Caudad Displacement Research Articles

Bilateral abducens nerve palsy from post-spinal-anesthesia-induced bilateral chronic subdural hematoma: case report

BackgroundA chronic cranial subdural hematoma arising after post-spinal anesthesia is a rare but serious and life-threatening complication of spinal anesthesia. It usually mimics the typical post-spinal-anesthesia headache or post-dural-puncture headache, potentially masking its detection. Abducens nerve palsy tends to occur in chronic subdural hematoma of post-dural-puncture etiology rather than in cases attributed to other causes of subdural hematoma. Preferential damage to the abducens nerve is frequent and can be attributed to its anatomic course because the abducens nerve runs in the direction of the typical caudad displacement of the brain related to intracranial hypotension.ObservationHere, we present a report on the clinical presentation, pathogenesis, and management of two cases that developed bilateral abducens nerve palsy following post-spinal anesthesia administered for cesarean sections due to obstetric indications.LessonPost-spinal-anesthesia-induced chronic subdural hematoma, although a rare, life-threatening complication, must be differentiated from post-spinal-anesthesia headache and treated surgically. Cranial nerve palsy (more commonly called abducens nerve palsy) is more common in post-spinal-anesthesia-induced subdural hematoma than subdural hematomas of other etiologies as the cerebrospinal fluid brain cushioning is partly lost. Cranial nerve palsies resolve in most cases if surgery is performed in a timely manner.

Colonic content in health and its relation to functional gut symptoms

Gut content may be determinant in the generation of digestive symptoms, particularly in patients with impaired gut function and hypersensitivity. Since the relation of intraluminal gas to symptoms is only partial, we hypothesized that non-gaseous component may play a decisive role. Abdominal computed tomography scans were evaluated in healthy subjects during fasting and after a meal (n = 15) and in patients with functional gut disorders during basal conditions (when they were feeling well) and during an episode of abdominal distension (n = 15). Colonic content and distribution were measured by an original analysis program. In healthy subjects both gaseous (87 ± 24 mL) and non-gaseous colonic content (714 ± 34 mL) were uniformly distributed along the colon. In the early postprandial period gas volume increased (by 46 ± 23 mL), but non-gaseous content did not, although a partial caudad displacement from the descending to the pelvic colon was observed. No differences in colonic content were detected between patients and healthy subjects. Symptoms were associated with discrete increments in gas volume. However, no consistent differences in non-gaseous content were detected in patients between asymptomatic periods and during episodes of abdominal distension. In patients with functional gut disorders, abdominal distension is not related to changes in non-gaseous colonic content. Hence, other factors, such as intestinal hypersensitivity and poor tolerance of small increases in luminal gas may be involved.

Progressive Displacement of Clavicular Fractures in the Early Postinjury Period

Historically, minimally to moderately displaced clavicular fractures have been managed nonoperatively. However, there is no clear evidence on whether clavicular fractures can progressively displace following injury and whether such displacement might influence decisions for surgery. We retrospectively reviewed data on 56 patients who received operative treatment for clavicular fractures at our institution from February 2002 to February 2007 and identified those patients who were initially managed nonoperatively based on radiographic evaluation (<2 cm displacement) and then subsequently went on to meet operative indications (≥2 cm displacement) as a result of progressive displacement. Standardized radiographic measurements for horizontal shortening (medial-lateral displacement) and vertical translation (cephalad-caudad displacement) were developed and used. Fifteen patients with clavicle fractures initially displaced less than 2 cm and treated nonoperatively underwent later surgery because of progressive displacement (14 diaphyseal and 1 lateral). Radiographs performed during the injury workup and at a mean of 14.8 days postinjury demonstrated that progressive deformity had taken place. Ten of 15 patients (67%) displayed progressive horizontal shortening. Average change in horizontal shortening between that of the injury radiographs and the repeat radiographs in this group was 14.3 mm (5.9-29 mm). Thirteen of 15 patients (87%) displayed progressive vertical translation. Eight of 15 patients (53%) displayed both progressive horizontal shortening and vertical translation. We have demonstrated that a significant proportion of clavicle fractures (27% of our operative cases over a 5-year period) are minimally displaced at presentation, but are unstable and demonstrate progressive deformity during the first few weeks after injury. Because of this experience, we recommend close monitoring of nonoperatively managed clavicular fractures in the early postinjury period. A prudent policy is to obtain serial radiographic evaluation for 3 weeks, even for initially, minimally displaced clavicle fractures.

G-Protection Mechanisms Afforded by the Anti-G Suit Abdominal Bladder With and Without Pressure Breathing

G protection afforded by the abdominal bladder of a pneumatic anti-G suit is usually attributed to counteraction of G-induced caudad displacement of the heart and pooling of blood in the abdominal veins. The study examined whether the abdominal bladder might provide G protection also via other mechanisms. Each subject was exposed to +Gz loads while sitting relaxed, wearing a full-coverage anti-G suit modified to permit separate pressurization of the abdominal and leg bladders. In two experimental series (N = 8, N = 14), subjects were breathing at positive airway pressure (PPB); in a third series, five subjects were breathing at atmospheric airway pressure. Intrathoracic pressures were estimated by use of esophageal catheters. During PPB at high G loads, intrathoracic pressure was higher with than without the pressurized abdominal bladder. In 7 of the 14 subjects, basilar intrathoracic pressure exceeded airway pressure during PPB when the abdominal bladder was pressurized. The mean arterial pressure response at high G loads was higher in this subset of subjects (55 +/- 23 mmHg) than in the subjects in whom airway pressure exceeded intrathoracic pressure (41 +/- 27 mmHg). Without PPB at increased G load, the intrathoracic pressure gradient was higher with than without the pressurized abdominal bladder. During PPB, the abdominal bladder acts as an airway counterpressure, thereby facilitating pressure transmission from the airways to the thorax and hence improving G protection. It also appears that in several individuals, pressure may be transmitted from the abdominal bladder to the thorax and heart.

Traction Vertical Shear Pelvic Ring Fracture: A Marker for Severe Arterial Injury? A Case Report

Vertical shear pelvic ring fractures have been described as being produced only by a force directed cephalad, typically from falls or motor vehicle collisions. We report a seemingly similar vertical injury with the displacement of the hemipelvis being caudad rather than cephalad. Caudad displacement of the hemipelvis might disrupt the pelvic floor and vasculature far more than a standard vertical shear injury would and might be more prone to vascular injury. The clinical examination of the pelvic wound in our patient was not impressive and the magnitude of displacement seen on the admission radiograph was not different from that seen with a typical vertical shear injury. It is the caudal direction of the displacement that we think should alert the surgeon to the possibility of massive vascular injury and potential for limb loss.

Augmentation of tibial plateau fractures with Trabecular Metal™: a biomechanical study

BackgroundRestoration and maintenance of the plateau surface are the key points in the treatment of tibial plateau fractures. Any deformity of the articular surface jeopardizes the future of the knee by causing osteoarthritis and axis deviation. The purpose of this study is to evaluate the effect of Trabecular Metal (porous tantalum metal) on stability and strength of fracture repair in the central depression tibial plateau fracture.MethodSix matched pairs of fresh frozen human cadaveric tibias were fractured and randomly assigned to be treated with either the standard of treatment (impacted cancellous bone graft stabilized by two 4.5 mm screws under the comminuted articular surface) or the experimental method (the same screws supporting a 2 cm diameter Trabecular Metal (TM) disc placed under the comminuted articular surface). Each tibia was tested on a MTS machine simulating immediate postoperative load transmission with 500 Newton for 10,000 cycles and then loaded to failure to determine the ultimate strength of the construct.ResultsThe trabecular metal construct showed 40% less caudad displacement of the articular surface (1, 32 ± 0.1 mm vs. 0, 80 ± 0.1 mm) in cyclic loading (p < 0.05). Its mechanical failure occurred at a mean of 3275 N compared to 2650 N for the standard of care construct (p < 0, 05).ConclusionThe current study shows the biomechanical superiority of the trabecular metal construct compared to the current standard of treatment with regards to both its resistance to caudad displacement of the articular surface in cyclic loading and its strength at load to failure.

Diplopia: a complication of dural puncture.

Diplopia: a complication of dural puncture.

Vaginal opacification during defecography: direction of vaginal migration aids in diagnosis of pelvic floor pathology.

To determine whether direction of vaginal displacement during defecography aids in diagnosing pelvic floor pathology. Ninety patients underwent defecography over a 2-year period. Each study was retrospectively reviewed by three radiologists who recorded whether the vagina was displaced cephalad, caudad, or nondisplaced in relation to the urogenital hiatus. This information was then correlated with radiologic diagnosis rendered for the study. Of the 26 patients with normal defecograms, 19 (73%; p < 0. 001) demonstrated no vaginal displacement during the procedure. Comparatively, 10 (83%; p < 0.001) of the 12 patients with cystoceles showed caudad vaginal displacement, and no patients with cystoceles showed cephalad displacement of the vagina. Of the 17 patients with rectoceles, 10 (58%) showed cephalad displacement, one (6%) showed caudad displacement, and six (35%) patients showed no vaginal displacement. Thirteen (46%) of 28 patients with enteroceles showed cephalad vaginal displacement, nine (32%) showed no vaginal displacement, and six (21%) demonstrated caudad displacement. Caudad displacement of the opacified vagina suggests the presence of a cystocele. Cephalad vaginal displacement is suggestive of the presence of an enterocele or rectocele.

Human Chest Wall Function while Awake and during Halothane Anesthesia

Data concerning chest wall configuration and the activities of the major respiratory muscles that determine this configuration during anesthesia in humans are limited. The aim of this study was to determine the effects of halothane anesthesia on respiratory muscle activity and chest wall shape and motion during spontaneous breathing. Six human subjects were studied while awake and during 1 MAC halothane anesthesia. Respiratory muscle activity was measured using fine-wire electromyography electrodes. Chest wall configuration was determined using images of the thorax obtained by three-dimensional fast computed tomography. Tidal changes in gas volume were measured by integrating respiratory gas flow, and the functional residual capacity was measured by a nitrogen dilution technique. While awake, ribcage expansion was responsible for 25 +/- 4% (mean +/- SE) of the total change in thoracic volume (delta Vth) during inspiration. Phasic inspiratory activity was regularly present in the diaphragm and parasternal intercostal muscles. Halothane anesthesia (1 MAC) abolished activity in the parasternal intercostal muscles and increased phasic expiratory activity in the abdominal muscles and lateral ribcage muscles. However, halothane did not significantly change the ribcage contribution to delta Vth (18 +/- 4%). Intrathoracic blood volume, measured by comparing changes in total thoracic volume and gas volume, increased significantly during inspiration both while awake and while anesthetized (by approximately 20% of delta Vth, P < 0.05). Halothane anesthesia significantly reduced the functional residual capacity (by 258 +/- 78 ml), primarily via an inward motion of the end-expiratory position of the ribcage. Although the diaphragm consistently changed shape, with a cephalad displacement of posterior regions and a caudad displacement of anterior regions, the diaphragm did not consistently contribute to the reduction in the functional residual capacity. Halothane anesthesia consistently increased the curvature of the thoracic spine measured in the saggital plane. The authors conclude that (1) ribcage expansion is relatively well preserved during halothane anesthesia despite the loss of parasternal intercostal muscle activity; (2) an inward displacement of the ribcage accounts for most of the decrease in functional residual capacity caused by halothane anesthesia, accompanied by changes in diaphragm shape that may be related to motion of its insertions on the thoracoabdominal wall; and (3) changes in intrathoracic blood volume constitute a significant fraction of delta Vth during tidal breathing.

What dictates the position of the diaphragm—The heart or the liver?: A review of sixty-five cases

Case histories of 65 patients with cardiac malposition were reviewed to assess abdominal taxis and hemidiaphragm posture. We present their roentographic findings to support the hypothesis that the cardiac mass determines the caudad displacement and lower position of the related hemidiaphragm. The popular hypothesis that the liver lifts the corresponding hemidiaphragm is questioned. Incidentally, a review of their echocardiographic findings demonstrate the presence of complex congenital heart defects in a majority of these patients. (J THORAC CARDIOVASC SURG 1994;108:687-91)

Mechanics of intercostal space and actions of external and internal intercostal muscles.

It is conventionally considered that because of their fiber orientations, the external intercostal muscles elevate the ribs, whereas the internal interosseous intercostals lower the ribs. The mechanical action of the intercostal muscles, however, has never been studied directly, and the electromyographic observations supporting this conventional thinking must be interpreted with caution. In the present studies, the external and internal interosseous intercostal muscles have been separately stimulated in different interspaces at, above, and below end-expiratory rib cage volume in anesthetized dogs. The axial (cephalo-caudal) displacements of the ribs were measured using linear displacement transducers. The results indicate that when contracting in a single interspace and other muscles are relaxed, both the external and internal intercostals have a net rib elevating action at end-expiratory rib cage volume. This action increases as rib cage volume decreases, but it progressively decreases as rib cage volume increases such that at high rib cage volumes, both the external and internal intercostals lower the ribs. Stimulating the intercostal muscles in three adjacent intercostal spaces simultaneously produced similar directional rib motion results. We conclude that (a) in contrast with the conventional thinking, the external and internal interosseous intercostals acting alone have by and large a similar effect on the ribs into which they insert; (b) this effect is very much dependent on rib cage (lung) volume; and (c) intercostal muscle action is primarily determined by the resistance of the upper ribs to caudad displacement relative to the resistance of the lower ribs to cephalad displacement. The lateral intercostals, however, might be more involved in postural movements than in respiration. Their primary involvement in rotations of the trunk might account for the presence of two differently oriented muscle layers between the ribs.

The changes in configuration of the rib cage and abdomen during breathing in the anaesthetized cat.

1. The external surface of the rib cage and abdominal wall in anaesthetized cats was surgically exposed in order to record their movements cinematographically in spontaneous breathing and in paralysed cats, during artificial positive pressure ventilation. 2. Cine-stereophotography was used to allow the recording of the movements of a set of markers placed on the external surface of the trunk wall and the corresponding stereometric data were numerically and graphically processed into three-dimensional drawings. The cine-film frames corresponding to the phases of maximum inflation and deflation of the lungs were analysed to reveal the changes in configuration associated with the respiratory movements of the trunk wall. 3. The changes in shape of the diaphragm and the diaphragm and the displacements of the abdominal viscera between extreme inflation and deflation were recorded by X-ray photography. 4. During spontaneous inspiratory movements, the ribs rotated outwards and rostrally about the costovertebral joints, bringing about an increase in the transverse dimensions of the cage all along its length; these movements were accompanied by a clear-cut caudad displacement of the sternum, caused by the straightening of the costal cartilages and by the widening of the angles defined at sternochondral joints between the sternum and each of the costal cartilages. 5. Neuromuscular blockade abolished muscle tone in the trunk wall, allowing the weight of the viscera markedly to deform its configuration. 6. The inspiratory rib movements of the paralysed animal during artificial inspiration were similar to those during spontaneous breathing but the movements of the sternum were inverted and showed small cranial displacements. 7. The loss of muscular tone under neuromuscular blockade made the abdominal wall more compliant than the rib cage to the positive lung pressure and allowed greater mobility of the viscera with consequent distortion of the shape of the diaphragm. 8. The role of rib cage muscle tone in meeting requirements of purely configurational character in such a shell-like structure is discussed in relation to the optimal mechanical performance of the diaphragm.

The manifestations of diaphragmatic and juxtadiaphragmatic diseases in the liver-spleen scintigraph.

Diaphragmatic and juxtadiaphragmatic abnormalities can be recognized on liver-spleen scintigraphs by alteration of the normal disparity in height between the liver and the spleen and by flattening of the superior margins of the liver and spleen. A unilateral abnormality is manifested by exaggeration or reversal of the normal disparity in height between the superior margins of the liver and spleen by cephalad or caudad displacement of one of these organs. Bilateral peridiaphragmatic abnormalities are manifested by flattening of the superior margins of the liver and spleen by caudad displacement of both organs.