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Spontaneous intracranial hypotension (SIH) is associated with cerebrospinal fluid (CSF) hypovolemia, often from a traumatic dural tear from a calcified spinal osteophyte. Visualizing osteophytes on CT imaging can guide decision making on candidate leak sites. We report the atypical case of a 41-year-old woman whose ventral CSF leak was associated with an osteophyte that resorbed over an 18-month period. Full workup and treatment were delayed due to unexpected pregnancy and completion of gestational cycle with delivery of a healthy term infant. The patient initially presented with persistent orthostatic headaches with nausea and blurred vision. Initial MRI suggested brain sagging among other findings consistent with SIH. CT myelogram showed an extensive thoracic CSF leak with a prominent ventral T11-T12 osteophyte and multiple small disc herniations. The patient did not respond to epidural blood patches and deferred additional imaging due to her pregnancy. CT myelography performed 5 months post-partum showed an absence of the osteophyte; a follow-up digital subtraction myelogram performed 10 months post-partum showed evidence of source leak at T11-T12 level. T11-T12 laminectomy visualized and repaired a 5 mm ventral dural defect with symptom resolution. This report highlights the potential for a resorbed osteophyte to be the causative agent for long-standing dural tears that do not show visible calcifications on myelography., Competing Interests: Declaration of conflicting interestsThe author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: Dr Robbins serves on the Board of Directors of the American Headache Society and the New York State Neurological Society, the editorial boards of Continuum and Current Pain and Headache Reports, and receives book royalties from Wiley.

Competing Interests: Competing interests: None declared.

We propose a modified dynamic CT-myelography technique for patients with fast CSF leaks caused by ventral dural tears in order to reduce radiation exposure and complications. A fluoroscopy-guided lumbar puncture using an epidural anesthesia kit replaces a CT-guided lumbar puncture, and a smaller volume of less concentrated contrast media is used. This approach has advantages, including speeding up the procedure, reduced radiation exposure, and elimination of the risk of contrast injection into the epidural space., Competing Interests: Declaration of Competing Interest All authors declare that they have no conflict of interest., (Copyright © 2023 The Author(s). Published by Elsevier Masson SAS.. All rights reserved.)

Background: We report the first case series of spontaneous intracranial hypotension (SIH) patients who underwent CT-guided percutaneous cyanoacrylate injection targeting the cerebrospinal fluid (CSF) leak., Methods: A retrospective analysis was performed for all consecutive cases of SIH patients with CSF leak confirmed on CT myelography, treated by CT-guided percutaneous cyanoacrylate injection at our institution from 2016 to 2022. On pretreatment brain and spine MRIs, we analyzed signs of SIH according to the Bern score, and dichotomized cases into positive/negative for spinal longitudinal extradural CSF collection (SLEC-P or SLEC-N). The leaks detected on CT myelography were classified into three types according to Schievink et al . We collected the Headache Impact Test 6 (HIT-6) scores throughout a 6-month follow-up, with a brain CT scan at each visit., Results: 11 patients were included (mean age 48.4 years, six men). Five SLEC-P type 1, three SLEC-P type 2, and three SLEC-N type 3 leaks were identified. All patients had significant signs of SIH on pretreatment brain MRI (mean Bern score 7.8±1.1). Six patients underwent a foraminal puncture, and five patients had a cervical epidural approach. Two patients experienced mild and transient locoregional pain after cervical epidural injection. Mean HIT-6 score at baseline was 66.8±3.2 and at the 6-month follow-up was 38±3.6 (P<0.001). All patients achieved improvement in their symptoms, with 82% of them (9/11) having complete resolution of headaches and SIH findings on CT scans at 6 months. No clinical worsening or recurrence was observed., Conclusions: CT-guided percutaneous cyanoacrylate injection may be a potential therapeutic option for the different types of CSF leak causing SIH., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2024. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Postoperative spinal cerebrospinal fluid (CSF) leaks are common but rarely cause extensive CSF collections that require specialized imaging to detect the site of the dural breach., Objective: To investigate the use of digital subtraction myelography (DSM) for patients with extensive extradural CSF collections after spine surgery., Methods: A retrospective review was performed to identify a consecutive group of patients with extensive postoperative spinal CSF leaks who underwent DSM., Results: Twenty-one patients (9 men and 12 women) were identified. The mean age was 46.7 years (range, 17-75 years). The mean duration of the postoperative CSF leak was 3.3 years (range, 3 months to 21 years). MRI showed superficial siderosis in 6 patients. DSM showed the exact location of the CSF leak in 19 (90%) of the 21 patients. These 19 patients all underwent surgery to repair the CSF leak, and the location of the CSF leak could be confirmed intraoperatively in all 19 patients. In 4 (19%) of the 21 patients, DSM also showed a CSF-venous fistula at the same location as the postoperative dural tear., Conclusion: In this study, DSM had a 90% detection rate of visualizing the exact site of the dural breach in patients with extensive postoperative spinal CSF leaks. The coexistence of a CSF-venous fistula in addition to the primary dural tear was present in about one-fifth of patients. The presence of a CSF-venous fistula should be considered if CSF leak symptoms persist in spite of successful repair of a durotomy., (Copyright © Congress of Neurological Surgeons 2023. All rights reserved.)

Background: Transvenous embolization is a new treatment for spinal cerebrospinal fluid (CSF)-venous fistula, with only 1 reported large case series from the center that invented this technique., Methods: We report the clinical and radiographic data of 5 consecutive patients who were diagnosed with CSF-venous fistula at a single community-academic medical center and were treated with transvenous embolization. All patients provided consent for this report. Institutional review board approval was not required because of the retrospective nature of this study describing standards of care., Results: Five patients, 3 men and 2 women, with a median age of 57 years, were diagnosed between March and December 2021with spontaneous intracranial hypotension (SIH) as a result of CSF-venous fistula. Two patients were originally referred for middle meningeal artery embolization for chronic subdural hematoma. All fistulae were in the thoracic spine at a single level in 3 patients, 2 levels in 1 patient, and multiple levels in 1 patient. Transvenous embolization was technically successful in all cases, with no significant complications. Four patients (80%) had complete or near-complete resolution of clinical symptoms and returned to baseline function and employment status. One patient (20%) has had a remitting relapsing course. Posttreatment brain magnetic resonance imaging showed resolution of spontaneous intracranial hypotension findings in 4 patients (80%) and minimal changes in 1 patient (20%), who had significant clinical improvement., Conclusions: Transvenous embolization for the treatment of CSF-venous fistula is feasible and seems effective in the short-term. The results reported by the previous case series can be reproduced in other centers with available expertise and adherence to published diagnostic and treatment protocols., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: We report outcomes of spontaneous intracranial hypotension (SIH) patients who underwent transvenous embolization of cerebrospinal fluid-venous fistulas (CSFVFs) confirmed on digital subtraction myelography (DSM) performed at our institution., Methods: This is a retrospective evaluation of a prospectively collected database of SIH patients who underwent transvenous embolization of CSFVFs. Only patients who had fistulas confirmed on DSM performed at our institution were included. All patients had a baseline MRI and an MRI performed at least 90 days post-embolization, as well as clinical evaluation using the six item Headache Impact Test (HIT-6) and the Patient Global Impression of Change (PGIC) scales. Paired t-test was used to report changes in Bern MRI scores and HIT-6 scores at follow-up., Results: 40 patients were included (29 female, 11 male). Mean age was 57.4±10.3 years. Mean Bern score improved from 5.7±3.0 at baseline to 1.3±2.0 at follow-up (p<0.0001). Mean HIT-6 score at baseline was 67.2±11.1 and at follow-up was 41.5±10.1 (p<0.0001). Median PGIC was 1, with 36 patients (90.0%) reporting at least minimal improvement and 32 patients (82.5%) reporting much or very much improvement. Complications included persistent local site pain in 12 patients (30%), suspected rebound intracranial hypertension requiring medical intervention in 7 patients (17.5%), and asymptomatic tiny Onyx emboli to the lungs in 3 patients (7.5%)., Conclusions: Transvenous embolization of CSFVFs using Onyx is safe and effective, resulting in significant improvement in headache and overall clinical outcomes in nearly 90% of patients, and substantial improvements in brain MRI abnormalities., Competing Interests: Competing interests: WB consultant for Medtronic, Microvention, Stryker, Cerenovus, MIVI. No other financial relationships., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Cerebrospinal fluid-venous fistula is an increasingly recognized cause of spontaneous intracranial hypotension.1 The site of the leak is between the dural sleeve around a spinal nerve root and the surrounding foraminal veins. In appropriately investigated patients, transvenous embolization of the draining foraminal and paraspinal veins has been shown to be an effective way of treating the disease, with low periprocedural morbidity, improvement in symptoms and radiological appearances.2 Video 1 shows the technique employed in a typical case using Onyx (Medtronic, Minnesota, USA) to embolize a CSF-venous fistula at the right T10 neural foramen. neurintsurg;14/9/948/V1F1V1Video 1Video showing the technique for trans-venous embolization of a right T10 CSF-venous fistula for the treatment of spontaneous intracranial hypotension. The first section covers patient selection and work up, before then focusing on the technical aspects of navigating through the azygos system to the target foramen and completely occluding the pathway for CSF outflow., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

Spontaneous intracranial hypotension (SIH) is a disorder of CSF dynamics that causes a complex clinical syndrome and severe disability. SIH is challenging to diagnose because of the variability of its presenting clinical symptoms, the potential for subtle imaging findings to be easily overlooked, and the need for specialized diagnostic testing. Once SIH is suggested by clinical history and/or supported by initial neuroim-aging, many patients may undergo initial nontargeted epidural blood patching with variable and indefinite benefit. However, data suggest that precise localization of the CSF leak or CSF-venous fistula (CVF) can lead to more effective and durable treatment strategies. Leak localization can be achieved using a variety of advanced diagnostic imaging techniques, although these may not be widely performed at nontertiary medical centers, leaving many patients with the potential for inadequate workup or treatment. This review describes imaging techniques including dynamic fluoroscopic and CT myelography as well as delayed MR myelography and treatment options including percutaneous, endovascular, and surgical approaches for SIH. These are summarized by an algorithmic framework for radiologists to approach the workup and treatment of patients with suspected SIH. The importance of a multidisciplinary approach is emphasized.

Background: Intrameningeal cysts are rare lesions without definitive etiologies that can involve the dura or arachnoid mater. Spinal arachnoid cysts have been described, and several different etiologies have been hypothesized. This includes one-way valve mechanisms, traumatic herniation of arachnoid through the dura, and abnormal arachnoid membrane proliferation. To the authors' knowledge, no such descriptions exist regarding purely dural-based cystic lesions; however, the authors hypothesize similar mechanisms may be involved. Most notably, a traumatic injury to the dura leading to a one-way valve mechanism may allow for egress of cerebrospinal fluid between the dural layers, splitting them open. This progressive enlargement can lead to displacement of neural elements and subsequent neurological compromise., Methods: We describe a 17-year-old girl who presented with progressive neck and back pain, left upper-extremity numbness, bilateral lower-extremity weakness, paresthesias, and numbness without obvious etiology despite an extensive neurologic investigation. She had undergone conservative management options including multiple medications, physical and chiropractic therapy, and epidural steroid injections. Computed tomography myelography revealed a cerebrospinal fluid leak into the lumbar epidural space for which surgical exploration was performed. Despite utilizing fluoroscopy and intrathecal fluorescein, no leak source was identified. Fluid collection was found contained within the dural layers rather than the epidural space., Results: An intracystic blood patch was performed with near-complete resolution of the lesion by 6-week follow-up and near-complete return of neurologic function., Conclusions: Ventral panspinal cysts are an exceedingly rare cause of radiculopathy and myelopathy that can be resolved by an intracystic blood patch., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Objective: Spontaneous intracranial hypotension (SIH) can be effectively treated by epidural blood patch (EBP) following the primary unsuccessful conservative therapy. Nevertheless, multi-site cerebrospinal fluid (CSF) leaks or those originating at the cervical or thoracic spine remain therapeutically challenging. Therefore, this study aimed to present our experience in the treatment of thoracic CSF leaks using epidural catheters for the EBP infusion., Methods: Three patients presenting with typical orthostatic headaches were qualified for an EBP procedure. Preoperative MRI scans, myelography, and CT myelography were performed. Additionally, delayed CT myelography was repeated after 3 h to identify the CSF leakage site. Patients were followed-up clinically and radiologically for three months., Results: The CT myelography identified CSF leak at the T2-3 (case 1), T5-12 (case 2), and T3-7 level (Case 3). A 0.06" diameter lumbar drainage catheter (Case 1 and 2) or Abbot's spinal cord stimulation (SCS) catheter (Case 3) was inserted epidurally through the lower thoracic/lumbar single-entry point and advanced into the identified thoracic leak site. The average volume of injected blood was 15.7 ml. No procedure-related complications were observed, and all patients improved clinically., Conclusions: Epidural catheters remain safe and effective in treating thoracic and multi-site CSF leaks. In addition, Abbot's SCS catheter was found superior to the lumbar drainage catheter due to higher rigidity and bigger diameter despite being shorter than the lumbar drainage catheter., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)

Brain sagging dementia (BSD), caused by spontaneous intracranial hypotension (SIH), is a rare syndrome that is only recently recognized, mimicking the clinical findings of behavioral variant frontotemporal dementia (bvFTD). Being aware of its signs and symptoms is essential for early diagnosis and treatment in this potentially reversible form of dementia. Our objective was to identify cases of BSD in the literature and present its clinical characteristics, diagnostic workup, treatment options, and outcome. The review was reported according to PRISMA guidelines and registered with the PROSPERO database (CRD42020150709). MEDLINE, EMBASE, PsychINFO, and Cochrane Library were searched. There was no date restriction. The search was updated in April 2021. A total of 983 articles were screened and assessed for eligibility. Twenty-nine articles (25 case reports and 4 series) and 70 patients were selected for inclusion. No cranial leak cases were identified. BSD diagnosis should be made based on clinical signs and symptoms and radiologic findings. There is a male predominance (F:M ratio 1:4) and a peak incidence in the 6th decade of life. The main clinical manifestation is insidious onset, gradually progressive cognitive and behavioral changes characteristic for bvFTD. Headache is present in the majority of patients (89%). The presence of brain sagging and absence of frontotemporal atrophy is an absolute criterion for the diagnosis. CSF leak is identified with myelography and digital subtraction myelography. The treatment and repair depend on the etiology and extent of the dural defect, although an epidural blood patch is the first-line treatment in most cases. With treatment, 81% experienced partial and 67% complete resolution of their symptoms. This review highlights the most important clinical aspects of BSD. Due to the sparse evidence and lack of BSD awareness, many patients are likely left undiagnosed. Recognizing this condition is essential to provide early treatment to reverse the cognitive and behavioral changes that may otherwise progress and fully impair the patient. Moreover, patients with longstanding SIH must be assessed carefully for cognitive and behavioral changes., (© 2022 American Academy of Neurology.)

Syndrome of spontaneous intracranial hypotension is increasingly described in the literature as a multifactorial disease with impairment of the quality of life and risk of mortality. CSF-venous fistula as a cause of intracranial hypotension syndrome is extremely rare and requires complex diagnosis and timely surgical treatment., Objective: We present a 55-year-old patient with acute spontaneous intracranial hypotension and spinal CSF-venous fistula. Literature data are also analyzed., Results: Algorithm for diagnosis and efficacy of microsurgical resection of CSF-venous fistula is demonstrated., Conclusion: Intracranial hypotension following spinal fistula requires careful examination. Accurate understanding of pathophysiological and anatomical features of this disease is necessary to select an effective treatment method.

Study Design: A retrospective study of prospectively collected data., Objective: This study aimed to examine how radiological parameters affect dynamic changes in the cross-sectional area of the spinal cord (CSA) in cervical spondylotic myelopathy (CSM) patients and how they correlate with the severity of myelopathy, by evaluating multi-modal spinal cord evoked potentials (SCEPs)., Summary of Background Data: Appropriate assessments of dynamic factors should reveal hidden spinal cord compression and provide useful information for choosing surgical procedures., Methods: Seventy-nine CSM patients were enrolled. They were examined with kinematic CT myelography (CTM), and the spinal levels responsible for their CSM were determined via SCEP examinations. The C2-7 angle, C2-7 range of motion, and percentage of slip were measured on the midsagittal view during flexion and extension, and the CSA was measured on the axial view in each neck position using kinematic CTM. The patients who exhibited the smallest CSA values during extension and flexion were classified into Groups E and F, respectively., Results: Fifty-two (65.8%) and 27 (34.2%) cases were included in Groups E and F, respectively. The preoperative JOA score did not differ significantly between the groups; however, the preoperative lower-limb JOA score of Group F was significantly lower than that of Group E (2.24 ± 0.82 vs. 2.83 ± 1.09, P = 0.016). In the multiple logistic regression analysis, a small C2-7 angle during extension (β = 5°, odds ratio: 0.69, 95% confidence interval [CI]: 0.54-0.90) and the slip percentage during flexion (β = 5%, odds ratio: 1.42, 95% CI: 1.09-1.85) were identified as significant predictors of belonging to Group F., Conclusion: Exhibiting more severe spinal cord compression during neck flexion was associated with a small C2-7 angle and anterior spondylolisthesis. The neurological status of the patients in Group F was characterized by severe lower limb dysfunction because of a disturbed blood supply to the anterior column.Level of Evidence: 4., (Copyright © 2020 Wolters Kluwer Health, Inc. All rights reserved.)

Transient spinal shock is a previously unreported complication of intrathecal contrast. A 63-year-old man presented with the chief complaint of worsening back pain. Computed topography of lumbar spine without contrast showed a lytic lesion. After international normalized ratio (INR) correction, patient was sent for CT myelogram. After intrathecal contrast injection, the patient dropped his blood pressure profoundly and developed clinical manifestations of spinal shock. Emergent intravenous bolus fluids were initiated resulting in improvement in blood pressure. Patient's spinal shock resolved within hours. CT myelogram was normal except previously known lytic lesion. It was concluded that the transient shock was most likely due to contrast injection. We believe that this is the first reported case of transient spinal shock following CT myelogram using water-soluble iodinated non-ionic contrast agent administered intrathecally., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.)

Background: Gastroesophageal reflux (GER) has been reported to be a common finding in dogs under general anesthesia., Objectives: The aim of this retrospective study was to assess the esophageal and gastric contents in a population of dogs undergoing computed tomographic myelography (myelo-CT) examination and to evaluate the factors influencing the presence of esophageal fluid (gastric content, duration of anesthesia, body position, and intrinsic factors)., Methods: Esophageal and gastric contents of 83 non-brachycephalic dogs were retrospectively assessed based on plain and myelo-CT scans. Age, weight, breed, sex, and the time between the 2 computed tomography [CT] scans were included., Results: Esophageal fluid was present in 19% (16/83) of the animals, and 14% (12/83) and 46% (37/83), respectively, had fluid or food material in their stomachs. The frequency of observing esophageal fluid on myelo-CT scans was significantly increased compared with plain CT scans ( p = 0.006). The presence of gastric fluid was significantly associated with an increased frequency of observing esophageal fluid compared to other gastric contents ( p = 0.049; odds ratio, 3.1). The presence of esophageal fluid was not correlated with alimentary gastric contents ( p = 0.17). Increased body weight and duration of anesthesia were significantly associated with an increased frequency of observing esophageal fluid ( p = 0.022, p = 0.021)., Conclusions: Unlike alimentary gastric contents, fluid gastric contents were correlated with the presence of esophageal fluid upon myelo-CT. The observation of fluid in the esophagus may be consistent with GER. This study provides data additional to pH monitoring studies of GER and may support previous studies recommending shorter pre-anesthetic fasting periods in dogs., Competing Interests: The authors declare no conflicts of interest., (© 2020 The Korean Society of Veterinary Science.)

OBJECTIVE. Myelography is a commonly used procedure to evaluate the spinal canal. However, the procedure is not without risk, chiefly risk of seizure after intrathecal administration of iodinated contrast material. CONCLUSION. The risk of seizure remains an important concern for radiologists, who should strongly consider practice parameter guidelines that address this risk.

Background: Myelography, frequently supplanted by noninvasive, efficient magnetic resonance imaging, remains a useful technique when evaluating the spinal canal in nerve root avulsion, radiation therapy treatment planning, cerebrospinal fluid (CSF) loculation, and CSF leak. Myelography is achieved through a lumbar puncture and instillation of nonionic, water-soluble intrathecal iohexol (Omnipaque, GE Healthcare, Marlborough, Massachusetts, USA) contrast. The aim of the study was to highlight a possible complication of obstruction of a shunt valve due to an increased viscosity of the CSF after intrathecal Omnipaque contrast administration during myelography., Case Description: The authors report a case of myelography that resulted in obstruction of a ventriculoperitoneal (VP) shunt. A 23-year-old female with significant medical history of neurofibromatosis type I, obstructive hydrocephalus, anterior cervical diskectomy and fusion, and VP shunt placement underwent diagnostic computed tomography after myelography with Omnipaque contrast to assess possible CSF loculation and cord impingement from her cervical instrumentation. The patient experienced somnolence after myelography from obstruction of the VP shunt, with marked ventriculomegaly demonstrated by computed tomography of the head. A shunt tap and shunt pumping regimen resulted in resolution of the obstruction and hydrocephalus, with return to neurologic baseline., Conclusions: This is a recent case of VP shunt obstruction after myelography, of which previous cases reported are decades old. A shunt pumping regimen may be a nonoperative, effective mean for similar mechanical obstructions of VP shunts for restoration of flow and patency of the shunt system in these patients. We encourage physicians to consider the possibility of shunt obstruction after diagnostic myelography. Caution and close observation should be considered in patients undergoing myelography with a programmable VP shunt., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: The lumbar intrathecal (subarachnoid) space is accessed for both therapeutic and diagnostic purposes. Occasionally, the needle may unintentionally enter the intrathecal space during lumbar interlaminar epidural steroid injections (LESIs)-one of the most commonly performed medical procedures in the United States. Ordinarily, this merely constitutes a minor complication or even a desired placement (in the case of some diagnostic procedures). However, some patients have a rare condition wherein the spinal cord terminates below the L2 vertebral level (tethered cord). In such cases, injections administered at the lumbar level may potentially result in spinal cord damage and irreversible paraplegia if the physician performing the intervention does not recognize the intramedullary position of the needle., Objective: The aim of this study is to describe and analyze an unintentional L2-L3 injection of contrast medium into a tethered spinal cord. Many physicians may consider lumbar injections "safe" because the spinal cord usually terminates at or above the L2 vertebral level. However, complacency stemming from this false impression of safety contributes to nonadherence to practice guidelines, which may lead to catastrophic neurological complications. Presented here is the first published occurrence of paraplegia that resulted from contrast medium injection into the spinal cord during a myelography study performed below the L2 vertebral level., Conclusions: Disregard of the procedural guidelines by the physicians performing an elective diagnostic intervention may cause devastating neurological complications. The described casualty occurred because of failure to review previous imaging studies, injection of the contrast medium despite unsuccessful attempts to aspirate cerebrospinal fluid, and an unwillingness to terminate the procedure immediately when the patient reported an unusual sensation in both of his lower extremities. Consequently, we suggest that not only for cervical and thoracic but also for lumbar interlaminar ESIs, previous imaging studies should be reviewed before the injection., (© 2019 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Study Design: Retrospective matched cohort study., Objective: To determine if low-pressure lumbar provocation discography (PD) results in long-term accelerated disc degeneration, internal disc disruption, or disc herniation in patients with symptomatic low back pain (LBP)., Summary of Background Data: Study of subjects without clinically-significant LBP suggests that high-pressure PD may accelerate disc degeneration., Methods: Consecutive patients with symptomatic LBP who underwent magnetic resonance imaging (MRI), PD, and repeat MRI more than 7 years later, but did not undergo subsequent spinal fusion surgery, were included. Punctured discs were matched (1:2 to 1:4) to corresponding discs in a control cohort by age, BMI, Pfirrmann score (±2), and presence of disc herniation; control cohort inclusion required MRIs for symptomatic LBP, separated by more than 7 years. The primary outcome of the study was a progression in Pfirrmann score category (I-II, III-IV, V). MRI disc-to-CSF T2 signal-intensity ratio, disc height, disc herniations, high intensity zones (HIZs), and Modic changes were assessed., Results: Baseline and follow-up MRIs were available for 77 discs exposed to PD, and for 260 discs in the matched control cohort. There was no difference in the proportion of punctured discs that advanced in Pfirrmann score category in the PD group (17%, 95% CI 9-27%) compared with corresponding discs in the Control group (21%, 95% CI 17-27%), P = 0.3578, or in non-punctured discs in the PD group (35%, 95% CI 21-51%) compared with corresponding discs in the Control group (34%, 95% CI 27-42%), P = 0.1169. There were no differences in disc-to-CSF T2 signal-intensity ratio, presence of disc herniations, HIZs, or Modic changes following puncture in the PD versus matched cohort discs or in the non-punctured PD cohort discs versus corresponding control cohort discs (P > 0.05)., Conclusion: Patients with symptomatic LBP who underwent low-pressure PD, but who did not undergo a subsequent spinal fusion surgery, developed disc degeneration and new disc herniations at a similar rate to corresponding discs in matched control patients., Level of Evidence: 3.

Background: Arachnoiditis ossificans (AO) is a rare entity characterized by the presence of calcified plaques formed by the metaplasia of arachnoid cells. Over 50 cases of AO have been reported, with predisposing factors including spinal trauma, hemorrhage, vascular abnormalities, and infection. The administration of oil-based contrast during myelography as an independent risk factor or in conjunction with other spinal pathology has been described in 9 cases., Case Description: A 70-year-old woman presented for neurosurgical consultation in 2013 with a 2-year history of progressive midthoracic pain, right-sided chest wall allodynia, lower extremity weakness, and gait ataxia. Approximately 30 years ago, she received an oil-based contrast myelogram for investigation of spontaneous spinal hemorrhage. The procedure was well tolerated, and the patient experienced no allergic, hemorrhagic, traumatic, or infectious complications. No etiology was found for the spinal hemorrhage, and the patient recovered fully from that episode. Magnetic resonance imaging (MRI) of the thoracolumbar spine demonstrated multiple compressive intradural lesions in the upper thoracic spine and ventral tethering of the spinal cord at T7. MRI also demonstrated syringomyelia throughout the thoracic spine. Initially, the diagnosis of epidural mass or diastematomyelia was considered. To further characterize the epidural lesion, an unenhanced computed tomography (CT) scan was obtained, demonstrating a long segment of extensive calcification in the periphery of the thoracolumbar spine, with near-complete circumferential involvement from T5 to T11. The diagnosis of AO with extensive thoracic spine calcifications, syringomyelia, and spine cord tethering was made and confirmed at surgery., Conclusions: In addition to acute inflammation, oil-based contrast myelography also leads to arachnoiditis, calcification, and retained mass lesions because of its chronic inflammatory properties and slow resorptive rate. Three decades after its replacement with water-based contrast material, the chronic sequelae of oil-based contrast myelography may continue to manifest clinically and on CT imaging. Because of calcifications often encasing the spinal cord or nerve roots, management of AO is challenging, and neurologic deficits may persist even after surgery., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background and Purpose: There is no consensus on whether patients undergoing myelography should discontinue medications that could lower their seizure threshold. The purpose of this study was to document the most commonly prescribed seizure threshold-lowering medications in patients undergoing myelography and determine whether withholding such medications decreases the incidence of seizures., Materials and Methods: We performed a retrospective observational study of all the myelograms obtained in 2016 at 2 affiliated hospitals. At hospital A, seizure threshold-lowering medications are discontinued before myelography, and prophylactic diazepam is given for all cervical myelograms. At hospital B, seizure threshold-lowering medications are not withheld before the procedure, and medical seizure prophylaxis is not implemented. The seizure threshold-lowering medications the patients were taking at the time of the procedure and postmyelographic seizure incidence were documented., Results: A total of 311 patients underwent myelography during 2016. One hundred eleven patients (36%) were on at least 1 seizure threshold-lowering medication, and 30 (10%) were on at least 2. The most common medications were duloxetine, sertraline, venlafaxine, bupropion, and trazodone. The most common tricyclic antidepressant was amitriptyline. Three patients across both sites had a controlled seizure disorder and were on antiepileptics. None of the patients at either hospital had seizures during or within 3 hours following any of the myelograms during the study period., Conclusions: Continuing seizure threshold-lowering medications during myelography does not increase the risk of seizures. Screening for and withholding seizure threshold-lowering medications are not indicated for routine myelography., (© 2019 by American Journal of Neuroradiology.)

Background and Purpose: Patient preparation for myelography and postprocedural monitoring varies widely between practices, despite published guidelines. Our aim was to examine the current practice variations in discontinuing reportedly seizure threshold-lowering medications before myelography and to assess the reported incidence of postmyelographic seizures., Materials and Methods: An e-mail survey was sent to American Society of Neuroradiology members concerning the number of postmyelographic seizures experienced in the past 5 years, the presence of an institutional policy for discontinuing seizure threshold-lowering medications, and the type of myelographic contrast used. We compared the postmyelographic seizure frequency in the responses., Results: Of 700 survey responses, 57% reported that they do not discontinue seizure threshold-lowering medications before myelography. Most (97%) indicated never having a patient experience a seizure following myelography. The number of postmyelographic seizures between those who discontinue seizure threshold-lowering medications and those who do not was not statistically significant (OR = 2.13; 95% CI, 0.91-4.98; P = .08). Most (95%) reported using nonionic hypo-osmolar agents., Conclusions: Survey results revealed widely variable practices for patient myelography preparation and postprocedural monitoring. We found no difference in reported seizures between those who discontinued seizure threshold-lowering medications and those who did not. In light of our findings, we propose that discontinuing reportedly seizure threshold-lowering medications is not warranted with the current nonionic water-soluble contrast agents and may be potentially harmful in some instances. This work supports revision of existing recommendations to withhold such medications before myelography., (© 2018 by American Journal of Neuroradiology.)

Objectives: To investigate the extent of spinal cord compression and cerebrospinal fluid (CSF) space after T9 paddle lead spinal cord stimulation (SCS) using three-dimensional myelographic computed tomography scans., Methods: Preoperative and postoperative three-dimensional myelographic computed tomography scans were performed in 15 patients with paddle lead SCS at T9 for neuropathic back and leg pain. Four axial levels between each row of the electrodes were selected and the cross-sectional areas of thecal sac and spinal cord, the width of anterior and posterior CSF space, and contact angle of the lead within T9 spinal canal were measured with 12-month pain relief assessment., Results: The cross-sectional areas of thecal sac and spinal cord under each contact of paddle leads decreased significantly (23.89 ± 11.48% and 9.45 ± 4.80%; P < 0.05, respectively). The width of posterior CSF space decreased by 38.65 ± 20.97% and that of anterior CSF space showed a greater reduction by 59.09 ± 18.39% (P < 0.05). We achieved a mean pain relief of 45.49 ± 13.73% at 12-month follow-up and found a significant correlation with percentage reduction in the area of the spinal cord., Conclusions: Significant reduction in the cross-sectional area of spinal cord and anterior CSF space as well as thecal sac and posterior CSF space resulted in deformation of the spinal cord under paddle leads at T9 within 7 postoperative days. Close approximation to the dorsal column and the mass effect of paddle leads may determine the clinical outcome of paddle lead SCS and also raise safety concerns., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Iophendylate is an oil-based contrast agent used in conventional myelography before the 1980s. We report an unusual case of an 82-year-old woman with iophendylate migration into the intracranial cerebrospinal fluid space after myelography 40 years ago. The patient was treated conservatively and followed up regularly.

Background: Exposure to radiation over many years prompts concerns regarding potential health-related effects, particularly the incidence of cataracts and the development of cancer. The purpose of this study was to examine and compare the exposure of the examiner to radiation during myelography versus radiculography and root block., Methods: A total of 114 examinations were performed in our institute in the 6 months. Sixty-two examinations were performed during myelography in the first 3 months (MG group), while 52 were performed during radiculography and root block in the last 3 months (RB group). The examiner wore a torso protector, a neck protector, radiation protection gloves, and radiation protection glasses. Optically stimulated luminescence (OSL) dosimeter badges were placed on both the inside and the outside of each protector. The dosimeters were exchanged every month. Radiation doses (mSv) were measured as the integrated radiation quantity every month from the OSL dosimeters. The effective dose and the equivalent doses of hand, skin, and eyes were investigated., Results: The mean equivalent doses were significantly lower outside the neck, torso, eye protectors, and inside the torso protector in the RB group than in the MG group. Conversely, the mean equivalent dose was significantly lower outside the hand protector in the MG group than in the RB group. The use of a neck protector significantly decreased the effective dose compared to the non-use of a neck protector in the RB group., Conclusions: The present study showed the standard radiation exposure to the examiner during myelography, radiculography, and root block. Receiving full protection including a neck protector and protection gloves is an easy and reliable means to reduce radiation exposure., (Copyright © 2016 The Japanese Orthopaedic Association. Published by Elsevier B.V. All rights reserved.)

Background: The study was prompted by a perceived high prevalence of myelographic complications varying in severity and type, and attributed to the contrast material or the procedure., Hypotheses: 1. Any adverse reaction (AAR) is associated with a change in CSF volume induced either by removal of CSF or addition of contrast material. 2. AAR occurs more frequently in horses with higher premyelography neurologic grade. 3. Nonspecific hyperthermia is attenuated by anti-inflammatory and osmotic agents., Animals: Horses (n = 278) that underwent myelography between 2000 and 2012 at 5 institutions: A (87), B (68), C (65), D (46), and E (12)., Methods: Multi-institutional, retrospective, observational cross-sectional study., Results: AAR were observed in 95/278 (34%) horses, were associated with longer general anesthesia time (P = .04) and higher contrast-medium volume (P = .04); euthanasia because of AAR was performed in 5/278 (2%) horses. Adverse neurologic reactions were the most common type of complication observed occurring in 15/278 (5%) and 42/235 (18%) of horses in the intra- and postmyelography periods. A relationship between AAR and premyelography neurologic grade was not identified (P = .31). Nonspecific hyperthermia was observed in 25/235 (11%) horses; no relationship was observed with administration of anti-inflammatory drugs and osmotic agents (P = .30)., Conclusions and Clinical Importance: The category of AAR occurred in one-third of the horses generally was mild and self-limiting. These reactions were associated with increased contrast-medium volume and longer anesthesia time; but, no specific procedural recommendations could be made because of small odds ratios (OR) of <2 for each 1 mL increase in contrast material and for each 1 minute of additional anesthesia time., (Copyright © 2015 The Authors. Journal of Veterinary Internal Medicine published by Wiley Periodicals, Inc. on behalf of the American College of Veterinary Internal Medicine.)

Modern imaging techniques with computed tomography (CT) and magnetic resonance imaging (MRI) have revolutionized neuroimaging. While eliminating the risks of invasive procedures, new risks must now be considered before ordering neuroimaging. Advanced imaging techniques with CT may pose a risk of significant radiation exposure. Contrast may pose a risk in patients with pre-existing renal failure. MR is associated with risks related to the static magnetic field, to risks associated with the magnetic field gradients, and to risk from contrast media. Neurointervenional techniques allow for nonoperative treatment of a variety of intracranial and spinal pathologies, but with associated risks of embolization, radiation exposure, bleeding complications at the access site and a potential for contrast-related nephropathy., (© 2014 Elsevier B.V. All rights reserved.)

Context: Myelography is a commonly performed diagnostic test used to assess spine pathology. Complications are unusual and usually self-limited. We report a rare case of transient paraplegia following myelography in a woman with thoracic stenosis., Findings: A 51-year-old woman, 20 months status post-thoracic laminectomy, presented with progressive lower extremity weakness. The patient underwent myelography and post-myelography CT, and became paraplegic after the lumbar injection. Intravenous steroids were administered and a lumbar puncture was performed. The patient's neurologic function returned to baseline over the next 96 hours., Conclusion and Clinical Relevance: Myelography is generally a safe procedure, but on rare occasions serious complications can arise. Therapeutic maneuvers may be helpful in reversing neurologic deficit.

Myelography has been of great use as a diagnostic modality, especially when other modalities were not conclusive.However, considering the invasive nature of myelography, it should receive the attention of medical personnel for them to be aware of its possible complications, especially when newer agents are applied as the contrast media. Myelography could lead to some common adverse effects and complications, but in this case report, we will present one of the most serious and uncommon complications accompanied with myelography using Omnipaque, a nonionic second-generation contrast agent. These complications include lower-extremity myoclonic spasms, tonic seizure leading to status epilepticus, rhabdomyolysis, disseminated intravascular coagulation and anaphylactic shock. Having the knowledge of possible complications and available solutions, particularly fatal ones, could prepare medical staff beforehand for primary and secondary preventions.

Purpose: To investigate an outbreak of bacterial meningitis at an outpatient radiology clinic (clinic A) and to determine the source and implement measures to prevent additional infections., Methods: A case was defined as bacterial meningitis in a patient undergoing myelography at clinic A from October 11 to 25, 2010. Patients who underwent myelography and other procedures at clinic A during that period were interviewed, medical records were reviewed, and infection prevention practices were assessed. Case-patient cerebrospinal fluid (CSF) specimens, oral specimens from health care personnel (HCP), and opened iohexol vials were tested for bacteria. Bacterial isolates were compared using pulsed-field gel electrophoresis. A culture-negative CSF specimen was tested using a real-time polymerase chain reaction assay., Results: Three cases were identified among 35 clinic A patients who underwent procedures from October 11 to 25, 2010. All case-patients required hospitalization, 2 in an intensive care unit. Case-patients had myelography performed by the same radiology physician assistant and technician on October 25; all patients who underwent myelography on October 25 were affected. HCP did not wear facemasks and reused single-dose iohexol vials for multiple patients. Streptococcus salivarius (a bacteria commonly found in oral flora) was detected in the CSF of 2 case-patients (1 by culture, 1 using real-time polymerase chain reaction) and in HCP oral specimens; 1 opened iohexol vial contained Staphylococcus epidermidis. Pulsed-field gel electrophoresis profiles from the case-patient S salivarius and the radiology physician assistant were indistinguishable., Conclusions: Bacterial meningitis likely occurred because HCP performing myelography did not wear facemasks; lapses in injection practices may have contributed to transmission. Targeted education regarding mask use and safe injection practices is needed among radiology HCP., (Published by Elsevier Inc.)

Objective: To establish the incidence of and risk factors for seizures following myelography performed with iohexol in dogs., Design: Retrospective case series., Animals: 503 dogs., Procedures: Medical records were searched for dogs that underwent myelography between April 2002 and December 2004. Data extracted included body weight, breed, age, sex, volume and dose of iohexol, site of injections, location of lesion, duration of anesthesia, surgical procedures immediately after myelography, use of acepromazine, and presence or absence of seizures., Results: 15 (3%) dogs had postmyelographic seizures. Risk factors significantly associated with seizures were size of dogs (large dogs were 35.35 times as likely to have seizures as were small dogs), location of contrast medium injection (dogs in which iohexol was injected into the cerebellomedullary cistern were 7.4 times as likely to have seizures as were dogs in which iohexol was injected into the lumbar cistern), location of lesion (dogs with lesions at the level of the cervical portion of the vertebral column were 4.65 times as likely to develop seizures as were dogs with lesions in other regions), and total volume of iohexol. Mean ± SD total volume of iohexol was 11.73 ± 5.52 mL (median, 10.5 mL [range, 3.0 to 21.0 mL]) for dogs that had seizures and 4.57 ± 4.13 mL (median, 3.5 mL [range, 0.75 to 45.0 mL]) for those that did not., Conclusions and Clinical Relevance: Large-breed dogs with cervical lesions and large volumes of iohexol injected into the cerebellomedullary cistern had the highest risk of seizures. The use of contrast medium volumes > 8 mL in large dogs should be avoided, with preference given to injections into the lumbar cistern.

Iophendylate (Myodil) was a popular oil-based contrast agent used until late 1980s for myelography, ventriculography and cisternography. Although several long-term sequelae have been reported in literature, they are extremely rare. We report a rare occurrence of symptomatic dorsal arachnoid cyst 40 years after Myodil myelography.

Objective: We sought to evaluate radioisotope cisternography (RICG)-related postpuncture CSF leakage by MRI., Methods: We conducted a prospective 3-day imaging study. Ten patients with orthostatic headache and other symptoms underwent pre-RICG brain and spinal MRI, magnetic resonance myelography (MRM), RICG, and post-RICG spinal MRI and MRM. For RICG, we used a 25-gauge pencil point spinal needle at the L3/4 or L4/5 level after which subjects took bed rest for 2.5 hours., Results: On pre-RICG MRI and MRM, none of the 10 patients showed CSF leakage. However, 5 subjects (50%) showed epidural abnormalities suggesting CSF leakage on MRI after lumbar puncture for RICG. On RICG and subsequent MRM, 4 of the subjects showed definite findings of CSF leakage and 1 showed minimal leakage., Conclusions: RICG carries a risk of iatrogenic CSF leakage even with careful puncturing using a fine needle. This leakage produces abnormal RICG and MRM findings at the lumbosacral level. Therefore, abnormal RICG findings restricted to the lumbosacral level should be carefully interpreted when diagnosing SIH.

Study Design: In vivo experimental study., Objective: The primary objective of the study was to investigate pressure transmission to adjacent discs during discography. A secondary objective was to quantify the transmitted pressure, both in contrast injected and noninjected porcine intervertebral discs., Summary of Background Data: Discography is used to before surgery identify painful discs. A pain response during discography that is concordant with the patient's experienced back pain is regarded as an indication that the injected disc is the source of pain. However, the sensitivity and specificity of discography are matters of debate. Pressure-controlled discographies have been reported to reduce the number of false-positive discs using low pressure criteria. Preliminary data indicated a transfer of pressure from an injected to an adjacent disc during discography. Pressure transmission in vivo during lumbar discography, not reported before might, if clinically present, contribute to a false-positive diagnosis., Methods: Thirty-six lumbar discs in 9 adolescent pigs were investigated. Intradiscal pressure was recorded during contrast injection, using a 0.36/0.25 mm fiber-optic pressure transducer inserted into the nucleus pulposus via a 22 G needle. The pressure was measured simultaneously in 2 adjacent discs during contrast injection into 1 of the discs at pressures up to 8 bar. Transmitted pressure was recorded both in noninjected discs and in discs that were prefilled with contrast., Results: Thirty-three discs were successfully examined. During contrast injection, there was an intradiscal pressure rise in the adjacent disc with a median value of 16.0% (range, 3.2-37.0) over baseline pressure. There was no significant difference in pressure increase between the noninjected and prefilled discs (P < 0.68)., Conclusion: Discography of porcine discs induces a pressure increase in adjacent discs. A similar pressure transfer during human clinical discography might elicit false-positive pain reactions.

Objective: To compare the incidence of seizures in dogs with intervertebral disk disease after iopamidol or iomeprol myelography, and to assess whether the incidence of seizures differed between the 2 agents when severity of neurological deficits, location of cord compression, duration of anesthesia, site of myelogram, volume of contrast, and concentration of contrast were evaluated., Design: Retrospective study., Setting: Veterinary teaching hospital., Animals: One hundred and sixty-one client-owned dogs with intervertebral disk disease., Interventions: Subarachnoid injection of contrast medium., Measurements and Main Results: One hundred and sixty-one dogs with intervertebral disk disease were subjected to myelography using iopamidol (n=74) or iomeprol (n=87). Cranial myelography was performed in 31 dogs, caudal myelography in 125 and both cranial and caudal myelography in 5. Seizures occurred in 23 of 161 (14%) dogs. There was no significant difference overall between iopamidol and iomeprol myelography. However, in dogs with thoracolumbar disk extrusion and paraplegia, seizures occurred more frequently after caudal myelography using iopamidol compared with iomeprol., Conclusions: Both iomeprol and iopamidol are suitable for myelography in dogs. Iomeprol is recommended for caudal myelography in paraplegic dogs with thoracolumbar disk extrusion due to the higher incidence of seizures in this group when iopamidol was used.

We compared the relative sensitivity of computed tomography (CT) and myelography for identification of disk herniation in dogs. Criteria for patient selection included presurgical CT, myelography, or both and surgical or necropsy confirmation of disk herniation between the T3 and L6 vertebral articulations. Imaging findings were described as positive or inconclusive. Adverse events such as hypotension, cardiac arrhythmias, seizures, death, and lower urinary tract infection were compared between imaging groups. One hundred and eighty-two dogs met the inclusion criteria, with 116 dogs having myelography performed as the initial diagnostic imaging modality and 66 dogs having CT performed as the initial modality. The relative sensitivity for locating the site of disk herniation was 83.6% when myelography was the first test performed and 81.8% when CT was the first test performed. CT was more sensitive than myelography at detecting lesions in chronically affected dogs (P = 0.025). Myelography was more sensitive than CT at detecting lesions in smaller dogs (< 5 kg; P = 0.004). Dogs that received both imaging modalities were significantly more likely to die or be euthanized compared with myelography alone (P < 0.001). Both myelography and CT are reasonable diagnostic imaging modalities for locating the site of disk herniation. CT should be considered especially in heavier, more chronically affected dogs. The major limitations of this study include lack of randomization to imaging modality and the use of surgical exploration or necropsy as the gold standard.

We describe the case of a patient with aseptic meningoencephalitis after intrathecal iohexol injection for myelography and review the previous literature on similar cases of contrast-induced neurotoxicity.

A 71-year-old patient presented with low back pain and slowly progressive weakness of both legs. Within a few hours after lumbar myelography, paraplegia below level L2 evolved. MR-imaging revealed a discogenic stenosis at level Th10/11. Immediate decompression by costo-transversectomy led to reversal of the neurological deficits.

Study Design: Retrospective chart review of documented adverse events in 637 consecutive patients after computed tomogram myelography and follow-up interview of the most recent 100 of these patients., Objectives: This study assessed documented prevalence of adverse events after diagnostic myelography in cervical spondylotic patients and compared with perceived adverse events and satisfaction in a subset of the same cohort of patients., Summary of Background Data: There are some data that suggest complimentary benefits of myelography to magnetic resonance imaging. However, given the invasive nature of myelography, there are little data documenting the adverse events and patient experience with myelography to guide informed consent and physician choice of this study., Methods: We analyzed the records of 637 consecutive patients (364 males and 273 females) after myelography. Five hundred forty-four patients (group 1) had a cervical approach and 93 (group 2) had a lumbar approach. The last 100 consecutive patients (85 in group 1 and 15 in group 2) were asked questions that addressed patient perceived adverse reactions, pain levels, and satisfaction., Results: There was a 4.4% (28/637) prevalence of documented abnormal reactions. Group 1 had a 4.9% (25/506) prevalence of adverse reactions compared with 3.4% (3/89) in group 2. Overall 6.6% (42/637) had to have their myelographic procedures converted. Group 1 had 7% (38/544) converted to the lumbar approach group 2 had 4.3% (4/93) converted to the cervical approach. Thirty percent of the 100 patients interviewed felt they had an unexpected reaction (28 group 1 and 2 group 2). When interviewed, 14% of patients had maximum pain scores of 10 during the procedure and 8% (all group 1) felt worse pain after the procedure was completed. Six group 1 and 2 group 2 patients would not have the procedure again even when recommended by the surgeon. There was no statistically significant difference between complication rates, conversion rates, or patient perceived unexpected reactions between the 2 groups (beta=0.90)., Conclusions: This paper demonstrated the discrepancy between documented adverse events with computed tomogram myelography and patient reported tolerance as recorded by telephone follow-up. The cervical approach had a greater degree of patient perceived discomfort and a trend toward higher documented and patient reported adverse events and rate of approach conversion to a lumbar approach (P>0.5). When choosing myelography to evaluate patients with cervical spondylosis, the surgeon should consider the low patient tolerance and frequent adverse reactions that often go undocumented.

A hyperosmolar ionic contrast medium, ioxithalamate (Telebrix), was inadvertently injected intrathecally to a dog during myelography. The resultant severe adverse effects were myoclonus, uncontrollable seizures, and hyperthermia. These symptoms have been described by some authors as "ascending tonic-clonic seizure syndrome". The dog completely recovered within 24 h. The literature on 47 humans receiving intrathecal ionic contrast medium after 1966, one dog and one horse was reviewed, including the drugs involved, the circumstances of their use, and the symptoms, treatment and outcome of patients who received the drugs intrathecally. Recommendations to prevent such a misuse are given. The present report and review are a reminder that ionic contrast media are absolutely contraindicated for myelography. Only nonionic contrast media can be used intrathecally. All of the hyperosmolar contrast media are ionic and therefore contraindicated for myelography.

Intracranial subarachnoid hemorrhage is a rare but serious complication of lumbar puncture in humans. Possible sequelae include increased intracranial pressure, cerebral vasospasm, or mass effect, which can result in dysfunction or brain herniation. We describe two dogs that developed intracranial subarachnoid hemorrhage following lumbar myelography. In both dogs, myelography was performed by lumbar injection of iohexol (Omnipaque). Both the dogs underwent uneventful ventral decompressive surgery for disk herniation; however, the dogs failed to recover consciousness or spontaneous respiration following anesthesia. Neurologic assessment in both dogs postoperatively suggested loss of brain stem function, and the dogs were euthanized. There was diffuse subarachnoid hemorrhage and leptomeningeal hemorrhage throughout the entire length of the spinal cord, brain stem, and ventrum of brain. No evidence of infectious or inflammatory etiology was identified. The diagnosis for cause of brain death was acute subarachnoid hemorrhage. Our findings suggest that fatal subarachnoid hemorrhage is a potential complication of lumbar myelography in dogs. The cause of subarachnoid hemorrhage is not known, but may be due to traumatic lumbar tap or idiosyncratic response to contrast medium. Subsequent brain death may be a result of mass effect and increased intracranial pressure, cerebral vasospasm, or interaction between subarachnoid hemorrhage and contrast medium.

In September of 2004, we investigated 7 cases of post-myelography meningitis. Streptococcal species were recovered from blood or cerebrospinal fluid in all cases. Our findings suggest that droplet transmission of the oral flora of the clinician performing the procedure was the most likely source of these infections. The Centers for Disease Control and Prevention recommends the use of face masks by those performing myelograms.

Dire consequences can occur after any medical or surgical procedure. Certain procedures may even cause sensorineural hearing loss (SNHL). Previous studies have demonstrated that certain surgical and medical procedures may result in hearing losses of varying degrees. Although hearing loss is a well-known phenomenon, little consistent information exists about hearing loss after medical or surgical procedures. This one-tailed, directional study compared the effect of myelogram procedures on hearing in selected outpatients. A pre/posttest design was used to measure audiograms in 27 myelogram subjects. Pre- and postprocedure hearing tests were measured by audiometry and compared for differences. Results did not support previous studies that low-frequency hearing loss can occur within 24 hours after myelogram procedure. Clinically relevant information was found in one subject 53 hours post myelogram.