Less commonly, a procedure that affects nerve roots, such as radio-frequency lesioning or IDET, or one that affects specific muscle groups, such as prolotherapy, may be used. There is limited research available for these techniques, and support may not be strong as a result. This does not mean these techniques have no value, but that the research literature support may be sparse. For most of these techniques, the intervention is placed directly at the source or site of the pain. These are not first-line therapies and are just options that some pain specialists have found to be helpful for pain relief.
This therapy uses a heated probe to deliver radiofrequency thermal energy to the painful disc. The process compresses and coagulates disc material and has been found to be most useful for patients who have an internally disrupted disc (Raj, 2008).
To perform the procedure, a cannula is inserted into the intervertebral disc. A catheter is inserted through the cannula and passed into the outer disc tissue. Current is then passed through the electrode, heating the surrounding tissue and eliminating the source of the pain (Raj, 2008).
To perform IDET, the patient receives conscious sedation. From the nonpainful side, a 17-gauge needle is inserted into the disc through the annulus to the site of the pain. A catheter is then threaded through the needle and the catheter tip is heated to 90°F over the span of 13 minutes (Raj, 2008). The process reduces the size of annular fissures, increases the stability of the disc, and destroys nociceptors in the annular walls, stopping nociceptive input of pain stimuli (Raj, 2008). This is an outpatient procedure; the patient should be able to return home when recovered from sedation.
This practice has provided anecdotal reports of pain relief for discogenic back pain. In a randomized, double blind, controlled trial of IDET versus placebo, the study outcomes demonstrated no significant benefit for the IDET patients over the placebo group (Freeman et al., 2005). This type of therapy should not be used as a first-line option, but reserved for use when other pain management options have failed to provide adequate pain relief.
Both radiofrequency lesioning and IDET have associated risks and benefits. The patient must be informed that even though pain relief is the goal, there is a risk of nerve root injuries, catheter breakage, disc herniation, infection, epidural abscess, and spinal cord damage (Raj, 2008).
Prolotherapy is classed as a regenerative therapy aimed at creating an inflammatory response that will raise growth factor levels promoting tissue repair or growth. The injection of an hypertonic dextrose solution or an irritant solution, such as dextrose/phenol/glycerine or pumice, into weakened back muscles to promote tissue repair and correct tendon and muscle laxity has been found to be an effective means of pain relief when combined with an aggressive physical therapy regimen. Additionally this type of therapy can be used as a joint injection or for soft tissue healing. In a study of low back pain patients who were treated with prolotherapy, 3 months after treatment there was a 60% increase in collagen fibril diameter, decreased pain, and increased range of motion (Weintraub, Mamtani, Micozzi, 2008).
There are several conditions for which this technique has been implemented, including:
■ Discogenic back pain
■ Chronic pain from ligament or tendons resulting from repetitive motion disorder
■ Cervical, thoracic, lumbar, lumbosacral, and sacroiliac instability the use of anti-inflammatory medication such as NSAIDs is discouraged to control the pain of the injections since the purpose of the injection is to create a low grade inflammatory process
Epiduroscopy involves the insertion of a fiber optic scope into the epi-dural space of the spine. It is used as a last line for treating low back pain. On the scope inserted into the epidural space scope are tools that can be used to remove scar tissue from nerve roots. Overall, the epidural adhesiolysis technique has only limited success. The evidence for using spinal endoscopy is strong for short term relief and moderate for long term improvement of refractory low back pain (Trescot, 2009).
When a patient gets to the point that medications and interventions such as epidural steroid injections are not working to control pain and functionality is heavily impaired a pain specialist may consider implanting an intrathecal pump. These pumps an be used for chronic pain or oncology pain management. The guide for pump placement in oncology patients is a survival expectancy of greater than 3 months (Figure 7.3). This technique is not a first-line option. There should be considerable trial use of other techniques for pain management before consideration of an implanted pump.
The technique consists of an implanted computerized pump that can be set by the pain specialist to deliver. The medication is placed
into a reservoir in the pump. The computer chip in the pump has the settings that are entered by the pain specialist that tells the pumps how to deliver the medication. It can be programmed to deliver a continuous rate most commonly but the pumps have the option of reducing or increasing flow rates at certain times of the day if programmed for variable flow. Medication flows from the pump to the intrathecal space by a flexible catheter that is tunneled from the spinal insertion point along the lateral aspect of the patient's body and connected to the pump. The pump is placed into a pocket usually on the patient's abdomen below the belt line or other subcutaneous tissue close to the skin's surface to facilitate refilling the pump.
Pump refills are done when needed, according to the concentration and the infusion rate of the medication. A refill kit with a specialized needle is used to withdraw any leftover medication from the pump reservoir, and new medication is inserted into the pump reservoir. The pump refill date is then reset to a new date that is set using the information on the concentration and delivery rate.
Medications that are FDA-approved for use in implanted in-trathecal pumps are as follows:
All medications used in implanted intrathecal pumps should be free of preservative. Morphine is the most common medication, and using an intrathecal medication delivery can provide morphine doses that are 300 times as potent as oral morphine (D'Arcy, 2010; Wallace & Staats, 2005). In order to test the feasibility of using an implanted pump there should be a trial with an external catheter places either intrathe-cally or epidurally to assure that there will be benefit for the patients. During the trial period, the drug selection is based on the following:
■ History of opioid tolerance
■ Side effect history
■ Pain afferent spinal cord level compared with catheter tip location (Wallace & Staats, 2005)
Thie lipophilicity of the selected pain medication, the available lipid supply of the spinal cord, and the accessibility of the cerebrospinal fluid and blood supply can directly affect the analgesic action of the medication being used (D'Arcy, 2010; Wallace & Staats, 2005). Zi-conotide (Prialt) is a unique medication classed as a neuronal-type calcium channel blocker. For medical use the venom of the marine cone snail is used as an continuous intrathecal infusion (Lynch, Cheng, & Yee, 2006). It can be effective for chronic and neuropthic pain conditions (Schroeder et al., 2006). There are some specific side effects, mainly neuropsychiatric, that can be significant. These include the following:
■ Cognitive impairment
■ Depressed levels of consciousness
■ Elevated creatinine kinase levels (Lynch, Cheng, & Yee, 2006)
Prialt use should be reserved for patients who have failed all other more conventional medications and interventions.
Practitioners run the risk of pump malfunction if other medications than the approved three are used in the pump (see Exhibit 7.2 for guidelines in selecting a candidate for intrathecal medication delivery).
Intrathecal medication use should be carefully considered before the pump is implanted. In a study of 202 patients with refractory cancer pain the decrease was determined to be 20% after pump implantation measured by pain ratings on a VAAS scale (de Leon-Casasola, 2009). A side benefit of IT therapy in this study was a reduction in constipation and impaired consciousness. As a rule of thumb if the patient does not have at least a 50% pain severity reduction while the pump trial is taking place, placing the device should be reconsidered. The patient risk—benefit ratio should be carefully weighed, and all other reasonable options should be tried before the pump implantation is tried. If the patient does not have a 50% reduction in pain levels with the prepump implantation trial, the final implantation should be reconsidered. There are
Criteria for Selecting a Candidate for Intrathecal Medication Delivery
In general, the successful candidate for referral for implanted in-
trathecal pump and intrathecal medication delivery includes the patient for whom:
■ Oral analgesia with multiple oral or transcutaneous trials, including dose titration, has been ineffective
■ Side effects, despite opioid rotation, are intolerable
■ Functional analgesia took effect and provided benefit during temporary trial infusion
■ Psychological stability and reasonable goals can be demonstrated
■ Access to care is manageable: the patient is to return to the pain clinic for pump refills and dose adjustments
■ Acceptance of the procedure has been demonstrated
■ Intractable spasticity was unrelieved by oral antispasmodics and spasticity was improved with baclofen test dosing
Source: Adapted from Wallace & Staats, 2005, p. 342.
some risks that the patient should be aware of before the catheter is placed (see Exhibit 7.3 for risks related to intrathecal medication administration).
Neurostimulation for the relief of pain was noted as early as 2,500 BC in Egypt where electric catfish or torpedo fish with electric shocking capacity of 220 volts were placed on painful areas hoping to relieve pain (Junkin, Lynch, Beradoni, 2009). The concept of spinal cord stimulation is based on the idea that using a non-noxious stimulus can reduce pain perception (Lynch et al., 2009) It is also thought that the sympathetic nervous system is activated by the pulse generation of the stimulator and that additional neuronal
Risks and Considerations when Evaluating the Candidacy of a Patient for Intrathecal Medication Administration
Risks and considerations for patient candidacy include the following:
■ Does the patient have any placement issues, such as spinal deformity, past spinal surgery, or abdominal surgery, that would make placement difficult?
■ All patients are at risk for infection, meningitis, arachnoiditis, and catheter-related granuloma formation.
■ Anticoagulation can cause a compressive hematoma when the catheter is being placed or removed.
■ Pump malfunction can cause a withdrawal syndrome.
■ Low pressure spinal headaches may occur.
■ There may be a need for dose escalation and the development of tolerance.
Source: Adapted from Wallace & Staats, 2005; D'Arcy, 2010.
pathways may be activated and provide additional pain relief (Wallace & Staats, 2005).
Most spinal cord stimulators use a low volt battery, similar to a pacemaker battery, connected to two or more leads that are implanted into the epidural space in the area determined to be the pain generator. These leads are placed either percutaneously or laminectomy. When activated the patient will experience a mild tingling sensation in the painful area. Many patients feel that this sensation is similar to a tran-scutaneous electrical nerve stimulator (TENS) unit. (Mailis-Gagnon et al., 2008; Figure 7.4).
Conditions that have found SCS to be helpful for pain relief include:
■ Peripheral vascular disease
■ Refractory angina
■ Chronic pancreatitis
■ Chronic pelvic pain
■ Idiopathic foot pain
■ Failed back syndrome
■ Chronic neuropathic pain; complex regional pain syndrome, phantom limb pain, diabetic neuropathy, radiculitis, post-thoracotomy pain postherpetic neuralgia (Mailis-Gagnon et al., 2008; McJunkin et al., 2009; Neuromodulation Therapy Access Coalition [NTAC], 2008).
Patients who are being considered for SCS should be given a very thorough physical and psychological examination. They should have used medication management and trialed combinations and doses of medication with limited results. Although the research results are not strong it is covered by Medicare, other government health care programs, all major commercial health plans, and most worker's compensation plans in the United States (D'Arcy, 2010). The chance that SCS will work and increase function is an outcome that should be considered if the trial stimulation relieves pain. The last positive
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