An intrathecal pump is an implanted device that delivers medication directly into the cerebrospinal fluid. Its advantage is not the delivery route for its own sake — it is what that route does to the dose required.
Why the dose falls so far
Medication placed in the intrathecal space bypasses the barriers an oral drug has to cross. Empire's curriculum puts the bioequivalency at roughly 300 percent greater than oral medication, which is why the pump delivers what the teaching describes as “very small quantities of medications.”
The consequence is the point of the whole device. A dose small enough to be delivered continuously into the spinal fluid produces pain control while avoiding much of the systemic burden the same drug carries by mouth — the sedation, the constipation, the cognitive dulling that limit oral therapy.
Agents used include morphine and baclofen, among others.
Around ninety percent — and how that compares
This is where the pump distinguishes itself from the other implanted option.
Spinal cord stimulation has a success rate of 50 to 70 percent. For the intrathecal pump, Empire's teaching puts it at around 90 percent, with approximately 5 percent of patients reporting that the pump is not providing sufficient pain control.
That is a substantially higher proportion of patients helped, and it is the reason the pump is considered where stimulation has failed or is unsuitable. The two devices are not competing for the same patient in the same situation, but where both are on the table the difference in expected benefit is real.
The trial comes first
As with stimulation, nobody is implanted without a trial.
Several trial approaches exist. The most straightforward is a single injection: a bolus of intrathecal morphine given via lumbar puncture, with the patient's response then assessed. Other approaches include continuous infusion over a period rather than a single dose.
This guide carries no doses, for the same reason the rest of this reference does not — dosing is determined by the prescriber for the individual patient, and reading a figure from an article is not how that decision should be made.
The fifty percent rule
The threshold for proceeding to permanent implantation is the same one used across neuromodulation: at least a 50 percent reduction in pain during the trial.
Achieve that, and the patient is a candidate for permanent implantation. Fall short, and they are not — which spares them a device that would not have delivered.
The rule only works if the baseline was recorded properly beforehand, in the same terms the trial response will be measured in. A vague recollection of how bad the pain was is not a baseline.
What the device involves long term
Two facts patients consistently want and are not always given.
Complications are rare. This is a well-established therapy with a long track record.
The device lasts approximately ten years. That is a finite lifespan, which means replacement is part of the plan rather than a surprise, and it should be part of the conversation before implantation rather than a decade afterwards.
Between those points the pump requires refilling at intervals, which ties the patient to a clinic capable of doing it — a practical consideration worth raising with anyone who travels, relocates, or lives at a distance.
Who it suits
The pump is considered for chronic pain that has not responded to less invasive treatment, and particularly where oral medication produces adequate relief but at a systemic cost the patient cannot tolerate. The 300 percent bioequivalency is precisely what addresses that problem.
It is also considered where spinal cord stimulation has failed or is unsuitable — the higher success rate being the reason.
The same selection discipline that governs stimulation applies: documented failure of conservative treatment, no major psychiatric disorder, willingness to stop inappropriate drug use, and the ability to give informed consent. Those criteria are set out in the spinal cord stimulation trial.
Questions worth asking
- Which medication, and why that one for my pain?
- What form will the trial take, and how will we measure the response?
- What is my baseline, recorded how?
- How often will it need refilling, and where?
- What happens at ten years?
- What is the plan if the trial does not reach fifty percent?
Where it sits in the treatment ladder
Near the end of it. An implanted drug delivery system is not an early option and is not offered before conservative treatment, injections and, in most pathways, consideration of stimulation.
What distinguishes it from everything earlier in the ladder is that it is a long-term commitment to a device rather than a procedure with an endpoint — which is exactly why the trial, the 50 percent threshold and the selection criteria carry as much weight as they do.
Learn blocks with your hands, not from a page
Empire’s Pain Management Training (THE Pain Show) is accredited for 25.25 AMA PRA Category 1 Credits™, jointly provided by AKH, Inc, and Empire Medical Training. For narrower peripheral work, Joint, Extremity and Non-Spinal Injection Training carries 6.75 credits for the complete in-person hybrid program, and Advanced Musculoskeletal Ultrasound Guided Injections builds the guidance skills above.
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