Vertebral Venous Plexus Research Articles

The vertebral venous plexus.

30 ~ , the jugular veins were often noted to be collapsed. Despite this, the carotid arteries were obviously transporting blood and the lack of postoperative cerebral damage suggested cerebral blood flow to be adequate. 2 Secondly, needles placed in the superior jugular bulb for the purpose of withdrawing cerebral venous blood samples failed to allow free withdrawal of blood in the head-up and hypotensive state, whereas when the patients were supine and normotensive, samples could be withdrawn easily without readjustment of the needle. The volume of blood within the jugular bulb appeared inadequate to permit free sampling in the head-up position. Thirdly, increasing intrathoracie pressure with the patient head up 30 ~ and hypotensive did not increase the bleeding in a neck wound. Intrathoracic pressure is often elevated during this technique to reduce venous return to the heart, pool blood in the dependent portion of the body and decrease cardiac output, thus allowing blood pressure to be controlled more readily. Ordinarily, increasing intrathoracic pressure causes venous engorgement of the face and neck and might be expected to cause more bleeding in a wound. The fact was that, under these conditions, it did not. The only eonclusion one could draw from these three observations was that blood was returning to the heart by a route other than the internal jugular veins, probably the vertebral venous plexus. The vertebral venous plexus is generally described as a thin walled, valveless network of veins within and surrounding the vertebral column and extending from cranium to pelvis. It consists of an internal division which lies within the epidural space with direct connections to the vertebral bodies. The internal plexus anastomoses freely with an external division which courses paravertebrally and empties into the cervical, thoracic and lumbar veins) Generally, three routes of exit for cerebral venous blood have been described; the internal jugular veins, the emissary veins, and the vertebral venous plexus. Many

The vertebral venous plexus as a major cerebral venous outflow tract.

Cerebral venous outflow in rhesus monkeys anesthetized with halothane has been studied by angiographic techniques. The effects of body position and pressure within the airway have been studied. With the monkey supine, injection of radiopaque contrast medium into the superior sagittal sinus permitted

Collateral pathways in occlusion of the superior vena cava and its tributaries.

Complete or partial occlusion of the superior vena cava and innominate veins is due to malignant tumors of the mediastinum in about 80 per cent of all cases (1, 3–5). Other causes reported are: benign tumors (5), tuberculosis (9), histoplasmosis (7), idiopathic fibrosis (2), syphilis (5), pyogenic infections (5), aneurysm of the ascending aorta (5), hematoma (5), and idiopathic thrombophlebitis (5). Clinical examination usually reveals unilateral or bilateral engorgement and tortuosity of the veins of the arms, neck, and thorax with or without soft-tissue edema. The areas of venous distension depend on the site of obstruction and the collateral pathways. At times, when there is no visible venous engorgement, edema may be the only clinical finding. Other observations are congestive changes in the eyes and nasal mucosa and facial cyanosis. Significant information about the site of obstruction and the collateral circulation is obtained by serial venography (8). Multiple occluded segments may be demonstrated. Recognition of thrombi extending from the occluded segment is important in the evaluation of therapy. The purpose of this paper is to discuss and illustrate the various collateral pathways noted on venography in occlusion of the superior vena cava and the innominate veins. Anatomy and Discussion The collateral venous pathways in obstruction of the superior vena cava or its major tributaries may be classified as follows: A. Collaterals bypassing the upper superior vena cava—anastomoses between innominate tributaries and azygos tributaries (Fig. 1, A and B). B. Collaterals between the superior vena caval system and the inferior vena caval system 1. Along the posterior trunk a. Azygos system (Fig. 1, A and B) b. Vertebral venous plexuses (Fig. 1, B and C) 2. Along the anterior trunk a. Internal thoracic, inferior epigastric anastomoses (Fig. 1, A) b. Lateral thoracic, superficial epigastric anastomoses (Fig. 1, A) C. Collaterals between the anterior and posterior aspects of the trunk 1. Anterior intercostal, posterior intercostal anastomoses (Fig. 1, A) 2. Lateral thoracic, internal thoracic anastomoses (Fig. 1, A) 3. Lateral thoracic, azygos system anastomoses (Fig. 1, A) D. Collaterals across the midline 1. Cervical venous network (Fig. 1, C) 2. Internal thoracic crossing veins 3. Azygos hemiazygos anastomoses (Fig. 1, A and B) 4. Vertebral venous plexuses (Fig. 1, B and C) E. Collaterals between the arm and thorax 1. Lateral thoracic, intercostal, internal thoracic anastomoses (Fig. 1, A) 2. Cephalic, jugular anastomoses over the shoulder and supraclavicular fossa (Fig. 1, A) Two major venous systems drain into the superior vena cava via the innominate veins.

Cervical vertebral phlebography.

The main features of the anatomy of the veins of the vertebral canal have long been known as a result of dissection studies. The first roentgenographic examinations of the epidural veins were carried out in 1952 by FISCHGOLD et coll., who injected a water-soluble contrast medium into the spinous process of a lower thoracic vertebra and succeeded in demonstrating these vessels in the thoracic and lumbar parts of the vertebral canal; SCHOBINGER described the roentgenologic appearances of these veins in more detail. HELANDER & LINDBOM, in an attempt to demonstrate changes in the epidural veins in connection with disk protrusions in the lumbar vertebral region, compressed the inferior vena cava and injected contrast medium into that vein. SCHOBINGER endeavoured to outline the epidural veins in the cervical vertebral region by injecting contrast medium into the spinous process of the second cervical vertebra; he was only partially successful, however, and even when the veins were visible they were poorly outlined. He summed up his results as follows: ‘Since injection of contrast medium into the spinous processes of the cervical vertebrae fails to outline well the internal vertebral venous plexus in the cervical region it presently can be assumed that this method is inadequate for the routine diagnosis of protruded cervical discs’. Anatomical investigations have shown that the red marrow in the bodies of the vertebrae contains several venous channels - the basivertebral veins which.unite in the cervical vertebral region into two stems running in an

Comparison of intraosseous vertebral venography and Pantopaque myelography in the diagnosis of surgical conditions of the lumbar spine and nerve roots.

Despite the widespread use and proclaimed safety of Pantopaque myelography (1–7) many still adopt a reluctant attitude toward its indiscriminate and repeated employment or condemn it as a screening procedure. The basis for this hesitancy are reports of occasional adverse reactions of the leptomeninges with early or late sequelae in the spinal canal or intracranial cavity. A method without the disadvantages associated with the introduction of a potentially irritating substance into the subarachnoid space but with comparable accuracy, even if limited to lesions of the lumbar spine, would indeed constitute a valuable addition to our diagnostic armamentarium. It was our feeling that intraosseous vertebral venography might hold such promise. We therefore set out to compare its potentialities with those of Pantopaque myelography in the diagnosis of such surgical lesions of the lumbar spine and nerve roots as disk protrusion, spondylolisthesis, symptomatic spina bifida occulta, tumors of the cauda equina, epidural tumors, and metastatic tumors of the vertebral column. Anatomic Considerations The blood from the medulla spinalis, nerve roots, meninges, vertebral column, and paravertebral muscles is drained by multiple veins constituting a network extending over the entire length of the spine. These venous plexuses are located in part outside and in part inside the spinal canal (Fig. 1). The external vertebral venous plexus surrounds the vertebral column and is best developed in the cervical region, an anatomic peculiarity which has been roentgenographically verified (8, 9). Its posterior division is located along the spinous processes and the posterior surface of the transverse processes, extending also between the posterior paravertebral muscles. The anterior division is situated laterally and anteriorly to the vertebral bodies and is linked to its posterior counterpart as well as to the internal vertebral plexus (Fig. 1). The external vertebral venous plexus assumes important collateral circulatory duties in the presence of some obstruction to the blood flow within the internal vertebral venous plexus. The internal vertebral venous plexus, which we prefer to call the epidural plexus, is located within the spinal canal between the dura and the bony surfaces of the vertebrae. The epidural veins run along the entire length of the spine and their anatomical continuity with the intracranial dural sinuses has been confirmed by Batson (10). The veins of the internal vertebral plexus surround the spinal dura and form two pairs of well developed longitudinal channels connected with each other by a series of venous rings, one opposite each vertebra.