Overview of Implantable Intrathecal Drug Delivery System
Chronic pain is a complicated condition that involves changes in the nerves of your body. This can be affected by mental well-being and may be unintentionally worsened by some treatments. The condition might arise when pain signals get abnormally amplified by your nervous system due to constant triggering over a period of time. This amplification can lead to intense, stubborn pain that can interfere with daily living activities and can be tough to control even with medication or mental health therapies. Managing severe chronic pain has become ever more challenging lately due to the risks and public health issues connected with using prescription opioids, which are strong pain relievers.
When traditional treatments aren’t working or meeting the pain-relief and mobility goals, advanced methods for managing pain may be looked at. One technique includes delivering pain-relief medication straight into the fluid surrounding your brain and spinal cord using a special pump and tube. This method was first used in 1981 to provide low doses of morphine for a patient with cancer-related pain. Since then, several studies have shown this method, known as intrathecal drug delivery systems, to be safe and effective for cancer-related pain as well as long-term, non-cancer pain.
Anatomy and Physiology of Implantable Intrathecal Drug Delivery System
When doctors need to give medicine to the brain, it can be difficult because the blood-brain barrier naturally works like a shield, keeping out many substances including larger molecules. This can prevent the medicine from getting into your central nervous system, which includes the brain and spinal cord. One way to solve this problem is through a process called intrathecal therapy. In this treatment, medicine is given directly into the cerebrospinal fluid, a fluid that surrounds the brain and spinal cord. This lets the medicine get where it needs to go without having to cross the blood-brain barrier. Intrathecal therapy also allows for lower doses since the medicine is delivered straight to the target. This also lowers the risk of side effects.
The equipment used for intrathecal therapy consists of a pump and a thin tube, called a catheter. The pump holds the medicine is placed under the skin in the belly area. The catheter is connected to the pump and delivers the medicine into your spinal fluid. The end of the catheter is usually placed in the spine at the level where you feel the most pain. The medicine goes into the spinal fluid and spreads to the surrounding tissues of the spinal cord where it needs to work.
There are currently three medicines approved by the U.S. Food and Drug Administration (FDA) that can be given this way. One of them is morphine, a strong painkiller that works by attaching to certain parts of the spinal cord to reduce pain signals. Another medication, ziconotide, is derived from the venom of cone snails. This drug works by blocking specialized structures called N-type voltage-gated calcium channels which are involved in our ability to feel pain. The third drug is baclofen, which is used to reduce muscle stiffness in conditions such as multiple sclerosis and cerebral palsy.
Why do People Need Implantable Intrathecal Drug Delivery System
Intrathecal drug delivery systems are used for managing illneses such as cancer-related pain, certain severe noncancer pain conditions, and severe muscle stiffness or spasms (also known as spasticity). These systems can be helpful when typically taken pain medications, like oral or skin patch medications, are not providing enough relief for people with cancer.
Patients who are experiencing difficult-to-treat pain conditions like phantom limb pain – a feeling of pain coming from a limb that has been amputated, complex regional pain syndrome – a chronic pain condition affecting an arm or a leg, or damage to complicated networks of nerves known as plexopathies might also improve with an intrathecal drug delivery system. This system could also be beneficial for those who have constantly struggled with pain even after having procedures or surgeries done that were meant to help.
In addition, it’s a treatment option for patients who are not getting enough relief from muscle stiffness or spasms through medications like baclofen, tizanidine, or dantrolene, or those who have severe side effects from these drugs.
Chronic or long-lasting pain is commonplace in patients with cancer and can significantly hurt the overall quality of their life. Studies have found that around 38% of cancer patients describe their pain as moderate or severe. This percentage increases for individuals with advanced stages of disease or those undergoing cancer treatments.
The World Health Organization (WHO) recommends using a mix of drug treatments and non-drug treatments to manage pain in adults and teenagers with cancer. These can vary based on the patient’s unique pain type, and may include over-the-counter pain relievers, anti-inflammatory medicines, opioids, anti-seizure medicines, antidepressants, muscle relaxants, or other drugs. Many patients with pain are treated using opioid medications, but many of them can cause uncomfortable side effects like nausea, vomiting, constipation or even slow breathing. There is also a risk of becoming reliant on these medications over time, and some patients might not find them effective, especially for types of pain related to nerve damage.
An intrathecal drug delivery system can be an effective way to manage persistent, hard to manage pain. It involves placing a small tube in the spinal fluid-filled space (also known as CSF), that can deliver pain medications directly to the brain’s pain-receiving area.This reduces the chance of side effects and need for system-wide high dosage of drugs.
Muscle spasticity is a problem characterized by stiff or rigid muscles that can affect voluntary movement. This can be a serious issue for patients with conditions like multiple sclerosis, spinal cord injuries, cerebral palsy, and brain damage after a stroke. It can limit movement and interfere with routine life activities, and might even cause other challenges like pain, skin wounds, contracture (permanent shortening of the muscle), and sleep problems. Treating this condition can involve therapies, oral drugs, botulinum injections, surgeries, but another commonly used method, often combined with these others, involves delivering the medication baclofen directly to the brain region controlling muscle movement via the intrathecal drug delivery system.
When a Person Should Avoid Implantable Intrathecal Drug Delivery System
There are times when certain conditions can make it too risky to undergo surgery for the implantation of an intrathecal pump, a device that delivers medication directly into the space around your spinal cord. Here are some specific reasons:
If a person has a bleeding disorder, which causes bleeding that’s hard to stop, it’s too risky to have surgery. This condition is also known as coagulopathy. Individuals with a weakened immune system, especially those battling cancer, could face an elevated risk of getting an infection after the procedure. If there’s an infection already present at the site where we’re supposed to implant the device, there’s a direct threat of spreading that infection into the surrounding space of the spinal cord. Systemic infections, or those affecting the entire body, could spread via the device into the fluid surrounding the spinal cord and brain. Allergic reactions to the implant material or the medications used during surgery can also prevent this type of surgery. Active intravenous drug use or having mental health conditions like psychosis or dementia might affect how the patient cooperates or manages the pump after the operation. Lastly, for patients whose life expectancy is three months or less, less invasive methods like external infusion systems might be more beneficial. If the patient chooses to refuse the procedure, that’s a valid reason too.
There are also some conditions that could escalate the risk associated with the surgery but do not necessarily prevent it. These include smoking and having poor blood sugar control, both of which can increase the risk of getting an infection at the surgical site. Ideally, patients are encouraged to quit smoking for at least four weeks before the surgery and try to achieve a blood sugar level of 7% or less. Conditions like spinal tumors and narrowing of the spinal canal can affect how the medication reaches the intended nerves and spinal cord, possibly reducing the effectiveness of the treatment. Patients with a low body weight might encounter difficulties with the implantation and management of the pump device. Being on blood-thinning medications can increase the risk of bleeding. If it’s safe, these medications should be stopped temporarily. Immediate risks during and after surgery are posed by active bleeding. A high tolerance to opioids can limit the effectiveness of pain management with this pump. Lack of family or social support might compromise postoperative care and pump management. Difficulty accessing medical care can create issues with the ongoing maintenance and management of the device. Having heart or brain vascular diseases might also pose increased risks.
The 2017 Polyanalgesic Consensus Conference recommends against this treatment method for widespread pain, headaches, or facial pain as they found it to be less effective for these types of pain. Since an intrathecal pump implantation is an elective procedure, which means it’s the patient’s choice, it’s crucial for all potential reasons that could complicate the procedure to be evaluated thoroughly before deciding whether to proceed with this form of therapy. This allows for a tailored approach, matching treatment options with individual conditions and needs.
Equipment used for Implantable Intrathecal Drug Delivery System
When your doctor is planning to insert a device to deliver medication directly into the space around your spine (this device is known as an “implantable intrathecal drug delivery system”), they will need several specific pieces of equipment. These include:
– An X-ray device for visualizing the area (called a “Fluoroscopy”)
– A special needle (the “Touhey needle”)
– The device that holds and releases the medication (the “implantable intrathecal infusion pump”)
– A tube to guide the medication (an “intrathecal catheter”)
– Various surgical tools that they will use during the procedure
– Local painkillers
– The actual medication that will be put into the device
– A device for adjusting the medication release from outside the body (the “External programmer”).
There are currently three medications that the FDA has approved for this type of delivery: morphine, ziconotide, and baclofen. Other medications like hydromorphone, fentanyl, and sufentanil, along with non-opioid medications such as bupivacaine and clonidine are also recommended. However, the effects different medications have on different patients might vary, hence the doctors need to consider individual patient characteristics before choosing a medication.
Morphine and ziconotide are particularly useful for treating different types of pain. They can either be used alone or combined with other medications. When morphine is used in this manner, it provides superior pain control and has fewer side effects than when it is taken orally. However, like any medication, there are risks involved, including respiratory problems, itching, nausea, vomiting, drowsiness, and in some cases, trouble passing urine.
Your doctor may also use a local anesthetic known as bupivacaine along with morphine, which enhances the painkilling effects while reducing the required dosage. The combination of bupivacaine and morphine is typically associated with effective pain management and fewer side effects.
Ziconotide is another kind of painkiller that comes from a certain type of sea snail. This medication works by blocking the release of specific signals in the spinal cord that contribute to the sensation of pain. The advantage of ziconotide is that it does not cause physical dependence and does not lead to withdrawal symptoms when treatment is stopped. On the downside, it can cause side effects such as dizziness, confusion, and blurred vision, among others. Specially, if you have a history of mental health issues, there is a small risk of experiencing serious psychiatric problems, therefore caution is advised when considering ziconotide.
Lastly, baclofen is a muscle relaxant that can also be used via the implantable intrathecal drug delivery system. Baclofen works by activating certain receptors in the brain and spinal cord, which helps in reducing muscle tone and controls muscle spasms.
Who is needed to perform Implantable Intrathecal Drug Delivery System?
A medical procedure called an intrathecal drug delivery system implantation is done mainly by doctors specialized in the nervous system (neurosurgeons), pain management, and spine diseases (orthopedic spine specialists). The process involves fitting a device, that delivers medicine directly to the area around your spinal cord. There are also other medical professionals who assist in the procedure:
A fluoroscopy technician helps the doctors by providing real-time X-ray images to guide the procedure.
A surgical technician or operating room nurse provides the necessary tools and materials during the operation.
A circulating or operating room nurse oversees the process, making sure the operating room runs smoothly and efficiently.
Anesthesia personnel are responsible for numbing you or putting you to sleep during the procedure, monitoring your vitals, and ensuring you feel no pain while the operation is ongoing.
These medical experts work as a team to make sure the procedure is done properly and effectively to treat your condition.
Preparing for Implantable Intrathecal Drug Delivery System
Before having a medical procedure involving the spine, several important steps need to be taken. First, your doctor will take a thorough medical history and do a comprehensive physical exam. They will also talk through with you the risks and benefits of the procedure to make sure you understand everything clearly.
Imaging, or getting pictures of inside your body, is critical for this kind of procedure. It helps the doctor to decide where to place the needle and catheter (a small, flexible tube). The best images to use are usually taken by a magnetic resonance imaging (MRI) scan. This scan will show the lower part of your backbone, where the entry point for the needle and catheter is usually located, but sometimes additional scans may be needed.
There are also lab tests that should be done immediately before the operation. These tests check your blood to assess your risk of bleeding; they include a complete blood count with platelets, prothrombin time, and partial thromboplastin time. If you take any blood-thinning medications, your doctor will discuss the possibility of temporarily stopping these medications before the procedure.
If you’re having this procedure to treat muscle stiffness, usually a trial dose of the selected medication will be given a few days to weeks ahead of the operation. For those with chronic pain, a trial dose may be considered, while it’s rarely given for cancer-related pain. Trial medication is given through a small tube connected to an external pump, and the goal is to reduce the pain by half. The success of the trial dose helps to determine the final medication dose that would be given continuously through a pump inside your body. However, to avoid excessive side effects, the initial daily dose begins at a lower level and is gradually increased until the target dose is reached.
The implantation procedure, where the pump is put in your body, is done in an operating centre. It may involve using sedatives and local anesthetic, or sometimes general anesthetic may be required. Conscious sedation, where you’re awake but relaxed, may be used to allow for real-time assessment of nerve function. However, some doctors may prefer to use general anesthetic to reduce pain and anxiety and to limit uncontrolled movement, which may lead to complications. The procedure also requires an antibiotic to be given within an hour of the first cut to prevent any infection, and its choice depends on your body weight and any known allergies.
How is Implantable Intrathecal Drug Delivery System performed
The doctor and you will decide together the best place in your belly to put the pump. The recommended places are the lower right or left side of your abdomen. Important landmarks in relation to the pump include the top edge of your hip bone, and the lower edge of your rib cage. The pump should not touch these bones once it’s placed under your skin.
Procedure
During the operation, you’ll lie on your side with the side where the pump will go facing upward. The doctor will clean your back and abdomen to make it sterile. A special X-ray machine called a C-arm fluoroscope will be used to guide the doctor and view the inside of your body. This machine will help the doctor place a thin tube, called a catheter, correctly inside your spine.
The doctor will make a cut in your back to reach a layer of tissue covering your spine, exposing the tough band of tissue along your spine (the supraspinous ligament). The doctor will then insert a special needle (Tuohy needle) into the space inside your spine (intrathecal space). This will be done at a level below where your spinal cord ends to avoid any harm to your spine and ensure a nice flow of cerebrospinal fluid (CSF). The catheter will then be threaded in through the needle and its positioning will be checked with the X-ray machine.
Using strong medical thread (sutures), the catheter will be secured on either side of the needle. Then the guiding needle and a thin flexible rod (the guidewire) inside the needle will be removed, making sure the catheter stays in place. The flow of CSF will then be checked again. Lastly, the catheter will be secured into a clip (an anchor) using sutures. The catheter will be clamped to prevent CSF from leaking out.
Next, the doctor will create a pocket under the skin in your belly to place the pump. This will be done by making a cut about 3 inches long and deep down to the fat under your skin. The pocket needs to be big and deep enough to contain the pump, but not more than 1 inch deep, so the pump can communicate properly with devices outside your body. The doctor will make sure there’s no bleeding at the incision sites to reduce any risk of complications after the surgery.
Then, the doctor will use a tool to create a tunnel under your skin from the incision in your back to the pump pocket in your belly. The catheter will be pushed through this tunnel to reach the pump. The catheter will be cut, leaving just enough extra length to avoid putting stress on the catheter during your regular activities. The catheter will then be attached to the pump and checked to ensure that it’s secure.
The pump is then placed in the pocket created under your skin and could be stitched in place to prevent it from moving around. Then, the doctor will carefully sew up the skin over the pump and the incision in your back.
Possible Complications of Implantable Intrathecal Drug Delivery System
When undergoing a medical procedure, there can be certain complications related to the procedure itself.
Bleeding: Bleeding might happen in the belly during the surgery. But the surgeons will try their best to control bleeding so that a pool of blood doesn’t form in the belly. Wearing a bandage on the belly right after surgery may also help to prevent blood or other fluids from building up at the site.
If you take certain medications before surgery, you might have a higher risk of bleeding around the spine. If this happens, you could have systems like increased back pain, trouble moving your legs, and losing control of when you go to the bathroom. Usually, this situation can be monitored with a specific type of scan and may need to be treated with emergency surgery if your symptoms get worse rapidly.
Infection: Another possible complication of surgery is an infection at your wound. Doctors usually give antibiotics before and during surgery to prevent this. Superficial infections can usually be managed with basic treatments. But more severe infections might require to remove the surgical implant. There is a risk that the infection could spread along the path of the implant and cause serious conditions like meningitis or an epidural abscess.
Injury to surrounding tissue: Sometimes, the tools used during surgery can harm the nearby nerve roots. But there is a way to reduce this risk. They can place the catheter under conscious sedation. With this approach, you will be awake but relaxed during your surgery. This means that if you start to feel a sensation like electric shocks or burning, the doctor can quickly adjust the needle to a better position.
Spinal cord injury: Spinal cord injury is a serious but unlikely risk of the procedure. The catheter used during surgery has a certain degree of stiffness that helps the doctor to guide it properly. If the catheter is forced, it can potentially penetrate the spinal cord, leading to symptoms like pain or stinging. If the symptoms occur right after the procedure, it’s crucial to get further evaluations including scans, and possibly a consultation with a neurosurgeon.
Cerebral Spinal Fluid Leak: Occasionally, there can be a fluid leak from the brain and spine because of an injury of the catheter. The common symptom is a severe headache that comes on after a dural puncture. It is usually managed with traditional treatments which include rest, hydration, caffeine, and painkillers like acetaminophen. If these fail to relieve the symptoms, a doctor may perform a treatment called a blood patch, where a small amount of your blood is injected above the injection site to seal the hole. In rare cases, this fluid can leak into the abdominal area, causing noticeable swelling. This can result in a condition called subdural hematoma, which is a medical emergency situation.
Device-Related Complications: Lastly, there can be issues with the catheter system or the pump, with complications related to the catheter being more common than ones related to the pump.
Symptoms like inconsistent pain relief or a difference in the expected and measured amount of medication suggest a potential malfunction in the catheter. You will then need a detailed check of your catheter to look for any twists, blockages or loose connections. Catheter issues are usually spotted by injecting a dye in the pump and checking where the dye goes. This procedure, however, needs to be done carefully as a sudden large dose of medication could cause an overdose.
Intrathecal granulomas are another possible concern, where the tissue around the tip of the catheter gets inflamed and starts causing more pain and nerve problems. This is generally related to painkiller medicine use, drug titration, and the duration of therapy. If a granuloma is suspected, it should be confirmed with a scan. Treatment can vary depending on the condition but usually involves either reducing the dose, switching the medication, or moving the catheter. In some extreme cases, surgical intervention may be necessary to treat the condition.
What Else Should I Know About Implantable Intrathecal Drug Delivery System?
Intrathecal drug delivery is a treatment method that involves using a special device to deliver medication directly into the space around your spine (called the ‘intrathecal space’). This method has been proven effective and safe for managing conditions like spasticity (muscle stiffness), and both cancer-related and non-cancer-related pain.
One of the main benefits of using an implantable drug delivery system is that it uses much smaller doses to reach the required pain relief effect compared to taking the same drug orally or through an IV. What’s more, it also leads to fewer side effects. This device can also control how much medication is released every day, helping to avoid the sudden rises and drops in drug levels that we often see with pills.
However, like all medical treatments, intrathecal treatment carries some risks. To manage and reduce these risks, it’s recommended that the treatment is carried out at specialized centers by a team of various medical experts. This team might include a cancer doctor (oncologist), imaging specialist (radiologist), surgeon, anesthesia expert (anesthesiologist), palliative care specialist (cares for people with severe, often terminal illnesses), pain medicine specialist, and nurses.
Their tasks include carefully selecting patients who will benefit most from the treatment, determining the best timing for implanting the device, and quickly identifying and dealing with any complications. All these factors are crucial for the best results from the treatment.
