Spinal Cord Diffusion-Tensor Imaging and Motor-evoked Potentials in Multiple Sclerosis Patients: Microstructural and Functional Asymmetry

Purpose: To assess possible association between intrinsic structural damage and clinical disability by correlating spinal cord diffusion-tensor (DT) imaging data with electrophysiological parameters in patients with a diagnosis of multiple sclerosis (MS). Materials and Methods: This study was approved by the local ethical committee according to the declaration of Helsinki and written informed consent was obtained. DT images and T1- and T2-weighted images of the spinal cord were acquired in 28 healthy volunteers and 41 MS patients. Fractional anisotropy (FA) and apparent diffusion coefficients were evaluated in normal-appearing white matter (NAWM) at the cervical level and were correlated with motor-evoked potentials (n = 34). Asymmetry index was calculated for FA values with corresponding left and right regions of interest as percentage of the absolute difference between these values relative to the sum of the respective FA values. Statistical analysis included Spearman rank correlations, Mann-Whitney test, and reliability analysis. Results: Healthy volunteers had low asymmetry index (1.5%-2.2%). In MS patients, structural abnormalities were reflected by asymmetric decrease of FA (asymmetry index: 3.6%; P = .15). Frequently asymmetrically affected among MS patients was left and right central motor conduction time (CMCT) to abductor digiti minimi muscle (ADMM) (asymmetry index, 15%-16%) and tibialis anterior muscle (TAM) (asymmetry index, 9.5%-14.1%). Statistically significant correlations of functional (ie, electrophysiological) and structural (ie, DT imaging) asymmetries were found (P = .005 for CMCT to ADMM; P = .007 for CMCT to TAM) for the cervical lateral funiculi, which comprise the crossed pyramidal tract. Interobserver reliability for DT imaging measurements was excellent (78%-87%). Conclusion: DT imaging revealed asymmetric anatomic changes in spinal cord NAWM, which corresponded to asymmetric electrophysiological deficits for both arms and legs, and reflected a specific structure-function relationship in the human spinal cord. © RSNA, 2013.

Diuretic-induced hyponatremia and osteoporotic fractures in patients admitted to the emergency department

Hyponatremia is a complication of diuretic treatment and has been recently identified as a novel factor associated with osteoporosis and fractures. The impact of diuretic-associated electrolyte disorders on osteoporotic fractures (OF) has rarely been studied systematically.

Technetium-99m-HDP uptake characteristics in equine fractures: a retrospective study

Bone scintigraphy is a very sensitive diagnostic tool to detect elevated bone metabolism. In cases of fractures and fissure fractures, the radiopharmaceutical uptake in the bone is said to be increased within a few hours after the injury. In this retrospective study, the scintigraphic uptake characteristics at the fracture site of 36 horses with radiographically confirmed fractures or fissure fractures were evaluated. Uptake ratios between the fracture region and adjacent normal bone or soft tissue activity respectively were calculated and compared to different anamnestic and radiographic data. The overall sensitivity of bone scintigraphy was 94.4% (34 positive cases out of 36). In the 36 horses, no correlation between the age of the fracture and the radiopharmaceutical uptake was found. However, there seems to be a lack of sensitivity in early detection of equine pelvic fractures when a standing bone scintigraphy examination protocol is used.

Creatine promotes the GABAergic phenotype in human fetal spinal cord cultures

In the present study, we investigated the expression pattern of cytosolic brain specific-BB-CK and ubiquitous mitochondrial-creatine kinases (uMt-CK) in developing human spinal cord. Consequently, we studied the effects of creatine treatment on cultured fetal human spinal cord tissue. We found that both CK isoforms were expressed in fetal spinal cord at all time points investigated (5 to 11.5 weeks post conception) and correspondingly specific CK activity was detected. Chronic creatine exposure resulted in significantly higher densities of GABA-immunoreactive neurons in the cultures, while total neuronal cell density was not altered, suggesting a differentiation inducing mechanism of creatine supplementation. Taken together, our observations favour the view that the creatine phosphocreatine system plays an important role in the developing CNS.

Dystonic movement disorders and spinal degenerative disease

The occurrence of degenerative spinal disease subsequent to dystonic movement disorders has been neglected and has received more attention only recently. Spinal surgery is challenging with regard to continuous mechanical stress when treatment of the underlying movement disorder is insufficient. To characterize better the particular features of degenerative spinal disease in patients with dystonia and to analyze operative strategies, we reviewed the available published data. Epidemiologic studies reveal that degenerative spinal disorders in patients with dystonia and choreoathetosis occur much earlier than in the physiological aging process. Dystonic movement disorders more often affect the spine at higher cervical levels (C(2-5)), in contrast to spinal degeneration with age which manifests more frequently at the middle and lower cervical spine (C(5-7)). Degenerative changes of the cervical spine are more likely to occur on the side where the chin is rotated or tilted to. Various operative approaches for treatment of spinal pathologies have been advocated in patients with dystonic movement disorders. The available data do not allow making firm statements regarding the superiority of one approach over the other. Posterior approaches were first used for decompression, but additional anterior fusion became necessary in many instances. Anterior approaches with or without instrumented fusion yielded more favorable results, but drawbacks are pseudarthrosis and adjacent-level disease. Parallel to the development of posterior fusion techniques, circumferential surgery was suggested to provide a maximum degree of cord decompression and a higher fusion rate. Perioperative local injections of botulinum toxin were used initially to enhance patient comfort with halo immobilization, but they are also applied in patients without external fixation nowadays. Treatment algorithms directed at the underlying movement disorder itself, taking advantage of new techniques of functional neurosurgery, combined with spinal surgery have recently been introduced and show promising results.

Lordoplasty: report on early results with a new technique for the treatment of vertebral compression fractures to restore the lordosis

Cement augmentation using PMMA cement is known as an efficient treatment for osteoporotic vertebral compression fractures with a rapid release of pain in most patients and prevention of an ongoing kyphotic deformity of the vertebrae treated. However, after a vertebroplasty there is no chance to restore vertebral height. Using the technique of kyphoplasty a certain restoration of vertebral body height can be achieved. But there is a limitation of recovery due to loss of correction when deflating the kyphoplastic ballon and before injecting the cement. In addition, the instruments used are quite expensive. Lordoplasty is another technique to restore kyphosis by indirect fracture reduction as it is used with an internal fixateur. The fractured and the adjacent vertebrae are instrumented with bone cannulas bipediculary and the adjacent vertebrae are augmentated with cement. After curing of the cement the fractured vertebra is reduced by applying a lordotic moment via the cannulas. While maintaining the pretension the fractured vertebra is reinforced. We performed a prospective trial of 26 patients with a lordoplastic procedure. There was a pain relief of about 87% and a significant decrease in VAS value from 7.3 to 1.9. Due to lordoplasty there was a significant and permanent correction in vertebral and segmental kyphotic angle about 15.2 degrees and 10.0 degrees , respectively and also a significant restoration in anterior and mid vertebral height. Lordoplasty is a minimal invasive technique to restore vertebral body height. An immediate relief of pain is achieved in most patients. The procedure is safe and cost effective.

Occupational maxillofacial fractures: a 3-year survey in central Switzerland

PURPOSE: The aim of this study was to determine occupational facial fractures in central Switzerland. Concomitant injuries were also studied. MATERIALS AND METHODS: The Department of Cranio-Maxillofacial Surgery at the University Hospital in Berne provides a 24-hour maxillofacial trauma service for its population (1.6 million). The present study was comprised of 42 patients (8.4% of treated maxillofacial injuries) with occupational maxillofacial fractures registered at this unit between 2000 and 2002. Information on the topic of occupation, the cause of the accidents, and the topographic location of the fractures was analyzed. RESULTS: The mean age of the patients was 44.4 years, with a male to female ratio of 41:1. Sixty-nine percent of the injuries occurred in farm and forestry workers and in construction laborers during the summertime (33%). Workers in these occupations carried a 127-fold (farm and forestry workers) and a 44-fold (construction laborers) higher risk of incurring maxillofacial fractures than did service and office workers. Injuries were most frequently (43%) caused by a thrown, projected, or falling object. Eighty-two percent of the fractures occurred in the midface region and at the skull base. Fifty-nine percent of the patients had concomitant injuries. In 69%, surgery was necessary, the mean duration of their hospital stay being 4.8 days. CONCLUSION: The probability of sustaining work-related maxillofacial traumata is correlated to the nature of the occupation. Farm and forestry workers are at the highest risk, most frequently injured by being struck by an object or an animal. The introduction of personalized safety measures should become obligatory in high-risk occupations.

The long-term mechanical integrity of non-reinforced PEEK-OPTIMA polymer for demanding spinal applications: experimental and finite-element analysis

Polyetheretherketone (PEEK) is a novel polymer with potential advantages for its use in demanding orthopaedic applications (e.g. intervertebral cages). However, the influence of a physiological environment on the mechanical stability of PEEK has not been reported. Furthermore, the suitability of the polymer for use in highly stressed spinal implants such as intervertebral cages has not been investigated. Therefore, a combined experimental and analytical study was performed to address these open questions. A quasi-static mechanical compression test was performed to compare the initial mechanical properties of PEEK-OPTIMA polymer in a dry, room-temperature and in an aqueous, 37 degrees C environment (n=10 per group). The creep behaviour of cylindrical PEEK polymer specimens (n=6) was measured in a simulated physiological environment at an applied stress level of 10 MPa for a loading duration of 2000 hours (12 weeks). To compare the biomechanical performance of different intervertebral cage types made from PEEK and titanium under complex loading conditions, a three-dimensional finite element model of a functional spinal unit was created. The elastic modulus of PEEK polymer specimens in a physiological environment was 1.8% lower than that of specimens tested at dry, room temperature conditions (P<0.001). The results from the creep test showed an average creep strain of less than 0.1% after 2000 hours of loading. The finite element analysis demonstrated high strain and stress concentrations at the bone/implant interface, emphasizing the importance of cage geometry for load distribution. The stress and strain maxima in the implants were well below the material strength limits of PEEK. In summary, the experimental results verified the mechanical stability of the PEEK-OPTIMA polymer in a simulated physiological environment, and over extended loading periods. Finite element analysis supported the use of PEEK-OPTIMA for load-bearing intervertebral implants.

Computer-assisted, fluoroscopy-based ventral spondylodesis of thoracolumbar fractures

OBJECTIVE: To design and evaluate a novel computer-assisted, fluoroscopy-based planning and navigation system for minimally invasive ventral spondylodesis of thoracolumbar fractures. MATERIALS AND METHODS: Instruments and an image intensifier are tracked with the SurgiGATE navigation system (Praxim-Medivision). Two fluoroscopic images, one acquired from anterior-posterior (AP) direction and the other from lateral-medial (LM) direction, are used for the complete procedure of planning and navigation. Both of them are calibrated with a custom-made software to recover their projection geometry and to co-register them to a common patient reference coordinate system, which is established by attaching an opto-electronically trackable dynamic reference base (DRB) on the operated vertebra. A bi-planar landmark reconstruction method is used to acquire deep-seated anatomical landmarks such that an intraoperative planning of graft bed can be interactively done. Finally, surgical actions such as the placement of the stabilization devices and the formation of the graft bed using a custom-made chisel are visualized to the surgeon by superimposing virtual instrument representations onto the acquired images. The distance between the instrument tip and each wall of the planned graft bed are calculated on the fly and presented to the surgeon so that the surgeon could formalize the graft bed exactly according to his/her plan. RESULTS: Laboratory studies on phantom and on 27 plastic vertebras demonstrate the high precision of the proposed navigation system. Compared with CT-based measurement, a mean error of 1.0 mm with a standard deviation of 0.1 mm was found. CONCLUSIONS: The proposed computer assisted, fluoroscopy-based planning and navigation system promises to increase the accuracy and reliability of minimally invasive ventral spondylodesis of thoracolumbar fractures.

Cementless hemiarthroplasty in femoral neck fractures: evaluation of clinical results and measurement of migration by EBRA-FCA

Aim of the present study was to evaluate migration rates of cementless primary hemiarthroplasty in acute femoral neck fractures. In a longitudinal, prospective study 46 patients were treated by cementless hemiarthroplasty. Clinical follow up was correlated with the EBRA-FCA method. In 30% of all patients stem migration amounted to more than 2 mm; further, these patients were seen to have a high level of activity. A high degree of migration in more than 30% of all patients requires critical scepticism toward further use of the investigated cementless stem as hemiarthroplasty. According to literature, migration of more than 2 mm suggests a high probability of early aseptic loosening. In patients with a low degree of activity good results could be observed; nevertheless, in patients with a high level of activity the combination of the investigated cementless stem with a solid fracture head cannot be recommended.

Comparison of different radiography systems in an experimental study for detection of forearm fractures and evaluation of the Müller-AO and Frykman classification for distal radius fractures

OBJECTIVES: We sought to compare the diagnostic performance of screen-film radiography, storage-phosphor radiography, and a flat-panel detector system in detecting forearm fractures and to classify distal radius fractures according to the Müller-AO and Frykman classifications compared with the true extent, depicted by anatomic preparation. MATERIALS AND METHODS: A total of 71 cadaver arms were fractured in a material testing machine creating different fractures of the radius and ulna as well as of the carpal bones. Radiographs of the complete forearm were evaluated by 3 radiologists, and anatomic preparation was used as standard of reference in a receiver operating curve analysis. RESULTS: The highest diagnostic performance was obtained for the detection of distal radius fractures with area under the receiver operating curve (AUC) values of 0.959 for screen-film radiography, 0.966 for storage-phosphor radiography, and 0.971 for the flat-panel detector system (P > 0.05). Exact classification was slightly better for the Frykman (kappa values of 0.457-0.478) compared with the Müller-AO classification (kappa values of 0.404-0.447), but agreement can be considered as moderate for both classifications. CONCLUSIONS: The 3 imaging systems showed a comparable diagnostic performance in detecting forearm fractures. A high diagnostic performance was demonstrated for distal radius fractures and conventional radiography can be routinely performed for fracture detection. However, compared with anatomic preparation, depiction of the true extent of distal radius fractures was limited and the severity of distal radius fractures tends to be underestimated.

A systematic review of prophylactic antibiotics in the surgical treatment of maxillofacial fractures

PURPOSE: A systematic review was performed to find evidence for prophylactic administration of antibiotics in relation to treatment of maxillofacial fractures. METHODS: Four studies were retrieved that fulfilled most of the requirements of being randomized controlled clinical trials. RESULTS: An analysis of these studies showed a 3-fold decrease in the infection rate of mandibular fractures in the antibiotic treated groups compared with the control groups. A variety of antibiotics had been used with an apparently uniform effect. A "1-shot" regimen or a 1-day treatment course had a similar or perhaps even better effect than 7 days of treatment. No infections were related to condylar, maxillary, or zygoma fractures. CONCLUSION: A 1-shot or 1-day administration of prophylactic antibiotics seem to be the best documented to reduce infections in the management of mandibular fractures not involving the condylar region.