change that accompanied the lucid reminiscences goes progressively into reverse. The first change is the reappearance of slow activity.
In the first state of impaired consciousness of the delirious state described above, although the patient seems awake, he is in fact virtually unconscious. He is able to remember little or nothing and to register and recall little or nothing.
We can refer to the second state as the 'lucid phase'. In the more normal stages of the delirious state the patient may be regarded as conscious but one would note minor impairments.
The episode of near normality during attacks of delirium occurs regularly but fluctuation is observed in most prolonged delirious states. After sunset, as darkness begins to descend, delirious patients tend to become confused, chaotic in their speech, and fearful. Their hallucinations and delusions are awakened. Their behaviour is restless and they may try to escape. By the following morning clouding begins to recede and by mid-morning or lunchtime the patient's mental functioning has returned to a normal state with only minor impediments. The difference between the two states is that, during the lucid intervals in the morning and early afternoon, the patient's mind is unequivocally in a conscious state. During the clouded phase, at its worst during the night, consciousness is in abeyance. These two states deserve to be compared with each other with the aid of detailed clinical criteria and distinguished by evaluation with standardized psychological tests.
The behaviour of the person during the awake-lucid phases is close to that of his normal self. He is aware from conversation that he has been ill and is able to describe and discuss his symptoms, though his memory is blank for experiences during the clouded phase.
3. Aspects of treatment
As most cases of delirium have a specific physical cause, treatment should be initially focused on elimination of this factor by full investigation and active, specific steps in treatment. Details of nursing care are important. The patient is often confused or ignorant of his whereabouts and repeated explanations have to be given and attempts made to correct his frightening misconceptions by regular, repeated accounts of where he is, banishing beliefs that he is in a prison, a concentration camp, or even a nightclub.
In most specialist centres the patient is treated in a quiet room. But this is not carried to an extreme. Related persons and familiar ones are encouraged to pay him regular visits and are advised to help him comprehend where he is and why he has been sent there and to provide reassurance.
The patient is neither nursed in complete darkness nor exposed to the opposite extreme of bright, intense illumination as both are harmful. In the initial stages sedation should be provided to ensure sleep which has a healing effect. Phenothiazines such as chlorpromazine or haloperidol are usually given. Short-acting benzodiazepines may be needed to ensure sleep. Chlormethazole is generally used in alcoholic cases but its withdrawal requires to be undertaken under close observation in hospital.
4. Some future perspectives
The progress of delirious states deserves to be explored from the beginning to end with the aid of clinical examination with rating scales and standardized cognitive tests and EEGs at regular intervals. The last is valuable in that, during the clouded phase, slow activity at high voltage is manifest at an early stage and gradually declines in parallel with an improvement in symptomatology.
Such enquiries might shed fresh light on the neuropsychological activities underlying delirium. It might also make some contribution to advancing understanding of the contribution of consciousness in mental life as a whole which has baffled clinicians, scientists, and philosophers in their different aspects down the ages. Studies of the phenomenology of the fluctuations between the disturbed and the quiescent phases of delirious illness and their neural correlates would be valuable. There are also related questions that are open to empirical investigation. A systematic comparison of the mental state of patients during the height of delirium and the mental state when normal consciousness has been restored for a period would provide valuable preliminary evidence in an approach to this problem. Comparative studies of the awakened and clouded phases of the delirious states with modern techniques of magnetic resonance imaging (MRI) as well as EEG would be of interest.
It would also require detailed clinical and psychological assessment of each of the cognitive, emotional, perceptual, behavioural, and physiological items. Clinical observations taken over periods of several hours might serve to define a number of deficits and abnormal features and their association with physiological measurements which are manifest during delirious phases but absent during periods of remission.
In this connection the results obtained in a comparative enquiry of patients with dementia and delirium and with schizophrenia of old age and depression is relevant. The data from 50 years ago was obtained with the aid of three standardized scales — the Wechsler–Bellvue Scale, Raven's Progressive Matrices, a special information test, and a diagnostic rating scale.
The distribution of scores of those with Alzheimer's or the vascular form of dementia was quite distinct from patients with depressive and schizophrenic disorders (Hopkins and Roth 1953, Roth and Hopkins 1953). It proved possible to undertake the tests in those with delirious states. The scores overlapped in a striking manner with those recorded in patients with the non-demented state, namely depressive and schizophrenic disorders. But it is plain that a diagnosis of delirious disorder cannot be made on the strength of cognitive tests alone. No attempt has been made to grade, measure, and report on the level of general awareness as inferred from clinical and EEG data. The problem outlined here had not been formulated. It is noteworthy that those with senile dementia who had much more serious physical illness with severe progressive cerebral damage as the main cause but no 'impaired consciousness' were judged to exclude a diagnosis of Alzheimer's disease. None of the cases was complicated by the delirious state. Further enquiries into the questions posed here might shed light on delirious disorder and also serve to define some of the features that separate the seemingly awake and responsive delirious persons from those who are in a fully awake and conscious state.
(Published 2004)— Martin Roth
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