Applied Evidence

Intrathecal analgesia: Time to consider it for your patient?

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When systemic analgesics or antispasmodics fail to control chronic pain or cause intolerable adverse effects, an intrathecal drug delivery system may be the best bet.




› Consider continuous intrathecal (IT) analgesia for chronic pain patients with refractory symptoms or intolerance to systemic medication. B
› Explore the possibility of using an IT delivery system 
to treat malignant pain syndrome, particularly for patients with a life expectancy of more than 6 months. A
› Do not rule out IT analgesia for patients with refractory nonmalignant pain; while considerations in such cases are more complex, benefits include the efficacy of lower doses and fewer adverse effects. B

Strength of recommendation (SOR)

A Good-quality patient-oriented evidence
B Inconsistent or limited-quality patient-oriented evidence
C Consensus, usual practice, opinion, disease-oriented evidence, case series

CASE Elaine G, a 42-year-old patient with abdominal pain related to metastatic ovarian cancer, was taking 200 mg/d of oral morphine for several months. The morphine provided excellent pain relief, bringing down her pain score on a visual analog scale (VAS) from 10 to 3. Recently, however, she developed renal failure and was no longer able to take oral morphine.

A switch to hydromorphone 20 mg/d—the physician used the 5:1 morphine-to-hydromorphone conversion ratio, then decreased the dose by 50% to account for incomplete cross-tolerance—left Ms. G lethargic. In addition, her pain score rose to 5, and she began having difficulty swallowing the medication. Prior to the drug rotation, she was able to perform light tasks and was alert enough to interact with her family.

If Ms. G were your patient, what would be your next step?

By bypassing 
first-pass metabolism, intrathecal drug delivery provides greater pain relief at lower dosages and with fewer adverse effects than systemic delivery. Continuous intrathecal (IT) drug delivery systems have been in use for more than 30 years.1 And, while IT administration of analgesia has become increasingly useful for patients with refractory chronic pain and spasticity, it remains an underutilized resource.2 Delivered directly into the pre- and post-synaptic opioid receptors in the dorsal horn of the spinal cord, IT analgesia bypasses first-pass metabolism. The result: a higher rate of efficacy, with smaller dosages and fewer adverse effects than systemic delivery.1

The drugs are delivered via a small battery-powered programmable pump that is implanted under the subcutaneous tissue of the abdomen and connected to a catheter tunneled to the site of spinal entry. The device must be refilled periodically—typically every one to 3 months—but this is not a difficult process. It can be done in an office setting or in the patient’s home by a specially trained visiting nurse.3

There is ample reason to consider this approach when systemic analgesics or antispasmodics fail to control pain or cause unacceptable adverse effects. So why isn’t it used more frequently? One factor may be that many primary care physicians—often the first practitioners called upon to manage these complicated cases—know too little about it.

Who is a potential candidate for IT analgesia? What medications can be administered via this route? What is the role of a family physician (FP) in coordinating and overseeing the care of a patient being treated with IT therapy? Our goals in writing this review are to address these questions.

Patient selection: Not just for cancer pain

Because of the invasive nature and high cost of implantation, intrathecal pumps are typically reserved for patients with a life expectancy of more than 6 months. FPs interested in referring patients for IT therapy have many factors to consider before consulting a pain specialist. Foremost among them are the different criteria for individuals with cancer-related pain and those with chronic nonmalignant pain.

IT analgesia for cancer pain has been shown to improve patients’ quality of life and potentially increase long-term survival due to a decrease in systemic toxicity.4-6 An appropriate candidate is an individual who, like Ms. G, was initially responsive to systemic opioids but later developed refractory symptoms or intolerance.7 Because of the invasive nature and high cost of implantation, subcutaneous IT pumps are typically reserved for patients with a life expectancy of more than 6 months.7 But implantation may be considered for those with a shorter life expectancy if they have severe pain or cannot tolerate the adverse effects of systemic analgesia.

Noncancer pain is more complex

The use of IT analgesia in patients with chronic nonmalignant pain, such as failed back surgery syndrome, spasticity associated with multiple sclerosis, or diabetic neuropathy, is both more controversial and more complex. It is important for FPs to recognize the multidimensional nature of this type of pain, which may be complicated by physical, psychological, and behavioral factors, including the possibility of addiction.8-11

Although IT analgesia is less subject to abuse and diversion than systemic opioids, the dependent relationship associated with a continuous delivery system makes risk stratification a necessity.12 Psychological testing is commonly used to evaluate potential candidates for long-term IT analgesia.


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