ABSTRACT
<b>Introduction</b>: Few studies have examined neuropathological changes such as the degenerative necrosis and demyelination of spinal nerve cells accompanying intrathecal administration of opioids (ITO) to relieve refractory cancer pain. Previous studies have produced conflicting results as to whether or not ITO causes nerve tissue damage. The current study neuropathologically investigated autopsy specimens from patients who received ITO. <b>Methods</b>: Subjects were 7 patients who received continuous intrathecal analgesia and who were later autopsied (4 males, 3 females). Six patients were administered morphine and bupivacaine while 1 patient was administered fentanyl and bupivacaine. The duration of administration ranged from 6-345 days. <b>Results</b>: Two patients who received long-term administration of morphine were found to have severe necrotic degeneration and gliosis of spinal neurons and demyelination in the dorsal horn and dorsal roots. However, neuropathological changes were not noted in Patient 4, who was briefly administered morphine, or in the patient who was administered fentanyl. <b>Conclusion</b>: The total dose of morphine used for ITO and the duration of its administration were suggested to be related to the extent of nerve tissue damage. Thus, nerve tissue damage due to ITO might be primarily associated with morphine.