Some of the patients that we see with pain from cancer, which has proved very difficult to treat with medications and other treatments, may be suitable for the administration of painkilling drugs into the spine. Although this administration can be into either the epidural space which is just outside the membrane - the dura, or theca, that surrounds the spinal cord, nerves and spinal fluid (CSF) or alternatively it can be into the intrathecal space inside this membrane, within the CSF. For various reasons, we normally use the intrathecal route. The use of these techniques in pain in conditions not due to cancer is far less common and is rarely appropriate.
What is an intrathecal catheter? What may be the benefits?
An intrathecal catheter is a thin plastic tube that is inserted into the cerebro-spinal fluid (CSF) that bathes the nerves of the spinal cord. Painkilling medications can be given through this tube by a pump to act on the nerves carrying pain.
To position the catheter, one end is placed between the vertebrae (bones) in the spine at a level chosen to give the best painkilling results. The other end is threaded (tunnelled) under the skin and is usually brought out through the skin over the front of the lower ribs. This helps to reduce the risk of infection and to make the fixation of the catheter more secure. Painkilling medication is then given through the catheter, using a small portable battery powered programmable pump. Special filters on the outside of the catheter and pump guard against infection.
The use of intrathecal drugs is normallly considered only when we have tried all other options for pain control. Typically this is in situations either where drugs do not control the pain adequately, or where getting adequate pain control with painkillers given either by mouth or subcutaneous (under the skin) infusion causes unacceptable side-effects.
The benefits from intrathecal drug administration include:
- Better pain control
- Needing lower doses of painkilling drugs
- Fewer unwanted side effects
What are the alternatives to an intrathecal catheter?
If this procedure is being considered, it is likely that all other options to manage pain will already have been tried. However, the procedure and its potential side-effects will be discussed with you and your family in detail and, if you have any concerns about the treatment, your consultant will be happy to discuss it with you.
It is very important that you discuss the intrathecal catheter and plans for its care and potential side effects with your doctors, nurses, carers and family. During the assessment, you will learn about the pump equipment and filters, and discuss with your consultant exactly where the catheter will be placed. It is our practice, wherever possible and provided you are happy with this, to ensure that we have had this discussion both with you and your family.
Implanting the catheter
The catheter will be inserted with full precautions against infection. This will, apart from exceptional circumstances, be done in the operating theatre by one of the pain clinic consultants, using local anaesthetic to numb the skin and muscles. We will normally put up a drip to give you some fluids, and normally give some antibiotics to help prevent infection. We may or may not give some sedative drugs to make you a bit sleepy and relaxed. Insertion of the catheter is normally straightforward and takes about 30 minutes to an hour.
Management after the catheter is inserted
Once the catheter is in position, painkiling medication will be given via the pump directly into the spinal fluid. We normally start with a combination of a low dose of local anaesthetic and morphine or diamorphine, although other drugs may be added to these.
For the first few hours after the drugs are started, your pain, pulse, blood pressure , temperature and breathing wil be closely monitored and the effects of the painkilling medication assessed. During the following few days we will assess what is the best type and dose of medication for you to achieve the best possible pain relief. You will also be carefully monitored for side effects or complications, and our team will train other professionals involved in caring for you in how to look after the pump.
You will still need to continue to take some of your normal painkilling medication, although this will gradually be reduced as we assess the pain relief you are gaining.
Following the implantation of the catheter our team will keep regular contact with you and the team caring for you. Our teams will watch for any potential problems and assess your pain relief, and refill your pump with medication. You will be given instructions about what to do if you experience problems.
With good care of the pump and catheter, and depending on the medication required, you should be able to manage greater activity levels. However, excessive physical activity should be avoided in case it causes displacement of the catheter.
Are there any risks, complications or side effects?
With careful management and attention the intrathecal catheter is very safe and effective. However, total pain relief cannot be guaranteed, and side effects and/or complications do rarely occur.
The average failure or complication risk is about 3%.
Minor complications that can occur include: bleeding, headache, soreness at the site of insertion of the catheter, technical problems with the catheter. All of these can usually be treated or corrected.
Major complications are rare. These can include infection (which can potentially be life-threatening, though thankfully this is very rare) and the potential of damage to nerves in the spine (again very rare) during the catheter insertion procedure or due to bleeding. There are some extremely rare complications such as formation of scar tissue or granulomas around the catheter tip, but these happen with very high morphine concentrations in the pump over long periods, which is far less relevant in our patient group.
One of the potential issues that we have seen in a number of patients over the years is a situation where reduction or removal of the pain, and the resulting ability to reduce the painkiliing drugs that may be clouding thinking, allows greater and distressing awareness of all the other unpleasant aspects of the cancer diagnosis. We feel it is important to warn our patients and their families about this when discussing the use of this treatment.
Further information for professionals
More detailed information designed to support professionals involved in the care of patients with intrathecal catheters is given at this linked page.
Considerably more background information on intrathecal catheters and other interventional techniques for cancer pain is given in an article written by Dr de Courcy which can be accessed via this link.
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Pain Service Website, Gloucestershire Hospitals NHS Foundation Trust
Webmaster Dr J G de Courcy, Consultant in Pain Medicine and Anaesthesia
Page updated 22/6/2016