Treatments: Intrathecal Pump Management

Overview

A “pain pump” is a method of giving medication directly to your spinal cord. The system uses a small pump that is surgically placed under the skin of your abdomen. The pump delivers medication through a catheter to the area around your spinal cord. Because the drug is delivered directly to the pain area, your symptoms can be controlled with a much smaller dose than is needed with oral medication. Thus reducing the side effects of medication.

What is an intrathecal drug pump?

The fluid-filled space around your spinal cord is called the subarachnoid or intrathecal space. Cerebrospinal fluid (CSF) flows through this area, bathing and protecting your brain and spinal cord. An intrathecal drug pump works more efficiently than oral medication because it delivers medicine directly into the CSF, bypassing the path that oral medication takes through your body. In fact, you generally need about 1/300 the amount of medication (morphine or baclofen) with a pump than when taken orally.

The pump is a round metal device about the size of a hockey puck that is surgically implanted beneath the skin of your abdomen. A small plastic tube, called a catheter, is surgically placed in the intrathecal space of the spine and is connected to the pump (Fig. 1). A space inside the pump called the reservoir holds the medication.

The pump is programmed to slowly release medication over a period of time. It can also be programmed to release different amounts of medication at different times of the day, depending on your changing needs. The pump stores the information about your prescription in its memory, and your doctor can easily review this information with the program. When the reservoir is empty, the doctor or nurse refills the pump by inserting a needle through your skin and into the fill port on top of the reservoir.

Who is a candidate?

You may be a candidate for intrathecal drug delivery if you meet the following criteria:

• Conservative therapies have failed

• You would not benefit from additional surgery
• You are dependent on pain medication
• You do not have psychological problems
• You have no medical conditions that would keep you from undergoing implantation
• You are not allergic to any of the drugs used in the pump

• You have had positive response with a trial dose of medication

Who performs the procedure?

Neurosurgeons who specialize in pain management and spine disorders implant drug pumps.

The surgical decision

Determining whether an implantable drug pump will be a good pain management option for you is a complex process. Before a permanent pump can be implanted, you must undergo a trial to see if the device decreases your level of pain or spasticity. Depending on your particular condition, one of the following screening tests will be necessary:

• Single injection: you will receive one injection of intrathecal medicine (morphine or baclofen) through a lumbar puncture .
• Multiple injections: you are given multiple injections over a series of days by either a lumbar puncture or catheter.

Continuous trial: a catheter is placed in the correct area of your spine and connected to an external pump. The dose is increased every 2 hours until you notice pain relief.

During the trial, the doctor gathers information about the best location for the catheter and the type and amount of drug that works best for you. If the trial is successful, you will be scheduled for surgery.

What happens before surgery?

You may be scheduled for presurgical tests (e.g., blood test, electrocardiogram, chest X-ray) several days before surgery. In the doctor’s office, you will fill out paperwork and sign consent forms. Patients are admitted to the hospital on the morning of the procedure. No food or drink is permitted past midnight the night before surgery. An intravenous (IV) line is started in your arm. An anesthesiologist will explain the effects of anesthesia and its risks.

What happens during surgery?

There are two parts to the procedure: 1) placement of the catheter in the intrathecal space surrounding the spinal cord, and 2) placement of the pump/reservoir in the abdomen. There are five main steps of the procedure. The operation generally takes 3 to 4 hours.

What are the results?

Results will vary depending on the underlying condition being treated and its severity. Chronic pain patients may experience a reduction in pain, as well as an overall improvement in activities of daily living [1]. Spasticity patients may experience a reduction in rigidity and muscle spasms [2]. Oral medications are reduced because the medicine is delivered directly to the spinal cord and much smaller dosages are needed.

What are the risks?

Side effects for intrathecal drug pumps are minimal, although they do exist. As with all surgeries, complications may include infection and bleeding. The catheter could move or become blocked, or the pump could stop working (rare). Accumulation of fluid (cerebrospinal fluid leak) can occur around the pump causing a clear watery discharge from your incisions or a headache. These usually disappear on their own, but may require a drain. Reasons for removal of the device include infection, failure to relieve pain, and patient misuse.

Side effects from the drugs (over- or underdose) may include respiratory depression, twitching, muscle spasm, urinary retention, constipation, nausea, vomiting, dizziness, anxiety, depression, and edema.

Depending on how much medication the pump delivers, the battery will eventually need to be replaced every 5 to 7 years.