[Stiffness of the AO spinal external fixator. Experimental results of stiffness of the AO spinal external fixator with 3 different pedicle screw systems]. / Steifigkeit des AO-Wirbelfixateur externe.Experimentelle Ergebnisse zur Steifigkeit des AO Wirbelfixateur externe mit drei verschiedenen Pedikelschraubensystemen.

The stiffness of the AO external pedicular fixator was analysed in an experimental laboratory study using three different sets of pedicle screws and different configurations of the implant. The experiments were performed with a wooden model as well as with bi-segmental human lumbar spine specimens with disc and ligaments intact. The capacity of the AO external pedicular fixator to compensate axial load, transversal- and torsion forces was compared to physiological requirements. Of particular interest was the effect of preload on the axial stiffness. It is demonstrated that the axial stiffness of the AO external pedicular fixator is so low that the axial load on the lumbar spine level in humans cannot be influenced by the fixator even when preloaded. However the resistance against torsion and transversal slipping is probably higher than required in vivo. No significant differences were found between the three types of pedicular screws. The effect of the triangular counter nuts of the AO external pedicular fixator on the transversal- and torsion stability was important. The presented results suggest that the AO external pedicular fixator can be of significant value in segmental rotation- and translocation pathologies of the lumbar spine and that the effect of isolated segmental distraction has probably been overestimated.

Discography with manometry and discographic CT: their value in patient selection for percutaneous lumbar nucleotomy.

In minimally invasive spinal surgery and percutaneous disc surgery the exact preoperative structural analysis of the disc herniation becomes a prerequisite in patient selection. Discography including discal manometry and discographic CT (in addition to CT and MRI) are used to review the anatomy of disc herniations prior to surgery. The analysis of the findings of discography in 360 lumbar discs examined from 1988 to 1994 are presented. In 68 discs operated with hemilaminectomy, later intraoperative findings were available for comparison with preoperative discographic findings. The diagnostic accuracy of determining the exact anatomical location of the herniation with discography alone was 75%. The diagnostic accuracy increased to 99.55% with the use of CT discography. The authors conclude that CT discography is an accurate and useful diagnostic aid.

Varicose veins combined with mucoid degeneration of the venous wall.

We report on a 56-year-old woman with bilateral chronic venous insufficiency, a cavernous hemangioma at the right thigh and an aneurysm of the left femoral vein, without bone or soft tissue hypertrophy. Histopathology revealed a mucoid degeneration of the media musculature of the venous wall. Such a finding has not yet been described in the world literature. The differential diagnosis must consider a secondary hitherto unknown alteration of varicose veins, a variety of a vascular malformation not yet described, and a primary degeneration of the smooth muscles of the vascular wall followed by the development of varicose veins.

Phlebosclerosis, phlebothrombosis, and thrombophlebitis: A current perspective.

Phlebosclerosis, phlebothrombosis, and thrombophlebitis are three fundamentally different structural changes affecting superficial, deep, visceral, and cerebral veins. Phlebosclerosis is a frequent, age-dependent fibrotic degeneration of one or all three wall layers. It does not represent a distinct disease entity but may impair the venous function and contribute to the development of thrombosis. Phlebothrombosis represents a serious circulatory disorder. It may be due to a variety of factors including phlebitis, i.e., a primary inflammatory disease of the venous wall. Thrombophlebitis may be a relatively harmless disorder, such as represented by idiopathic skipping phlebitis (phlebitis saltans), or it may be a symptom of an underlying systemic disease. Whereas phlebothrombosis in nonvaricose veins is suspicious of an underlying malignancy or a coagulation disorder, thrombophlebitis is not related to malignancies but may accompany Buerger's disease or other systemic vasculitides. The histopathological distinction of phlebothrombosis and thrombophlebitis is therefore of paramount importance and determines further clinical investigations. A proposal for classification of thrombophlebitides and some guidelines for clinicopathological differentiation of the various types of phlebitides are presented.

[Thrombosis and phlebitis of superficial veins. Differential histopathologic diagnosis]. / Thrombose und Phlebitis der oberflächlichen Venen. Histopathologische Differentialdiagnose.

Primary thrombosis and phlebitis with secondary thrombosis of superficial veins are frequent. A biopsy may be performed if the clinician suspects an underlying systemic disease. The pathologist must be aware of the different types and their etiology because the further diagnostic and therapeutic procedures depend on his evaluation. The different types of primary thrombotic and primary phlebitic disorders are described and their possible etiology is discussed.

Microvascular changes in chronic venous insufficiency--a review.

Chronic venous insufficiency is the result of an impairment of the main venous conduits, causing microvascular changes. The driving force responsible for the alterations in the microcirculation is probably the intermittently raised pressure propagated from the deep system into the capillaries. The capillaries are dilated, elongated and tortuous and their endothelium is injured (irregular luminal surface, increased cytopempsis, dilated interendothelial spaces). Through the latter an increased extravasation can be observed, leading to an enlarged pericapillary space, oedema in the interstitial tissue and to the clinical finding of swelling. Haemoglobin from extravasated erythrocytes and erythrocyte fragments in the pericapillary space is degraded to haemosiderin which is responsible for hyperpigmentation. Microthrombosis in the capillaries causes microinfarction and micronecrosis. Skin areas with severe microangiopathy have reduced numbers of perfused nutritional capillaries and are characterized by a low transcutaneous (tc) PO2. The increased blood flow in the deeper skin layers does not contribute to nutrition of the superficial skin layers. The microvascular ischaemia is patchy and appears to be the main factor determining trophic changes and venous ulceration. The process of microinfarction and micronecrosis is followed by the formation of a granulation tissue, proliferation of capillaries and fibroblasts and finally wound healing by formation of scar tissue destroying the microlymphatic network. Clinically this process leads to lipodermatosclerosis, atrophy and in its most extreme form to ulceration where the compensating mechanisms are no longer able to repair the damage.

Classification of vasculitides. A survey.

Many proposals for the classification of vasculitides have been presented but none have been universally recognized. This survey deals critically with the recently proposed nomenclatures and shows up their advantages and disadvantages. Finally a new trial is presented which includes also phlebitic and lymphangitic disease entities and tries to consider all known vasculitic disease entities.

[True aneurysm of the ascending aorta in HIV disease]. / Aneurysma verum der Aorta ascendens im Rahmen einer HIV-Krankheit.

A 31-year-old male who presented with a true aneurysm of the ascending aorta had for 5 years been seropositive for HIV-1 following intravenous drug abuse. Elective aneurysmectomy was refused. Controls by computerized tomography and echocardiography gave evidence of a progressive dilatation during the following 8 months. In February 1992 a further increase of the aneurysm with severe thoracic pain necessitated an emergency graft implantation. Histopathology of the resected aorta revealed a granulomatous giant cell mesaortitis. The postoperative course was uneventful and the patient remained free of cardiovascular symptoms, but died 25 months later due to multiple HIV-associated opportunistic infections. The differential diagnosis (Marfan's syndrome, vasculitis due to tuberculosis, syphilis and other infectious agents, rheumatological diseases, HIV-associated vasculitis) and the etiopathological considerations are discussed.

A case of dissection of intracranial cerebral arteries with segmental mediolytic "arteritis".

The intravital diagnosis of intracranial arterial dissection is not always possible due to atypic and non-specific clinical and radiological presentations. The postmortem pathological examination of cerebral blood vessels is therefore necessary to establish or confirm the presence of a dissecting aneurysm of intracranial arteries. Most of the described cases showed no significant underlying vascular pathology. Here we present the case of a 24-year-old women who died 5 days after admission to the hospital for a rapidly developing right-sided hemisyndrome. Neuroradiological examination had revealed ill-defined bifrontal hypodense lesions and angiographic findings were compatible with a dissection of the left extracranial internal carotid artery with embolic subocclusion of both anterior cerebral arteries. The pathological evaluation ruled out a thromboembolic occlusion of cerebral arteries and an extracranial internal carotid artery dissection but showed an extended dissecting process of variable age in the anterior circulation of the circle of Willis. The dissected vessels showed pathological changes characteristic of segmental mediolytic "arteritis" [Slavin and Gonzalez-Vitale 1976]. To our knowledge this is the first report on intracranial arteries being affected by this pathologic entity. Our case illustrates the importance of a postmortem examination of dissecting aneurysms of intracranial arteries. Careful serial section studies of dissected intracranial arteries in young subjects should be performed and may allow for a better understanding of the vascular pathology underlying the dissection processus.

Cerebrovascular accidents resulting from segmental mediolytic arteriopathy of the cerebral arteries in young adults.

Five cases of cerebrovascular accident or transient ischaemia in young adults resulting from segmental mediolytic arteriopathy are reported. The aetiology of segmental mediolytic arteriopathy is unknown but the disorder is characterized by focal, non-inflammatory mucoid degeneration of the media of muscular, non-arteriosclerotic arteries, frequently involving cerebral intracranial or extracranial vessels. It is similar to Erdheim-Gsell's medionecrosis of the aorta and may occur in any muscular artery. The consequences are mostly fatal in cerebral arteries. Histological analysis of each case is described. Clinicians should be aware of the possibility of intramural haemorrhage and dissecting aneurysm as a result of mucoid degeneration of the arterial media in young adults with cerebrovascular accident.

Phlebitides--a survey.

Classification of phlebitides is difficult and none of the suggestions made so far has been internationally recognized. Already the definition of "primary" and "secondary" presents difficulties. For practical purposes the phlebitides are classified in this survey according to their importance as disease entities and their etiology. The role of phlebitis saltans as an idiopathic disease or as an indicator of underlying disorders is emphasized and the differential diagnosis between symptomatic skipping phlebitis and paraneoplastic thrombosis with secondary inflammation is outlined.

[Micromorphologic changes in the skin in primary and secondary (post-thrombotic) chronic venous insufficiency]. / Mikromorphologische Veränderungen in der Haut bei der primären und seukundären (post-thrombotischen) chronisch-venösen Insuffizienz.

The micromorphological alterations in chronic venous insufficiency are characterized by a patchlike distribution. At least in the initial stages, normal skin areas may alternate with regions containing severe alterations. The capillaries may be rarified, or elongated and dilated with formation of glomerulus-like clusters, or they may show proliferation within a granulomatous repair tissue. Pericapillary accumulation of fibrin may be observed only within necrotic tissue surrounding an ulcer. The pericapillary space which is enlarged and edematous in chronic venous insufficiency, cannot be anatomically defined. The interstitial tissue may contain a secondary chronic inflammation with repair function. Finally a hyaline scar tissue with so-called "avascular" fields and dystrophic calcification/ossification may result.

[The current concept of the pathogenesis of trophic skin lesions in chronic venous insufficiency from the morphologic viewpoint]. / Aktuelles Konzept der Entstehung trophischer Hautläsionen bei der chronisch-venösen Insuffizienz aus morphologischer Sicht.

Disturbances of the venous macrocirculation are the main cause of trophic skin lesions in primary and secondary chronic venous insufficiency. The microcirculatory process initiates with functional and organic endothelial alterations in the cutaneous and subcutaneous capillaries, followed by increased permeability for blood plasma and erythrocytes, and later by edema and micronecroses in the interstitial tissue. Subsequently a reactive chronic inflammation develops. A vicious circle consisting of repeated tissue necrosis alternating with repair processes and later with tissue fibrosis may develop. This injury and repair process is non-specific and characteristic for all types of tissue necrosis. Intensity and duration of the process depend on degree and persistence of the underlying disorder.

Systemic phlebitis of visceral veins with intramural giant cell granulomas--a new entity?

We report a case of granulomatous giant cell poly-phlebitis of the mesenteric veins in a 38-year-old man, resulting in a segmental infarction of the ileum. Multiple epithelioid granulomas with giant cells of the Langhans type were situated in media/adventitia of small and middle-sized mesenteric veins with subsequent thrombotic occlusions. No involvement of arterial vessels could be detected. The etiology of the disease remains unknown. Any known type of vasculitis could be excluded. An immunology-related vasculopathy is assumed, but could not be definitely proved. This is the first case of a granulomatous giant cell poly-phlebitis of visceral veins reported in the world literature.