Management of flatback and related kyphotic decompensation syndromes

STUDY DESIGN: The authors, in this retrospective study, examined a group of patients with flatback syndrome and a related kyphotic decompensation syndrome. Results of nonrealignment treatment as well as revision surgery with sagittal realignment were reviewed. OBJECTIVES: To determine effectiveness of physical therapy and limited surgical (instrumentation removal) as well as major realignment surgical treatment in the sagittally malaligned spine. SUMMARY OF BACKGROUND DATA: Flatback is a sagittal plane deformity associated with distraction instrumentation for scoliosis correction. Kyphotic decompensation syndrome involves malaligned fusions from the sacrum for disease other than scoliosis. Several studies describe surgical realignment for flatback involving instrumentation systems no longer commonly applied. Guidelines for a systematic approach to flatback and kyphotic decompensation syndromes are lacking. METHODS: Forty-eight patients with flatback and kyphotic decompensation syndromes were reviewed. Treatment groups were defined by treatment approach and level of previous fusion. Effectiveness of treatment was reviewed in terms of radiographic sagittal alignment and self-reported pain. RESULTS: Twenty patients were treated without realignment revision surgery. Twenty-eight patients were treated with anterior and posterior osteotomies and realignment with instrumentation. For patients originally fused to the sacrum, realignment averaged 12 cm. Pain was reduced from 7 to 3 (10-point scale). In patients fused to L4 or L5, realignment averaged 7 cm. Pain was reduced from 6 to 2. Magnetic resonance imaging revealed viable caudal discs in four patients who were consequently spared extension of fusion to the sacrum. CONCLUSIONS: Treatment without realignment surgery demonstrated long-term success in 27% of cases. The latter all had two intact discs below the previous fusion and sagittal malalignment less than 4 cm. Realignment surgery effectively reduced pain in patients failing a conservative approach.     

Modulatory role of endothelial and nonendothelial nitric oxide in 5-hydroxytryptamine-induced contraction in cerebral arteries after subarachnoid hemorrhage

OBJECTIVE: Endothelial dysfunction is claimed to play a role in the pathogenesis of delayed cerebral vasospasm after subarachnoid hemorrhage (SAH). We have examined the effect of experimental SAH on the modulatory action of endothelial and nonendothelial nitric oxide (NO) in the contractile response of goat middle cerebral artery to 5-hydroxytryptamine (5-HT). METHODS: We compared the 5-HT-induced contractile responses of cerebral arteries from control goats and from goats with SAH that had been experimentally induced 3 days earlier by delivery of autologous arterial blood into the subarachnoid space. Contractile responses were examined by recording the isometric tension in isolated cerebral arteries. To assess the influence of endothelium, this cell layer was mechanically removed in some of the arteria, segments (rubbed arteries) from both control goats and goats with SAH. RESULTS: In arteries from control goats, contractile responses to 5-HT were significantly higher in rubbed arteries than in arteries with intact endothelium; 5-HT-induced contractions were significantly enhanced by a competitive inhibitor of NO synthesis, NG-nitro-l-arginine, in arteries both with and without endothelium. In arteries from goats with SAH, 5-HT contracted cerebral arteries without showing significant differences between segments with endothelium and those that had been rubbed; in both cases, 5-HT-induced contractions were significantly higher than those obtained in arteries from control goats. NG-Nitro-l-arginine significantly enhanced the contractile response to 5-HT of cerebral arteries from goats with SAH. CONCLUSION: These results suggest that cerebral arteries after SAH exhibit hyperreactivity to 5-HT via a mechanism that involves the absence of the modulatory role of endothelial NO, that SAH does not modify the modulatory role of nonendothelial NO, and that impairment of the modulatory action of endothelial NO on vascular responses to 5-HT could contribute to the pathogenesis of cerebral vasospasm after SAH.     

Selection of task-dependent diffusion filters for the post-processing of SPECT images

Iterative reconstruction from single photon emission computed tomography (SPECT) data requires regularization to avoid noise amplification and edge artefacts in the reconstructed image. This is often accomplished by stopping the iteration process at a relatively low number of iterations or by post-filtering the reconstructed image. The aim of this paper is to develop a method to automatically select an optimal combination of stopping iteration number and filters for a particular imaging situation. To this end different error measures between the distribution of a phantom and a corresponding filtered SPECT image are minimized for different iteration numbers. As a study example, simulated data representing a brain study are used. For post-reconstruction filtering, the performance of 3D linear diffusion (Gaussian filtering) and edge preserving 3D nonlinear diffusion (Catté scheme) is investigated. For reconstruction methods which model the image formation process accurately, error measures between the phantom and the filtered reconstruction are significantly reduced by performing a high number of iterations followed by optimal filtering compared with stopping the iterative process early. Furthermore, this error reduction can be obtained over a wide range of iteration numbers. Only a negligibly small additional reduction of the errors is obtained by including spatial variance in the filter kernel. Compared with Gaussian filtering, Catté diffusion can further reduce the error in some cases. For the examples considered, using accurate image formation models during iterative reconstruction is far more important than the choice of the filter.     

A systematic antilipidemic structure-activity relationship study was carried out on a series of alcoyl- and benzoyl-phenoxy-carboxylic acids

A systematic antilipidemic structure-activity relationship study was carried out on a series of alcoyl- and benzoyl-phenoxy-carboxylic acids. The introduction of a p-chlorobenzoyl moiety into the original phenoxy-isobutyric acid enhanced antilipidemic activity significantly. Chlorine meta substitution or chlorine disubstitution abolished activity. Among the esters synthetized, the isopropylester has been selected for further studies.