A review of intrathecal morphine therapy related granulomas

The development of catheter associated granulomatous masses in intrathecal morphine therapy is an uncommon, but potentially serious problem. While these systems have historically been used in patients with short life expectancies, more recently patients with pain from a benign source have benefited from this therapy, and new complications are being encountered secondary to the patients' longer life spans. Morphine is the most commonly used intrathecal opioid and evidence exists that the formation of granulomatous masses are related to the use of higher doses. When the patients' requirement of morphine increases significantly, the physician should be alert for signs of spinal cord compression, such as new neurological deficits, myelopathy, or radiculopathy. Patients that require these higher doses should be properly informed of the association with granulomas and their associated risks. Indolent infection may also be the etiology of granulomatous masses, and the presence of organisms, both aerobic and anaerobic, should be routinely investigated. Patients with catheter-associated granulomas appear to share several features. They exhibit the onset of symptoms several months following the initiation of intraspinal opioids and commonly present with an increase in pain that precedes signs and symptoms of neurological deterioration. While MRI might be the preferred method of detection of intrathecal granulomas, its cost and availability are prohibitive for routine screening. CT myelogram via pump side port injection of contrast can also be performed to detect catheter tip related granulomas/obstructions. Serial neurological examinations for new deficits may be performed and recorded during pump refill visits to recognize a granulomatous mass in its early stages. If an abnormality is identified, imaging studies are appropriate. Awareness of the condition and vigilance are the keys to successful management of this complication.