The concept of placement of drugs into the cerebral spinal fluid (CSF) to impact a patient's perception or sensation is not a novel concept. In the early 19th century scientists and physicians sought this route to impact health care. Early pioneers of this therapy can be traced back to the origins of spinal anesthesia, and many people are responsible for the current state of the art.1 In 1885, Corning performed the first “spinal block.” This was followed by August Bier in Germany, who was a self-volunteer for a spinal injection. In 1898, the first spinal anesthetic was documented using cocaine as the drug, followed in 1901 with the first epidural used for pain treatment. The use of corticosteroids for treatment of pain occurred in 1952. Development of newer agents slowed at this point, with no major advances until the 1980s when intrathecal morphine and intrathecal baclofen were approved for the treatment of chronic pain and spasticity, respectively.2 Ziconotide received US Food and Drug Administration (FDA) approval in 2004 as a non-opioid intrathecal alternative for treatment of pain. Current studies have been conducted on hydromorphone, gabapentin, octreotide, and new calcium channel blocking drugs, but no new positive reports have been noted. The history of intrathecal therapy has been shaped by a series of consensus conferences that have given guidance based on information provided by experts in the field. The history to be written in the next decade will most likely focus on new drugs and improved safety.
Intrathecal drug delivery (IDD) has undergone a renaissance in the last few years, positioning the therapy as less of a salvage therapy in the pain care algorithm and earlier in patients who fail more conservative therapies. Advances in the platform technology, including patient-controlled bolusing, as well as new medications positioned as monotherapy, including ziconotide, suggest that intrathecal therapy will continue to be an important strategy in the pain care armamentarium. This chapter focuses on methods to improve outcomes and to position drugs properly in the pain treatment algorithm. The abuse of opioids given by the oral route has made this a particularly timely issue, since proper use of intrathecal administration of opioids may deter the escalating use of opioids and thus may reduce morbidity and mortality from currently used strategies.
As with any therapy, outcomes depend largely on patient selection. This chapter will discuss pharmacokinetics and pharmacodynamics of the intrathecal space, patient indications, candidacy, methodology for trialing and therapy initiation, maintenance strategies, efficacy, and comorbidities associated with intrathecal therapy and then comment on future directions.
Simply stated, IDD is a platform to deliver medication into the intrathecal space. It does not define a specific therapy. The theoretical advantages of intrathecal therapy, in contrast to systemic therapy, include delivery of medications largely to the site of action, i.e., the dorsal horn of the ...