Delirium is an acute confusional state that results from a sudden change in cerebral function. It occurs when there is an impairment in the normal signal pathway in the brain and it is usually temporary and reversible. Delirium manifests clinically as a wide range of neural and psychiatric abnormalities.
Obtaining a thorough history is very important for diagnosis of this condition as there are no medical investigations that can diagnose delirium. Delirious patients are often confused and unable to provide accurate information so the history should be obtained from relatives and caregivers. Some of the symptoms that would be mentioned are disorientation, difficulty is maintaining concentration, shifting attention, illusions, reversal in sleep-wake cycle and hallucinations. These symptoms are usually worse at night and show improvement during the day. Other neurological symptoms that could be reported are motor abnormalities, uremia, tremors, dysarthria and dysphagia .
Elderly patients who present with symptoms of delirium usually have an underlying illness precipitating it.
There is no one test for diagnosing delirium, but there are numerous tests that could be useful for diagnosing precipitating symptoms. Blood tests like complete blood count, sedimentation rate and bacterial/viral culture are used to rule out underlying infections. Blood tests also help to detect electrolyte derangement and problems with glucose metabolism. They are useful to determine renal, hepatic and thyroid function. Urine tests are also used to check for infections and toxicology screening to check for drugs and poisons. HIV tests and tests for vitamin B12 and thiamine are also carried out.
Imaging studies are also done to check the structure of the brain and they include CT scans and MRI. Electroencephalogram (EEG) is also useful in delirium as it may also give an indication to the cause of the delirium based on the wave patterns. A chest radiograph also is used diagnose congestive heart failure or pneumonia.
The most important step in treatment is to identify the underlying cause and eliminate it. The mainstay of delirium treatment is supportive therapy and drug therapy.
Supportive therapy involves maintaining normal hydration as nutrition levels. Thiamine should be given to patients who are undergoing alcohol withdrawal. It is important for the patient’s environment to be quiet, stable and well-lit.
Memory cues like clocks, family photos and calendars are useful in reorientation. Reorientation should be reinforced by family members. Sensory defects should be corrected as required. It is important to avoid physical restraints as it only heightens the patient’s perception of problems and could lead to combative behaviour. It is important that these patients are closely monitored and never left alone .
Medication should be considered in patients who cause injuries to themselves or others. Medications used include neuroleptics like haloperidol and risperidone and short-acting sedatives like lorazepam. Sedatives are used in patients withdrawing from alcohol or sedative hypnotics .
There are mortality rates of up to 26% in patients admitted with delirium. Patients who develop delirium in the hospital have a mortality rate of up to 76%. For post-operative and elderly patients, delirium could lead to extended hospital stay, increased complications, extra costs and disability .
Delirium is often a result of conditions that impair the supply of oxygen and other substances in the brain. Some of the causes include infections like urinary tract infections (UTI) and pneumonia, dehydration, metabolic derangements, withdrawal symptoms from alcohol and drugs, drug toxicity, chemicals, seizures, head injuries, surgeries and chronic illnesses amongst others .
It is a fairly common condition and is seen is about 14 to 56% of hospitalized elderly patients. Up to 30% of cases develop after admission and 40% of patients admitted to intensive care units develop delirium. The prevalence of post-surgical delirium is also high with as high as 40% of patients developing delirium after orthopaedic surgery. Delirium is also very common in nursing home residents and as much as 80% of people develop delirium near death. It has no race or sex predilection .
There are 3 recognizable delirium types based on the state of arousal. Hyperactive delirium is associated with intoxication with some stimulant drugs or withdrawal from alcohol. Hypoactive delirium is seen in patients with hepatic encephalopathy. In the third type, mixed delirium, there is usually sedation during the day and at night, patients develop behavioural problems.
There has been no clear understanding of the mechanism by which delirium occurs as it results from various psychological and physical insults. The widely accepted hypothesis is that there are multiple neurotransmitter abnormalities and reversible impairment of the cerebral oxidative mechanism. Observations such as reduced cholinesterase activity and increased dopaminergic activity support the hypothesis of neurotransmitter abnormalities .
There is no specific prevention for delirium as it is a consequence of various other conditions. The preventive measures implemented for specific conditions which cause disturbance in cerebral function can indirectly prevent delirium.
Delirium is a syndrome that results from multiple causes that have similar type of symptoms. Early diagnosis and resolution of symptoms are important to avoid morbidity and mortality. It is a medical emergency and should be treated as one .