Posterior Bulging Research Articles

Comparative analysis of mechanical wall shear stress and hemodynamics to study the influence of asymmetry in abdominal aortic aneurysm and descending thoracic aortic aneurysm

An aneurysm's rupture is commonly associated with its maximum diameter, yet biomechanical studies emphasize the significant influence of mechanical wall shear stress (WSS) in this process. This study focuses on two models of aortic aneurysms: abdominal aortic aneurysm and descending thoracic aortic aneurysm. Five cases, comprising two for model 1 and three for model 2, are examined to explore both axisymmetric and asymmetric shapes, as patient geometry may manifest as either fusiform (axisymmetric) or saccular (asymmetric), while maintaining a consistent aneurysm diameter and adjusting the bulge shape factor to induce asymmetry. Hemodynamic factors, including WSS and wall shear stress gradient, are computed to evaluate thrombus formation and rupture risk within the aneurysms. Our results indicate the presence of recirculation zones in both the medial and transverse planes, generating vortices within the aneurysm. These vortices are more prominent in asymmetric cases compared to axisymmetric cases, leading to increased blood residence time within the aneurysm and a higher likelihood of thrombus formation. Thrombus formation can further impede blood flow, heightening the risk of embolism or ischemic events. Rupture occurs when the WSS surpasses tissue strength; thus, if the tissue strength of all aneurysms is same, our findings suggest that rupture risk varies according to asymmetry. In the transverse direction, our results demonstrate that in model 1, case 1 exhibits uniform WSS on both sides, while in case 2, WSS is higher at the posterior sides of the aneurysm sac. Conversely, in model 2, WSS is higher at the anterior side of the aneurysm. In the medial direction of the aneurysm, WSS is highest for case 5, followed by case 3, case 4, case 2, and case 1, respectively, indicating elevated WSS when the anterior bulge dominates over the posterior bulge for each model. Overall, a higher rupture risk is observed in model 2 compared to model 1 due to increased mechanical stresses.

Taxonomic and phylogenetic studies on two marine Cyrtophoria ciliates (Protista: Ciliophora: Phyllopharyngea) with the description of a new species

The subclass Cyrtophoria is a group of morphologically specialized ciliates with diverse characteristics, which can be found in a variety of aquatic and terrestrial habitats. In the present study, two cyrtophorian ciliates, Aegyria oliva Claparède & Lachmann, 1859 and A. peculiaris sp. nov., isolated from coastal waters of China, were investigated based on microscopic observations of live and protargol-stained specimens, and SSU rRNA gene sequence analyses. For A. oliva, the type species of the genus, detailed morphometric data, and improved diagnosis are provided. The new species, Aegyria peculiaris sp. nov. is characterized by a body size of 70–115 × 30–65 μm in vivo, an inverted oval body shape with a protrusion at the anterior left and a posterior bulge on the dorsal side, 45–58 somatic kineties, 31–46 nematodesmal rods, 4–6 transpodial segments, and about six contractile vacuoles. Phylogenetic analyses unveiled a close relationship between the newly identified species and A. foissneri, thereby confirming the monophyly of the genus Aegyria. http://zoobank.org/urn:lsid:zoobank.org:pub:F5566374-DA6C-4E95-B8DA-19F935D949C8

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy presenting as severe herniated nucleus pulposus: A case report

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy is the most common inherited cerebral microangiopathy. Its clinical features include recurrent central nervous system symptoms—including lacunar stroke, migraine, psychiatric disturbance, acute reversible encephalopathy, and cognitive impairment. We report a case of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy in a patient presenting with severe low back pain and a herniated nucleus pulposus. A 45-year-old female patient with a prior history of right-sided sciatic pain, hypoesthesia, and paresthesia in the right S1 sensory dermatome was referred after back surgery because of persistent low back pain and a spastic gait abnormality. Imaging revealed a right protruding disc herniation of L5/S1 with right S1 nerve root compression and right posterior disc bulging at L4/5 with foraminal stenosis and disc degeneration, for which she underwent surgery. After surgery, she experienced mild sciatica, an antalgic limping gait with foot-dragging, and progressive motor weakness. Her family history was significant for a parent and sibling affected by stroke. The diagnosis of cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy was established by polymerase chain reaction sequencing, which showed a mutated exon 11 of NOTCH3 on chromosome 19. Clinicians should assess patients with non-specific extra-central nervous system symptoms or atypical courses for potential underlying diseases.

Measurement of Force Required for Anterior Displacement of Intraocular Lenses and Its Defining Parameters.

Intraocular stability during or after cataract and glaucoma filtration surgeries and vitreous surgery with a gas/silicone oil tamponade might differ among intraocular lenses (IOLs). We used six different one-piece IOL models and measured the force that displaced the IOLs from the vitreous cavity to anterior chamber as a measure of stability against the pressure gradient between the anterior and posterior IOL surfaces. We measured IOL hardness, haptics junction area, and posterior IOL bulge to identify what determines the IOL displacement force. The KOWA YP2.2 IOL (1.231 mN) required significantly greater force than the HOYA XY1 (0.416 mN, p = 0.0004), HOYA 255 (0.409 mN, p = 0.0003), Alcon SN60WF (0.507 mN, p = 0.0010), and Nidek NS60YG (0.778 mN, p = 0.0186) IOLs; J&J ZCB00V IOL (1.029 mN) required greater force than the HOYA XY1 (p = 0.0032) and HOYA 255 (p = 0.0029) IOLs; the Nidek NS60YG IOL required greater force than the HOYA 255 (p = 0.0468) IOL. The haptics junction area was correlated positively with the IOL displacement force (r = 0.8536, p = 0.0306); the correlations of the other parameters were non-significant. After adjusting for any confounding effects, the haptics junction area was correlated significantly with the IOL displacement force (p = 0.0394); the IOL hardness (p = 0.0573) and posterior IOL bulge (p = 0.0938) were not. The forces that displace IOLs anteriorly differed among one-piece soft-acrylic IOLs, and the optics/haptics junction area was the major force determinant.

Occlusion of the lumbar spine canal during high-rate axial compression

BACKGROUND CONTEXTWhile burst fracture is a well-known cause of spinal canal occlusion with dynamic, axial spinal compression, it is unclear how such loading mechanisms might cause occlusion without fracture. PURPOSETo determine how spinal canal occlusion during dynamic compression of the lumbar spine is differentially caused by fracture or mechanisms without fracture and to examine the influence of spinal level on occlusion. STUDY DESIGNA cadaveric biomechanical study. METHODSTwenty sets of three-vertebrae specimens from all spinal levels between T12 and S1 were subjected to dynamic compression using a hydraulic loading apparatus up to a peak velocity between 0.1 and 0.9 m/s. The presence of canal occlusion was measured optically with a high-speed camera. This was repeated with incremental increases of 4% compressive strain until a vertebral fracture was detected using acoustic emission measurements and computed tomographic imaging. RESULTSFor axial compression without fracture, the peak occlusion (Omax) was 29.9±10.0%, which was deduced to be the result of posterior bulging of the intervertebral disc into the spinal canal. Omax correlated significantly with lumbar spinal level (p<.001), the compressive displacement (p<.001) and the cross-sectional area of the vertebra (p=.031). CONCLUSIONSSpinal canal occlusion observed without vertebral fracture involves intervertebral disc bulging. The lower lumbar spine tended to be more severely occluded than more proximal levels. CLINICAL SIGNIFICANCEClinically, intermittent canal occlusion from disc bulging during dynamic compression may not show any radiographic features. The lower lumbar spine should be a focus of injury prevention intervention in cases of high-rate axial compression.

Improvement in determining the risk of damage to the human lumbar functional spinal unit considering age, height, weight and sex using a combination of FEM and RSM.

Human functional spinal unit (FSU) is comprised of two adjacent vertebrae, the intervertebral disc (IVD), the cartilage endplates and the connecting ligamentous tissues. As humans age, trabecular, cortical bone and IVD change in mechanical properties. These changes influence the movement of the FSU (displacements, rotations and disc bulges). This paper proposes a method to determine the influence of sex, age, weight and height on the movements of the FSU using a combination of the FEM and RSM. The work concentrates on the medium-sized human FSU (L3-L4 lumbar level with standard dimensions of IVD: width = 50mm, depth = 35mm and height = 11mm). Also, the proposed method could be an improvement to the determination of risk of damage based on body mass index (BMI), as well as an alternative method of searching for a healthy weight. The method was developed as follows: First, a three-dimensional parameterized human healthy FSU FE model was generated based on the standard test (for compression, flexion, extension, lateral bending, torsion and shear). The movements of the FSU FE model based on the aforementioned standardized test when the sex, age, weight and height varies in a range for each individual (30-80 years; 70-120 kg; 160-190 cm) were simulated. Quadratic regression models were generated for each standardized test using RSM. An ANOVA test showed that all of the tests have a significant influence on weight and age, whereas height influences only those tests that involve rotation of the FSU (flexion, extension and lateral bending). Normal weight, overweight and obesity BMI classifications were considered in determining the healthy weight with the following constraints: the limit angles of flexion and lateral bending, as well as the maximum posterior bulge limit of the IVD, could not exceed of one-third of the spinal canal. The proposed method concluded that: (1) normal BMI values do not cause damage to the FSU, (2) some overweight BMI values may cause damage to the FSU for a certain range of ages and heights and (3) for BMI obesity values, the risk of damage to the FSU may be imminent.

Is it appropriate to measure age-related lumbar disc degeneration on the mid-sagittal MR image? A quantitative image study.

Even though phenotypes of disc degeneration vary on different sagittal magnetic resonance images (MRI), measurements typically are acquired on the mid-sagittal MRI. This study investigated the appropriateness of using the mid-sagittal MRI to measure various phenotypes of age-related disc degeneration. Lumbar spine MRIs of 66 subjects (mean age 50.3years, standard deviation 16.5years, range 22-84years) were studied. An image analysis program Spine Explorer was used to obtain quantitative measurements for disc height, bulging, and signal on para- and mid-sagittal T2-weighted MRIs. Measurements on para- and mid-sagittal MRIs and their associations with age were compared. Measurements of disc height, signal, and posterior disc bulging acquired on the mid-sagittal MRI were greater than those on the para-sagittal MRIs. Disc height measurements were not linearly associated with age. Greater age was correlated with greater anterior (r=0.45, P<0.001) and posterior (r=0.33, P<0.01) bulging on para-sagittal MRIs, but not posterior disc bulging on the mid-sagittal MRI (r=-0.10, P>0.05). Disc signal intensity measurements on the mid-sagittal MRI had stronger correlations with age than those on para-sagittal MRIs. Mean and standard deviation of disc signal intensity acquired on the mid-sagittal MRI had the strongest correlations with age among all measures of disc degeneration studied (r=-0.50, -0.67, respectively, P<0.001 for both). Disc signal measurements acquired on the mid-sagittal MRI were reliable and had strong correlations with age and thus can be used as an appropriate measure of disc degeneration. Disc bulging had better be measured on para-sagittal MRIs. Although severe disc narrowing clearly is a sign of severe disc degeneration, disc height was not linearly associated with age.

Pattern of lumbosacral magnetic resonance imaging findings in diagnosed cases of disc degenerative disease among Nigerian adults with low back pain

Background: Lumbar spine disc degenerative disease (DDD) has been proven to be the most common cause of low back pain which causes musculoskeletal disability. Magnetic resonance imaging (MRI) allows detailed evaluation of all components of the lumbar spine and assesses abnormalities that may be associated with disc degeneration. Objective: To document the frequency of lumbosacral MRI findings in DDD with correlation to age, gender, and lumbar disc level. Methodology: Two hundred and eighty-one out of three hundred archived magnetic resonance images of patients aged 18 years and above investigated for low back pain at Memfys Hospital for Neurosurgery were enrolled into the study. Axial and sagittal magnetic resonance images were acquired at 5 mm slice thickness with 1 mm gap using spin echo pulse sequence. Results: The mean age of the study population was 55.11 years with a range of 18-91 years. Highest frequency of disc degenerative changes fell within 50-59 years age group and L4/L5 level with male preponderance. Positive findings were disc bulge 51.2%, disc protrusion 87.5%, disc extrusion 19.6%, disc sequestration 1.78%, Modic endplate changes 47.4%, Modic I 10.7%, Modic II 15.3%, and Modic III 21.4%. Logistic regression analysis showed that only posterior disc protrusion and disc bulge were significant. Odd ratio 0.062 and 0.015, respectively, while the beta values are −4.190 and −2.780, respectively. Conclusion: The most common lumbosacral MRI findings in diagnosed cases of DDD among patients with low back pain in this study were posterior disc protrusion, posterior disc bulge, and endplate changes.

Type II Modic Changes May not Always Represent Fat Degeneration: A Study Using MR Fat Suppression Sequence.

A radiological study of type II Modic changes (MCs). The aim of this study was to determine the characteristics of type II MCs on fat suppression (FS) magnetic resonance (MR) images and its association with radiological disc degeneration. Type II MCs are common endplate signal changes on MR images. On the basis of limited histological samples, type II MCs are thought to be stable fat degeneration. FS technique on MR, which can quantify fat content, may be an alternative to explore the pathology of MCs. To date, however, the characteristics of type II MCs on FS sequence have not been studied. Lumbar MR images conducted in a single hospital during a defined period were reviewed to include those with type II MCs and FS images. On FS images, signal status of type II MCs was visually classified as suppressed or not-suppressed. Signal intensity of vertebral regions with and without MCs was measured quantitatively on T2-weighted (T2W) and FS images to calculate fat content index and validate the visual classification. Using image analysis program Osirix, MCs size and adjacent disc degeneration were measured quantitatively. Paired t-tests and logistic regressions were used to determine the associations studied. Sixty-four lumbar MRIs were included and 150 endplates with type II MCs were studied. Although signal of 37 (24.7%) type II MCs was suppressed on FS images, that of 113 (75.3%) was not suppressed. The discs adjacent to type II MCs had lower signal intensity (0.13 ± 0.003 vs. 0.14 ± 0.004, P < 0.001), lesser disc height (9.73 ± 1.97 vs. 11.07 ± 1.99, P < 0.001) and greater bulging area (80.0 ± 31.4 vs. 61.3 ± 27.5 for anterior bulging, 33.72 ± 21.24 vs. 27.93 ± 12.79 for posterior bulging, and 113.7 ± 39.9 vs. 89.2 ± 35.2 for total bulging, P < 0.05) than normal controls. Type II MCs that were not suppressed on FS image were associated with greater age [odds ratio (OR) = 1.11, P < 0.001], lower height (OR = 0.94, P < 0.05), and greater posterior bulging (OR = 1.05, P < 0.001) at the adjacent disc. Signal of most type II MCs was not suppressed on FS MR images, suggesting that there are ongoing complicated pathologies. Type II MCs may not merely represent fat replacement. 3.

Sylvian Aqueduct Syndrome and Parkinsonism in Aqueduct Stenosis

Objective and Importance: Sylvian aqueduct syndrome (SAS) is associated with a complex clinical picture, which suggests global rostral midbrain dysfunction. Clinical Presentation: A 34-year-old woman developed SAS and Parkinsonism secondary to aqueductal stenosis and was treated by endoscopic third ventriculostomy (ETV) as an initial treatment, which led to the successful resolution of the symptoms. At admission, she exhibited only memory disturbance, slight cognitive impairment and urinary incontinence after recent childbirth. Magnetic resonance imaging (MRI) revealed aqueductal stenosis with the enlargement of the third and lateral ventricle with normal sized fourth ventricle. Several days later, the patient displayed upward gaze paralysis (Parinaud’s syndrome), Parkinsonian hands tremor, and somnolent confusional state. An MRI revealed abnormal intensity in the midbrain and upper pons as well as bulging of the posterior portion of the third ventricle. The dramatic resolution of the patient’s Parinaud’s syndrome, Parkinsonian tremor, and drowsy state after ETV was accompanied by the disappearance of the abnormal intensity in the midbrain and posterior bulging of the third ventricle. This characteristic change, which occurred simultaneously in both the clinical and MRI findings, revealed the lesion responsible for the SAS and Parkinsonism. A drastic change in the ventricular size or transtentorial pressure gradient might have also caused distortion and stretching of the midbrain. Conclusions: The simultaneous resolution of the clinical symptoms and abnormal MRI findings after ETV revealed the lesion responsible for this patient’s SAS and Parkinsonism. Early ETV allowed the reversal of the SAS and Parkinsonism and should be considered as the first-line treatment.

Role of Percutaneous Image Guided Biopsy in Spinal Lesions: Adequacy and Correlation with MRI Findings

Although, MRI has increased our understanding of spinal pathologies, accurate diagnosis of spinal lesions need biopsy, so that early treatment can be initiated. To evaluate the accuracy of biopsy, safety and yield of percutaneously done image guided spinal biopsy using a large bore needle and correlate between MRI findings and biopsy as well as the importance of various MRI findings in establishing the diagnosis. All spinal lesions after clinical and MRI evaluation were subjected to Jamshidi Needle biopsy using 11 gauge needles. Biopsy material was sent for culture/sensitivity, AFB smear and histopathological examination. The outcome assessment included percentage of patients in whom diagnosis was changed after biopsy, yield in biopsy and complications of biopsy. MRI findings, biopsy findings and final diagnosis were correlated to know the sensitivity and specificity of MRI and biopsy diagnosis. Logistic regression analysis was used to study the importance of each of MRI findings in making a diagnosis. Forty five patients with spinal lesions underwent biopsy using an 11 gauge Jamshidi needle. Initial biopsy was inconclusive in 4 patients giving a positive yield in about 91.2% of cases and a repeat biopsy ensured conclusive report in all cases. Following biopsy there was a change in diagnosis in 8% cases. MRI showed sensitivity of 85.71% and specificity of 93.54% for the diagnosis of malignancy and sensitivity of 85.71% and specificity of 86.48% for the diagnosis of tuberculosis. In contrast, initial biopsy had sensitivity of 92.85% and specificity of 100% for the diagnosis of malignancy and sensitivity of 71.42% and specificity of 100 % for the diagnosis of infection. Logistic regression analysis showed good correlation between malignancy and posterior bugle in the vertebral body in the absence of a fracture (p = 0.007), involvement of pedicles and posterior elements (p = 0.001) and soft tissue extension (p = 0.002); there was good correlation between infection and epidural abscess (p<0.001) as well as paradiscal involvement (p<0.001). Image guided biopsy done with good technique helps in accuracy of diagnosis thus ensuring the correct treatment at the earliest and has minimal complications. This study also shows that presence of epidural abscess and paradiscal involvement in MRI are highly suggestive of infection, while pedicle involvement and posterior bulge of vertebral body before the onset of pathological fracture are suggestive of malignancy, but all spinal lesions should be biopsied to confirm the diagnosis.

Role of posterior elements in the disc bulging of a degenerated cervical spine

Many studies have been developed to characterize the mechanical behavior of the intervertebral disc specifically for the lumbar spine and there have been limited studies done on the cervical spine with the goal to evaluate the strength of the cervical spine under compression without any information on the bulging of the intervertebral discs. The goal of the current study is to examine the deformation response of the cervical intervertebral disc classified with grade III or greater degeneration and analyze the relationship between axial deformation and anterior and posterior bulge under compression up to 550 N. Each specimen was compressed for 3 cycles to a maximum load of 550N in steps of 50 N. The bulge was measured using Linear Variable Differential Transformers (LVDTs on an intact spinal segment, spinal segment with post laminectomy, and spinal segment post facetectomy. The anterior budge for an intact spinal segment shows a change of slope at loads of 262N±66N. For a physiological load of 250N the vertical displacement or spine segment height was reduced by 10.1% for an intact segment and 8.78% for the laminectomy and facetectomy configurations with F = 0.159 (Fcrit = 3.89) with no statistical difference observed. For the post laminectomy there was a decrease of 35% in anterior bulge compared to the intact specimen. Our results show that for grade III disc degeneration the cervical segments bulging for both the laminectomy and facetectomy procedures are not significantly different. In post laminectomy the average anterior and posterior bulges are similar to the average anterior and posterior bulge post facetectomy.

Implementation of a standardized digital rectal exam to improve the accuracy of rectocele diagnosis.

The standardized evaluation of posterior compartment prolapse using the Pelvic Organ Prolapse Quantification (POP-Q) system is limited. The primary objective of this study is to develop and validate the interexaminer reliability of a new system for assessing the posterior vaginal wall for the presence of a rectocele. This was a cross-sectional study of women presenting to an academic urogynecology clinic. Subjects underwent a routine pelvic examination that included a standard POP-Q followed by two Standardized Digital Rectal Exams (SDRE) by two different providers, each blinded to the other's results. The SDRE measures the distance from the leading edge of a posterior bulge to the hymen with a finger in the distal rectum - first visually and then an actual measured distance using a marked cotton swab (Q-tip measurement). Correlations between examiners for the SDRE and the POP-Q were analyzed using Pearson's correlation coefficient (ρ). Eight attending and fellow urogynecologists examined 50 subjects. Mean age was 57.3 years, mean BMI 30.9 kg/m(2), with an overall median POP-Q stage 2 (range 0-3), and median posterior POP-Q stage 1 (range 0-3). Overall, 54 % of women had a noteworthy rectocele by typical digital rectal exam. Interexaminer correlations with SDRE for both the visual assessment (ρ = 0.697, p < 0.0001) and the Q-tip measurement (ρ = 0.767, p = p < 0.001) were strong. The intraexaminer visual assessment and the Q-tip measurement were highly correlated (ρ = 0.934, p = <0.001). This standardized rectal examination provides a consistent method for the reporting of distal rectoceles that can lend additional information to the POP-Q exam.

Preoperative detection of posterior capsule tear with ultrasound biomicroscopy in traumatic cataract

We report ultrasound biomicroscopy (UBM) evaluation of a paintball-related traumatic cataract with a posterior capsule tear. Slitlamp examination revealed anterior and posterior subcapsular cataracts with a suspicious tiny posterior capsule tear within the larger area of posterior bulging. Ultrasound biomicroscopy (35 MHz) confirmed the presence of a sub-1.0 mm posterior capsule tear, which was clearly observed intraoperatively and postoperatively. This is the first report illustrating the high performance of 35 MHz UBM in detecting a sub-1.0 mm posterior capsule tear. No author has a financial or proprietary interest in any material or method mentioned.

An Almost Crypto(genic) Cause of Radiculopathy (P01.253)

Objective: We describe a rare case of non-HIV/AIDS related cryptococcal neurological infection with a very unusual presentation in the form of a radiculopathy. Background Cryptococcal Neurological infections have been well described in patients who are immunocompromised secondary to HIV/AIDS but less well described in patients immunocompromised secondary to other etiologies. Design/Methods: Our patient is was a 70 year old right handed man with myelodysplastic syndrome, on chemotherapy and platelet transfusion-dependent who presented with acute onset of left leg weakness. Seven days prior to presentation he developed numbness and tingling in his left leg following a fall, which progressed over an hour into left lower extremity weakness with inability to ambulate without a walker. Also, he had intermittent diffuse headache and episodic confusion. On neurological examination, his left lower extremity power was (3/5), absent left patellar reflex, diminished sensation in the left lower extremity below the knee. He underwent a head CT, MRI of the cervical, thoracic and lumbar spine were significant for degenerative changes of the vertebra most prominent at C3-C4, a small posterior disc bulge T8-T9 with no cord compression and pelvic MRI which was negative for retroperitoneal hemorrhage; a normal EEG; EMG was consistent with a subacute left high lumbar through L4 radiculopathy with active denervation. CSF analysis revealed a lymphocytoc pleocytosis with low glucose (16) and elevated protein (146) with 2+ yeast on gram stain and he was initiated on ambisome for presumed fungal meningitis. Serum cryptococcal antigen was negative. CSF cryptococcal antigen was positive with a titer of 1:4096. Results: Our patient was discharged on long-term ambisome infusions with little recovery in the function of his left leg. Conclusions: Cryptococcal neurological infections need to be considered in patients with other underlying immunocompromised states besides HIV/AIDS so that appropriate therapy can be instituted in a timely manner. Disclosure: Dr. Goldstein has nothing to disclose. Dr. Dangayach has nothing to disclose. Dr. Riley has received personal compensation for activities with Allergan, Ipsen, Lundbeck, Merz and Teva as a consultant.Dr. Riley has received research support from Cleveland Medical Devices.

Patient with Posterior Mediastinal Mass Requiring Urgent Cardiopulmonary Bypass

T HE literature on anesthetic concerns and perioperative care of patients with mediastinal masses has focused almost exclusively on anterior mediastinal masses. Posterior mediastinal masses traditionally have been suggested to carry a low risk of anesthetic implications. We present the case of a patient with a posterior mediastinal mass who experienced hemodynamic and respiratory decompensation upon induction of general anesthesia and required urgent transition to cardiopulmonary bypass (CPB). Our case illustrates the importance of real-time imaging provided by transesophageal echocardiography (TEE) in explaining the etiology of intractable hemodynamic instability and a new finding of significant pericardial and left pleural effusion not seen on preoperative imaging. TEE made clear the urgent need to initiate CPB because it revealed a near total compression of the left atrium, which was obstructing delivery of volume to the left ventricle. In addition, this case demonstrates the inadequacy of “stand-by” CPB and the need for every institution to establish an interdisciplinary team to develop, before surgery, a formal plan for the perioperative care of patients with mediastinal masses.

One-Stage Repair of Ventricular Septal Defect and Severe Tracheomalacia by Aortopexy and Posterior Tracheal Wall Stabilization

Tracheomalacia complicates the clinical course of congenital heart disease among infants; however, the surgical treatment of tracheomalacia in conjunction with open heart operations is rarely reported. We report an infant with ventricular septal defect and severe tracheomalacia. The patient was treated with simultaneous intracardiac repair, and the tracheomalacia was relieved by aortopexy for anterior wall collapse and a new technique to fix the posterior wall bulging.

Description of Trichotokara nothriae n. gen. et sp. (Apicomplexa, Lecudinidae) – An intestinal gregarine of Nothria conchylega (Polychaeta, Onuphidae)

The trophozoites of a novel gregarine apicomplexan, Trichotokara nothriae n. gen. et sp., were isolated and characterized from the intestines of the onuphid tubeworm Nothria conchylega (Polychaeta), collected at 20 m depth from the North-eastern Pacific Coast. The trophozoites were 50–155 μm long with a mid-cell indentation that formed two prominent bulges (anterior bulge, 14–48 μm wide; posterior bulge, 15–55 μm wide). Scanning electron microscopy (SEM) demonstrated that approximately 400 densely packed, longitudinal epicytic folds (5 folds/μm) inscribe the surface of the trophozoites, and a prominently elongated mucron (14–60 μm long and 6–12 μm wide) was covered with hair-like projections (mean length, 1.97 μm; mean width, 0.2 μm at the base). Although a septum occurred at the junction between the cell proper and the mucron in most trophozoites, light microscopy (LM) demonstrated that the cell proper extended into the core of the mucron as a thin prolongation. A spherical nucleus (8–20 μm) was situated in the middle of the trophozoites, and gamonts underwent caudal syzygy. The small subunit (SSU) rDNA sequence and molecular phylogenetic position of T. nothriae was also characterized. The sequence from this species was the most divergent of all SSU rDNA sequences currently known from gregarines and formed a weakly supported clade with Lecudina polymorpha, which also possesses densely packed epicyctic folds (3–5 folds/μm) and a prominently elongated mucron.

Dynamic Bulging of Intervertebral Discs in the Degenerative Lumbar Spine

The effect of postural change on degenerative lumbar discs was quantified using novel kinematic magnetic resonance imaging (kMRI). The purpose is to describe the bulging of degenerative intervertebral lumbar discs in vivo subjected to different postural loads using a novel kMRI. Symptomatic lumbar disc degeneration is a leading cause of pain and disability throughout the world. Over 70% of US citizens will experience a debilitating episode of low back pain. Earlier reports of degenerative disc changes are cadaver studies or are performed with recumbent MRI that eliminates the functional effects of gravity and muscle power. Little data are available on the behavior of degenerative intervertebral discs in vivo under physiologic loads. A total of 513 patients obtained kMRI. Disc bulging beyond the intervertebral space was quantified during upright neutral, flexion, and extension imaging. The degree of intervertebral disc degeneration was correlated using the Pfirrmann Classification. Moderately degenerated intervertebral discs (grade III and IV) demonstrated greater bulging than mildly degenerated discs (grade II). Severely degenerated discs (grade V) also showed a trend toward greater bulging, but this was not significant. Grade I discs at all levels moved posteriorly in flexion and anteriorly in extension when compared to neutral posture. However, mild to severe (grade II-V) degenerative discs behaved differently in response to postural loads. Extension resulted in significant posterior bulging, while flexion did not demonstrate obvious anterior derangement. Disc bulging increases with the severity of disc degeneration. Grade I discs demonstrate the expected sagittal migration in response to postural load. However, more degenerative discs behave less predictably, and spine extension may result in significant posterior disc bulging. Degenerative changes in the intervertebral disc significantly affect the kinematic patterns under postural load in vivo. kMRI is a useful tool to quantify the kinematic behavior of degenerative intervertertebral discs.

The narrowing of the lumbar spinal canal during loaded MRI: the effects of the disc and ligamentum flavum

Load and activity changes of the spine typically cause symptoms of nerve root compression in subjects with spinal stenosis. Protrusion of the intervertebral disc has been regarded as the main cause of the compression. The objective was to determine the changes in the size of the lumbar spinal canal and especially those caused by the ligamentum flavum and the disc during loaded MRI. For this purpose an interventional clinical study on consecutive patients was made. The lumbar spines in 24 supine patients were examined with MRI: first without any external load and then with an axial load corresponding to half the body weight. The effect of the load was determined through the cross-sectional areas of the spinal canal and the ligamentum flavum, the thickness of ligamentum flavum, the posterior bulge of the disc and the intervertebral angle. External load decreased the size of the spinal canal. Bulging of the ligamentum flavum contributed to between 50 and 85% of the spinal canal narrowing. It was concluded that the ligamentum flavum, not the disc had a dominating role for the load induced narrowing of the lumbar spinal canal, a finding that can improve the understanding of the patho-physiology in spinal stenosis.