Delirium And Intoxications

Delirium is also known as the acute confusional state, and is a nonspecific syndrome. It may be the result of a medical condition, such as major organ failure (e.g., hepatic encephalopathy or sepsis), or

Table 10

World Health Organization Diagnostic Criteria for Creutzfeldt-Jakob Disease

1. Creutzfeldt-Jakob Disease (CJD) clinical diagnosis:

Criteria for probable sporadic CJD: The clinical diagnosis of CJD is currently based on the combination of progressive dementia, myoclonus, and multifocal neurological dysfunction, associated with a characteristic periodic electroencephalogram (EEG). However, new variant CJD, most growth hormone-related iatrogenic cases, and up to 40% of sporadic cases are not noted to have the characteristic EEG appearance. This hampers clinical diagnosis, and hence surveillance, and illustrates the need for additional diagnostic tests. Proposed criteria for probable sporadic CJD:

a. Progressive dementia. and b. At least two out of the following four clinical features:

i. Myoclonus.

ii. Visual or cerebellar disturbance.

iii. Pyramidal/extrapyramidal dysfunction.

iv. Akinetic mutism. and

2. A typical EEG during an illness of any duration. and/or

3. A positive 14-3-3 cerebral spinal fluid assay and a clinical duration to death less than 2 years.

4. Routine investigations should not suggest an alternative diagnosis.

Note: Results from a recent study suggest that the detection of high signal from the basal ganglia on T2- and proton-density-weighted magnetic resonance imaging support the diagnosis of sporadic CJD. These abnormalities can be particularly prominent if a fluid-attenuated inversion recovery sequence or diffusion-weighted images are obtained.

(Adapted from World Health Organization. Human transmissable spongiform encephalopathies. Wkly Epidemiol Rec 1998;73:361-365.)

Table 11

Electroencephalogram Interpretation in Creutzfeldt-Jakob Disease

No widely agreed and validated definition of a diagnostic electroencephalogram tracing is available, leading to potential inconsistencies in case ascertainment between centers. To enhance Creutzfeldt-Jakob disease surveillance, a workable definition of a diagnostic electroencephalogram is required. The following criteria devised by Steinhoff and Knight are suggested for use now, with results being evaluated further:

1. Strictly periodic activity:

a. Variability of intercomplex intervals is less than 500 ms.

b. Periodic activity is continuous for at least one 10-second period.

2. Bi- or triphasic morphology of periodic complexes.

3. Duration of majority of complexes ranges from 100 to 600 ms.

4. Periodic complexes may be generalized or lateralized, but not regional or asynchronous.

Adapted from World Health Organization. Human transmissable spongiform encephalopathies. Wkly Epidemiol Rec 1998;73:361-365.

of the effects of intoxication (e.g., alcohol or phencyclidine, etc.). The cardinal finding in delirium is altered mental status, which helps distinguish it from dementia, generally conceived of as occurring in clear consciousness. Not all individuals with delirium are agitated or hyperexcitable. In that regard, there is broad overlap with conditions capable of causing stupor or coma. The evaluation and differential diagnosis of delirium is essentially the same as evaluation of the comatose individual with consideration to signs, symptoms, and etiologies.

It should also be borne in mind that dementia itself is a risk factor for delirium, but should not be diagnosed when the mental status changes of dementia occur exclusively during a delirious episode.

The DSM-IV diagnostic criteria for delirium because of a general medical condition are presented in Table 17. The section on intoxications is drawn from the International Statistical Classification of Diseases and Related Health Problems, 10th edition, classification scheme.

Table 12

New-Variant Creutzfeldt-Jakob Disease: Suspect Case Definition

New-variant Creutzfeldt-Jakob disease (nvCJD) cannot be diagnosed with certainty on clinical criteria alone at present. However, based on the 23 neuropathologically confirmed cases, the diagnosis of nvCJD should be considered as a possibility in a patient with a progressive neuropsychiatry disorder, with at least five out of the following six List 1 clinical features. The suspicion of nvCJD is strengthened by the following criteria in List 2. A patient with a progressive neuropsychiatry disorder and five out of the six clinical features in List 1 and all of

the criteria in List 2 should be considered as a suspect case of nvCJD for surveillance purposes.

List 1

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