Implantable Intrathecal Pumps

22nd December 2006 at 12:01 GMT by Dr C.A.Jenner MB BS, FRCA. Permalink.

Article on the indications, technique and adverse effects of Implantable Intrathecal Pumps

Introduction to Implantable Intrathecal Pumps

An implantable intrathecal pump is a medical device used to deliver very small quantities of medications to the spinal fluid. Medications such as morphine or baclofen are delivered in this manner in order to minimize side effects associated with oral medications.

The intrathecal drug delivery places medication directly into the cerebrospinal fluid that surrounds the spinal cord. Morphine delivered directly into the intrathecal space is particularly effective because it does not have to circulate systemically to reach the CSF and the dorsal horn of the spinal cord.

Consequently, a much smaller dose is needed to bring in the desired results, for instance 1/300 of an oral morphine dose. The frequency of side effects is also thus reduced.

Benefits of Implantable Intrathecal Pumps

An implantable intrathecal pump offers the following benefits as a form of treatment:

• Pain relief for patients whose pain has not been controlled with therapies that are more conservative.
• Reduction in side effects such as nausea, vomiting, sedation and constipation.
• Decreased need for oral analgesia.
• Improved physical assessment and increased ability to perform activities of daily living.

Besides, the patients who receive this form of treatment are more awake, function better, and receive lesser amount of systemic medication. In the end, they are even more cost effective than oral or IV medication for relief from severe chronic pain.

In addition, medications taken orally also have a systemic effect .i.e. they flood the whole body rather than staying concentrated in any single area.

What is the procedure?

The intrathecal pump is a method of delivering the pain medications in to our bodies, straight into the space around the nerves and the spinal cord. This is where most of the pain receptors are.

The intrathecal pump is a very fine device that slowly delivers concentrated morphine, local anesthetic or other medication into the intrathecal space, which is nearby the spinal cord. The pain receptors in the spinal cord thus are blocked, therefore providing relief from pain.

To begin with, a surgeon will usually perform a trial intrathecal injection or introduce a temporary intrathecal pump to determine if the patient’s symptoms improve. A permanent intrathecal pump is implanted if the patient derives at least 50% improvement in the symptoms.

Complications of Implantable Intrathecal Pumps

The procedure of an intrathecal drug delivery carries various potential risks. These risks can be related to the drug, procedural or catheter complications and the like. Here we list the most important risk factors:

• Drug withdrawal symptoms
• Return of underlying symptoms
• Underinfusion of the drug
• Damage to the spinal cord
• Inflammatory mass
• Sensory changes (numbness, tingling)
• Hyperesthesia
• Sleep disturbances
• Myelopathy
• Paralysis
• Drug toxicity
• Constipation, nausea
• Spinal headaches
• Bleeding
• Meningitis