MILAN, Italy--Opioids are not usually the cause of organic brain syndromes (most often delirium and hallucinations) in patients with chronic cancer pain, when other common medical conditions that develop in advanced cancer are considered, says Augusto Caraceni, MD, of the Pain Therapy and Palliative Care Division, National Cancer Institute, Milan.
Dr. Caraceni and his colleagues reviewed 161 hospitalized patients who received opioids for chronic cancer pain during a 14-month period; 15 developed an organic brain syndrome. In four patients, opioids were found to be the only cause of the syndrome, but in 11 cases, concomitant conditions could not be excluded as contributing to the etiology, and in some cases appeared to be the primary cause.
When opioids were clearly implicated as the cause of the organic brain syndrome, opioid dosages were reduced to relieve mental symptoms, but patients were sometimes left with only partial pain relief, the researchers say (J Pain Symptom Management 9:527-533, 1994).
The concomitant conditions included brain metastases, liver failure, renal failure, and hyponatremia (the three patients with hyponatremia improved when electrolytes were corrected and their morphine(Drug information on morphine) dosages were reduced). Two patients were also receiving psychoactive drugs (amitriptyline and lorazepam(Drug information on lorazepam)), and both recovered when these drugs were discontinued.
In two patients with melanoma and bone metastases, use of IL-2 or IL-2 and interferon appeared to be the primary cause of their mental problems, and another patient was found to have hydrocephalus stemming from a metastatic brain lesion.
Dr. Caraceni concluded that in all cases of organic brain syndrome, "a very careful differential diagnosis is important to rule out concomitant, and sometimes treatable, conditions."
His colleagues in the study were Drs. Cinzia Martini, Franco De Conno, and Vittorio Ventafridda, all with the National Cancer Institute, Milan.