By T. Mojok. Eastern Washington University.
Compare the outlined areas of the radiograph with the contour of an actual Scottish terrier shown in the inset in the lower right corner of this image maxolon 10 mg with mastercard. The patient is instructed to Proper testing for sensory-motor dissociation is conducted assess his or her degree of pain relief in the hours immedi- (the patient should report pain or tingling during stimula- ately following the diagnostic blocks safe maxolon 10mg. There- Block Technique: Radiofrequency Treatment after order maxolon 10mg without a prescription, great care must be taken to prevent any movement Radiofrequency cannulae are placed using a technique iden- of the cannulae. Cannula placement for lumbar pulsed radiofre- plane so the active tip of the radiofrequency cannulae will quency treatment is carried out in the same manner. Once the needle is seated against the superior Radiofrequency Treatment margin of the transverse process, where it joins the supe- rior articular process of the facet, the cannula is walked off Complications associated with diagnostic medial branch the superior margin of the transverse process and advanced nerve blocks are uncommon and similar to those follow- 2 to 3 mm to position the active tip along the course of the ing intra-articular facet injection. Unlike intra-articular Chapter 7 Facet Injection: Intra-articular Injection, Medial Branch Block, and Radiofrequency Treatment 115 A Superior articular process Transverse Spinous process processes L3 Laminae Needle tips Pedicles L4 Iliac crest B C Figure 7-40. A: Bony anatomy relevant to lumbar medial branch blocks and radiofrequency treatment. Three radiofrequency cannulae are in place at the base of the transverse processes and superior articular processes at the L3, L4, and L5 levels on the right. There is a transitional vertebra at L5, with sacralization of the L5 vertebra (thin laminar arch and absence of a discernable inferior articular pro- cess at L5, yet clear segmentation of the L5 vertebral body on the lateral image shown in Fig. A Pedicle Needle tips L3 Superior articular processes L4 Iliac crest L5 B C Figure 7-41. A: Bony anatomy relevant to lumbar medial branch blocks and radiofrequency treatment. Three-dimensional reconstruction computed tomography of the lumbar spine as viewed in the lateral projection. B: Lateral radiograph of the lumbar spine during lumbar radiofrequency treatment of the lumbar facet joints. Three radiofrequency cannulae are in place at the base of the transverse processes and superior articular processes at the L3, L4, and L5 levels on the right. Note the angle of the entering cannulae and their distance from the intervertebral foramina. Discerning the location of the superior articular surface is simple: identify the superior end plate of the vertebral body at the level of interest and follow the margin posteriorly until the posterior margin of the vertebral body joins the pedicle. The superior margin of the pedicle forms the inferior border of the intervertebral foramen. There is signiﬁcant rotation at the L4 and L5 vertebral levels in this image, but the left and right foramina are well aligned at the L3 level. Follow the superior border of the pedicle posteriorly and it will slope upward where it joins the superior articular process of the facet joint. The superior extent of the superior articular process is easily identiﬁed as notch along the posterior margin of the intervertebral foramen. The articular surface is then easily identiﬁed as a line sloping in a posterior and inferior direction. Patients should be warned to expect American Society of Anesthesiologists Task Force on Chronic Pain mild pain at the injection site lasting a day or two after the Management; American Society of Regional Anesthesia and procedure. Although conventional ment: an updated report by the American Society of Anesthe- radiofrequency produces actual tissue destruction, injury siologists Task Force on Chronic Pain Management and the to the spinal nerves is uncommon. This is likely due to the American Society of Regional Anesthesia and Pain Medicine. Occipital headaches stemming from sensory and motor testing are carried out before each lesion the lateral atlanto-axial (C1–2) joint. Controlled zygapophysial joint blocks: the cannula will be close enough to the anterior primary ramus travesty of cost-effectiveness. The cervical zygapophysial joints as a lowing conventional radiofrequency treatment is common, source of neck pain. A smaller group of and interdisciplinary rehabilitation for low back pain: an evidence-based clinical practice guideline from the American patients will report uncomfortable dysesthesia, usually in Pain Society. The surgical anatomy of thoracic facet spinous processes at the level of treatment often accom- denervation. Lumbosacral radiculopathy adverse effect is more common following cervical radiofre- following radiofrequency ablation therapy. Low back pain and the zygapophysial the lateral branch of the posterior primary ramus, which (facet) joints. Radiofrequency facet joint denervation in the treatment of low back pain: a placebo- lying the spinous processes. Injury to the spinal nerve with new-onset radicu- after C1-C2 intraarticular facet steroid injection: evidence for dif- lar pain with or without radiculopathy (nerve dysfunction fuse microvascular injury. Radiofrequency neurotomy for sory or motor loss) has been reported following radiofre- the treatment of third occipital headache. J Neurol Neurosurg quency treatment, but it is rare when physiologic testing Psychiatry. Percutaneous radio-frequency neurotomy for chronic cervical zygapophyseal-joint pain. Pulsed radiofrequency ing treatment or a transient, mild exacerbation that is short application in treatment of chronic zygapophyseal joint pain. The longitudinal effective- It is precisely because of this lack of neural destruction ness of lateral atlantoaxial intra-articular steroid injection in the and associated adverse effects that pulsed radiofrequency treatment of cervicogenic headache. Radiofrequency dener- vation for neck and back pain: a systematic review within the controlled trials emerge to support the efﬁcacy of pulsed framework of the Cochrane Collaboration Back Review Group. Role of the C2 articular frequency gained rapid popularity, but the majority of branches in occipital headache: an anatomical study. A critical review of the failed to demonstrate the beneﬁt of using the pulsed tech- evidence for the use of zygapophysial injections and radio- frequency denervation in the treatment of low back pain. Chapter 8 Sacroiliac Joint Injection 119 L4 L4 L5 L5 o o 0– 30 25–35 from sagittal plane Figure 8-1. Accessing the joint is facilitated by a caudad-cephalad approach of 25 to 35 degrees to avoid the overlying posterior-superior iliac spine and iliac crest. Level of Evidence Quality of Evidence and Grading of Recommendation Grade of Recommen- Beneﬁt vs.
Exposure This mode substitutes brief maxolon 10mg with mastercard, periodic spot images separated by an interval without exposure (e cheap maxolon 10mg without a prescription. Because no dose of ionizing threading an epidural catheter or spinal cord stimulation radiation is without biologic effects and can be considered lead; see Figure 2-2) generic maxolon 10mg mastercard. Table 2–3 Minimum Target Organ Radiation Doses to Produce Organ Pathologic Effects Organ Dose (rad) Dose (Gy) Results Eye lens 200 2 Cataract formation Skin 500 5 Erythema 700 7 Permanent alopecia Whole body 200–700 2–7 Hematopoietic failure (4–6 wk) 700–5,000 7–50 Gastrointestinal failure (3–4 d) 5,000–10,000 50–100 Cerebral edema (1–2 d) Chapter 2 Radiation Safety 11 Table 2–4 Comparative Radiation Doses for Common Diagnostic X-ray and Fluoroscopic Procedures X-ray—chest 0. Optimize the Position of the X-ray Tube Employ Shielding Whenever Possible Radiation exposure to the patient is best minimized by The use of lead shielding can prevent exposure of regions ensuring optimal distance between the patient and the x-ray adjacent to the area that is to be imaged from being exposed tube (Fig. Small lead shields can be placed the patient, a small area of skin will be exposed to radia- on the table underneath the patient, directly in front of the tion, but due to the close proximity of the x-rays, the dose x-ray beam before it penetrates the patient to protect the that this smaller area will be exposed to is much higher. The should be readily available in the ﬂuoroscopy suite, they are x-ray tube should be positioned as far from the patient as seldom practical for use during image-guided injection of possible, without including unnecessary structures in the the lumbosacral spine because the shield would lie directly ﬁeld of view. Linear collimation employs shutters that can be moved in from either side of the exposure ﬁeld and is helpful in imag- 20 ing long, thin structures such as the spine (Fig. Circu- lar or “iris” collimation can be helpful when a small, circular 0 area is to be imaged (Fig. Useful employment of collimation can exclude Effect of pulsed ﬂuoroscopy on radiation dose (patient entrance areas of greatly varying radiodensity to improve image qual- skin dose). For example, by switching from continuous ﬂuo- ity by reducing the range of densities included in the ﬁeld. Linear collimation Image intensifier adjustable height Image intensifier (detector) Patient A. Optimal spacing between the x-ray source and the patient to minimize radiation exposure. Use of adjustable (linear) collimator to decrease radiation expo- sure to the patient, while improving image resolution by decreas- Use of adjustable (iris) collimator to limit the ﬁeld to the area ing the range of tissue density included in the image ﬁeld. Likewise, imaging in the cervical spine is for the radiodense leaded gloves, and negate their protec- fraught with the same difﬁculties when the air on either side tive effects. Techniques that eliminate the practitioner’s of the neck is included in the x-ray ﬁeld (see Fig. Either hands from direct exposure within the x-ray ﬁeld should linear collimation or circular collimation (see Fig. Protective eyeglasses are available be used to limit the ﬁeld to the area of interest, improving that dramatically reduce eye exposure during ﬂuoros- image quality and reducing radiation exposure. Modern copy; leaded eyewear is recommended for practitioners ﬂuoro units may also allow for magniﬁcation of the image who accumulate monthly readings on collar badges above by electronically magnifying the area of interest. Levels of exposure in this range are typi- tion allows better visualization of a smaller area but leads to cally encountered only in areas where continuous cine- increased radiation exposure as the system increases output angiography is conducted frequently (e. Practitioner Position The practitioner must understand the geometry of the radia- Minimizing Practitioner Exposure tion path as it passes from the x-ray tube to the image inten- siﬁer and adopt positions that minimize his or her exposure Employ Proper Shielding during ﬂuoroscopy (Fig. The dose drops proportion- Only the personnel needed to conduct the procedure ally to the square of the distance from the x-ray source. All personnel should Thus, standing as far from the x-ray tube as practical is the be shielded with lead aprons before use of ﬂuoroscopy ﬁrst means to minimize exposure. The practitioner using the ﬂuoroscopy unit should extension tube and taking a step back from the table dur- alert everyone in the room that he or she is about to begin ing periods where contrast is injected under continuous or and ensure that personnel are shielded. When the x-ray tube thyroid shields can minimize the long-term risk of thy- is rotated to obtain a lateral image, the practitioner should roid cancer. Although protective lead gloves can reduce step completely away from the table beneath the x-ray tube the exposure of the hands to radiation, they can produce and out of the path of the x-ray beam or move to the side a false sense of security. B: The oblique projection results in C markedly increased exposure to the practitio- ner. C: During use in the lateral projection, the practitioner should step completely behind the x-ray tube (source) to minimize radiation 5 1. When it is necessary to work close to the patient during lateral ﬂuoroscopy, the practitioner should step away from 2 1. D: Radiation exposure to both the patient and the practitioner is dramatically increased when the x-ray tube (source) is inverted above the 0. Some practitioners invert the C-arm to mSv/hr allow for more extreme lateral angle (e. Radiation exposure can be reduced by rotating the patient on the table and keeping the x-ray source below the table. Flat plate detectors employ a grid-like elec- tice dramatically increases exposure to both the patient and tronic detector that eliminates both vignetting and pin- the practitioner by bringing them in close proximity to the cushion distortion, providing optimum image quality from x-ray source. Available at http:// ity of small structures, or image detail, can be improved by www. Radiation safety in pain roscopic images also have less sharpness at the periphery of medicine. Public Health Advisory: Avoid- This results in an effect much like a ﬁsheye camera lens ance of Serious X-ray Induced Skin Injuries to Patients During Fluoroscopically-guided Procedures. Food with a splaying outward of objects toward the periphery and Drug Administration, Center for Devices and Radiological of the image. Within the scopic guidance: technique, results, procedure time, and radia- past several years, several manufacturers have developed tion dose. Chapter 3 Radiographic Contrast Agents 17 Contrast in the ventral and dorsal Contrast in epidural space the subdural compartment Figure 3-1. This typical lateral lumbar epidu- rogram demonstrates the “double-line” or “railroad track” appearance of radiographic contrast in the anterior and pos- Figure 3-2. The contrast is contained posteriorly by the dural membrane, but Adverse Reactions to Radiographic extends only partially anteriorly, as it is contained by the thin Contrast Media arachnoid membrane. Compare with Figure 3-3, subarachnoid administration, where the contrast extends all the way from Modern contrast agents have reduced, but not eliminated, the posterior to the anterior limits of the thecal space. The risk of adverse reac- tions is signiﬁcantly greater with use of high-osmolar, ionic Idiosyncratic reactions are the most feared and most serious agents when compared with low-osmolar, nonionic agents. At present, we cannot This discussion is limited to the risks associated with low- predict or prevent this type of reaction reliably, and they osmolar, nonionic agents because they are used almost occur without warning. This typi- B cal myelogram demonstrates contrast within the thecal sac (arrows) on this lateral radiograph of the lumbar spine. Reg injection is typically not seen on still images because the con- Anesth Pain Med. During real-time or live ﬂuoroscopy, intravenous contrast injection appears as in this anterior-posterior radiograph of the cervi- cal spine taken during cervical transforaminal injection.