Don't Assume That Mental Symptoms Are Due to Opioids

MILAN, Italy--Opioids are not usually the cause of organic brainsyndromes (most often delirium and hallucinations) in patientswith chronic cancer pain, when other common medical conditionsthat develop in advanced cancer are considered, says Augusto Caraceni,MD, of the Pain Therapy and Palliative Care Division, NationalCancer Institute, Milan.

Dr. Caraceni and his colleagues reviewed 161 hospitalized patientswho received opioids for chronic cancer pain during a 14-monthperiod; 15 developed an organic brain syndrome. In four patients,opioids were found to be the only cause of the syndrome, but in11 cases, concomitant conditions could not be excluded as contributingto the etiology, and in some cases appeared to be the primarycause.

When opioids were clearly implicated as the cause of the organicbrain syndrome, opioid dosages were reduced to relieve mentalsymptoms, but patients were sometimes left with only partial painrelief, 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 hyponatremiaimproved when electrolytes were corrected and their morphine dosageswere reduced). Two patients were also receiving psychoactive drugs(amitriptyline and lorazepam), and both recovered when these drugswere discontinued.

In two patients with melanoma and bone metastases, use of IL-2or IL-2 and interferon appeared to be the primary cause of theirmental problems, and another patient was found to have hydrocephalusstemming from a metastatic brain lesion.

Dr. Caraceni concluded that in all cases of organic brain syndrome,"a very careful differential diagnosis is important to ruleout concomitant, and sometimes treatable, conditions."

His colleagues in the study were Drs. Cinzia Martini, Franco DeConno, and Vittorio Ventafridda, all with the National CancerInstitute, Milan.