Safety and histopathologic yield of percutaneous CT-guided biopsies of the skull base, orbit, and calvarium.

PURPOSE: Although CT-guided biopsies of the calvarium, skull base, and orbit are commonly performed, the best approaches, efficacy, and safety of such procedures remain scantly described in the literature. This retrospective review of percutaneous biopsies illustrates several approaches to challenging biopsy targets and provides a review of procedural planning considerations and histopathologic yield. METHODS: A retrospective review of CT-guided biopsies of the skull base, calvarium, and orbit between 1/1/2010 and 10/30/2020 was conducted. Patient demographics and procedural factors were recorded, including lesion size and location, biopsy approach, and needle gauge. Outcomes were also noted, including CT dose length product, complications, and histopathologic yield. RESULTS: Sixty-one CT-guided biopsies were included in the final analysis: 34 skull base, 23 calvarial, and 4 orbital lesions. The initial diagnostic yield was 32/34 (94%) for skull base lesions, with one false-negative and one non-diagnostic sample. Twenty-one of twenty-three (91%) biopsies in the calvarium were initially diagnostic, with one false-negative and one non-diagnostic sample. In the orbit, 4/4 biopsies were diagnostic. The total complication rate for the cohort was 4/61 (6.6%). Three complications were reported in skull base procedures (2 immediate and 1 delayed). A single complication was reported in a calvarial biopsy, and no complications were reported in orbital biopsies. CONCLUSION: Percutaneous CT-guided core needle biopsies can be performed safely and with a high diagnostic yield for lesions in the skull base, calvarium, and orbit.

Clinical applications of photon counting detector CT.

The X-ray detector is a fundamental component of a CT system that determines the image quality and dose efficiency. Until the approval of the first clinical photon-counting-detector (PCD) system in 2021, all clinical CT scanners used scintillating detectors, which do not capture information about individual photons in the two-step detection process. In contrast, PCDs use a one-step process whereby X-ray energy is converted directly into an electrical signal. This preserves information about individual photons such that the numbers of X-ray in different energy ranges can be counted. Primary advantages of PCDs include the absence of electronic noise, improved radiation dose efficiency, increased iodine signal and the ability to use lower doses of iodinated contrast material, and better spatial resolution. PCDs with more than one energy threshold can sort the detected photons into two or more energy bins, making energy-resolved information available for all acquisitions. This allows for material classification or quantitation tasks to be performed in conjunction with high spatial resolution, and in the case of dual-source CT, high pitch, or high temporal resolution acquisitions. Some of the most promising applications of PCD-CT involve imaging of anatomy where exquisite spatial resolution adds clinical value. These include imaging of the inner ear, bones, small blood vessels, heart, and lung. This review describes the clinical benefits observed to date and future directions for this technical advance in CT imaging. KEY POINTS: • Beneficial characteristics of photon-counting detectors include the absence of electronic noise, increased iodine signal-to-noise ratio, improved spatial resolution, and full-time multi-energy imaging. • Promising applications of PCD-CT involve imaging of anatomy where exquisite spatial resolution adds clinical value and applications requiring multi-energy data simultaneous with high spatial and/or temporal resolution. • Future applications of PCD-CT technology may include extremely high spatial resolution tasks, such as the detection of breast micro-calcifications, and quantitative imaging of native tissue types and novel contrast agents.

Seeing More with Less: Clinical Benefits of Photon-counting Detector CT.

Photon-counting detector (PCD) CT is an emerging technology that has led to continued innovation and progress in diagnostic imaging after it was approved by the U.S. Food and Drug Administration for clinical use in September 2021. Conventional energy-integrating detector (EID) CT measures the total energy of x-rays by converting photons to visible light and subsequently using photodiodes to convert visible light to digital signals. In comparison, PCD CT directly records x-ray photons as electric signals, without intermediate conversion to visible light. The benefits of PCD CT systems include improved spatial resolution due to smaller detector pixels, higher iodine image contrast, increased geometric dose efficiency to allow high-resolution imaging, reduced radiation dose for all body parts, multienergy imaging capabilities, and reduced artifacts. To recognize these benefits, diagnostic applications of PCD CT in musculoskeletal, thoracic, neuroradiologic, cardiovascular, and abdominal imaging must be optimized and adapted for specific diagnostic tasks. The diagnostic benefits and clinical applications resulting from PCD CT in early studies have allowed improved visualization of key anatomic structures and radiologist confidence for some diagnostic tasks, which will continue as PCD CT evolves and clinical use and applications grow. ©RSNA, 2023 Quiz questions for this article are available in the supplemental material. See the invited commentary by Ananthakrishnan in this issue.

Safety profile and technical success rate of computed tomography-guided atlanto-axial lateral articulation injections.

OBJECTIVE: To describe the technique, safety profile, and outcome of computed tomography (CT)-guided atlanto-axial lateral articulation injections performed at our institution. METHODS: Consecutive cases of all CT-guided atlanto-axial injections performed from January 2017 to April 2022 at our institution were searched in the electronic medical records. Patient charts were reviewed for demographics, characterization of pain, potential altered anatomy, pain level before and immediately after the procedure, procedure technique, complications, and follow-up outcomes, if available. RESULTS: Forty-five injections in 40 different patients were included. The average age was 67.4 years, and 28 (70%) of the patients were female. Of the 45 injections, 43 (96%) were technically successful. The average change in pain score (0-10) from immediately before to immediately after the injection was -3.36 (SD = 2.87, range = -8 to +3). Of all injections, 14 (31%) had a postprocedural pain score of zero. In 2 cases (4%), patients reported an increase in pain score immediately after the injection. In 3 cases (7%), transient non-vertebral artery vascular uptake of contrast was documented during the procedure, which could be cleared with needle repositioning. There were no complications. CONCLUSION: CT-guided atlanto-axial lateral articulation injection is a safe procedure with a high technical success rate. It allows for direct visualization of vital structures and provides an alternative option to the traditional fluoroscopic guidance, especially in cases of prior technically unsuccessful fluoroscopically guided injection or altered anatomy.

First Clinical Photon-counting Detector CT System: Technical Evaluation.

Background The first clinical CT system to use photon-counting detector (PCD) technology has become available for patient care. Purpose To assess the technical performance of the PCD CT system with use of phantoms and representative participant examinations. Materials and Methods Institutional review board approval and written informed consent from four participants were obtained. Technical performance of a dual-source PCD CT system was measured for standard and high-spatial-resolution (HR) collimations. Noise power spectrum, modulation transfer function, section sensitivity profile, iodine CT number accuracy in virtual monoenergetic images (VMIs), and iodine concentration accuracy were measured. Four participants were enrolled (between May 2021 and August 2021) in this prospective study and scanned using similar or lower radiation doses as their respective clinical examinations performed on the same day using energy-integrating detector (EID) CT. Image quality and findings from the participants' PCD CT and EID CT examinations were compared. Results All standard technical performance measures met accreditation and regulatory requirements. Relative to filtered back-projection reconstructions, images from iterative reconstruction had lower noise magnitude but preserved noise power spectrum shape and peak frequency. Maximum in-plane spatial resolutions of 125 and 208 µm were measured for HR and standard PCD CT scans, respectively. Minimum values for section sensitivity profile full width at half maximum measurements were 0.34 mm (0.2-mm nominal section thickness) and 0.64 mm (0.4-mm nominal section thickness) for HR and standard PCD CT scans, respectively. In a 120-kV standard PCD CT scan of a 40-cm phantom, VMI iodine CT numbers had a mean percentage error of 5.7%, and iodine concentration had root mean squared error of 0.5 mg/cm3, similar to previously reported values for EID CT. VMIs, iodine maps, and virtual noncontrast images were created for a coronary CT angiogram acquired with 66-msec temporal resolution. Participant PCD CT images showed up to 47% lower noise and/or improved spatial resolution compared with EID CT. Conclusion Technical performance of clinical photon-counting detector (PCD) CT is improved relative to that of a current state-of-the-art CT system. The dual-source PCD geometry facilitated 66-msec temporal resolution multienergy cardiac imaging. Study participant images illustrated the effect of the improved technical performance. © RSNA, 2022 Online supplemental material is available for this article. See also the editorial by Willemink and Grist in this issue.

Successful fusion versus pseudarthrosis after spinal instrumentation: a comprehensive imaging review.

PURPOSE: Following spinal instrumentation and fusion, differentiating between successful arthrodesis and pseudoarthrosis on imaging can be challenging. Interpretation of such examinations requires understanding both the expected evolution of postoperative findings and the subtle indicators of pseudoarthrosis across multiple imaging modalities. Due to this level of intricacy, many clinicians lack familiarity with the subject beyond the more rudimentary concepts. METHODS: This review provides an in-depth overview of the imaging of the post-operative spine, with particular emphasis on differentiating between pseudoarthrosis and arthrodesis. RESULTS: A comprehensive overview of imaging of the post-operative spine is given, including the most common imaging modalities utilized, the expected post-operative findings, imaging findings in pseudoarthrosis, and imaging definitions of fusion. CONCLUSION: Differentiating between pseudoarthrosis and arthrodesis in the postoperative spine is complex, and requires a robust understanding of various findings across many different modalities.

Lateral decubitus dynamic CT myelography for fast cerebrospinal fluid leak localization.

Dynamic CT myelography is used to precisely localize fast spinal CSF leaks. The procedure is most commonly performed in the prone position, which successfully localizes most fast ventral leaks. We have recently encountered a small subset of patients in whom prone dynamic CT myelography is unsuccessful in localizing leaks. We sought to determine the added value of lateral decubitus dynamic CT myelography, which is occasionally attempted in our practice, in localizing the leak after failed prone dynamic CT myelography. We retrospectively identified 6 patients who underwent lateral decubitus dynamic CT myelography, which was performed in each case because their prone dynamic CT myelogram was unrevealing. Two neuroradiologists independently reviewed preprocedural spine MRI and all dynamic CT myelograms for each patient. Lateral decubitus positioning allowed for precise leak localization in all 6 patients. Five of six patients were noted to have dorsal and/or lateral epidural fluid collections on spine MRI. One patient had a single prominent diverticulum on spine MRI (larger than 6 mm), whereas the others had no prominent diverticula. Our study suggests that institutions performing dynamic CT myelography to localize fast leaks should consider a lateral decubitus study if performing the study in the prone position is unrevealing. Furthermore, the presence of dorsal and/or lateral epidural fluid collections on spine MRI may suggest that a lateral decubitus study is of higher yield and could be considered initially.

Injection into the Space of Okada During Transforaminal Epidural Steroid Injections.

OBJECTIVE: Ensuring medication delivery to the epidural space is crucial for effective transforaminal epidural steroid injections. Epidural needle placement is determined by injecting a small amount of contrast at the final needle position. The purpose of this study is to illustrate the appearance of contrast flow in the retrodural retroligamentous space of Okada during computed tomography- and fluoroscopy-guided cervical and lumbar transforaminal epidural steroid injections. DESIGN: This retrospective study will use a series of cases to demonstrate contrast within the space of Okada during epidural transforaminal steroid injections. SETTING: Tertiary medical center. SUBJECTS: Study subjects are adult patients who underwent transforaminal epidural steroid injection at our institution. METHODS: Cases were identified through the use of a search engine of existing radiology reports at our institution. Epidural steroid injection procedural reports were searched for the terms "Okada" and "retrodural space." Images from the procedure were reviewed by the authors (all proceduralists with dedicated training in spinal injections) to confirm the presence of contrast within the space of Okada. RESULTS: This case series illustrates six examples of contrast injection into the retrodural space of Okada during cervical and lumbar transforaminal epidural steroid injections. CONCLUSIONS: Contrast uptake in the retrodural space of Okada may be seen during transforaminal epidural injections. Although relatively uncommon, it is likely underrecognized. It is extremely important that providers who perform transforaminal epidural steroid injections be familiar with this non-epidural contrast flow pattern so they can adjust needle positioning to deliver steroid to the epidural space.

Evaluation of hearing loss in young adults after exposure to 3.0T MRI with standard hearing protection.

Standard clinical protocols require hearing protection during magnetic resonance imaging (MRI) for patient safety. This investigation prospectively evaluated the auditory function impact of acoustic noise exposure during a 3.0T MRI in healthy adults. Twenty-nine participants with normal hearing underwent a comprehensive audiologic assessment before and immediately following a clinically indicated head MRI. Appropriate hearing protection with earplugs (and pads) was used per standard of practice. To characterize noise hazards, current sound monitoring tools were used to measure levels of pulse sequences measured. A third audiologic test was performed if a significant threshold shift (STS) was identified at the second test, within 30 days post MRI. Some sequences produced high levels (up to 114.5 dBA; 129 dB peak SPL) that required hearing protection but did not exceed 100% daily noise dose. One participant exhibited an STS in the frequency region most highly associated with noise-induced hearing loss. No participants experienced OSHA-defined STS in either ear. Overall, OAE measures did not show evidence of changes in cochlear function after MRI. In conclusion, hearing threshold shifts associated with hearing loss or OAE level shifts reflecting underlying cochlear damage were not detected in any of the 3.0T MRI study participants who used the current recommended hearing protection.

Intracranial long-term complications of radiation therapy: an image-based review.

BACKGROUND AND PURPOSE: Radiation therapy is commonly utilized in the majority of solid cancers and many hematologic malignancies and other disorders. While it has an undeniably major role in improving cancer survival, radiation therapy has long been recognized to have various negative effects, ranging from mild to severe. In this manuscript, we review several intracranial manifestations of therapeutic radiation, with particular attention to those that may be encountered by radiologists. METHODS: We conducted an extensive literature review of known complications of intracranial radiation therapy. Based on this review, we selected complications that had salient, recognizable imaging findings. We searched our imaging database for illustrative examples of these complications, focusing only on patients who had a history of intracranial radiation therapy. We then selected cases that best exemplified expected imaging findings in these entities. RESULTS: Based on our initial literature search and imaging database review, we selected cases of radiation-induced meningioma, radiation-induced glioma, cavernous malformation, enlarging perivascular spaces, leukoencephalopathy, stroke-like migraine after radiation therapy, Moyamoya syndrome, radiation necrosis, radiation-induced labyrinthitis, optic neuropathy, and retinopathy. Although retinopathy is not typically apparent on imaging, it has been included given its clinical overlap with optic neuropathy. CONCLUSIONS: We describe the clinical and imaging features of selected sequelae of intracranial radiation therapy, with a focus on those most relevant to practicing radiologists. Knowledge of these complications and their imaging findings is important, because radiologists play a key role in early detection of these entities.

The Use of Contrast Agents in Interventional Pain Procedures: A Multispecialty and Multisociety Practice Advisory on Nephrogenic Systemic Fibrosis, Gadolinium Deposition in the Brain, Encephalopathy After Unintentional Intrathecal Gadolinium Injection, and Hypersensitivity Reactions.

This Practice Advisory presents a comprehensive and evidence-based set of position statements and recommendations for the use of contrast media in interventional pain procedures. The advisory was established by an international panel of experts under the auspices of 11 multinational and multispecialty organizations based on a comprehensive review of the literature up to December 31, 2019. The advisory discusses the risks of using gadolinium-based contrast agents. These include nephrogenic systemic fibrosis, gadolinium brain deposition/retention, and encephalopathy and death after an unintentional intrathecal gadolinium injection. The advisory provides recommendations on the selection of a specific gadolinium-based contrast agent in patients with renal insufficiency, those who had multiple gadolinium-enhanced magnetic resonance imaging examinations, and in cases of paraspinal injections. Additionally, recommendations are made for patients who have a history of mild, moderate, or severe hypersensitivity reactions to contrast medium.

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.

Clinical presentation, natural history and outcomes of intramedullary spinal cord cavernous malformations.

OBJECTIVE: There is a paucity of literature investigating the clinical course of patients with spinal intramedullary cavernous malformations (ISCMs). We present a large case series of ISCMs to describe clinical presentation, natural history and outcomes of both surgical and conservative management. METHODS: We retrospectively reviewed the clinical course of patients diagnosed with ISCMs at our institution between 1995 and 2016. Haemorrhage was defined as clinical worsening in tandem with imaging changes visualised on follow-up MRI. Outcomes assessed included neurological status and annual haemorrhage rates. RESULTS: A total of 107 patients met inclusion criteria. Follow-up data were available for 85 patients. While 21 (24.7%) patients underwent immediate surgical resection, 64 (75.3%) were initially managed conservatively. Among this latter group, 16 (25.0%) suffered a haemorrhage during follow-up and 11 (17.2%) required surgical resection due to interval bleeding or neurological worsening. The overall annual risk of haemorrhage was 5.5% per person year. The rate among patients who were symptomatic and asymptomatic on presentation was 9.5% and 0.8%, respectively. Median time to haemorrhage was 2.3 years (0.1-12.3). Univariate analysis identified higher ISCM size (p=0.024), history of prior haemorrhage (p=0.013) and presence of symptoms (p=0.003) as risk factors for subsequent haemorrhage. Multivariable proportional hazards analysis revealed presence of symptoms to be independently associated with haemorrhage during follow-up (HR 9.39, CI 1.86 to 170.8, p=0.013). CONCLUSION: Large, symptomatic ISCMs appear to be at increased risk for subsequent haemorrhage. Surgery may be considered in such lesions to prevent rebleeding and subsequent neurological worsening.

Unilateral Epidural Targeting of Resiniferatoxin Induces Bilateral Neurolysis of Spinal Nociceptive Afferents.

OBJECTIVE: This study modeled image-guided epidural drug delivery to test whether intraprocedural distribution of pre-injected contrast reliably predicts the neuroanatomical reach of resiniferatoxin-mediated nociceptive neurolysis. METHODS: Swine (N = 12) received unilateral L4-S2 computed tomography fluoroscopy injections by a blinded neuroradiologist; 0.25 mL of contrast was pre-injected to confirm dorsal periganglionic targeting, followed by a 0.5-mL injection of 5 µg of resiniferatoxin/Tween80 or vehicle control. Epidural contrast distribution was graded according to maximum medial excursion. Spinal cord substance P immunostaining quantified the magnitude and anatomical range of resiniferatoxin activity. RESULTS: Periganglionic injection was well tolerated by all animals without development of neurological deficits or other complications. Swine were a suitable model of human clinical spinal intervention. The transforaminal approach was used at all L4 and 50% of L5 segments; the remaining segments were approached by the interlaminar route. All injections were successful with unilateral contrast distribution for all resiniferatoxin injections (N = 28). Immunohistochemistry showed bilateral ablation of substance P+ fibers entering the spinal cord of all resiniferatoxin-treated segments. The intensity of substance P immunostaining in treated segments fell below the lower 99% confidence interval of controls, defining the knockout phenotype. Substance P knockout occurred over a narrow range and was uncorrelated to the anatomical distribution of pre-injected contrast. CONCLUSIONS: Periganglionic resiniferatoxin/Tween80 induced bilateral ablation of spinal cord substance P despite exclusively unilateral targeting. These data suggest that the location of pre-injected contrast is an imperfect surrogate for the neuroanatomical range of drugs delivered to the dorsal epidural compartment that may fail to predict contralateral drug effects.

A randomized trial of epidural glucocorticoid injections for spinal stenosis.

BACKGROUND: Epidural glucocorticoid injections are widely used to treat symptoms of lumbar spinal stenosis, a common cause of pain and disability in older adults. However, rigorous data are lacking regarding the effectiveness and safety of these injections. METHODS: In a double-blind, multisite trial, we randomly assigned 400 patients who had lumbar central spinal stenosis and moderate-to-severe leg pain and disability to receive epidural injections of glucocorticoids plus lidocaine or lidocaine alone. The patients received one or two injections before the primary outcome evaluation, performed 6 weeks after randomization and the first injection. The primary outcomes were the score on the Roland-Morris Disability Questionnaire (RMDQ, in which scores range from 0 to 24, with higher scores indicating greater physical disability) and the rating of the intensity of leg pain (on a scale from 0 to 10, with 0 indicating no pain and 10 indicating "pain as bad as you can imagine"). RESULTS: At 6 weeks, there were no significant between-group differences in the RMDQ score (adjusted difference in the average treatment effect between the glucocorticoid-lidocaine group and the lidocaine-alone group, -1.0 points; 95% confidence interval [CI], -2.1 to 0.1; P=0.07) or the intensity of leg pain (adjusted difference in the average treatment effect, -0.2 points; 95% CI, -0.8 to 0.4; P=0.48). A prespecified secondary subgroup analysis with stratification according to type of injection (interlaminar vs. transforaminal) likewise showed no significant differences at 6 weeks. CONCLUSIONS: In the treatment of lumbar spinal stenosis, epidural injection of glucocorticoids plus lidocaine offered minimal or no short-term benefit as compared with epidural injection of lidocaine alone. (Funded by the Agency for Healthcare Research and Quality; ClinicalTrials.gov number, NCT01238536.).

Nested Cohort Study to Identify Characteristics That Predict Near-Term Disablement From Lung Cancer Brain Metastases.

OBJECTIVE: To test whether the presence of patient- and imaging-level characteristics (1) are associated with clinically meaningful changes in mobility among patients with late-stage cancer with metastatic brain involvement, and (2) can predict their risk of near-term functional decline. DESIGN: Prospective nested cohort study. SETTING: Quaternary academic medical center. PARTICIPANTS: The study population consisted of a nested cohort of the patients with imaging-confirmed brain metastases (n=66) among a larger cohort of patients with late-stage lung cancer (N=311). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Functional evaluations with the Activity Measure for Post-Acute Care Computer Adaptive Test (AM-PAC-CAT) and symptom intensity ratings were collected at monthly intervals for up to 2 years. RESULTS: In exploratory univariate models, whole brain radiation therapy (WBRT) and imaging findings of cerebellar or brainstem involvement were associated with large AM-PAC-CAT score declines reflecting worsening mobility (-4.55, SE 1.12; -2.87, SE, 1.0; and -3.14, SE 1.47, respectively). Also in univariate models, participants with new neurologic signs or symptoms at imaging (-2.48; SE .99), new brain metastases (-2.14, SE .99), or new and expanding metastases (-2.64, SE 1.14) declined significantly. Multivariate exploratory mixed logistic models, including WBRT, cerebellar/brainstem location, presence of new and expanding metastases, and worst pain intensity, had excellent predictive capabilities for AM-PAC-CAT score declines of 7.5 and 10 points (C statistics ≥0.8). CONCLUSIONS: Among patients with lung cancer and brain metastases, cerebellar/brainstem location, new and expanding metastases, and treatment with WBRT may predict severe, near-term mobility losses and indicate a need to consider rehabilitation services.

Long-Term Effects of Repeated Injections of Local Anesthetic With or Without Corticosteroid for Lumbar Spinal Stenosis: A Randomized Trial.

OBJECTIVE: To determine the overall long-term effectiveness of treatment with epidural corticosteroid injections for lumbar central spinal stenosis and the effect of repeat injections, including crossover injections, on outcomes through 12 months. DESIGN: Multicenter, double-blind, randomized controlled trial comparing epidural injections of corticosteroid plus lidocaine versus lidocaine alone. SETTING: Sixteen clinical sites. PARTICIPANTS: Participants with imaging-confirmed lumbar central spinal stenosis (N=400). INTERVENTIONS: Participants were randomized to receive either epidural injections with corticosteroid plus lidocaine or lidocaine alone with the option of blinded crossover after 6 weeks to receive the alternate treatment. Participants could receive 1 to 2 injections from 0 to 6 weeks and up to 2 injections from 6 to 12 weeks. After 12 weeks, participants received usual care. MAIN OUTCOME MEASURES: Primary outcomes were the Roland-Morris Disability Questionnaire (RDQ) (range, 0-24, where higher scores indicate greater disability) and leg pain intensity (range, 0 [no pain] to 10 [pain as bad as you can imagine]). Secondary outcomes included opioid use, spine surgery, and crossover rates. RESULTS: At 12 months, both treatment groups maintained initial observed improvements, with no significant differences between groups on the RDQ (adjusted mean difference, -0.4; 95% confidence interval [CI], -1.6 to 0.9; P=.55), leg pain (adjusted mean difference, 0.1; 95% CI, -0.5 to 0.7; P=.75), opioid use (corticosteroid plus lidocaine: 41.4% vs lidocaine alone: 36.3%; P=.41), or spine surgery (corticosteroid plus lidocaine: 16.8% vs lidocaine alone: 11.8%; P=.22). Fewer participants randomized to corticosteroid plus lidocaine (30%, n=60) versus lidocaine alone (45%, n=90) crossed over after 6 weeks (P=.003). Among participants who crossed over at 6 weeks, the 6- to 12-week RDQ change did not differ between the 2 randomized treatment groups (adjusted mean difference, -1.0; 95% CI, -2.6 to 0.7; P=.24). In both groups, participants crossing over at 6 weeks had worse 12-month trajectories compared with participants who did not choose to crossover. CONCLUSIONS: For lumbar spinal stenosis symptoms, epidural injections of corticosteroid plus lidocaine offered no benefits from 6 weeks to 12 months beyond that of injections of lidocaine alone in terms of self-reported pain and function or reduction in use of opioids and spine surgery. In patients with improved pain and function 6 weeks after initial injection, these outcomes were maintained at 12 months. However, the trajectories of pain and function outcomes after 3 weeks did not differ by injectate type. Repeated injections of either type offered no additional long-term benefit if injections in the first 6 weeks did not improve pain.