An intrathecal pump is a surgically implanted device that delivers pain or spasticity medication directly into the fluid surrounding your spinal cord. It consists of a small reservoir (about the size of a hockey puck) placed under the skin of your abdomen and a thin catheter that runs to your spine. Because the medication goes straight to the spinal cord instead of traveling through your bloodstream, the doses needed are dramatically smaller. For morphine, the ratio is roughly 100 to 1: a patient who needed 100 mg orally might need just 1 mg delivered intrathecally.
How the Pump Works
Your body has a protective barrier between your bloodstream and your central nervous system. When you swallow a pill or receive an injection into a vein, most of the drug gets filtered out or broken down before it ever reaches the spinal cord. An intrathecal pump bypasses that barrier entirely. The catheter tip is positioned at the level of the spinal cord that corresponds to your primary pain source, and medication flows directly into the cerebrospinal fluid surrounding it.
From there, the drug penetrates through the outer layers of the spinal cord to reach the nerve receptors involved in processing and transmitting pain signals. Because so little medication enters the rest of your body, side effects like drowsiness, nausea, and constipation are significantly reduced compared to oral medications at equivalent pain-relieving doses.
Conditions That Qualify
Three major categories of patients receive intrathecal pumps: those with chronic non-cancer pain, those with cancer-related pain, and those with severe spasticity (persistent muscle tightness and spasms, often from conditions like multiple sclerosis, cerebral palsy, or spinal cord injury).
For chronic non-cancer pain, the pump is not a first-line treatment. It’s reserved for people with a clear medical diagnosis who have tried and failed other approaches, including medications, physical therapy, and often spinal cord stimulation. Typical candidates include people with persistent back and leg pain from spinal disease that hasn’t responded to surgery, complex regional pain syndrome, pain from osteoporotic spinal fractures, or chronic neuropathic pain from nerve injuries. A comprehensive psychological evaluation is required before implantation to screen for conditions that might interfere with a successful outcome.
For cancer pain, the threshold is somewhat different. The main indication is pain that can’t be adequately controlled through standard medication routes, either because the doses needed cause intolerable side effects or because the pain simply doesn’t respond. A psychological assessment isn’t mandatory in cancer cases, though it may be recommended depending on the circumstances.
For spasticity, intrathecal delivery of a muscle-relaxing medication (baclofen) has been used since 1984. Only a small fraction of oral baclofen actually crosses into the central nervous system, so delivering it directly to the spinal fluid provides far better muscle relaxation with fewer side effects like excessive sedation.
The Trial Before Implantation
Before committing to a permanent pump, you go through a trial period to see if the therapy actually helps. There are two basic approaches: a single injection (bolus) or a continuous infusion through a temporary catheter. The continuous method involves placing a catheter, tunneling it under the skin, and connecting it to an external pump for a short inpatient stay, typically three to five days. During that time, the medical team adjusts the dose and monitors your response.
If the trial significantly reduces your pain, permanent implantation is scheduled a few weeks later. If it doesn’t help, the temporary catheter is simply removed.
What the Surgery Looks Like
The permanent implantation procedure takes about one hour. The surgeon places the catheter into the spinal space, routes it under the skin to your abdomen, and connects it to the pump reservoir, which sits in a pocket created beneath the subcutaneous tissue. Most patients go home the same day and spend 30 to 60 minutes in a recovery area for monitoring afterward.
Recovery is generally straightforward, though you’ll have two incision sites: one on your back where the catheter enters the spine and one on your abdomen where the pump sits. You’ll be able to feel the pump under your skin as a firm, round disc, but for most people it becomes less noticeable over time.
Medications Used in the Pump
The three medications with the strongest track record for intrathecal use are morphine (for pain), a non-opioid pain blocker called ziconotide (derived from cone snail venom, which blocks pain signals through a completely different mechanism than opioids), and baclofen (for spasticity). Doctors sometimes use combinations depending on the type of pain.
Ziconotide is particularly useful for patients who can’t tolerate opioids or who have conditions like sleep apnea or lung disease that make opioid-based therapy risky. However, it’s not appropriate for anyone with a history of psychosis, as it can affect mood and cognition.
Living With a Pump: Refills and Maintenance
The pump reservoir holds a limited supply of medication that must be refilled at regular intervals. For baclofen pumps, the average refill interval is roughly every 57 days, though this varies based on your daily dose. Higher doses mean more frequent visits. Refills are done in an outpatient setting: a healthcare provider locates the pump’s refill port through your skin (sometimes using previous X-rays for guidance in patients with altered anatomy), inserts a needle through the skin into the reservoir, and injects a fresh supply of medication. The pump has a low-volume alarm set to go off before it runs empty, and refill appointments are scheduled a day or two before that alarm date.
Keeping refill appointments is critical. For baclofen pumps in particular, suddenly running out of medication can trigger a withdrawal syndrome that includes dangerous increases in muscle tone, fever, and in rare cases, life-threatening complications. This is one reason the evaluation process considers whether you have adequate caregiver support and the ability to reliably attend appointments.
How Long the Pump Lasts
Modern intrathecal pumps are battery-powered, and the battery eventually wears out. In a large study of 365 patients, the median pump lifespan was 5.9 years for devices that reached their natural end of battery life. The manufacturer estimates 4 to 7 years depending on the flow rate, with higher flow rates draining the battery faster. When the battery nears depletion, the pump is surgically replaced in a procedure that’s generally simpler than the original implantation, since the catheter can often be left in place.
Risks and Complications
Like any implanted device, intrathecal pumps carry risks. The most common issues fall into a few categories.
- Catheter problems. The catheter can fracture, kink, or migrate out of position over time. When this happens, medication delivery stops abruptly, which can cause a sudden return of pain or, with baclofen, a withdrawal reaction. Catheter issues are one of the most frequent reasons for reoperation.
- Infection. Both the pump pocket in the abdomen and the catheter site can become infected, sometimes requiring removal of the entire system.
- Cerebrospinal fluid leaks. A persistent leak at the catheter entry point can cause severe positional headaches. In some cases, a suture can erode through the catheter itself, creating an ongoing leak that requires surgical repair.
- Granuloma formation. Inflammatory masses can develop at the catheter tip, particularly with higher-concentration opioid infusions. These can compress the spinal cord and cause new neurological symptoms if not caught early.
- Fluid collection around the pump. Weight changes can alter the pocket where the pump sits, sometimes leading to fluid accumulation that needs to be drained.
Who Should Not Get a Pump
Certain conditions make intrathecal therapy inappropriate or require careful medication selection. Patients with chronic lung diseases like severe asthma or obstructive pulmonary conditions face an elevated risk of respiratory depression with intrathecal opioids. People with active substance abuse issues, uncontrolled psychological conditions, or cognitive impairments that would prevent them from managing refill schedules are generally not considered good candidates. For those who can’t safely receive opioids, ziconotide may be an alternative, provided there’s no history of psychosis.
The ideal candidate has a well-defined pain condition, has genuinely exhausted less invasive options, has the psychological readiness to participate in long-term management, and has a support system to help maintain the routine care the device requires.