Intrathecal pump (baclofen and pain pumps): how it works, risks and living with one

Intrathecal means within the space around the spinal cord, which is filled with cerebrospinal fluid. A programmable pump system consists of a titanium pump, about the size of a round metal disc, and a thin catheter. According to Leeds Teaching Hospitals, the reservoir in the pump stores the medicine, and the catheter connects the reservoir to the fluid around the spinal cord. The complete system remains under the skin.

The most common use is baclofen, an anti-spasticity drug, for severe spasticity from conditions such as stroke, multiple sclerosis, cerebral palsy, and head or spinal cord injury. Leeds also runs a service that uses intrathecal pumps for pain management, where the medicines in the pump are chosen for pain control and are refilled at intervals ranging from every few weeks to every 6 months depending on the drug and dose.

The Leeds leaflet describes spasticity as involuntary muscle stiffness that is a common symptom of neurological disease and can range from mild to severe. Most people with mild to moderate spasticity can manage with exercises, physiotherapy, avoiding trigger factors and oral anti-spasticity medicines. Triggers listed include urinary retention or infections, constipation, red or broken skin, poor positions in lying or sitting, tight clothing or splints, pain and low mood.

Oral baclofen does not work for everyone. The leaflets explain that the blood-brain barrier makes it difficult for baclofen taken as a tablet to reach the spinal cord, so there can be too much in the bloodstream, causing weakness, drowsiness and dizziness, and too little where it is needed. Giving it into the spinal fluid delivers it directly to the receptors in the spinal cord. The pump is usually considered after all conservative measures have failed, and the leaflets stress that it manages the symptoms of spasticity but does not cure the underlying neurological condition or influence its course.

Not everyone responds, so a trial is carried out. Leeds describes admission to a neurosurgical ward, goal setting and measurements by a physiotherapist, then insertion of a thin lumbar catheter under general anaesthetic and a standard test dose of 25 micrograms, which can be repeated at a higher dose over the next 2 to 3 days if there is no effect. The effect wears off in about 6 hours, after which the catheter is removed.

UCLH describes giving 25 to 75 micrograms by lumbar puncture, with the effect peaking after 4 to 6 hours and then wearing off, bed rest for 4 hours and close observation of oxygen levels, pulse, blood pressure, breathing and limb power. It explains that at worst breathing could be affected and intensive care support might be needed overnight until the drug wears off. The team then decides together with you whether you would benefit from a pump.

Leeds says the pump is usually implanted under general anaesthetic by a neurosurgeon, with the pump placed under the skin of the abdomen and a catheter connected to the spinal fluid space. The operation, including being anaesthetised and recovering, takes approximately 2 to 4 hours, and patients are generally discharged the following day. Stitches or clips are removed after about 10 days and there is a follow-up in the neurosurgical clinic at 6 to 8 weeks.

The pump starts delivering baclofen as soon as you are awake, but it takes at least 4 hours to feel the full effect at a given dose and possibly a few weeks to feel the full benefit, because the dose is much smaller and continuous. Finding the best dose and gradually reducing oral medicines may take 2 to 3 months or longer.

Leeds explains that the dose is programmed with a tablet app and a wireless communicator placed over the skin. Refills involve a needle through the skin into the pump's refill port, and usually take place every 3 to 6 months for baclofen. The needle procedure may be uncomfortable but is not usually painful. The pump has an alarm that sounds if there is a problem.

The battery has an expected life of 5 to 7 years, after which the pump is replaced in a further operation. Between visits it helps to keep a record of what is in the pump and the dose, and to take this to any medical appointment or hospital admission.

Leeds says the main complication of the implanted system is that something goes wrong with the catheter, which may be dislodged, kinked or torn, requiring a further operation. It quotes studies suggesting a risk in the order of 5% each year, and says problems are more common early after implantation, in less than 10% of people. The pump itself very rarely breaks down, but if it stops working the main risk is baclofen withdrawal. Infection and blood clots are risks of any surgery.

Both trusts list signs of underdose or withdrawal: increased stiffness or spasms, itching, a fast heart rate, low blood pressure, fever, and confusion, hallucinations or seizures. Signs of overdose include drowsiness, weakness of the legs and dizziness, and other effects such as nausea, low blood pressure, slurred speech, blurred vision, difficulty breathing and seizures. Leeds advises that if you have any urgent problem with the pump, such as an alarm or overdose or underdose symptoms, you should go straight to A&E or call an ambulance rather than waiting for a call back.

• Underdose or withdrawal: new stiffness, spasms, itching, fast heartbeat, fever, confusion.

• Overdose: drowsiness, leg weakness, dizziness, difficulty breathing.

• Alarm sounding, or a swollen, red or leaking wound.

Leeds says you can wash and shower once wounds have healed, pumps are usually not visible under clothes, and an MRI scan is possible but the pump must be checked afterwards because the motor may stall. It advises telling the team immediately if you become pregnant, and never stopping oral medicines suddenly. It also advises checking with the pump manufacturer and your team before travelling abroad, and carrying information about the pump.

Intrathecal pumps are provided through specialist NHS spasticity, rehabilitation, neurosurgery and pain services, each with nurse specialists who manage refills. Private hospitals may offer implantation, but long-term follow-up needs a service with the expertise and a refill pathway, so it is worth asking who will do refills and handle emergencies before committing.