What is the Value of Laboratory Testing, Lumbar Puncture, or Electroencephalogram?
Laboratory testing of delirious patients should include: complete blood count, electrolyte panel, metabolic panel, thyroid function tests, urinalysis, electrocardiogram and chest radiograph. CT or MRI Imaging studies are indicated in patients with a history of or signs of head trauma, those with focal neurologic symptoms or signs, and those without a reasonable explanation for delirium. The lumbar puncture is indicated in the delirious patient in the absence of an apparent precipitant. Although a lumbar puncture should always be performed when the cause of delirium is inapparent, many elderly patients with localized infections, such as a urinary tract infection, develop delirium without spread of the infection to the central nervous system. The electroencephalogram may be useful in diagnosing delirium. However, the electroencephalogram is not pathognomonic of delirium, nor can it distinguish delirium from dementia. Diffuse slowing can be seen with either condition. In patients in whom
