Intrathecal Therapy and Associated Masses
Ahmed Ghaleb M.D., Gentian Meta,M.D., Carmelita Pablo,M.D.
Dept: Anesthesiology, University Of Arkansas For Medical Sciences

Introduction
Intrathecal analgesic therapy has become a great asset in the treatment of chronic pain. Initially, this modality was designed for terminal cancer patients, but has been lately utilized for chronic non-malignant pain. Unfortunately, serious complications have been observed with this modality. One serious complication is inflammatory mass formation in patients receiving chronic intrathecal opioid infusion. Reports indicate that morphine is the drug mostly associated with mass formation. Cases on hydromorphone that developed masses have also been on morphine. Our case developed an intrathecal inflammatory mass after long-term hydromorphone + bupivacaine intrathecal infusion and was not on morphine.

Case report
Our patient is 48 year old male with a history of ankylosing spondylitis, early stage osteoporosis, vertebral fractures and pain. The patient has been on 41 mg/day hydromorphone and bupivacaine and presented with progressive weakness of the lower extremities. His new complaints prompted further radiological studies including MRI, myelogram and postmyelographic CT-scan. Myelogram demonstrated an extra-dural defect on the left side at T9-10 and a small lucent area at T10-11, read as meningioma by the
radiologist. Mass was found to encase the catheter, was resected, and the catheter tip was removed.

Discussion:
Patients with intrathecal catheter associated masses have variable clinical presentations. They may present late with spinal cord compression symptoms but be completely asymptomatic at early stages. Most inflammatory masses have been associated with preservative-free morphine use alone or in combination with other analgesic substances, such as hydromorphone or local anesthetics. High doses of morphine and prolonged therapy are the two most important factors of mass formation. Doses of 10 mg morphine per day
and a 16-24 month therapy have been implicated with mass formation. Our case has been on hydromorphone + bupivacaine for 8 years. In one case report, McMillan et al demonstrated that using hydromorphone instead of morphine resulted in the cessation of the mass growth.
Intrathecal pump placement in terminal cancer pt seems warranted due to the short duration of use expected. In our practice, intrathecal pumps are used only for patients who have terminal cancer. Other chronic pain indications of intrathecal pump use should be weighed against the risk of complications including inflammatory mass formation.

Conclusion:
Most intrathecal inflammatory masses have been reported to form after long-term intrathecal opioid infusion. These patients have almost always been on morphine at least initially in their therapy. Duramorph and baclofen are approved by FDA for chronic intrathecal infusion, whereas hydromorphone is not. The delay of the diagnosis could result in temporary or even permanent neurological deficits as in our case.

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