Organic brain diseases result from structural pathology, as in senile dementia, or from disturbed eNS function, as in fever-induced delirium. A classification of organic brain syndromes, derived from the American classification, DSM III, is shown in Table 19.5.
Organic delusional syndrome
Organic affective syndrome
Intoxication and withdrawal syndromes
Classification of organic brain syndromes
Delirium, also termed toxic confusional state, is an acute or subacute condition in which impairment of consciousness is accompanied by abnormalities of perception and mood. The impairment of consciousness can range from mild befuddlement to serious disorientation and confusion. The degree of impairment classically fluctuates, so that there are intermittent lucid periods. Confusion is usually worse at night. During the acute phase, thought and speech are incoherent, memory is impaired and misperceptions occur. Transient hallucinations, usually visual, and delusions may occur and, as a consequence, the patient may be frightened, suspicious, restless and uncooperative. A large number of diseases may be accompanied by delirium; this is particularly so in elderly patients. Some causes of delirium are listed in Table 19.6. Delirium usually clears within a few days as the underlying illness resolves. If the delirium runs a subacute course, more permanent disorders of cognition, memory or personality may occur.
INVESTIGATION AND TREATMENT
Investigation and treatment of the underlying physical disease should be undertaken. The patient should be carefully nursed and rehydrated. Pain relief should be adequate and sedation provided if necessary. If a high fever is present, the temperature should be reduced with fans, ice-packs and antipyretic drugs. All current drug therapy should be reviewed and, where possible, stopped. Benzodiazepines are the drugs of choice in the management of minor restlessness, but in severe delirium haloperidol is probably a more effective choice, the daily dose usually ranging between 10 and 60 mg. If necessary, the first dose of 2-10 mg can be administered intramuscularly.
Any infection, particularly with high fever (e.g. malaria,
Disorders of electrolyte balance
Thiamine (Wernicke-Korsakoff syndrome, beriberi)
Nicotinic acid (pellagra)
Antichol inerg ic
Industrial poisons, e.g. DOT, trichloroethylene
DOT, dichlorodiphenyl trichloroethane.
Some causesof delirium.
MANAGEMENT OF THE DISTURBED OR VIOLENT PATIENT
Psychotic, organically impaired and intoxicated patients may be frightened, aggressive, confused and difficult to manage. It is important that those involved in their acute management refrain from threatening behaviour, appear in control (even if they do not feel it l) and avoid being drawn into a confrontation.
When evaluating a disturbed patient in the emergency department, a crucial question is: Could this behaviour be the result of an organic disturbance? Organic psychiatric disorders, particularly those associated with drugs and alcohol, are important causes of behavioural and thought disturbances in emergency clinic attenders. Some organic disorders initially showing signs and symptoms of psychosis, such as poisoning, meningitis and hypoxia, may be life-threatening. Treatment is with chlorpromazine in doses of 25-50 mg orally; i.m. haloperidol causes less hypotension and is an alternative.
Dementia is a syndrome due to disease of the brain in which there is a disturbance of multiple higher cortical functions, including memory, thinking, orientation, comprehension, calculation, learning capacity, language and judgement. However, consciousness is not clouded. There is often an associated deterioration in emotional control, social behaviour and motivation. Presenile dementia and early onset dementia are terms used for patients under 70 years of age and senile dementia for older patients; there is, however, no clinical difference.
About 25% of the elderly population suffer from a psychiatric disability, mainly anxiety and depression. However, dementia affects about 10% of those aged over 65 years and 20% of those over 80 years of age-a total of 650000 people in England and Wales. The causes of dementia are shown in Table 19.7; 70% are due to Alzheimer’s disease.
DIFFERENTIAL DIAGNOSIS. This includes a depressive disorder which may exhibit many of the features of an early dementia, especially memory impairment, slowed thinking, and lack of spontaneity; delirium; mild or moderate retardation; iatrogenic mental disorders due to medication (Table 19.8).
This is a primary degenerative cerebral disease of unknown aetiology. A relationship between the ingestion or accumulation of aluminium ions has been suggested, but is not proven.
CLINICAL FEATURES. The onset is insidious and it develops slowly over a period of years. The onset can be in middle adult life or even earlier but the incidence is higher in later life. In cases with onset before the age of 65-70 years there is a likelihood of a family history of a similar dementia, a more rapid course and prominence of features of temporal and parietal lobe damage. Patients with Down’s syndrome are at a high risk of developing Alzheimer’s disease.
There are characteristic pathologic changes in the brain including:
NEURONAL REDUCTION in the hippocampus, substantia innominata, locus ceruleus and temporoparietal and frontal cortex.
NEUROFIBRILLARY TANGLES composed of paired helical filaments.
ARGENTOPHIL PLAQUES consisting largely of amyloid protein A4. The gene for the precursor protein of A4 (pro-Ad) is localized close to the defect on chromosome 21 causing familial Alzheimer’s disease. The significance of these findings is unclear.
Neurochemical changes have been found including a marked reduction in the enzyme choline acetyltransferase, in acetylcholine and in other neurotransmitters and neuromodulators.
Vascular dementia (multi-infarct dementia)
This is the second most common cause of dementia and is distinguished from Alzheimer’s disease by its history of onset, clinical features and subsequent course. There is usually a history of transient ischaemic attacks with brief impairment of consciousness, fleeting pareses or visual loss. The dementia may follow a succession of acute cerebrovascular accidents or, less commonly, a single major stroke.
This is a dementia in which the cortical atrophy is initially restricted to the frontotemporal region. The cause is unknown.
The presence of dementia is usually diagnosed clinically, but it can be confirmed by psychometric testing, e.g. Wechsler Scale. Secondary causes are infrequent, but they must be excluded by appropriate tests (Table 19.7) in all patients as some causes are potentially reversible.
CT or MRI scan will confirm the presence of cortical atrophy and exclude other lesions, e.g. brain tumours.
In most cases there is no specific treatment, but conditions such as anxiety and depression often need
therapy. The patient should be kept in the community as long as possible, institutional care being used only in the later stages. Carers must be given support and patients are often admitted to hospital for short periods to give carers respite
The amnestic syndrome is characterized by a marked impairment of memory occurring in clear consciousness and not as part of a delirium or dementia.
Long-term memory is affected but the typical feature is impairment of short-term memory. Often the patient is blandly unconcerned and commonly displays confabulation. One of the commonest causes is severe thiamine deficiency secondary to chronic alcohol abuse but other, less common causes are shown in Table 18.8.
Organic delusional syndrome
The organic delusional syndrome is characterized by a mental state dominated by delusions that are often accompanied by a persistent and distressing misperception of the environment, sometimes referred to as delusional tone. The delusions are very often persecutory but may also be hypochondriacal, pathologically jealous, grandiose or erotic.
Organic affective syndrome
The organic affective syndrome consists of marked mood changes that result from organic brain damage. There are depressive and manic phases, often occurring suddenly, or there may be a persistently dysphoric state. There is no significant intellectual loss, delusions or hallucinations, and a family history of an affective disorder is uncommon.