The S1 dorsal foramen: Nuances of anatomy.

Background: Access to the dorsal S1 neural foramen is frequently performed, but can be challenging. Purpose: To report previously undescribed nuances of dorsal S1 foraminal anatomy, including a bony flange that may obstruct access to the foramen. Methods: Fluoroscopic - advanced imaging correlations of the S1 foraminal aperture were performed. The anatomy of the S1 foramen was examined in 27 cadaveric specimens (N â€‹= â€‹49 S1 foramina) and the foraminal and flange dimensions quantified. The S1 foramen was examined in 50 CT datasets (N â€‹= â€‹100 S1 foramina), and its dimensions quantified in PA and ipsilateral oblique orientations. Results: The medial aspect of the S1 dorsal foramen is variably shielded by a bony flange, which extends from medial to lateral. The foraminal aperture is covered by a ligament extending from this flange to the lateral aspect of the foramen. On the cadaveric specimens, the mean vertical dimension of the foraminal aperture was 8.6 â€‹mm; the transverse dimension was 8.9 â€‹mm. The mean transverse dimension of the flange was 2.8 â€‹mm. The CT images demonstrated that the transverse dimension of the S1foraminal aperture increased from a mean of 6.23 â€‹mm in the PA orientation to 7.90 â€‹mm in the ipsilateral oblique. Discussion: The bony flange at the S1 dorsal foramen shields its medial aspect; the flange on average covers one-third of the transverse dimension of the foramen, and in 14% covered one-half. The flange has little cortical bone at its margins and may be unseen at fluoroscopy. Ligamentous tissue extending laterally from the flange covers the remainder of the foramen. The transverse dimension of the foramen increased significantly from a posterior-anterior trajectory to an ipsilateral oblique trajectory, as the flange no longer obstructed access. Conclusion: Access to the S1 dorsal foramen may be confounded by an unseen bony flange covering its medial aspect. An ipsilateral oblique trajectory targeting the lateral margin of the foramen will maximize successful access.

Subperiosteal Schwannoma of the Mid-Tibia: A Cause of Long-Lasting Unexplained Pain.

Schwannomas are benign tumors affecting the nerve sheath. Their presence in the subperiosteal region is extremely rare. We report a case of a 66-year-old male patient with a 10-year history of unexplained pain of the anterior leg that turned out to be caused by a subperiosteal schwannoma of the mid-tibia. We believe this case report will increase surgeons' index of suspicion about this condition when dealing with cases of unexplained bony pain, consequently allowing for early diagnosis and better outcomes.

Simultaneous Bilateral Avascular Necrosis of the Femoral Heads Associated With Cocaine Use.

We present a case of a 38-year-old female patient, presenting with debilitating simultaneous bilateral avascular necrosis of the femoral head (AVNFH) 10 years after cocaine detoxification, making her wheelchair-bound for six months. This case is reported for the rarity of association of cocaine with AVNFH, and for the unique fact of the simultaneous bilateral condition occurring a long time after cocaine ingestion in the absence of other important risk factors. This report postulates cocaine as a possible cause of bilateral AVNFH, which can increase the index of suspicion of this pathology, allowing early diagnosis and better outcomes.

Synovial Cysts Confounding Access to the Dorsal S1 Neural Foramen in Transforaminal Epidural Steroid Injections.

OBJECTIVES: The S1 dorsal foramen is the route for 30% of lumbar transforaminal epidural injections; it is therefore important to identify structures impeding S1 foraminal access. The study objective was to characterize the imaging findings, prevalence, and anatomic origin of synovial cysts presenting within the S1 neural foramen. METHODS: A case series (N = 14) established imaging characteristics of S1 synovial cysts. Imaging studies of 400 patients undergoing epidural injections were reviewed for lesions compromising S1 foraminal access. Cadaveric dissections defined the relationship of the inferior recess of the L5-S1 facet to the S1 dorsal foramen. RESULTS: Elderly patients (mean age = 76) exhibited S1 synovial cysts. Synovial cysts were typically 1-2 cm in diameter, hyperintense on sagittal T2 weighted magnetic resonance images (MRIs), fluid-density on computed tomography, and dorsal to the S1 spinal nerve. Sixty percent of cysts exhibited complex MRI signal characteristics (thick wall, internal structure). Tarlov cysts, in contrast, were larger, lobular, and exhibited pure fluid intensity. Lesions impeded access to the S1 dorsal foramina in 5% of reviewed imaging studies (16 Tarlov cysts, three synovial cysts, one conjoint S1-S2 nerve root). The multifidus muscle was interposed between the L5-S1 facet inferior recess and the S1 dorsal foramen on dissection specimens; severe atrophy of the ipsilateral multifidus was noted on imaging in 17/18 synovial cysts. CONCLUSIONS: The S1 neural foramina should be inspected on sagittal MRI, when available, for confounding lesions before performing S1 epidural injections. Tarlov cysts are more common than synovial cysts; the latter are seen in elderly patients with severe multifidus atrophy.

Immediate Adverse Events in Interventional Pain Procedures: A Multi-Institutional Study.

SETTING: Interventional procedures directed toward sources of pain in the axial and appendicular musculoskeletal system are performed with increasing frequency. Despite the presence of evidence-based guidelines for such procedures, there are wide variations in practice. Case reports of serious complications such as spinal cord infarction or infection from spine injections lack appropriate context and create a misleading view of the risks of appropriately performed interventional pain procedures. OBJECTIVE: To evaluate adverse event rate for interventional spine procedures performed at three academic interventional spine practices. METHODS: Quality assurance databases at three academic interventional pain management practices that utilize evidence-based guidelines [1] were interrogated for immediate complications from interventional pain procedures. Review of the electronic medical record verified or refuted the occurrence of a complication. Same-day emergency department transfers or visits were also identified by a records search. RESULTS: Immediate complication data were available for 26,061 consecutive procedures. A radiology practice performed 19,170 epidural steroid (primarily transforaminal), facet, sacroiliac, and trigger point injections (2006-2013). A physiatry practice performed 6,190 spine interventions (2004-2009). A second physiatry practice performed 701 spine procedures (2009-2010). There were no major complications (permanent neurologic deficit or clinically significant bleeding [e.g., epidural hematoma]) with any procedure. Overall complication rate was 1.9% (493/26,061). Vasovagal reactions were the most frequent event (1.1%). Nineteen patients (<0.1%) were transferred to emergency departments for: allergic reactions, chest pain, symptomatic hypertension, and a vasovagal reaction. CONCLUSION: This study demonstrates that interventional pain procedures are safely performed with extremely low immediate adverse event rates when evidence-based guidelines are observed.

Imaging Determinants of Clinical Effectiveness of Lumbar Transforaminal Epidural Steroid Injections.

OBJECTIVE: To examine associations between imaging characteristics of compressive lesions and patient outcomes after lumbar transforaminal epidural steroid injections (TFESIs) stratified by steroid formulation (solution versus suspension). DESIGN/SUBJECTS: Retrospective observational study, academic radiology practice. A 516-patient sample was selected from 2,634 consecutive patients receiving lumbar TFESI for radicular pain. METHODS: The advanced imaging study(s) preceding sampled TFESI were reviewed. Compressive lesions were described by a) nature of the lesion [disc herniation, fixed stenosis, synovial cyst, epidural fibrosis, no lesion] b) degree of neural compression [4 part scale], and c) presence of a tandem lesion. Associations between 2-month categorical outcomes (responder rates for pain, functional recovery) and imaging characteristics, stratified by steroid formulation, were examined with chi-squared tests of categorical outcomes and multivariable logistic regression models. RESULTS: Disc herniation patients had more responders for functional recovery than patients with fixed lesions (54% versus 38%, P = 0.01). Patients with fixed lesions receiving steroid solution (dexamethasone) had more responders for pain relief, with a similar trend for functional recovery, than patients receiving suspensions (59% versus 40%, P = 0.01). Outcomes for patients with fixed lesions treated with dexamethasone were not statistically different from those for disc herniation patients. Patients with single compressive lesions had more responders than those with tandem lesions (55% versus 41%, P = 0.03). CONCLUSION: In the entire sample, outcomes for disc herniations were more favorable than for fixed lesions. However, fixed lesions treated with dexamethasone had outcomes indistinguishable from disc herniations. Single lesions had better outcomes than tandem lesions.

Adverse Event Rates Associated with Transforaminal and Interlaminar Epidural Steroid Injections: A Multi-Institutional Study.

BACKGROUND: Transforaminal epidural steroid injections (TFESI) have demonstrated efficacy and effectiveness in treatment of radicular pain. Despite little evidence of efficacy/effectiveness, interlaminar epidural steroid injections (ILESI) are advocated by some as primary therapy for radicular pain due to purported greater safety. OBJECTIVE: To assess immediate and delayed adverse event rates of TFESI and ILESI injections at three academic medical centers utilizing International Spine Intervention Society practice guidelines. METHODS: Quality assurance databases from a Radiology and two physical medicine and rehabilitation (PM&R) practices were interrogated. Medical records were reviewed, verifying immediate and delayed adverse events. RESULTS: There were no immediate major adverse events of neurologic injury or hemorrhage in 16,638 consecutive procedures in all spine segments (14,956 TFESI; 1,682 ILESI). Vasovagal reactions occurred in 1.2% of procedures, more frequently (P = 0.004) in TFESI (1.3%) than ILESI (0.5%). Dural punctures occurred in 0.06% of procedures, more commonly after ILESI (0.2% vs 0.04%, P = 0.006). Delayed follow up on PM&R patients (92.5% and 78.5, next business day) and radiology patients (63.1%, 2 weeks) identified no major adverse events of neurologic injury, hemorrhage, or infection. There were no significant differences in delayed minor adverse event rates. Central steroid response (sleeplessness, flushing, nonpositional headache) was seen in 2.6% of both TFESI and ILESI patients. 2.1% of TFESI and 1.8% of ILESI patients reported increased pain. No long-term sequelae were seen from any immediate or delayed minor adverse event. CONCLUSIONS: Both transforaminal and ILESI are safely performed with low immediate and delayed adverse event rates when informed by evidence-based procedural guidelines. By demonstrating comparable safety, this study suggests that the choice between ILESI and TFESIs can be based on documented efficacy and effectiveness and not driven by safety concerns.

Lumbar transforaminal epidural steroid injections: does immediate post-procedure pain response predict longer term effectiveness?

OBJECTIVE: To assess whether the immediate anesthetic response of pain relief (sensory blockade) or weakness (motor blockade) after lumbar transforaminal epidural steroid injection (TFESI) is associated with longer term effectiveness in pain relief and functional recovery. DESIGN: Retrospective observational study. SETTING: Single academic radiology practice. SUBJECTS: Three thousand six hundred forty-five lumbar TFESIs performed on 2,634 subjects. METHODS: Subjects completed a pain numerical rating scale (NRS, 0-10) and Roland-Morris disability questionnaire (R-M) prior to and immediately after TFESI (NRS) and at 2 weeks and 2 months follow-up. Successful pain relief was ≥50% NRS reduction; functional success was ≥40% R-M reduction. Post-procedure motor weakness was recorded. Logistic regression models assessed association of immediate post-procedure NRS response, and NRS or R-M response at 2 weeks, with successful outcomes at 2 months. C-index assessed model discrimination; values closer to 1.0 indicated better discrimination. RESULTS: Immediate NRS response was weakly associated with 2-month outcomes (C-index = 0.58). NRS and R-M responses at 2 weeks were more strongly associated with the 2-month response (C-indices 0.77, 0.80, respectively). Post-procedure motor blockade had little association with successful 2-month NRS or R-M outcomes (C-indices 0.51, 0.50, respectively). Patients that responded at 2 weeks were more likely to be responders at 2 months than those who were non-responders at 2 weeks (odds ratio = 6.49, confidence interval 5.38, 7.84). CONCLUSION: Immediate post-TFESI pain relief does not strongly predict longer term effectiveness in pain relief or functional recovery. Response in pain relief or functional recovery at 2 weeks is more strongly associated with 2-month outcomes.

The noninferiority of the nonparticulate steroid dexamethasone vs the particulate steroids betamethasone and triamcinolone in lumbar transforaminal epidural steroid injections.

OBJECTIVE: To assess whether a nonparticulate steroid (dexamethasone, 10 mg) is less clinically effective than the particulate steroids (triamcinolone, 80 mg; betamethasone, 12 mg) in lumbar transforaminal epidural steroid injections (TFESIs) in subjects with radicular pain with or without radiculopathy. DESIGN: Retrospective observational study with noninferiority analysis of dexamethasone relative to particulate steroids. SETTING: Single academic radiology pain management practice. SUBJECTS: Three thousand six hundred forty-five lumbar TFESIs at the L4-5, L5-S1, or S1 neural foramina, performed on 2,634 subjects. METHODS/OUTCOME MEASURES: Subjects were assessed with a pain numerical rating scale (NRS, 0-10) and Roland-Morris disability questionnaire (R-M) prior to TFESI, and at 2 weeks and 2 months follow-up. For categorical outcomes, successful pain relief was defined as either ≥50% reduction in NRS or pain 0/10; functional success was defined as ≥40% reduction in R-M score. Noninferiority analysis was performed with δ = -10% as the limit of noninferiority. Continuous outcomes (mean NRS, R-M scores) were analyzed for noninferiority with difference bounds of 0.3 for NRS scores and 1.0 for R-M scores. RESULTS: With categorical outcomes, dexamethasone was demonstrated to be noninferior to the particulate steroids in pain relief and functional improvement at 2 months. Using continuous outcomes, dexamethasone was demonstrated to be superior to the particulate steroids in both pain relief and functional improvement at 2 months. CONCLUSION: This retrospective observational study reveals no evidence that dexamethasone is less effective than particulate steroids in lumbar TFESIs performed for radicular pain with or without radiculopathy.

Relationship of the lumbar lordosis angle to the abdominal aortic bifurcation and inferior vena cava confluence levels.

The objective of this study is to determine the relationship of the variations of the lumbar lordosis angle (LLA) to the aortic bifurcation level and inferior vena cava (IVC) confluence level using CT angiography. A retrospective study was conducted using the data available on abdominopelvic CT angiography scans. The LLA, the level and angle of bifurcation of the aorta, the level and angle of confluence of the IVC were identified using multiplanar and 3D reconstruction. Linear regression models were fitted to the data. We interpreted 181 scans for 181 individuals having a mean age of 55 years (18-89). The most common site of aortic bifurcation was at L4-L5 disc space (34.8%) and that of vena confluence was at the upper of L5 (29.3%). The mean LLA was 34.65° (13°-77°). The mean aortic bifurcation angle was 47.43° (17°-100°) and the mean IVC confluence angle was 71.86° (30°-120°). The positions of the aortic bifurcation and venous confluence levels showed a proximal shift with an increasing LLA P < 0.001. This study showed that the level of bifurcation of the aorta and the level of confluence of the IVC may vary with the variations of the LLA.

Fibula stress fracture mimicking a malignancy.

Stress fractures may be easily misdiagnosed as another entity, especially tumors, which may prompt very severe surgical treatment and sometimes amputation. The appropriate use of modern radiography may make the difference in proper diagnosis of stress fractures.