By P. Milten. Caldwell College.
In a specific sub- set buy generic aurogra 100mg online, the data suggested that patients with highly pressure-sensitive discs appeared to achieve better long-term outcomes with interbody or circumferential fusion than with intertransverse fusion buy aurogra 100mg with visa. For this rea- son, the authors suggested that there may be a biochemical component to discogenic pain. Another requirement for successful discography is the study of a large enough number of discs to permit inclusion of a rostral and, pos- sibly, caudal control. Given that many surgeons have empirically lim- ited arthrodesis to two- or three-level disease in the lumbar spine, the presence of appropriate control levels is critical. A final note of concern must also be added regarding surgical treat- ment for discogenic pain. The newer intradiscal therapies are promising but certainly not definitive, and substantial variability exists in surgical outcomes for discogenic pain. Whitecloud and Seago31 reported a 70% rate of clinical success for cervical arthrodesis on the basis of discogra- phy. In one study, an overall success rate of 46% was identified, with a clinical success rate of 96% in the subset that fused solidly. What then are the criteria for "definitive" discography and its use as an indication for reconstructive surgery? Ideally, the patient should be free of confounding organic and psychological pathologies, should have disease limited to one or two levels, and should have reasonable expectations. Perhaps it is in this final area that the thought processes of the diagnostician and sur- geon must be most closely aligned. Facet Blockade Numerous studies have demonstrated that the zygapophyseal joints, particularly in the lumbar spine, are a source of low back pain with or without referred sclerotomal pain. In this study, 18 asymptomatic individuals were assigned to L4-5 or L5, S1 facet blocks with radiographic contrast until capsular distention elicited pain. One week later 15 of the 18 underwent one of two randomized injections with saline or lidocaine. Thirty minutes after medial branch injections, the same individuals underwent repeat capsular distention of the joints that had been distended the preceding week. All five control individ- uals who received saline injections experienced pain with repeat cap- sular distention. Only one of the nine patients who received the active block experienced pain on capsular distention. Thus, with strict atten- tion to technique, including the avoidance of inadvertent venous up- take with medial branch injection, facet blockade was successfully ac- complished in 89% of the active treatment group. There are difficulties similar to those discussed for discogenic pain when one is attempting to identify patients who will be candidates for facet block on the basis of physical findings. Several studies to date38,41 have failed to identify predictive value for any clinical findings or fea- ture that would suggest a positive response to facet blockade. Specificity and sensitivity were increased when range of motion and functional tolerance were included: final sensitivity and specificity were, however, limited at 78 and 80%, respectively. As is the case with discography, there is no "gold standard" from a surgical point of view that can help to refine the diagnostic accuracy of facet blockade. However, 17% of block responders who did not have facet rhizotomy were improved as well. In the cervical spine, some evidence exists that intervention for a facet-mediated pain problem may be warranted. Several studies43–46 have investigated the reliability of facet blockade in the cervical spine, as well as the utility of radiofrequency (RF) neurotomy. Thus, at the present time the identification of facet-mediated pain by diagnostic blockade has little meaningful impact on surgical decision making. There are however, no convincing studies in the peer-reviewed literature suggesting that conventional surgical treatment (e. Sacroiliac Joint (SI) Injections The difficulties identified in terms of sensitivity and specificity, par- ticularly in comparing diagnostic blockade to a known, or reproducible, standard also apply to SI joint blockade. It is generally accepted that the SI joint can be a source of pain owing to posterior ligamentous dis- ruption, secondary to trauma, infection, or tumor. The characteristics of so-called SI joint pain without these obvious anatomical correlates, are, however, controversial. To date, no physical finding has proven to be specific enough to reliably diagnose sacroiliac joint pain. Additionally, in the presence of capsular incompetence, contrast extravasations may anesthetize nearby neural structures, further compounding the diagnostic difficulties with this particular injection. From a surgical point of view, perhaps the most telling limitation is the lack of any reproducible surgical procedure to treat sacroiliac joint pain. While joint reconstruction or arthrodesis has been demonstrated to restore pelvic stability in traumatic situations, there are no published reports in the peer-reviewed literature of significant pain relief fol- lowing SI joint fusion for clinical syndromes diagnosed by SI joint blockade. Thus, from a surgeon’s point of view, sacroiliac joint injections are therapeutic only because no firm recommendations can be made on surgical treatment for these presumed disorders. Selective Nerve Root Blockade Selective nerve root blockade has received attention as a diagnostic and therapeutic tool in the management of referred pain, presumably of radicular origin. From the surgical point of view, the potential utility Selective Nerve Root Blockade 59 of this test lies in diagnostic specificity: not in its ability to identify a radicular etiology as the source of referred pain, but to localize a symp- tomatic level. In certain instances with clinical evidence of radicu- lopathy and no underlying structural cause, nerve root blockade has been used to guide surgical intervention such as laminectomy or fu- sion. A particularly unfortunate clinical situation occurs when a patient who has been diagnosed with radiculopathy is informed that surgery is required for neural compression even though, from a strictly anatom- ical point of view, no surgical lesion exists. Again, the potential di- chotomy between the diagnostician and the surgeon bears scrutiny: al- though the patient may in fact have a radiculopathy that is helped by selective nerve root blockade, this may not be amenable to surgical treatment. Selective nerve root blockade has been used in the diagnosis of radic- ular syndromes.
The instrument is positioned to allow an anterior–posterior view for an easy lumbar puncture and identification of the catheter tip level order aurogra 100 mg fast delivery. A 5 cm incision is made in the skin purchase 100mg aurogra visa, down to the lumbar fascia, and then the catheter is implanted through a paraspinous approach. A good flow of spinal fluid is documented, the catheter is clamped to the drape to prevent CSF loss, and the incision is packed with an antibi- otic-soaked sponge. If the existing catheter is to be used as the permanent delivery catheter, the patient is positioned on the operating table in the decu- bitis position with the implant side upward and the exiting screening extension catheter downward. The previous back incision is reopened and the disposable extension catheter is disconnected from the permanent in- trathecal catheter and pulled from under the patient by the circulating nurse. The intrathecal catheter is then clamped to prevent CSF loss, and the implantation proceeds in the usual manner. Attention is then turned to the lower quadrant of the abdomen, where a 10 cm incision is made down to the underlying subcutaneous fat layer. A subcutaneous pocket large enough to admit the particular pump be- ing used is then fashioned. Generally, if all four fingers can be admitted to the metacarpal phalangeal joints in the pocket, it is large enough. The upper side of the incision is undermined roughly as the width of the pump, or about 2. The eccentric location of the pocket allows the pump to be placed so that the refill port is clear of the incisional scar and easier to locate. An ideal pocket is one that will allow placement of the pump without difficulty but is tight enough to aid in preventing pump rotation. In fashioning the pocket, metic- ulous hemostasis is important to avoid a postoperative hematoma. The catheter connecting the intrathecal catheter to the pump, or the extension catheter, is then tunneled from the pump pocket to the back incision by means of a malleable tunneling device. Shunt tunneling tools may also be 284 Chapter 15 Implanted Drug Delivery Systems used, and a tunneling system is provided with the programmable pump, which works well. Most constant flow rate pumps come with the extension catheter connected to the pump at the factory; the catheter must be attached to the programmable pump. A connection is now made between the extension catheter and the intrathecal catheter, using a titanium or plastic male-to-male tubing connector, usually provided with the catheter selected. This construct is covered by some type of anchoring device, which is secured to the connector with 2-0 nonabsorbable braided tie. The construct is an- chored to the underlying muscle fascia in a figure 8 fashion. The extension catheter is now connected to the previously prepped programmable pump and secured to the pump with a 2-0 braided tie. Pumps with a previously attached catheter must be placed into the pocket at the time of catheter tunneling. The Synchromed pump in its Dacron pouch may be placed without need for further suturing. Some pumps without this pouch have anchoring loops manufactured around the pump circumference, but their use may be problematic. At least two stitches are necessary to prevent rotation, and three may be necessary to prevent flipping (it happens! This usually requires a dermal or fascial stitch, with the risk that the anchor will be painful. If this technique is used, the stitches should be placed into the pocket first, then through the pump suture loops, whereupon the pump is placed into the pocket and the sutures tied. If the pocket is carefully fashioned, even a pump lacking a Dacron pouch may be placed with- out suturing, especially in thin patients. An interrupted, inverted layer of 2-0 absorbable suture in the abdomen and 3-0 absorbable suture in the back will suffice, followed by apposing the skin edges with Steri- Strips. If tension is a problem, surgical staples should be used to rein- force the closure. Outcomes While the majority of patients with chronic pain, either cancer related or not, are adequately managed with oral analgesic medications, elec- trostimulation, or behavioral techniques, studies indicate that only about half the patients so treated for back pain or neuropathic pain achieve good reduction in their pain, and a full 21% are unresponsive to opioid therapy. In a retrospective mul- ticenter study of the use of intraspinal morphine for all types of pain, 32. Cancer pa- tients were treated with higher initial doses and escalated to a stable level more rapidly than patients with non-cancer-related pain. The long-term stability of dos- ing in the cancer population has also been documented elsewhere. It is probable that about 5 to 10% of those in the cancer pain popula- tion are candidates for an implantable pump system using the selec- tion criteria noted earlier. Non-Cancer-Related Pain The use of intrathecal opioids for pain not due to cancer has burgeoned in recent years in spite of a lack of prospective studies. The most de- finitive data to date supporting such an increase in use are provided by the survey of physicians in the United States by Paice, Penn, and Shortt,17 cited in connection with cancer-related pain and including data on pain not related to cancer, and in the retrospective study by European authors Winkelmuller and Winkelmuller. Doses for neuropathic pain tended to be higher at 6 months than for somatic or visceral pain. These patients exhibited a linear in- crease in dose over time, eventually reaching stable levels by one year at 9. The best ini- tial response was seen in the nociceptive pain group, with a 77% ini- tial reduction in pain intensity that declined to 48% at last follow-up. Deafferentation and neuropathic pain groups benefited from therapy and in fact over the long term showed the best results, with 68 and 62% pain reduction as measured by VAS, respectively. While these results are impressive in a population of patients unre- sponsive to more conventional methods, prospective studies compar- ing this and alternative therapies would more rigorously establish in- trathecal infusion of medication as a treatment of choice.
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