A rare cause of chronic mesenteric ischemia from fibromuscular dysplasia: a case report

Introduction

Chronic mesenteric ischemia is a condition that is classically associated with significant atherosclerosis of the abdominal arteries, causing postprandial abdominal pain out of proportion to physical examination. The abdominal pain is exacerbated after meals due to the shunting of blood away from the intestines to the stomach, causing relative ischemia. More than 95% of chronic mesenteric ischemia cases are due to atherosclerosis. We report the first known case of chronic mesenteric ischemia from fibromuscular dysplasia. To the best of our knowledge, this is also the first known case in the literature where postprandial abdominal pain was the presenting symptom of fibromuscular dysplasia.

Case presentation

A 44-year-old Caucasian woman with a history of hypertension and preeclampsia, who had taken oral contraceptive pills for 15 years, presented with an intractable, colicky abdominal pain of two weeks duration. This abdominal pain worsened with oral intake. It was also associated with diarrhea and vomiting. Physical examination revealed stage III hypertension out of proportion to her risk factors and diffuse abdominal pain without peritoneal signs. An abdominal computed tomography scan, completed in the emergency room, revealed nonspecific colitis. Laboratory work revealed leukocytosis with a left shift, an erythrocyte sedimentation rate of 79 and a C-reactive protein level of 100. She was started on intravenous flagyl and intravenous ciprofloxacin. However, all microbial cultures were negative including three cultures for clostridium difficile. Urine analysis revealed nephritic range proteinuria. The laboratory profile was within normal limits for perinuclear-anti-neutrophil cytoplasmic antibody, cytoplasmic-anti-neutrophil cytoplasmic antibody, anti-saccharomyces cerevisiae antibody, antinuclear antibody test, celiac profile, lactate, carbohydrate antigen-125 and thyroid stimulating hormone. A colonoscopy was completed, which revealed diffuse colonic lymphoid reactive hyperplasia. A small bowel series was negative for any inflammation. An indium scan, pan-computed tomography scan and transvaginal ultrasound were also negative. Magnetic resonance angiography of her abdomen revealed proximal superior mesenteric artery stenosis, which was confirmed by computed tomography angiogram findings of severe proximal and distal superior mesenteric artery stenosis, consistent with the appearance of fibromuscular dysplasia on angiography in the absence of vasculitis or atherosclerotic disease. The patient's superior mesenteric artery stenosis was subsequently angioplastied suboptimally and had to be stented with an Angioplus stent. One month after she was admitted, her abdominal pain and tolerance to oral feeds improved tremendously.

Conclusion

Fibromuscular dysplasia most commonly presents with renal artery stenosis, which rarely causes abdominal pain. This case illustrates how fibromuscular dysplasia can present as a rare cause of chronic mesenteric ischemia, similar to chronic mesenteric ischemia from atherosclerosis.     

Biofeedback as a means to alter electromyographic activity in a total knee replacement patient

This paper presents a single case controlled study of a 75-year-old male having bilateral total knee replacement. Baseline EMG recordings demonstrated differential levels of vastus medialis and vastus lateralis muscle activity in both knees during exercise, with increased vastus lateralis activity compared to vastus medialis activity. The purpose of the study was to use electromyographic (EMG) biofeedback training to train the patient to equalize vastus medialis and vastus lateralis EMG activity during exercise. After 11 and 13 training sessions for the left and right knees, respectively, differences between vastus medialis and vastus lateralis activity had markedly decreased. Following the termination of biofeedback training, EMG activity during exercise showed a return toward baseline levels. Several concomitant changes in psychological and physical function were noted. These results suggested that EMG biofeedback can be used to train vastus medialis and vastus lateralis activity in total knee replacement patients, and that biofeedback training may produce positive benefits in other functional areas.The authors wish to express thanks to Dr. Karen Gil for her helpful comments on a draft of this article, and Christianne Herman and Allison Roodman for their help in data collection and entry.     

Biofeedback as a means to alter electromyographic activity in a total knee replacement patient

This paper presents a single case controlled study of a 75-year-old male having bilateral total knee replacement. Baseline EMG recordings demonstrated differential levels of vastus medialis and vastus lateralis muscle activity in both knees during exercise, with increased vastus lateralis activity compared to vastus medialis activity. The purpose of the study was to use electromyographic (EMG) biofeedback training to train the patient to equalize vastus medialis and vastus lateralis EMG activity during exercise. After 11 and 13 training sessions for the left and right knees, respectively, differences between vastus medialis and vastus lateralis activity had markedly decreased. Following the termination of biofeedback training, EMG activity during exercise showed a return toward baseline levels. Several concomitant changes in psychological and physical function were noted. These results suggested that EMG biofeedback can be used to train vastus medialis and vastus lateralis activity in total knee replacement patients, and that biofeedback training may produce positive benefits in other functional areas.     

Measurements of constraint of total knee replacement

Measurement of the constraint of total knee components in a test machine provides an objective method of describing the laxity and stability characteristics of the implant itself, independent of the knee joint into which it would be implanted. A special fixture was designed and fitted to a Bionix multi-channel loading machine. The test consisted of applying a compressive load, applying a cyclic AP force or internal-external torque, and measuring all of the displacements and rotations. Three different commonly-used TKR's showed widely different constraint characteristics. In the cyclic AP test, along with the cyclic AP displacement, displacements and rotations occurred in the other directions. This indicated that all degrees of freedom should be free to move, otherwise anomalous results would be obtained. The paper concludes with recommendations for standardized constraint tests.     

Computational assessment of constraint in total knee replacement

Anterior-posterior (AP) and internal-external (IE) rotational constraint of total knee replacement (TKR) components is frequently assessed experimentally in a multi-axis loading machine. This constraint is of clinical interest because it represents the contribution of the implants to passive joint constraint following surgery. A standard has been published to establish a uniform protocol of constraint testing (American Society of Testing and Materials (ASTM) International, 2005; Designation: F 1223-05. Standard Test Method for Determination of Total Knee Replacement). In the present study a dynamic computer simulation of a posterior-substituting TKR design undergoing an AP and IE range of constraint test was developed and tested. Implant surfaces in the simulation were specified based on the manufacturer's CAD representations, and contact between implants was computed using a rigid-body-spring-model formulation. Predictions of constraint force compared favorably to experimental values when the compliance of the testing frame was modeled. The simulated constraint test was then used to evaluate the selective locking of secondary degrees of freedom (motions other than AP displacement and IE rotation) during constraint testing. The published ASTM standard does not clearly define either the design of the testing machine to accommodate secondary motions or which coupled motions should be allowed. Predicted component constraint for a posterior cruciate-retaining TKR design was sensitive to both varus-valgus joint location and the combinations of allowed secondary motions. Computational prediction of implant constraint can expedite the design cycle and allow an objective comparison between TKR components tested in different locations.     

Pre-clinical assessment of total knee replacement anterior-posterior constraint

Pre-clinical, bench-top assessment of Total Knee Replacements (TKR) can provide information about the inherent constraint provided by a TKR, which does not depend on the condition of the patient undergoing the arthroplasty. However little guidance is given by the ASTM standard on test configurations such as medial-lateral (M:L) loading distribution, flexion angle or restriction of secondary motions. Using a purpose built rig for a materials testing machine, four TKRs currently in widespread clinical use, including medial-pivot and symmetrical condyle types, were tested for anterior-posterior translational constraint. Compressive joint loads from 710 to 2000 N, and a range of medial-lateral (M:L) load distributions, from 70:30% to 30:70% M:L, were applied at different flexion angles with secondary motions unconstrained. It was found that TKA constraint was significantly less at 60 and 90° flexion than at 0°, whilst increasing the compressive joint load increased the force required to translate the tibia to limits of AP constraint at all flexion angles tested. Additionally when M:L load distribution was shifted medially, a coupled internal rotation was observed with anterior translation and external rotation with posterior translation. This paper includes some recommendations for future development of pre-clinical testing methods.     

Accuracy of intramedullary alignment in total knee replacement

The accuracy of a system of intramedullary alignment using 6 mm rods was assessed in 100 patients undergoing total knee replacements. Post-operative, full length weight-bearing X-rays were used; the mechanical axis from head was used as the reference axis. The method of calculating the errors produced by flexion and rotation of the limb in relation to the X-ray beam is described, the mean deviation from the mechanical axis in 100 cases being 0.67° valgus with a standard deviation of 2.47°. The maximum error was 6.68° valgus and 4.62° varus. The purpose of this study is twofold, first to assess the accuracy of this system of intramedullary alignment and, second, to develop a method of correcting for apparent radiological misalignment using standard radiographic equipment.     

Eosinophilic bronchitis-like lesion as the cause of death in a Macaca mulatta: a first case report

BACKGROUND: Eosinophilic bronchitis is a recently described, relatively benign condition in humans that is characterized by a corticosteroid-responsive chronic cough and sputum eosinophilia without the abnormalities of airway function seen in asthma. The exact cause of this condition is currently unknown, however has been associated with various occupational exposures in humans. It has also been reported to progress to irreversible airway obstruction. This disease has been reported in dogs and horses, but not in non-human primates. METHODS: Gross examination of an otherwise healthy 13-year-old, colony-born Macaca mulatta, which died of severe non-responsive respiratory distress revealed that the lungs were markedly inflated and moist. RESULTS: Hematoxylin and eosin-stained sections from the lungs contained widespread accumulation of eosinophils, sloughed epithelial cells, and mucus centered around bronchioles and adjacent airways. There was no evidence of mast cell infiltration of peribronchiolar smooth muscle, goblet cell hyperplasia, or basement membrane thickening. CONCLUSIONS: This ruled out recurrent episodes as would be expected in asthma, favoring the diagnosis of an eosinophilic bronchitis-like lesion. We report a first case of eosinophilic bronchitis-like features in a M. mulatta.     

Computational wear prediction of a total knee replacement from in vivo kinematics

Wear of ultra-high molecular weight polyethylene bearings in total knee replacements remains a major limitation to the longevity of these clinically successful devices. Few design tools are currently available to predict mild wear in implants based on varying kinematics, loads, and material properties. This paper reports the implementation of a computer modeling approach that uses fluoroscopically measured motions as inputs and predicts patient-specific implant damage using computationally efficient dynamic contact and tribological analyses. Multibody dynamic simulations of two activities (gait and stair) with two loading conditions (70-30 and 50-50 medial-lateral load splits) were generated from fluoroscopic data to predict contact pressure and slip velocity time histories for individual elements on the tibial insert surface. These time histories were used in a computational wear analysis to predict the depth of damage due to wear and creep experienced by each element. Predicted damage areas, volumes, and maximum depths were evaluated against a tibial insert retrieved from the same patient who provided the in vivo motions. Overall, the predicted damage was in close agreement with damage observed on the retrieval. The gait and stair simulations separately predicted the correct location of maximum damage on the lateral side, whereas a combination of gait and stair was required to predict the correct location on the medial side. Predicted maximum damage depths were consistent with the retrieval as well. Total computation time for each damage prediction was less than 30 min. Continuing refinement of this approach will provide a robust tool for accurately predicting clinically relevant wear in total knee replacements.     

Explicit finite element modeling of total knee replacement mechanics

Joint kinematics and contact mechanics dictate the success of current total knee replacement (TKR) devices. Efficient computer models present an effective way of evaluating these characteristics. Predicted contact stress and area due to articulations at the tibio-femoral and patello-femoral interfaces indicate potential clinical performance. Previous finite element (FE) knee models have generally been used to predict contact stresses and/or areas during static or quasi-static loading conditions. Explicit dynamic FE analyses have recently been used to efficiently predict TKR kinematics and contact mechanics during dynamic loading conditions. The objective of this study was to develop and experimentally validate an explicit FE TKR model that incorporates tibio-femoral and patello-femoral articulations. For computational efficiency, we developed rigid body analyses that can reasonably reproduce the kinematics, contact pressure distribution, and contact area of a fully deformable system. Results from the deformable model showed that the patello-femoral and tibio-femoral kinematics were in good agreement with experimental knee simulator measurements. Kinematic results from the rigid body analyses were nearly identical to those from the fully deformable model, and the contact pressure and contact area correlation was acceptable given the great reduction in analysis time. Component mesh density studied had little effect on the predicted kinematics, particularly for the patellar component, and small effects on the predicted contact pressure and area. These analyses have shown that, at low computational cost, a force-control dynamic simulation of a gait cycle can yield useful and predictable results.     

Echinococcal cyst of the subcutaneous tissue: a rare case report

Hydatid disease is an endemic zoonosis caused by the cestode Echinococcus granulosus. The most common affected organs are the liver and the lungs. Echinococcal cyst located in the subcutaneous tissue constitutes an extremely rare manifestation of the hydatid disease. Here we present a case report with a cystic mass in the subcutaneous tissue of the left gluteal area, diagnosed as being a hydatid cyst.     

Hydatid disease of the parotid gland: a rare case report

A 40-year-old female suffering from hydatid disease located in the parotid gland is presented. Although Greece remains an endemic area for echinococcosis, this presentation of the disease is rare. Total excision of the cyst with partial parotidectomy was performed. The patient refused to receive general anesthesia and the operation was carried out under local anesthesia. Perioperative adjuvant medical therapy with albendazole was administered. In a two-year follow-up no recurrence has occurred.