Chronic opioid neurotoxicity after successful palliative treatment for painful bone metastases

We describe a case of chronic opioid neurotoxicity in a sixty four year old man with severe bone pain secondary to pathological fracture of a vertebra which required large doses of morphine to obtain pain relief. After receiving effective palliative antitumour treatment, we postulate that the gradual reduction in pain over a period of time precipitated the development of more chronic opioid toxicity, presenting as confusion.

Delayed opioid toxicity is a potential complication of disease-modifying therapies that needs to be recognised and treated appropriately when it occurs. The increasing use of community based palliative care after hospitalisation means that the community practitioner needs also 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 recognise 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.