What side effects can occur from intrathecal analgesics?
Intrathecal delivery of analgesic medications carries with it the potential for all side effects of systemic administration, with a few additional risks specific to the intrathecal route. For example, intrathecal opioids can cause pruritus, urinary retention, and respiratory depression, while intrathecal local anesthetics can cause weakness, numbness, arrhythmias, and seizures. These side effects tend to occur less frequently with intrathecal administration than with systemic administration, because of the much lower doses that are required for analgesia. Ziconotide, a peptide antagonist of voltage-gated calcium channels, is only approved for intrathecal use. Common side effects of this medication include dizziness, nausea, altered mental status, nystagmus, and urinary retention. Lastly, catheter-tip associated inflammatory masses (“granuloma”) are an uncommon but potentially serious reaction that can occur with intrathecal drug delivery—particularly opioids.