Stem cell transplants have been hailed as medical miracles. Cancer patients with leukemias and lymphomas, in particular, are benefiting from transplants that replace their cancer-riddled blood and immune systems with cancer-free versions courtesy of stem cells. But it turns out there can be a side effect—delirium. It can be serious if not treated: It can keep patients from informing doctors and nurses of troublesome physical symptoms, and because of this, delirium has been linked to death during hospitalization, as well as a higher risk of falls and wound infection. A new study shows that with stem cells, the delirium symptoms are especially subtle and can be missed if the doctor isn't paying close attention.

What the researchers wanted to know: Does delirium occur after stem cell transplants, and does it have any special features?

What they did: Ninety patients, with leukemia, myeloma, lymphoma, or other cancers were examined several times a week, starting seven days before they underwent stem cell transplants and continuing 30 days past their operations. They were given psychological tests for delirium, distress, and pain.

What they found: A full 50 percent of these patients had episodes of delirium. The episodes lasted an average of 10 days. But they didn't have classic delirium symptoms like hallucinations. Instead, sleep-wake-cycle disturbances, impaired attention, memory problems, and withdrawing into themselves were common. Pain symptoms went up during delirium episodes

What this study means to you: Doctors can't rely on classic symptoms like hallucinations to diagnose delirium in stem cell transplant patients. They need to be more careful and check patients more closely in order to avoid bad consequences down the road.

Caveats: Some patients were seriously ill, and that may have affected their responses to the psychological tests, so the incidence of delirium may be exaggerated.

Find out more: The American Society of Clinical Oncology has info on mental confusion and delirium during cancer treatment.

Read the article: Fann, J. R. et al. "Clinical Presentation of Delirium in Patients Undergoing Hematopoietic Stem Cell Transplantation: Delirium and Distress Symptoms and Time Course." Cancer. Feb. 15, 2005. Published online Jan. 10, 2005.

Abstract online: www3.interscience.wiley.com