MASSIVE OPIOID RESISTANCE IN AN INFANT WITH A LOCALIZED METASTASIS TOTHE MIDBRAIN PERIAQUEDUCTAL GRAY

We report the case of a 4-month-old infant with terminal malignancy wh o had systemic metastases and a localized metastasis to the dorsal mid brain periaqueductal gray (PAG). Extraordinary doses of opioids (dose equivalent of 2680 mg morphine sulfate/h, i.v.) were required to achie ve adequate analgesia. The behavior of the infant, interpreted as bein g representative of a response to pain, may have been an aversive reac tion due to the location of the lesion in the dorsal PAG. We propose t hat the lesion in the PAG impaired the responsiveness of this infant t o the effect of opioids. This report is to alert clinicians to the pos sible role of the PAG in impaired opioid responsiveness in patients wi th terminal malignancy, as well as the possibility that pain-like sign s (e.g., tachycardia,tachypnea, vocalization, facial grimacing) may in dicate an aversive reaction rather than pain in non-verbal patients.