Neurotoxicity from Chronic Opioid Therapy After Successful Palliative Treatment for Painful Bone Metastases

Abstract

A 64-year-old man with severe bone pain secondary to pathological fracture of a vertebra required large doses of morphine to obtain pain relief. After receiving effective palliative anti-tumor treatment, he developed chronic opioid neurotoxicity. We postulate that the gradual reduction in pain over a period of time precipitated the development of toxicity that presented as cognitive failure. Delayed opioid toxicity is a potential consequence of effective disease-modifying therapies that needs to be recognized and treated appropriately when it occurs. The increasing use of community-based palliative care after hospitalization means that the community practitioner also needs to be aware of the development of chronic opioid toxicity at home. Optimal timing for going back down the ladder of opioid doses, after reduction of the noxious stimulus, requires clinicians to recognize different types of symptoms and signs and to consider the effect of other treatments and time on the noxious stimulus. A suggested protocol warrants consideration as a means of improving clinical practice; however, it requires prospective evaluation in the clinical setting.