Cervical Medial Branch Block Volume Dependent Dispersion Patterns as a Predictor for Ablation Success: A Cadaveric Study.

BACKGROUND: Neck pain is one of the most common causes of chronic pain and the fourth leading cause of disability worldwide; it is estimated that between 36% and 67% of this pain is due to facet arthropathy. For patients who have pain refractory to conservative treatments literature supports management with diagnostic cervical medial branch blocks (MBBs) to identify the associated facet innervation as the source of pain followed by therapeutic radiofrequency ablation (RFA) of the identified nerves. Cervical RFA has good published outcomes; however, the procedure is dependent upon the specificity of the diagnostic block to achieve maximal success. Currently, this prerequisite test has false positive rates between 27% and 63% and recent studies have shown that this may, in part, be a consequence of currently accepted injection volumes of 0.50 mL or more, which may decrease the sensitivity of MBBs. OBJECTIVE: To evaluate the possible differences in volume dispersion between 0.25 and 0.50 mL of injectate during cervical MBBs. STUDY DESIGN: Cadaveric study. SETTING: An academic medical center in the United States. PATIENTS: Not applicable. METHODS: This was a cadaveric study in which six subjects were chosen with intact cervical spines. Cervical MBB were performed bilaterally at the midcervical spine, using a posterior approach under fluoroscopic guidance. 0.25 or 0.50 mL of a 9:1 solution of Omnipaque 180 mg iodine/mL and 1% medical grade methylene blue were administered on the left and right sides, respectively. Postinjection computed tomography (CT) imaging and gross dissection were performed to assess injectate spread. MAIN OUTCOME MEASURES: Outcome measures after using commonly injected volumes for cervical MBB, included visualized and measured spread (by CT and gross dissection) of cervical medial branch blocks, coating adjacent structures not targeted by RFA. RESULTS: Postinjection CT imaging and cadaveric dissection demonstrated that, although both volumes adequately coated the medial branches, the 0.50 mL cohort reliably spread dorsally to superficial muscles (splenius) and nerves distant from the targeted nerves (dorsal motor branches to splenius), whereas the 0.25 mL injectate cohort was contained in the deep and intermediate muscular cervical layers directly juxtaposed to the targeted cMBBs. CONCLUSION: Results suggest that 0.50 mL injections of local anesthetic during cervical MBBs contacts many nonintended targets, thus decreasing the specificity of a targeted diagnostic cervical MBB. Furthermore, we demonstrated that 0.25 mL of injectate reliably bathed the cervical medial branches without extensive extravasation. This indicates that there would potentially be fewer local anesthetic effects on distant tissues, increasing the specificity of cervical MBBs and likely improving RFA planning.

Lumbar Medial Branch Block Volume-Dependent Dispersion Patterns as a Predictor for Ablation Success: A Cadaveric Study.

BACKGROUND: Lumbar facet arthropathy is a common cause of low back pain. Literature supports treatment with radiofrequency ablation (RFA) of associated nerves that innervate lumbar facets when alternative conservative therapies have failed. Diagnostic local anesthetic blocks precede therapeutic ablation, but have a false-positive rate of 27%-63%, and some authors have questioned their utility in predicting therapeutic response to RFA. The authors of the current study believe that injectate volume may be a contributing factor to false positivity. OBJECTIVE: To evaluate the difference in volume dispersion between 0.25 mL and 0.5 mL of injectate when performing lumbar medial branch blocks. We hypothesized that injection volumes greater than 0.25 mL during lumbar medial branch blocks would affect the distal branches of the adjacent medial branches, thus decreasing the specificity of the procedure. Thus, we attempted to demonstrate that injection volumes greater than 0.25 mL during lumbar medial branch blocks would affect the distal branches of the adjacent medial branches, which might increase false positivity of the blocks. STUDY DESIGN: Cadaveric investigation. SETTING: Tertiary care center. PARTICIPANTS: Not applicable. OUTCOME MEASUREMENTS: To demonstrate that the spread of lumbar medial branch blocks using commonly injected volume coats adjacent structures that are not affected by radiofrequency ablation. METHODS: Six cadavers were chosen with nondissected lumbar spines. Fluoroscopically guided medial branch injections were performed bilaterally using the posterior oblique approach. A volume of 0.25 mL or 0.50 mL of a 9:1 solution of Omnipaque 240 and 1% medical grade methylene blue were delivered to the left and right sides, respectively. Postinjection computed tomographic imaging was performed, followed by dissection. RESULTS: Both volumes adequately coated the medial branches, but in the 0.5-mL injectate cohort there was consistent spread dorsally to the superficial muscles and distal segments of the dorsal branches distant to the target nerves, whereas in the 0.25-mL injectate cohort the spread was contained in the deep and intermediate muscular lumbar layers, close to the intended target. CONCLUSION: We suggest that a 0.5-mL injectate volume in clinical practice may produce an adjacent-level nerve block in addition to the intended injection level, thus decreasing the specificity of a targeted lumbar medial branch block. A 0.25-mL quantity of injectate reliably contacted the lumbar medial branches without extensive extravasation. Presumably, this means that 0.25 mL total volume for a lumbar medial branch block may provide greater specificity for RFA planning. LEVEL OF EVIDENCE: NA.

Ultrasound-Guided Fenestration of the Carpal Ligament Using a Double-Needle Approach.

Injection techniques for carpal tunnel syndrome have evolved from landmark palpation injection techniques to more accurate ultrasound-guided approaches. Presented is a case report describing a technique serendipitously discovered during a carpal ligament fenestration. The case involved a 66-year-old man with a diagnosis of carpal tunnel syndrome. After a failed attempt at treatment using a wrist splint and activity modification, he was treated by median nerve hydrodissection with 100% temporary pain relief. When his symptoms recurred, a carpal tunnel combined hydrodissection/fenestration technique was performed. Because of difficulty extricating the carpal ligament from the median nerve with the first needle, which was placed longitudinal to the median nerve, a second needle was placed transverse to the median nerve to aid in hydrodissection. The second needle was left in because it was found to be helpful in maintaining a safe distance between the median nerve and the carpal ligament by intermittent injection through the second needle. The patient reported 70% relief of his symptoms at 2-week follow-up and 50% sustained relief at 3 months. A 2-needle technique is feasible and can be helpful during median nerve hydrodissection/carpal ligament fenestration when technical or anatomical issues arise preventing treatment using the traditional single needle approach. This double needle approach allows for use of injectate to maintain separation between the median nerve and the ligament during the fenestration.

Use of Platelet-Rich Plasma in Intra-Articular Knee Injections for Osteoarthritis: A Systematic Review.

OBJECTIVE: To systematically analyze the literature on the use of platelet-rich plasma (PRP) for intra-articular injections of the knee and its efficacy in the treatment of knee osteoarthritis (OA). DESIGN: Systematic literature reviews were conducted in PubMed, Embase, and CINAHL (ie, Cumulative Index to Nursing and Allied Health Literature) on October 30, 2013, using the keywords "platelet-rich plasma" and "knee" and "osteoarthritis." Inclusion criteria included (1) studies with human subjects, (2) prospective clinical studies (including either clinical trials or observational studies), and (3) full-text articles published in English. Exclusion criteria were: (1) animal studies; (2) retrospective studies; (3) patients with previous surgical intervention with total knee arthroplasty or reconstruction of the anterior cruciate ligaments; and (4) articles not published in English RESULTS: A total of 319 abstracts and titles were reviewed (60 from PubMed, 250 from Embase, and 9 from CINAHL). A total of 8 relevant journal articles were identified, all of which were published between 2010 and 2013. One-half of the studies were prospective observational studies that included only PRP treatment; the rest were prospective comparative studies including both PRP and controls-2 were randomized controlled trials. Of the 4 comparative studies, 3 compared PRP with hyaluronic acid, which was considered as a commonly used effective treatment for knee OA; the other one used saline injection (ie, placebo) as the control. Although most of the analyses suffered from small sample size and was thus inconclusive, the findings consistently indicated that PRP might have better outcomes in patients with a lesser degree of degeneration and in younger patients. CONCLUSION: PRP intra-articular injections of the knee may be an effective alternative treatment for knee OA. However, current studies are at best inconclusive regarding the efficacy of the PRP treatment. A large, multicenter randomized trial study is needed to further assess the efficacy of PRP treatment for patients with knee OA.

Optimal needle entry angle for cervical transforaminal epidural injections.

BACKGROUND: Cervical epidural steroid injections can be performed through either interlaminar or transforaminal approaches, although the interlaminar approach is more frequently used, for cervical radicular pain as a result of cervical disc herniation or spinal stenosis. Cervical selective nerve root block (CSNRB) is an injection that uses a similar approach to that of cervical transforaminal epidural steroid injection (CTFESI) but CSNRB is mainly used for diagnostic injection, often with local anesthetic only. OBJECTIVE: The aim of this study was to investigate an optimal needle entry angle for cervical transforaminal epidural steroid injection (CTFESI) or cervical selective nerve root block (CSNRB) using the fluoroscopically guided anterior oblique approach. The angle for optimal entry into the neuroforamen was measured at various vertebral levels using cross-sectional cervical spine computed tomography (CT) scans. STUDY DESIGN: Retrospective case series analysis. METHODS: From March 2009 to July 2012, consecutive patients with presumed discogenic neck pain underwent cervical post discography CT scans. The axial images of these CT scans were used to measure the optimal angle for needle entry into the neuroforamen. The angles were taken bilaterally at levels of C3-4, C4-5, C5-6, C6-7, and C7-T1. The average angle between the patient's left and right side was calculated. A total of 190 patients were analyzed, including 73 men and 117 women, with ages ranging from 21 to 78 years old. RESULTS: In both men and women, the mean optimal angle (in degrees) with standard deviation measured in the 190 patients at C3-4, C4-5, C5-6, C6-7, and C7-T1 were 48 ± 4, 49 ± 4, 49 ± 4, 49 ± 5, 48 ± 6, respectively. The 95% confidence interval for the true value of the parameter is within 39.84 to 57.56 degrees. LIMITATIONS: The data for the optimal needle entry angle for CTFESI has yet to be tested or confirmed in clinical studies. CONCLUSION: This is the first study investigating the optimal needle entry angle for performing CTFESIs or CSNRB. Based on a patient population of 190, the optimal entry angle using the anterior oblique approach appears to be between the range of 33 to 68 degrees with an average of slightly less than 50 degrees. Further research with angle of needle entry and/or initial fluoroscopic alignment of approximately 50 degrees in CTFESI or CSNRB is warranted to confirm the usefulness of these findings.