[Sequelae of proximal venous stenosis].

We describe three typical consequences of chronic or subacute proximal vein obstruction: venous claudication, narrowing of the spinal canal by dilated veins that function as collaterals, and hypovolemia caused by trapping of blood in the periphery and slow return. Venous claudication is a well recognized clinical entity. We emphasize that the syndrome is often diagnosed in patients who do not remember acute thrombosis and that the signs on the skin of chronic venous insufficiency are typically absent in these patients. Venous drainage after proximal thrombosis often involves the veins of the spinal canal. Under the condition of sustained physical activity these veins become dilated and occupy space causing the syndrome of a narrow spinal canal. The clinical features differ from those encountered in other forms of a narrow spinal canal; the symptoms appear only after prolonged and strenuous exercise, do barely depend on the posture of the spine and do not disappear readily with cessation of the effort. In patients with bilateral pelvic vein occlusions we regularly found evidence for a shock-like syndrome that follows vigorous exercise. The patients experience sudden weakness and dizziness, with sweats, pallor and tachycardia and have to interrupt the effort to prevent collapse and fainting. The clinical features depend on the anatomical localisation of the obstruction as well as on the pathways of the collaterals. In patients with typical symptoms a venographic workup may be indicated to assess the possibility of recanalisation by endoluminal stenting. The presence of peripheral valve incompetence may be regarded as a contraindication to stenting since it may increase the volume overload and make the chronic venous insufficiency worse.