Thoracic outlet syndrome: a neurological and vascular disorder.

Thoracic outlet syndrome (TOS) is a condition arising from compression of the subclavian vessels and/or brachial plexus as the structures travel from the thoracic outlet to the axilla. Despite the significant pathology associated with TOS, there remains some general disagreement among experts on the specific anatomy, etiology, and pathophysiology of the condition, presumably because of the wide variation in symptoms that manifest in presenting patients, and because of lack of a definitive gold standard for diagnosis. Symptoms associated with TOS have traditionally been divided into vascular and neurogenic categories, a distinction based on the underlying structure(s) implicated. Of the two, neurogenic TOS (nTOS) is more common, and typically presents as compression of the brachial plexus; primarily, but not exclusively, involving its lower trunk. Vascular TOS (vTOS) usually involves compression of the vessel, most commonly the subclavian artery or vein, or is secondary to thrombus formation in the venous vasculature. Any anatomical anomaly in the thoracic outlet has the potential to predispose a patient to TOS. Common anomalies include variations in the insertion of the anterior scalene muscle (ASM) or scalenus minimus muscle, the presence of a cervical rib or of fibrous and muscular bands, variations in insertion of pectoralis minor, and the presence of neurovascular structures, which follow an atypical course. A common diagnostic technique for vTOS is duplex imaging, which has generally replaced more invasive angiographic techniques. In cases of suspected nTOS, electrophysiological nerve studies and ASM blocks provide guidance when screening for patients likely to benefit from surgical decompression of TOS. Surgeons generally agree that the transaxillary approach allows the greatest field of view for first rib excision to relieve compressed vessels. Alternatively, a supraclavicular approach is favored for scalenotomies when the ASM impinges on surrounding structures. A combined supraclavicular and infraclavicular approach is preferred when a larger field of view is required. The future of TOS management must emphasize the improvement of available diagnostic and treatment techniques, and the development of a consensus gold standard for diagnosis. Helical computed tomography offers a three-dimensional view of the thoracic outlet, and may be valuable in the detection of anatomical variations, which may predispose patients to TOS. This review summarizes the history of TOS, the pertinent clinical and anatomical presentations of TOS, and the commonly used diagnostic and treatment techniques for the condition.

Mitral valve prolapse: evaluation with ECG-gated cardiac CT angiography.

OBJECTIVE: The purpose of our study was to evaluate the feasibility of detecting mitral valve prolapse with ECG-gated 64-MDCT angiography in comparison with the reference standard, transthoracic echocardiography. MATERIALS AND METHODS: The charts of patients consecutively referred for clinically indicated 64-MDCT angiography were reviewed. The study cohort consisted of patients who had undergone transthoracic echocardiography. Two experienced radiologists performed blinded consensus review of the MDCT angiograms of 20 patients, and the findings were compared with those of transthoracic echocardiography, which was the reference standard. RESULTS: With the findings on each anterior and posterior leaflet as separate data points, sensitivity was calculated to be 69.2-84.6% and specificity, 100%. The positive and negative predictive values were estimated to be 100% and 87.0-93.1%. CONCLUSION: ECG-gated cardiac 64-MDCT angiography can be used reliably to detect mitral valve prolapse.

Aortic valve area: meta-analysis of diagnostic performance of multi-detector computed tomography for aortic valve area measurements as compared to transthoracic echocardiography.

Degenerative aortic valve stenosis (AS) has an incidence of 2-7% in the Western European and North American populations over 65 years of age. The aim of this study was to perform a meta-analysis of the published literature evaluating the accuracy of CT planimetry to measure the aortic valve area. The PUBMED and OVID databases were searched up to May 2008. Major criteria for article inclusion was the use of (a) multi-detector computed tomography as a diagnostic test for the assessment of AVA in patients with AS, and (b) TTE as the reference standard. Nine studies were included in the analysis with 175 women and 262 men. The mean AVA as measured by CT was 1.0 +/- 0.1. The mean AVA measured by TTE was 0.9 +/- 0.1. The correlation between CT and TTE AVA measurements was r = 1.45. The mean difference was 0.03 +/- 0.05. The results of our meta-analysis suggest that multi-detector CT is an accurate method for obtaining AVA measurements in patients with AS.

Arcuate line of the rectus sheath: clinical approach.

The rectus sheath has been extensively described in gross anatomic studies but there is very little information available regarding the arcuate line (AL). The aim of the present study therefore was to explore and delineate the morphology, topography and morphometry of the arcuate line and provide a comprehensive picture of its anatomy across a broad range of specimens. The AL was present in all specimens examined. In addition, the AL was found to be located at a mean of 70.2% (67.3-75.2%) of the distance between the pubic symphysis and the umbilicus, and at 33.9% (30.2-35.4%) of the distance between the pubic symphysis and the xiphoid process. This location was found to be at a mean of 2.1 +/- 2.3 cm superior to the level of the anterior superior iliac spines. Furthermore, there were three distinct types of AL morphology. In type I (65%), the fibers of the posterior rectus sheath (PRS) gradually disappeared over the transversalis fascia, creating an incomplete demarcation of the actual location of the AL. In type II (25%) the termination of the fibers of the PRS was acutely demarcated over the transversalis fascia, creating a clear border with the AL. In type III (10%) the fibers of the PRS created a double and thickened aponeurotic line. In these cases a double AL was observed. Better preoperative knowledge of the location of the AL may, in some cases, help preoperative planning to facilitate primary fascial repair, which can then be supported with on-lay mesh, depending on the clinical situation.