Efficacy of Epidural Blood Patching or Surgery in Spontaneous Intracranial Hypotension: A Systematic Review and Evidence Map

BACKGROUND

Spontaneous intracranial hypotension is an important cause of treatable secondary headaches. Evidence on the efficacy of epidural blood patching and surgery for spontaneous intracranial hypotension has not been synthesized.

PURPOSE

Our aim was to identify evidence clusters and knowledge gaps in the efficacy of treatments for spontaneous intracranial hypotension to prioritize future research.

DATA SOURCES

We searched published English language articles on MEDLINE (Ovid), the Web of Science (Clarivate), and EMBASE (Elsevier) from inception until October 29, 2021.

STUDY SELECTION

We reviewed experimental, observational, and systematic review studies assessing the efficacy of epidural blood patching or surgery in spontaneous intracranial hypotension.

DATA ANALYSIS

One author performed data extraction, and a second verified it. Disagreements were resolved by consensus or adjudicated by a third author.

DATA SYNTHESIS

One hundred thirty-nine studies were included (median, 14 participants; range, 3-298 participants). Most articles were published in the past decade. Most assessed epidural blood patching outcomes. No studies met level 1 evidence. Most were retrospective cohort or case series (92.1%, n = 128). A few compared the efficacy of different treatments (10.8%, n = 15). Most used objective methods for the diagnosis of spontaneous intracranial hypotension (62.3%, n = 86); however, 37.7% (n = 52) did not clearly meet the International Classification of Headache Disorders-3 criteria. CSF leak type was unclear in 77.7% (n = 108). Nearly all reported patient symptoms using unvalidated measures (84.9%, n = 118). Outcomes were rarely collected at uniform prespecified time points.

LIMITATIONS

The investigation did not include transvenous embolization of CSF-to-venous fistulas.

CONCLUSIONS

Evidence gaps demonstrate a need for prospective study designs, clinical trials, and comparative studies. We recommend using the International Classification of Headache Disorders-3 diagnostic criteria, explicit reporting of CSF leak subtype, inclusion of key procedural details, and using objective validated outcome measures collected at uniform time points.

The clue is in the kidneys: greater renal contrast medium accumulation on ipsilateral side down CT myelogram after lateral decubitus digital subtraction myelogram as a predictor of laterality of cerebrospinal fluid leak

AIM

To assess the potential correlation of the laterality of a cerebrospinal fluid (CSF)-venous fistula with the laterality of decubitus computed tomography (CT) myelogram (post decubitus digital subtraction myelogram) based on which side demonstrated more renal contrast medium excretion.

MATERIALS AND METHODS

Patients with CSF-venous fistulas diagnosed at lateral decubitus digital subtraction myelograms were reviewed retrospectively. Patients who did not have CT myelogram following one or both left and right lateral decubitus digital subtraction myelograms were excluded. Two neuroradiologists independently interpreted the CT myelogram for the presence or absence of renal contrast, and whether subjectively more renal contrast medium was visualised on the left or right lateral decubitus CT myelogram.

RESULTS

Renal contrast medium was seen in lateral decubitus CT myelograms in 28 of 30 (93.3%) patients with CSF-venous fistulas. Having more renal contrast medium in right lateral decubitus CT myelogram was 73.9% sensitive and 71.4% specific for the diagnosis of a right-sided CSF-venous fistula, whereas having more renal contrast medium in the left lateral decubitus CT myelogram was 71.4% sensitive and 82.6% specific for a left-sided CSF-venous fistula (p=0.02).

CONCLUSION

When the CSF-venous fistula lies on the dependent side of a decubitus CT myelogram performed after decubitus digital subtraction myelogram, relatively more renal contrast medium is visualised compared to when the fistula lies on the non-dependent side.

Fluoroscopy- and CT-Guided Gold Fiducial Marker Placement for Intraoperative Localization during Spinal Surgery: Review of 179 Cases at a Single Institution-Technique and Safety Profile

BACKGROUND AND PURPOSE

Wrong-level spinal surgery, especially in the thoracic spine, remains a challenge for a variety of reasons related to visualization, such as osteopenia, large body habitus, severe kyphosis, radiographic misinterpretation, or anatomic variation. Preoperative fiducial marker placement performed in a dedicated imaging suite has been proposed to facilitate identification of thoracic spine vertebral levels. In this current study, we report our experience using image-guided percutaneous gold fiducial marker placement to enhance the accuracy and safety of thoracic spinal surgical procedures.

MATERIALS AND METHODS

A retrospective review was performed of all fluoroscopy- or CT-guided gold fiducial markers placed at our institution between January 3, 2019, and March 16, 2022. A chart review of 179 patients was performed detailing the procedural approach and clinical information. In addition, the method of gold fiducial marker placement (fluoroscopy/CT), procedure duration, spinal level of the gold fiducial marker, radiation dose, fluoroscopy time, surgery date, and complications (including whether wrong-level surgery occurred) were recorded.

RESULTS

A total of 179 patients (104 female) underwent gold fiducial marker placement. The mean age was 57 years (range, 12-96 years). Fiducial marker placement was performed by 13 different neuroradiologists. All placements were technically successful without complications. All 179 (100%) operations were performed at the correct level. Most fiducial markers (143) were placed with fluoroscopy with the most common location at T6-T8. The most common location for placement in CT was at T3 and T4.

CONCLUSIONS

All operations guided with gold fiducial markers were performed at the correct level. There were no complications of fiducial marker placement.

Enhancement in the Round Window Niche: A Potential Pitfall in High-Resolution MR Imaging of the Internal Auditory Canal

BACKGROUND AND PURPOSE

There is limited discussion in current literature about the normal imaging appearance of the round window. The purpose of this study was to assess the prevalence and imaging characteristics of gadolinium enhancement in the round window niche on MR imaging to the internal auditory canal.

MATERIALS AND METHODS

The presence or absence and laterality of enhancement in the round window niche on MR imaging was retrospectively reviewed in 95 patients from 1 institution. All studies included high-resolution (≤0.5-mm section thickness) pre- and postgadolinium 3D FSE T1 with fat-saturation and postgadolinium 3D FLAIR image sequences. T1 and T2 acquisitions were viewed as coregistered overlays to confirm that enhancement was lateral to the round window membrane within the round window niche. CT was reviewed when available to assess the presence and laterality of soft tissue in the round window niche.

RESULTS

Ninety-five patients with internal auditory canal MRIs were included. Enhancement was present in the round window of 15 of 95 patients (15.8%). Of the 27 patients who underwent CT, 4 (14.8%) had concordant soft tissue on CT and MR imaging enhancement in the round window niche. One patient had MR imaging enhancement within the round window niche without a corresponding abnormality on CT. The absence of soft tissue on CT and the corresponding lack of MR imaging enhancement were present in 22 (81.5%) patients.

CONCLUSIONS

Enhancement can be visualized within the round window niche on MR imaging as an incidental finding. This enhancement probably represents postinflammatory granulation tissue and does not require further intervention. However, the potential for this enhancement to be misdiagnosed as a pathologic process can be a pitfall in MR imaging.

The Monro-Kellie Doctrine: A Review and Call for Revision

The Monro-Kellie doctrine is a well-accepted principle of intracranial hemodynamics. It has undergone few consequential revisions since it was established. Its principle is straightforward: The combined volume of neuronal tissue, blood, and CSF is constant. To maintain homeostatic intracranial pressure, any increase or decrease in one of these elements leads to a reciprocal and opposite change in the others. The Monro-Kellie doctrine assumes a rigid, unadaptable calvaria. Recent studies have disproven this assumption. The skull expands and grows in response to pathologic changes in intracranial pressure. In this review, we outline what is known about calvarial changes in the setting of pressure dysregulation and suggest a revision to the Monro-Kellie doctrine that includes an adaptable skull as a fourth component.

Utility of Dual-Energy CT to Improve Diagnosis of CSF Leaks on CT Myelography following Lateral Decubitus Digital Subtraction Myelography with Negative Findings

CSF leaks, including CSF-venous fistulas, which cause spontaneous intracranial hypotension, remain difficult to diagnose, even on digital subtraction myelography and CT myelography. Dual-energy CT technology has been used to improve diagnostic utility within multiple organ systems. The capability of dual-energy CT to create virtual monoenergetic images can be leveraged to increase conspicuity of contrast in CSF-venous fistulas and direct epidural CSF leakage to improve the diagnostic utility of CT myelography. Six cases (in 5 patients) are shown in which virtual monoenergetic images demonstrate a leak location that was either occult or poorly visible on high- or low-kilovolt series. This clinical report describes the novel application of dual-energy CT for the detection of subtle CSF leaks including CSF-venous fistulas.

Normal Enhancement within the Vestibular Aqueduct: An Anatomic Review with High-Resolution MRI

BACKGROUND AND PURPOSE

The normal appearance of the vestibular aqueduct on postcontrast MR images has not been adequately described in the literature. This study set out to characterize the expected appearance of the vestibular aqueduct, with particular emphasis on the enhancement of the structure on both 3D FSE T1 and 3D-FLAIR sequences.

MATERIALS AND METHODS

All MR imaging examinations of the internal auditory canals performed between March 1, 2021, and May 20, 2021, were retrospectively reviewed. All studies included high-resolution (≤0.5-mm section thickness) pre- and postgadolinium 3D FSE T1 with fat-saturated and postgadolinium 3D-FLAIR sequences. Two neuroradiologists independently reviewed the MR images of the vestibular aqueduct for the presence or absence of enhancement on both T1 and FLAIR images and compared the relative intensity of enhancement between sequences. The presence or absence of an enlarged vestibular aqueduct was also noted.

RESULTS

Ninety-five patients made up the patient cohort, of whom 5 did not have postcontrast FLAIR images available (50 women [55.6%]). On both sides, enhancement was significantly more commonly seen on postgadolinium FLAIR (76/180, 42.2%) than on T1 fat-saturated images (41/190, 21.6%) (P < .001). The intensity of enhancement was significantly greater on postgadolinium FLAIR images than on T1 fat-saturated images (38.9% versus 3.7%, respectively; P < .001).

CONCLUSIONS

Enhancement within the vestibular aqueduct is an expected finding on MR imaging and is both more common and more intense on postgadolinium 3D-FLAIR than on T1 fat-saturated sequences. Such enhancement should not be confused with pathology on MR imaging unless other suspicious findings are present.

Diffuse Calvarial Hyperostosis and Spontaneous Intracranial Hypotension: A Case-Control Study

BACKGROUND AND PURPOSE

Diagnosing spontaneous intracranial hypotension and associated CSF leaks can be challenging, and additional supportive imaging findings would be useful to direct further evaluation. This retrospective study evaluated whether there was a difference in the prevalence of calvarial hyperostosis in a cohort of patients with spontaneous intracranial hypotension compared with an age- and sex-matched control population.

MATERIALS AND METHODS

Cross-sectional imaging (CT of the head or brain MR imaging examinations) for 166 patients with spontaneous intracranial hypotension and 321 matched controls was assessed by neuroradiologists blinded to the patient's clinical status. The readers qualitatively evaluated the presence of diffuse or layered calvarial hyperostosis and measured calvarial thickness in the axial and coronal planes.

RESULTS

A significant difference in the frequency of layered hyperostosis (31.9%, 53/166 subjects versus 5.0%, 16/321 controls, P < .001, OR = 11.58) as well as the frequency of overall (layered and diffuse) hyperostosis (38.6%, 64/166 subjects versus 13.2%, 42/321 controls, P < .001, OR = 4.66) was observed between groups. There was no significant difference in the frequency of diffuse hyperostosis between groups (6.6%, 11/166 subjects versus 8.2%, 26/321 controls, P = .465). A significant difference was also found between groups for calvarial thickness measured in the axial (P < .001) and coronal (P < .001) planes.

CONCLUSIONS

Layered calvarial hyperostosis is more prevalent in spontaneous intracranial hypotension compared with the general population and can be used as an additional noninvasive brain imaging marker of spontaneous intracranial hypotension and an underlying spinal CSF leak.

Imaging Review of Paraneoplastic Neurologic Syndromes

Paraneoplastic syndromes are systemic reactions to neoplasms mediated by immunologic or hormonal mechanisms. The most well-recognized paraneoplastic neurologic syndrome, both clinically and on imaging, is limbic encephalitis. However, numerous additional clinically described syndromes affect the brain, spinal cord, and peripheral nerves. Many of these syndromes can have imaging findings that, though less well described, are important in making the correct diagnosis. Moreover, imaging in these syndromes frequently mimics more common pathology, which can be a diagnostic challenge for radiologists. Our goal is to review the imaging findings of paraneoplastic neurologic syndromes, including less well-known entities and atypical presentations of common entities. Specifically, we discuss limbic encephalitis, paraneoplastic cerebellar degeneration, paraneoplastic brain stem encephalitis, cranial neuropathy, myelitis, and polyneuropathy. We also demonstrate common diagnostic pitfalls that can be encountered when imaging these patients.

Safety of Consecutive Bilateral Decubitus Digital Subtraction Myelography in Patients with Spontaneous Intracranial Hypotension and Occult CSF Leak

BACKGROUND AND PURPOSE

Digital subtraction myelography performed with the patient in the lateral decubitus position has the potential for increased sensitivity over prone-position myelography in the detection of spinal CSF-venous fistulas, a well-established cause of spontaneous intracranial hypotension. We report on the safety of performing routine, consecutive-day right and left lateral decubitus digital subtraction myelography in these patients.

MATERIALS AND METHODS

In this retrospective case series, all patients undergoing consecutive-day lateral decubitus digital subtraction myelography for suspected spinal CSF leak between September 2018 and September 2019 were identified. Chart review was performed to identify any immediate or delayed adverse effects associated with the procedures. Procedural parameters were also analyzed due to inherent variations associated with the positive-pressure myelography technique that was used.

RESULTS

A total of 60 patients underwent 68 pairs of consecutive-day lateral decubitus digital subtraction myelographic examinations during the study period. No major adverse effects were recorded. Various minor adverse effects were observed, including pain requiring analgesics (27.2%), nausea/vomiting requiring antiemetics (8.1%), and transient neurologic effects such as syncope, vertigo, altered mental status, and autonomic dysfunction (5.1%). Minor transient neurologic effects were correlated with increasing volumes of intrathecal saline injectate used for thecal sac prepressurization.

CONCLUSIONS

In patients with spontaneous intracranial hypotension and suspected spontaneous spinal CSF leak, consecutive-day lateral decubitus digital subtraction myelography demonstrates an acceptable risk profile without evidence of neurotoxic effects from cumulative intrathecal contrast doses. Higher intrathecal saline injectate volumes may correlate with an increased incidence of minor transient periprocedural neurologic effects.

Time to Resolution of Inadvertent Subdural Contrast Injection during a Myelogram: When Can the Study Be Reattempted?

BACKGROUND AND PURPOSE

Inadvertent subdural contrast injections can occur during any myelogram. Currently, there are no guidelines defining when residual subdural iodinated contrast will be cleared and no longer interfere with subsequent procedure and imaging. We investigated the time to resolution of subdural contrast using a 2-day lateral decubitus digital subtraction myelogram and associated CT myelogram data in patients undergoing evaluation for spontaneous intracranial hypotension.

MATERIALS AND METHODS

Retrospective review of 63 patients with lateral decubitus digital subtraction myelograms from September 4, 2018, to October 1, 2019, was performed. Patients with 2-day lateral decubitus digital subtraction myelograms on 2 consecutive days, with or without a same-day CT myelogram on day 1 and with a same-day CT myelogram on day 2, were included. Patients with next-day CT covering at least the abdomen and pelvis after either-day injection were also included. In cases of subdural injection, next-day CT scans were evaluated for residual subdural contrast.

RESULTS

Of 49 included patients, 5 had subdural injection on day 1, with the second-day CT myelogram available for review. One of these 5 patients had subdural injections on 2 different days and subsequently had chest/abdomen/pelvis CTA a day after the second subdural injection. In all 6 cases of subdural injections, there was complete resolution of subdural contrast on the next-day CT, with the shortest time to resolution of approximately 20.5 hours (range, 20.5-28.5 hours).

CONCLUSIONS

Our study suggests that resolution of inadvertently injected subdural contrast occurs within 1 day, and the myelogram can be reattempted as early as the next day.

Spontaneous Intracranial Hypotension: Atypical Radiologic Appearances, Imaging Mimickers, and Clinical Look-Alikes

Spontaneous intracranial hypotension is a condition characterized by low CSF volume secondary to leakage through a dural defect with no identifiable cause. Patients classically present with orthostatic headaches, but this symptom is not specific to spontaneous intracranial hypotension, and initial misdiagnosis is common. The most prominent features of spontaneous intracranial hypotension on intracranial MR imaging include "brain sag" and diffuse pachymeningeal enhancement, but these characteristics can be seen in several other conditions. Understanding the clinical and imaging features of spontaneous intracranial hypotension and its mimickers will lead to more prompt and accurate diagnoses. Here we discuss conditions that mimic the radiologic and clinical presentation of spontaneous intracranial hypotension as well as other disorders that CSF leaks can imitate.

Lateral Decubitus Digital Subtraction Myelography: Tips, Tricks, and Pitfalls

Digital subtraction myelography is a valuable diagnostic technique to detect the exact location of CSF leaks in the spine to facilitate appropriate diagnosis and treatment of spontaneous spinal CSF leaks. Digital subtraction myelography is an excellent diagnostic tool for assessment of various types of CSF leaks, and lateral decubitus digital subtraction myelography is increasingly being used to diagnose CSF-venous fistulas. Lateral decubitus digital subtraction myelography differs from typical CT and fluoroscopy-guided myelograms in many ways, including equipment, supplies, and injection and image-acquisition techniques. Operators should be familiar with techniques, common pitfalls, and artifacts to improve diagnostic yield and prevent nondiagnostic examinations.

Imaging Findings Related to the Valsalva Maneuver in Head and Neck Radiology

Forced exhalation against a closed glottis, known as the Valsalva maneuver, is an important clinical diagnostic and therapeutic tool due to its physiologic effects. Several unique conditions and anatomic changes can occur with repetitive or acute changes in pressure from the Valsalva maneuver. We will discuss and review various pertinent head and neck imaging cases with findings resulting from induced pressure gradients, including the Valsalva maneuver. Additionally, we will demonstrate the diagnostic utility of the Valsalva maneuver in head and neck radiology.

Carotid Artery Tortuosity Is Associated with Connective Tissue Diseases

BACKGROUND AND PURPOSE

There is a general assumption in the cerebrovascular literature that there is an association between carotid artery tortuosity and connective tissues disease; however, this has not been firmly established. The purpose of this study was to determine the prevalence of carotid artery tortuosity in patients with connective tissue diseases relative to matched controls.

MATERIALS AND METHODS

Patients with previous CTA or MRA and a diagnosis of connective tissue diseases were identified and compared with a cohort of age-matched controls. Radiologists blinded to the diagnosis reviewed the images and evaluated the presence of carotid artery tortuosity (including loops, kinks, or coils). Continuous variables were compared using the Student t test, and categoric variables with χ² tests.

RESULTS

One hundred forty-three patients with connective tissue disease and 143 controls were included in this study. Specific diagnoses included Marfan (n = 33), nonvascular Ehlers-Danlos (n = 36), Ehlers-Danlos vascular-type (n = 32), neurofibromatosis type 1 (n = 26), and Loeys-Dietz (n = 16) syndromes. The presence of carotid tortuosity was 44% in connective tissue disease and 16% in controls (P < .001). Of tortuosity manifestations, coils were most prevalent (23% versus 3%; P < .001). Among the various connective tissue diseases, the rates of any carotid tortuosity were 88% for Marfan syndrome, 63% for Loeys-Dietz syndrome, 42% for neurofibromatosis type 1, and 19% for both vascular- and nonvascular-type Ehlers-Danlos syndrome. The positive predictive value of the combination of aortic aneurysm and carotid tortuosity being associated with connective tissue disease was 95.4%. The specificity was 98.6%.

CONCLUSIONS

Carotid artery tortuosity is highly associated with connective tissue diseases, particularly Marfan syndrome, Loeys-Dietz syndrome, and neurofibromatosis type 1. Such findings are relevant in risk assessment for vascular complications in connective tissue disease, endovascular treatment planning, and in understanding the pathomechanisms of vascular tortuosity in general.

Review of the Imaging Features of Benign Osteoporotic and Malignant Vertebral Compression Fractures

Vertebral compression fractures are very common, especially in the elderly. Benign osteoporotic and malignant vertebral compression fractures have extremely different management and prognostic implications. Although there is an overlap in appearances, characteristic imaging features can aid in the distinction between these 2 types of compression fractures. The aim of this review is to characterize the imaging features of benign and malignant vertebral compression fractures seen with CT, PET, SPECT, and MR imaging.

Dentate Update: Imaging Features of Entities That Affect the Dentate Nucleus

The dentate nucleus is a cerebellar structure involved in voluntary motor function and cognition. There are relatively few entities that affect the dentate, and the clinical features of these conditions are often complex and nonspecific. Because these entities are rarely encountered, the formulation of a differential diagnosis can be difficult. Many of the conditions are reversible or treatable with early intervention. Therefore, it is important to recognize classic clinical presentations and their associated characteristic imaging findings. We provide a summary of entities that affect the dentate nucleus and a diagnostic workflow for approaching dentate nucleus imaging abnormalities.

SAPHO Syndrome: Imaging Findings of Vertebral Involvement

BACKGROUND AND PURPOSE

Imaging findings in patients with a combination of synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) are often misinterpreted as discitis/osteomyelitis or metastases, resulting in multiple biopsies and delayed diagnosis. We have incidentally noted a semicircular morphology in vertebral body imaging in several cases of SAPHO syndrome with vertebral involvement. Our goal was to evaluate the prevalence of this distinctive morphology in these patients.

MATERIALS AND METHODS

A retrospective review of patients with SAPHO syndrome diagnosed between July 1998 and August 2013 was conducted. A descriptive analysis of MR imaging, CT, radiography, bone scanning, and PET imaging was performed for the presence and distribution of vertebral body signal intensity or attenuation changes and/or enhancement; contiguous vertebral body involvement; vertebral body collapse; endplate irregularity; disc space, facet, and spinous process involvement; subligamentous thickening; and paraspinal soft-tissue involvement.

RESULTS

Eighteen patients (16 women [89%]; mean age, 52.9 years) with SAPHO and spine involvement were included. Contiguous involvement of ≥2 vertebral bodies was found in 16 patients (89%), with a curvilinear or "semicircular" pattern involving portions of adjacent vertebral bodies in 10 (63%, P = .14). Most intervertebral discs demonstrated absence of abnormal T2 hyperintensity (73%) and enhancement (89%). Subligamentous thickening was present in 12 (67%). Paraspinal soft-tissue involvement was present in 6 (33%).

CONCLUSIONS

SAPHO syndrome should be included in the differential diagnosis in a patient with a curvilinear or semicircular pattern of vertebral involvement, contiguous vertebral body involvement, and absence of intervertebral disc edema and enhancement.

Predicting High-Flow Spinal CSF Leaks in Spontaneous Intracranial Hypotension Using a Spinal MRI-Based Algorithm: Have Repeat CT Myelograms Been Reduced?

BACKGROUND AND PURPOSE

We adopted an imaging algorithm in 2011 in which extradural fluid on spinal MR imaging directs dynamic CT myelography. We assessed algorithm compliance and its effectiveness in reducing repeat or unnecessary dynamic CT myelograms.

MATERIALS AND METHODS

CT myelograms for CSF leaks from January 2011 to September 2014 were reviewed. Patients with iatrogenic leaks, traumatic brachial plexus injuries, or prior CT myelography within 2 years were excluded. Completion and results of spinal MR imaging, CT myelographic technique, and the need for repeat CT myelography or unnecessary dynamic CT myelograms were recorded.

RESULTS

The algorithm was followed in 102 (79%) of 129 patients. No extradural fluid was detected in 75 (74%), of whom 70 (93%) had no leak, 4 (5%) had a slow leak, and 1 (1%) had a fast leak. Extradural fluid was detected in 27 (26%): 24 (89%) fast leaks, 1 (4%) slow leak, and 2 (7%) with no leaks. When the algorithm was followed, 1 (1%) required repeat CT myelography and 3 (3%) had unnecessary dynamic CT myelograms. The algorithm was breached in 27 (21%) cases, including no pre-CT myelogram MR imaging in 11 (41%), performing conventional CT myelography when extradural fluid was present in 13 (48%), and performing dynamic CT myelography when extradural fluid was absent in 3 (11%). Algorithm breaches resulted in 4 (15%) repeat CT myelograms and 3 (12%) unnecessary dynamic CT myelograms, both higher than with algorithm compliance.

CONCLUSIONS

Using spinal MR imaging to direct CT myelography resulted in significant reduction in repeat CT myelograms to localize fast leaks with minimal unnecessary dynamic CT myelograms.

MRI Findings of Disc Degeneration are More Prevalent in Adults with Low Back Pain than in Asymptomatic Controls: A Systematic Review and Meta-Analysis

BACKGROUND AND PURPOSE

Imaging features of spine degeneration are common in symptomatic and asymptomatic individuals. We compared the prevalence of MR imaging features of lumbar spine degeneration in adults 50 years of age and younger with and without self-reported low back pain.

MATERIALS AND METHODS

We performed a meta-analysis of studies reporting the prevalence of degenerative lumbar spine MR imaging findings in asymptomatic and symptomatic adults 50 years of age or younger. Symptomatic individuals had axial low back pain with or without radicular symptoms. Two reviewers evaluated each article for the following outcomes: disc bulge, disc degeneration, disc extrusion, disc protrusion, annular fissures, Modic 1 changes, any Modic changes, central canal stenosis, spondylolisthesis, and spondylolysis. The meta-analysis was performed by using a random-effects model.

RESULTS

An initial search yielded 280 unique studies. Fourteen (5.0%) met the inclusion criteria (3097 individuals; 1193, 38.6%, asymptomatic; 1904, 61.4%, symptomatic). Imaging findings with a higher prevalence in symptomatic individuals 50 years of age or younger included disc bulge (OR, 7.54; 95% CI, 1.28-44.56; P = .03), spondylolysis (OR, 5.06; 95% CI, 1.65-15.53; P < .01), disc extrusion (OR, 4.38; 95% CI, 1.98-9.68; P < .01), Modic 1 changes (OR, 4.01; 95% CI, 1.10-14.55; P = .04), disc protrusion (OR, 2.65; 95% CI, 1.52-4.62; P < .01), and disc degeneration (OR, 2.24; 95% CI, 1.21-4.15, P = .01). Imaging findings not associated with low back pain included any Modic change (OR, 1.62; 95% CI, 0.48-5.41, P = .43), central canal stenosis (OR, 20.58; 95% CI, 0.05-798.77; P = .32), high-intensity zone (OR = 2.10; 95% CI, 0.73-6.02; P = .17), annular fissures (OR = 1.79; 95% CI, 0.97-3.31; P = .06), and spondylolisthesis (OR = 1.59; 95% CI, 0.78-3.24; P = .20).

CONCLUSIONS

Meta-analysis demonstrates that MR imaging evidence of disc bulge, degeneration, extrusion, protrusion, Modic 1 changes, and spondylolysis are more prevalent in adults 50 years of age or younger with back pain compared with asymptomatic individuals.

Increases in plasma sheet temperature with solar wind driving during substorm growth phases

During substorm growth phases, magnetic reconnection at the magnetopause extracts ∼10¹⁵ J from the solar wind which is then stored in the magnetotail lobes. Plasma sheet pressure increases to balance magnetic flux density increases in the lobes. Here we examine plasma sheet pressure, density, and temperature during substorm growth phases using 9 years of Cluster data (>316,000 data points). We show that plasma sheet pressure and temperature are higher during growth phases with higher solar wind driving, whereas the density is approximately constant. We also show a weak correlation between plasma sheet temperature before onset and the minimum SuperMAG AL (SML) auroral index in the subsequent substorm. We discuss how energization of the plasma sheet before onset may result from thermodynamically adiabatic processes; how hotter plasma sheets may result in magnetotail instabilities, and how this relates to the onset and size of the subsequent substorm expansion phase.

Space magnetometer based on an anisotropic magnetoresistive hybrid sensor

We report on the design and development of a low resource, dual sensor vector magnetometer for space science applications on very small spacecraft. It is based on a hybrid device combining an orthogonal triad of commercial anisotropic magnetoresistive (AMR) sensors with a totem pole H-Bridge drive on a ceramic substrate. The drive enables AMR operation in the more sensitive flipped mode and this is achieved without the need for current spike transmission down a sensor harness. The magnetometer has sensitivity of better than 3 nT in a 0-10 Hz band and a total mass of 104 g. Three instruments have been launched as part of the TRIO-CINEMA space weather mission, inter-calibration against the International Geomagnetic Reference Field model makes it possible to extract physical signals such as field-aligned current deflections of 20-60 nT within an approximately 45,000 nT ambient field.

Time-of-flight secondary ion mass spectrometry (ToF-SIMS) analysis of the application of a cationic conditioner to "clean" hair

In this study the applicability of the surface-sensitive ToF-SIMS technique to hair analysis and associated aqueous processing is evaluated. ToF-SIMS analysis of "as received" human hair indicates the presence of silicones, anionic surfactants, and cationic conditioners, from previous treatments, on the fiber surface. Cleaning of the hair with SLS or SLES results in adsorption of the surfactants onto the fiber surface. In particular, the more non-polar surfactant components have greater substantivity for the fiber surface, as indicated by the relative increase in their ToF-SIMS intensity. Application of the Incroquat Behenyl 18-MEA conditioner to both "virgin" and bleached hair results in the adsorption of the cationic C18, C20, C22, and C21 surfactant components onto the hair surface. The ToF-SIMS data indicate higher levels of conditioner on the bleached hair relative to the undamaged hair.

The creators of England's inter-war suburbs

Despite the transformation of English cities by the growth of suburbs in the inter-war years, there is a dearth of reliable information about the processes, and especially the firms, that brought these suburbs into existence. Contrary to accepted wisdom – and paradoxically, in view of the scorn heaped upon suburbs by the architectural literati – architects are shown to have been heavily involved in the preparation of building applications for the construction of suburban houses. In spite of the unprecedented amount of house building in the inter-war period, the geographical spheres of influence of both builders and architects were highly localized. However, unlike in the nineteenth century, there is little evidence of speculative building having been undertaken by people whose livelihood was not primarily derived from house building or house selling.

Ordering the final events in yeast exocytosis

In yeast, assembly of exocytic soluble N-ethylmaleimide-sensitive fusion protein (NSF) attachment protein receptor (SNARE) complexes between the secretory vesicle SNARE Sncp and the plasma membrane SNAREs Ssop and Sec9p occurs at a late stage of the exocytic reaction. Mutations that block either secretory vesicle delivery or tethering prevent SNARE complex assembly and the localization of Sec1p, a SNARE complex binding protein, to sites of secretion. By contrast, wild-type levels of SNARE complexes persist in the sec1-1 mutant after a secretory block is imposed, suggesting a role for Sec1p after SNARE complex assembly. In the sec18-1 mutant, cis-SNARE complexes containing surface-accessible Sncp accumulate in the plasma membrane. Thus, one function of Sec18p is to disassemble SNARE complexes on the postfusion membrane.

The changing fabrics of ordinary residential areas

An increasing proportion of change to the built environments of Western countries consists of adaptations of existing physical forms. Many changes are small-scale and piecemeal, but cumulatively they have a major impact on the physical character of the environment. This paper considers the physical changes that have taken place in one of the most extensive types of area in English cities: the suburbs created by private enterprise between the two world wars. Within each of the two cities studied, Birmingham and London, the form and density of the original development were major factors influencing the distribution of additional dwellings, demolitions and modifications of existing houses, and the types of new dwelling constructed. Between the mid 1950s and the mid 1960s in London, but a few years later in Birmingham, the insertion of additional houses by developers was the main type of change. From the early 1970s, individual householders became major instigators of change to existing houses, especially in London, where incomes rose more rapidly. House extensions were an important element in this change, despite the decline in household size. The large majority of planning applications for changes to existing houses, but only about one-half of those for the construction of additional dwellings, were approved.

Influenza hemagglutinin is spring-loaded by a metastable native conformation

Enveloped viruses enter cells by protein-mediated membrane fusion. For influenza virus, membrane fusion is regulated by the conformational state of the hemagglutinin (HA) protein, which switches from a native (nonfusogenic) structure to a fusion-active (fusogenic) conformation when exposed to the acidic environment of the cellular endosome. Here we demonstrate that destabilization of HA at neutral pH, with either heat or the denaturant urea, triggers a conformational change that is biochemically indistinguishable from the change triggered by low pH. In each case, the conformational change is coincident with induction of membrane-fusion activity, providing strong evidence that the fusogenic structure is formed. These results indicate that the native structure of HA is trapped in a metastable state and that the fusogenic conformation is released by destabilization of native structure. This strategy may be shared by other enveloped viruses, including those that enter the cell at neutral pH, and could have implications for understanding the membrane-fusion step of HIV infection.

Subdomain folding of the coiled coil leucine zipper from the bZIP transcriptional activator GCN4

One popular model for protein folding, the framework model, postulates initial formation of secondary structure elements, which then assemble into the native conformation. However, short peptides that correspond to secondary structure elements in proteins are often only marginally stable in isolation. A 33-residue peptide (GCN4-p1) corresponding to the GCN4 leucine zipper folds as a parallel, two-stranded coiled coil [O'Shea, E.K., Klemm, J.D., Kim, P.S., & Alber, T.A. (1991) Science 254, 539-544]. Deletion of the first residue (Arg 1) results in local, N-terminal unfolding of the coiled coil, suggesting that a stable subdomain of GCN4-p1 can form. N- and C-terminal deletion studies result in a 23-residue peptide, corresponding to residues 8-30 of GCN4-p1, that folds as a parallel, two-stranded coil with substantial stability (the melting temperature of a 1 mM solution is 43 degrees C at pH 7). In contrast, a closely related 23-residue peptide (residues 11-33 of GCN4-p1) is predominantly unfolded, even at 0 degrees C, as observed previously for many isolated peptides of similar length. Thus, specific tertiary packing interactions between two short units of secondary structure can be energetically more important in stabilizing folded structure than secondary structure propensities. These results provide strong support for the notion that stable, cooperatively folded subdomains are the important determinants of protein folding.