Vertical Fracture of the Odontoid Process.

Fractures of the odontoid process of the axis usually occur transversely at the neck or base of the odontoid, are often displaced, and frequently require surgical fixation. Sagittal or coronal fractures are uncommon and can best be visualized on coronal or sagittal reconstruction of CT scans. Routine radiographs may not allow precise diagnosis. Vertical fractures, either sagittal or coronal, generally do not require operative treatment. This report describes an unusual fracture of the odontoid process sustained by a 56-year-old male after falling down a flight of stairs. He was neurologically intact, and the fracture healed with immobilization in a rigid cervical brace. Only 11 other case reports have been identified in a literature review. Both coronal and sagittal reconstructions should be obtained in suspected cases of odontoid fracture. Without instability on flexion/extension views or ligamentous injury on an MRI scan, a rigid brace or halo vest can be used to promote healing of the fracture, which may occur in 12 weeks.

Microvascular Brainstem Ischemia After Vestibular Schwannoma Surgery: A Clinical and Microanatomic Study.

OBJECTIVE: To identify a potential microvascular etiology in patients who underwent vestibular schwannoma surgery (VSS) complicated by postoperative microvascular brainstem ischemia. METHODS: Charts were retrospectively reviewed of all patients who had an MRI within 14 days of VSS in years 2005-2016. Patient characteristics, preoperative and postoperative imaging features, clinical course and potential predictors of brainstem ischemia were recorded. Cadaveric dissections of 4 cerebellopontine angle (CPA) cisterns with focus on the anterior inferior cerebellar artery (AICA) microvascular were also performed to identify candidate vessels and potential etiology. RESULTS: Fifty-four of 258 patients had an MRI within 14 days of VSS. Retrosigmoid approach was used in 61.1% of patients, translabyrinthine approach in 25.9%, and middle fossa approach in 13.0%. Four patients (7.4%) had acute microvascular ischemia involving the middle cerebellar peduncle (MCP) adjacent to the cranial nerve (CN) VII-VIII complex demonstrated on postoperative MRI. A statistically significant association was found between the translabyrinthine approach and acute brainstem ischemia (odds ratio, 10.6; 95% confidence interval, 1.004-112.7). Dissection of CPAs revealed 10-20 perforating arteries per specimen originating from the lateral pontine and the flocculopeduncular segments of the AICA. Most microvessels travelled in retrograde fashion along the anteroinferior surface of the CN VII-VIII complex to perforate the cisternal surface of the MCP. No patient had residual or delayed neurologic deficits related to brainstem ischemia at final follow-up. CONCLUSIONS: While effort should be made to preserve perforating vessels, microvascular brainstem ischemia is often asymptomatic and did not lead to permanent neurologic deficits in our series.

Cerebrospinal fluid velocity amplitudes within the cerebral aqueduct in healthy children and patients with Chiari I malformation.

PURPOSE: To assess the effects of cerebrospinal fluid (CSF) bidirectional motion in Chiari malformation type I (CMI), we monitored CSF velocity amplitudes on phase contrast MRI (PC-MRI) in patients before and after surgery; and in healthy volunteers. MATERIALS AND METHODS: 10 pediatric volunteers and 10 CMI patients participated in this study. CMI patients underwent PC-MRI scans before and approximately 14 months following surgery. Two parameters-amplitude of mean velocity (AMV) and amplitude of peak velocity (APV) of CSF-were derived from the data. Measurements were made at the mid-portion of the cerebral aqueduct, and anterior and posterior compartments of the spinal canal at the craniovertebral junction (CVJ). RESULTS: AMV and APV within the cerebral aqueduct were greater in preoperative assessments of the CMI patients compared to normal volunteers. Statistical significance was noted when comparing aqueductal AMV between the preoperative values and normal controls (P = 0.03), and before and after surgery in the CMI patients (P = 0.02). Lower values of AMV (P = 0.02) were noted in the anterior CVJ compartment in the patients before and after surgery when compared to the normal volunteers. There were no significant correlations (P = 0.06) noted for the APV at the CVJ between the normal control and patients, before or after surgery. CONCLUSION: In pediatric CMI patients, AMV for CSF within the cerebral aqueduct and anterior CVJ subarachnoid space are significantly elevated preoperatively and normalize following surgery. Given the biphasic CSF motion, measuring amplitude accounts for cranial and caudal flow. It may offer an alternative parameter to assess postsurgical outcome. J. Magn. Reson. Imaging 2016;44:463-470.

Interobserver Variation in Cerebellar Tonsillar Tip Localization: Comparison of 3 Different Osseous Landmarks on Magnetic Resonance Imaging.

PURPOSE: The aim was to evaluate the interobserver agreement in the assessment of cerebellar tonsil position on sagittal magnetic resonance imaging using 3 different osseous landmarks. MATERIALS AND METHODS: This retrospective study consisted of brain magnetic resonance imagings performed at our institution in patients with and without Chiari I malformation between January 2010 and 2012. Sagittal T1-weighted images were reviewed by 2 senior board-certified neuroradiologists (blinded to underlying clinical diagnosis) with measurement of both cerebellar tonsillar positions based on lines drawn perpendicular from the tonsillar tip to the foramen magnum [FM] line, C1 line, and C2 line. Spearman correlation coefficients were calculated. Interobserver variation between the readers was assessed using Bland-Altman analysis and intraclass correlation coefficient. RESULTS: A total of 320 cerebellar tonsils on 160 patients, 50 with Chiari I malformations, and 110 control subjects without Chiari I malformation were evaluated. The Spearman correlation coefficients for the entire cohort were 0.86 (FM), 0.94 (C1), and 0.90 (C2). Bland-Altman analysis for the entire cohort showed the best interobserver agreement for C1 line (-0.3 mm bias) and the least for C2 line (4.6 mm bias). The Intraclass correlation coefficients for all patients were 0.84 (FM), 0.92 (C1), and 0.54 (C2). The least bias and highest correlation coefficients were also seen individually in the Chiari and non-Chiari cohorts with the C1 technique. CONCLUSIONS: Determination of cerebellar tonsillar position using a C1 arch landmark may be superior to the currently more commonly used FM-based landmark with lesser interobserver variability and higher interobserver correlation.

Differences in vascular endothelial growth factor receptor expression and correlation with the degree of enhancement in medulloblastoma.

OBJECT: Vascular endothelial growth factor (VEGF) is the major proangiogenic factor in many solid tumors. Vascular endothelial growth factor receptor (VEGFR) is expressed in abundance in pediatric patients with medulloblastoma and is associated with tumor metastasis, poor prognosis, and proliferation. Gadolinium enhancement on MRI has been suggested to have prognostic significance for some tumors. The association of VEGF/VEGFR and Gd enhancement in medulloblastoma has never been closely examined. The authors therefore sought to evaluate whether Gd-enhancing medulloblastomas have higher levels of VEGFR and CD31. Outcomes and survival in patients with enhancing and nonenhancing tumors were also compared. METHODS: A retrospective analysis of patients with enhancing, nonenhancing, and partially enhancing medulloblastomas was performed. Primary end points included risk stratification, extent of resection, and perioperative complications. A cohort of 3 enhancing and 3 nonenhancing tumors was selected for VEGFR and CD31 analysis as well as microvessel density measurements. RESULTS: Fifty-eight patients were analyzed, and 20.7% of the medulloblastomas in these patients were nonenhancing. Enhancing medulloblastomas exhibited strong VEGFR1/2 and CD31 expression relative to nonenhancing tumors. There was no significant difference in perioperative complications or patient survival between the 2 groups. CONCLUSIONS: These results suggest that in patients with medulloblastoma the presence of enhancement on MRI may correlate with increased vascularity and angiogenesis, but does not correlate with worse patient prognosis in the short or long term.

Sonographically guided lumbar puncture in pediatric patients.

Our aim with this study was to develop a user-friendly method for pediatric sonographically guided lumbar punctures so that we can visualize intrathecal anatomy, confirm intrathecal injection at the time of injection, and, most importantly, avoid ionizing radiation to a child's already radiosensitive pelvis. Sonographically guided lumbar puncture was prospectively performed in children aged 7 weeks to 16 years. All attempts (n = 9) were successful. We were able to identify relevant anatomy (including the conus in children 10 years and younger), confirm intrathecal injection, visualize intrathecal hematoma, and avoid radiation. Sonography is a promising modality for image-guided lumbar punctures without radiation in children.

Nerve root sedimentation sign for the diagnosis of lumbar spinal stenosis: reliability, sensitivity, and specificity.

STUDY DESIGN: Retrospective review of magnetic resonance images. OBJECTIVE: Examine the diagnostic accuracy, discriminative ability, and reliability of the sedimentation sign in a sample of patients with clinically diagnosed lumbar spinal stenosis (LSS), low back pain (LBP), and vascular claudication, and in asymptomatic controls. SUMMARY OF BACKGROUND DATA: The nerve root sedimentation sign (SedSign) was recently described as a new diagnostic test for LSS; however, the degree to which this sign is sensitive and specific in diagnosis of LSS is unknown. METHODS: All LSS images were obtained from subjects who had clinically diagnosed LSS confirmed on imaging by a spine specialist. The other images were obtained from people with LBP but no LSS, people with severe vascular claudication, and asymptomatic participants. Three blinded raters independently assessed the images. A positive sign was defined as the absence of nerve root sedimentation at the level above or below the level of maximum stenosis. RESULTS: Images from 148 subjects were reviewed (67 LSS, 31 LBP, 4 vascular, and 46 asymptomatic). Intrarater reliability for the sign ranged from κ= 0.87 to 0.97 and inter-rater reliability from 0.62 to 0.69. Sensitivity ranged from 42% to 66%, and specificity ranged from 49% to 78%. Sensitivity improved to a range of 60% to 96% when images with only a smallest cross-sectional area of the dural sac less than 80 mm were included. The sign was able to differentiate (P = 0.004) between LSS and asymptomatic controls but not between LSS and LBP or between LSS and vascular claudication. CONCLUSION: The SedSign was shown to have high intrarater reliability and acceptable inter-rater reliability. The Sign appears most sensitive in defining severe LSS cases, yet may not aid in the differential diagnosis of LSS from LBP or vascular claudication, or add any specific diagnostic information beyond the traditional history, physical examination, and imaging studies that are standard in LSS diagnosis. LEVEL OF EVIDENCE: 4.

The impact of MRI on stroke management and outcomes: a systematic review.

RATIONALE, AIMS AND OBJECTIVES: Magnetic resonance imaging (MRI) is widely used in stroke evaluation and is superior to computed tomography for the detection of acute ischaemia. We sought to evaluate the evidence that conventional MRI influences doctor management or patient outcomes in routine care. METHODS: We systematically searched PubMED, EMBASE and proceedings of the International Stroke Conference. Studies were included if they included patients presenting with possible stroke syndromes and they reported MRI results and resulting changes in management or outcome. Multiple reviewers determined inclusion/exclusion for each study, abstracted study characteristics and assessed study quality. RESULTS: Of 1813 articles screened, nine studies met inclusion criteria. None were randomized controlled trials, cohort studies or case-control studies. We found little evidence that MRI affects outcomes - one single-centre case series presented three patients. The remaining articles were studies of diagnostic tests or vignette-based studies that described changes in doctor management attributed to MRI. In the studies that suggested MRI influenced management, it did so in two ways. First, MRI distinguished stroke from mimics (e.g. brain tumours), thus enabling more appropriate selection of therapies. Second, even when MRI confirmed a suspected stroke diagnosis, it sometimes provided information (on stroke mechanism, localization, timing or pathophysiology) that influenced management. CONCLUSIONS: The impact of MRI on management and outcomes in stroke patients has been inadequately studied. Further research is needed to understand how MRI may productively affect stroke management and outcomes.

The risk of hematoma following extensive electromyography of the lumbar paraspinal muscles.

INTRODUCTION: The purpose of this study is to provide a controlled trial looking at the risk of paraspinal hematoma formation following extensive paraspinal muscle electromyography. METHODS: 54 subjects ages 55-80 underwent MRI of the lumbar spine before or shortly after electromyography using the paraspinal mapping technique. A neuroradiologist, blinded to the temporal relationship between the EMG and MRI, reviewed the MRIs to look for hematomas in or around the paraspinal muscles. RESULTS: Two MRIs demonstrated definite paraspinal hematomas, while 10 were found to have possible hematomas. All hematomas were < 15 mm, and none were close to any neural structures. There was no relationship between MRI evidence of hematoma and either the timing of the EMG or the use of aspirin or other nonsteroidal anti-inflammatory drugs. CONCLUSIONS: Paraspinal electromyography can be considered safe in the general population and those taking nonsteroidal anti-inflammatory drugs.

Utility of electrodiagnostic testing and computed tomography myelography in the preoperative evaluation of neonatal brachial plexus palsy.

OBJECT: The rate of neonatal brachial plexus palsy (NBPP) remains 0.4%-4% despite improvements in perinatal care. Among affected children, the extent of brachial plexus palsy differs greatly, as does the prognosis. Controversial elements in management include indications and timing of nerve repair as well as type of reconstruction in patients in whom function will ultimately not be recovered without surgical intervention. Differentiating preganglionic (avulsion) from postganglionic (rupture) lesions is critical because preganglionic lesions cannot spontaneously recover motor function. Distinguishing between these lesions at initial presentation based on clinical examination alone can be difficult in infants. The purpose of the present study was to determine the sensitivity of preoperative electrodiagnostic studies (EDSs) and CT myelography (CTM) in determining the presence of nerve root rupture and avulsions in infants with NBPP. METHODS: After receiving institutional review board approval, the authors conducted a retrospective review of patients referred to the Neonatal Brachial Plexus Program between 2007 and 2010. Inclusion criteria included children who underwent brachial plexus exploration following preoperative EDSs and CTM. The CTM scans were interpreted by a staff neuroradiologist, EDSs were conducted by a single physiatrist, and intraoperative findings were recorded by the operating neurosurgeon. The findings from the preoperative EDSs and CTM were then compared with intraoperative findings. The sensitivities and 95% confidence intervals were determined to evaluate performance accuracy of each preoperative measure. RESULTS: Twenty-one patients (8 male amd 13 female) met inclusion criteria for this study. The sensitivity of EDSs and CTM for detecting a postganglionic rupture was 92.8% (CI 0.841-0.969) and 58.3% (CI 0.420-0.729), respectively. The sensitivity for EDSs and CTM for preganglionic nerve root avulsion was 27.8% (CI 0.125-0.509) and 72.2% (CI 0.491-0.875), respectively. In cases in which both CTM and EDSs gave concordant results, the sensitivity for both modalities combined was 50.0% (CI 0.237-0.763) for avulsion and 80.8% (CI 0.621-0.915) for rupture. Overall, EDSs were most useful in identifying ruptures, particularly in the upper plexus, whereas CTM was most sensitive in identifying avulsions in the lower plexus. CONCLUSIONS: Knowledge of the spinal nerve integrity is critical for early management of patients with NBPP. Surgical management, in the form of nerve repair/reconstruction, and optimal prognostication of NBPP depend on the accurate diagnosis of the level and type of lesion. Both EDSs and CTM scans must always be interpreted in the context of a comprehensive evaluation of the patient. They provide supplemental information (in addition to the physical examination) for early detection of nerve root rupture and avulsion injuries, aiding surgical decision making and preoperative planning for NBPP. Continued advances in imaging, EDSs, and microsurgical nerve repair techniques will allow surgeons to achieve greater success for functional recovery in management of NBPP.

Consideration of dose limits for organs at risk of thoracic radiotherapy: atlas for lung, proximal bronchial tree, esophagus, spinal cord, ribs, and brachial plexus.

PURPOSE: To review the dose limits and standardize the three-dimenional (3D) radiographic definition for the organs at risk (OARs) for thoracic radiotherapy (RT), including the lung, proximal bronchial tree, esophagus, spinal cord, ribs, and brachial plexus. METHODS AND MATERIALS: The present study was performed by representatives from the Radiation Therapy Oncology Group, European Organization for Research and Treatment of Cancer, and Soutwestern Oncology Group lung cancer committees. The dosimetric constraints of major multicenter trials of 3D-conformal RT and stereotactic body RT were reviewed and the challenges of 3D delineation of these OARs described. Using knowledge of the human anatomy and 3D radiographic correlation, draft atlases were generated by a radiation oncologist, medical physicist, dosimetrist, and radiologist from the United States and reviewed by a radiation oncologist and medical physicist from Europe. The atlases were then critically reviewed, discussed, and edited by another 10 radiation oncologists. RESULTS: Three-dimensional descriptions of the lung, proximal bronchial tree, esophagus, spinal cord, ribs, and brachial plexus are presented. Two computed tomography atlases were developed: one for the middle and lower thoracic OARs (except for the heart) and one focusing on the brachial plexus for a patient positioned supine with their arms up for thoracic RT. The dosimetric limits of the key OARs are discussed. CONCLUSIONS: We believe these atlases will allow us to define OARs with less variation and generate dosimetric data in a more consistent manner. This could help us study the effect of radiation on these OARs and guide high-quality clinical trials and individualized practice in 3D-conformal RT and stereotactic body RT.

Calcified brainstem cavernoma in a patient with hundreds of intracranial cavernomas.

INTRODUCTION: Unexpected identification of hundreds of lesions on intracranial imaging can be a disconcerting discovery, but familiarity with the possible etiologies of such a finding may help guide further evaluation. We present a case report and literature review of multiple intracranial cavernous hemangiomas. CASE REPORT: A 67-year-old non-Hispanic white man developed the sudden onset of painless right-sided hearing loss in August 2006. Magnetic resonance imaging (MRI) of the brain revealed a lesion in the left lateral pontomesencephalic junction with mixed T1-weighted and decreased T2-weighted signal without mass effect or contrast enhancement. There were numerous additional lesions with low T2 signal involving both the cerebellum and the bilateral cerebral hemispheres. In January 2008, further imaging studies, including gradient-echo MRI, were obtained to assess for additional interval changes in the appearance of the intracranial lesions. Results of the patient's current and previous studies were considered most consistent with a clinical and imaging diagnosis of multiple cavernous hemangiomas. CONCLUSION: For patients with numerous intracranial lesions, such as those found in cases of multiple cavernous hemangiomas, the use of susceptibility-weighted or gradient-echo MRI can be useful for arriving at an appropriate differential diagnosis and to help guide proper management.

Cerebrospinal fluid leak with recurrent meningitis following tonsillectomy.

The authors report an unusual case of bilateral large petrous apex cephaloceles in a 14-year-old boy with a history of recurrent meningitis. Although these lesions are rare and usually asymptomatic, surgical correction is recommended if they are associated with a persistent CSF leak. In this patient, the extensive bilateral cranial defects were not adequately treated by an intracranial approach alone. Repair of a defect in the posterior pharyngeal wall, the site of a prior tonsillectomy, ultimately resulted in repair of the CSF fistula.

Frequency and spectrum of errors in final radiology reports generated with automatic speech recognition technology.

PURPOSE: Automatic speech recognition technology has a high frequency of transcription errors, necessitating careful proofreading and report editing. The purpose of this study was to determine the frequency and spectrum of significant dictation errors in finalized radiology reports generated with speech recognition technology. METHODS: All 265 radiology reports that were reviewed in preparation for 12 consecutive weekly multidisciplinary thoracic oncology group conferences were examined for significant dictation errors; reports were compared with the corresponding imaging studies. In addition, departmental radiologists were surveyed regarding their estimates of overall and individual report error rates. RESULTS: Two hundred six of 265 (78%) reports contained no significant errors, and 59 (22%) contained errors. Report error rates by individual radiologists ranged from 0% to 100%. There were no significant differences in error rates between native and nonnative English speakers (P > .8) or between reports dictated by faculty members alone and those dictated by trainees and signed by faculty members (P > .3). The most frequent types of errors were wrong-word substitution, nonsense phrases, and missing words. Fifty-five of 88 radiologists (63%) believed that overall error rates did not exceed 10%, and 67 of 88 radiologists (76%) believed that their own individual error rates did not exceed 10%. CONCLUSIONS: More than 20% of our reports contained potentially confusing errors, and most radiologists believed that report error rates were much lower than they actually were. Knowledge of the frequency and spectrum of errors should raise awareness of this issue and facilitate methods for report improvement.

Spinal canal size and clinical symptoms among persons diagnosed with lumbar spinal stenosis.

OBJECTIVE: Clinical symptoms associated with lumbar spinal stenosis (LSS) are believed to be due to neurogenic claudication caused by narrowing of the central and lateral spinal canals. However, there is a paucity of published data on these relationships. The purpose of the present study was to examine the relationship between clinical symptoms associated with LSS and osseous anterior-posterior (AP) spinal canal diameter as measured on axial magnetic resonance imaging. DESIGN: Cross-sectional study conducted at a University Spine Program. Fifty persons with a clinical diagnosis of LSS were administered measures of clinical pain and perceived function. Walking distance in the laboratory and community was also assessed. Participants also underwent magnetic resonance imaging of the spine. RESULTS: Using recommended upper limits from the literature, patients with smaller canals reported greater perceived disability, but no other group differences emerged. In the entire sample, AP spinal canal diameter was not significantly associated with any of the clinical symptom measures examined. Body mass index was found to be significantly related to walking distance, but not perceived function or pain. CONCLUSIONS: AP spinal canal diameter is not predictive of clinical symptoms associated with LSS. The findings also suggest that body mass may play a significant role in functional limitations observed in this population.

Electromyographic and magnetic resonance imaging to predict lumbar stenosis, low-back pain, and no back symptoms.

BACKGROUND: Magnetic resonance imaging is commonly used to diagnose lumbar spinal stenosis. Some persons without symptoms have a small lumbar spinal canal. Electrodiagnosis has been used to diagnose spinal stenosis for over sixty years, but we are aware of no masked, controlled trials of the use of electrodiagnosis for that purpose. This study was performed to evaluate the relationships of magnetic resonance imaging measures and electrodiagnostic data with the clinical syndrome of spinal stenosis. METHODS: One hundred and fifty persons between the ages of fifty-five and eighty years old, including asymptomatic volunteers and persons referred for lumbar magnetic resonance imaging, underwent clinical examination, electrodiagnosis, and magnetic resonance imaging. Subjects were excluded if they had neuromuscular disease, sacral cancer, or inadequate test results, which left 126 subjects for the final analysis. The final cohort was divided into three groups--no back pain, mechanical back pain, and clinical spinal stenosis--on the basis of the impression of the examining physician, for whom the results of the magnetic resonance imaging and electrodiagnostic testing were masked. A spine surgeon also reviewed both the imaging and clinical examination data. RESULTS: The examining physician's diagnosis of clinical spinal stenosis was significantly related to the neurological findings on examination (p < 0.05) and to the spine surgeon's diagnosis (p < 0.001). The diagnosis of clinical spinal stenosis was also significantly related to the presence of fibrillations on electrodiagnostic testing (p < or = 0.003), the minimum anteroposterior diameter of the spinal canal on the magnetic resonance images (p = 0.016), and the average of the two smallest spinal canal diameters (p = 0.008) on the images. Measurements on magnetic resonance imaging did not differentiate subjects with clinical spinal stenosis from controls better than chance, whereas paraspinal mapping electrodiagnosis scores did. CONCLUSIONS: This prospective, controlled, masked study of electrodiagnosis and magnetic resonance imaging for older subjects showed that imaging does not differentiate symptomatic from asymptomatic persons, whereas electrodiagnosis does. We believe that radiographic findings alone are insufficient to justify treatment for spinal stenosis.