At the time of this writing, there are only three drugs approved by the U.S. Food and Drug Administration (FDA) for the intrathecal (“spinal”) route of administration: ziconotide, morphine, and baclofen.
Note the lack of local anesthetics on that list. Lidocaine? No. Hyperbaric bupivacaine? No. Good ‘ol tetracaine? Nope. All local anesthetics in the intrathecal space are off-label. Yet these are the very drugs that serve as the cornerstone for spinal anesthesia.
With a spinal needle and a few milliliters of local anesthetic like bupivacaine or lidocaine, we can achieve an anesthetic which enables surgeons to operate on the abdomen or lower extremities pain-free without any significant cardiopulmonary drawbacks. Sure, sympathectomies are a concern, but we’ve become extremely good at predicting and mitigating the effects of hypotension, tachy/bradycardias, etc.
For patients reading this concerned about the off-label use of local anesthetics in spinals… please keep in mind that there are MANY things we do in medicine which are off-label but well accepted practices. Spinal anesthetics are predictable, effective, and often times safer than general anesthesia. Just like everything else, we have to weigh the pros and cons and individualize our anesthetics for a patient, their operation, and their comorbidities.