The spine has four curves. Two of them curve forward toward the belly side of the body. They are the cervical (neck) and lumbar (low back) spines. The other two arch backward toward the back and buttocks. They are the thoracic spine which supports the ribcage, and the sacrum which sits in the back of the pelvis beneath the low back. It is the pedestal the spine rests on and, similar to the thoracic spine, bends backward to support a load.
The term kyphosis refers to the normal curves of the thoracic spine and sacrum. It also refers to an exaggeration of the thoracic curve that causes a pronounced hump or backward bend in the upper back called a Gibbus deformity that pitches the shoulders and neck forward of the normal gravity line. Exaggerated kyphosis also causes a loss in height. In severe cases it can interfere with breathing as it alters the rib cage which contains the lungs and heart. Exaggerated kyphosis is sometimes referred to as hyperkyphosis.
The term kyphosis can also be used to describe an abnormal curve of the spine that goes in the opposite or wrong direction. For example, it can be used to describe a reversal of the curve in the low back. More commonly, it is used to describe a reversal of the normal curvature in the cervical spine, which is the neck. The x-ray on the right is a good example of a kyphotic (backwards) curve in the cervical spine. Kyphosis occurring in any area of the spine can be inherited as a developmental design problem or it can be acquired later in life through trauma, aging and diseases such as arthritis, osteoporosis, compression fractures and Parkinson’s disease.
Scoliosis is an abnormal lateral (sidewards) curve of the spine. Scoliosis is sometimes associated with kyphosis and is referred to as kyphoscoliosis. Scoliosis is typically a problem that becomes apparent in childhood. It affects females far more than males. Adults, however, can acquire scoliosis later in life due to trauma, degenerative conditions of the spine, inherited and acquired connective tissue disorders and other causes.
Scoliosis has been shown to cause functional stenosis of the spinal canal and subsequent compression of the vertebral veins which decreases venous blood flow. The problem occurs as the veins get compressed against the inside curvature of the spinal canal. Kyphosis most likely causes functional stenosis of the spinal canal and vertebral veins similar to scoliosis.
The images below are used with permission from a member of the TiMS website who underwent testing for chronic cerebrospinal venous insufficiency (CCSVI). The patient was found to have impingement of both internal jugular veins which was corrected by the placement of stents. Subsequent to placement of the stents the patient had considerable improvement in signs and symptoms.
The image is composed of three different views superimposed on one screen. The view to the left is a plain view x-ray of the upper back and neck. If you look closely at the spinous processes (they look like teardrops that go down the middle of the spine) you will see that they deviate to the left side of the spine. Likewise, if you follow the contour of the sides of the spine you will see that the spine is curved to the left. Since the x-rays were taken from front to back the left side of the film is the right side of the patient.
The middle image is a venogram which is an MRI with contrast dye injected into the veins. In this case, the red arrow points to an area of impingement or stenosis of the internal jugular veins just in front of the upper cervical spine. The impingement decreases blood flow through the internal jugular veins, which can back up in the brain.
The image on the right is an x-ray of the stents that were inserted using interventional radiology. More often, most physicians doing the procedure use venoplasty in which a balloon is inserted into the vein and then filled to stretch the vein and open it up. Venoplasty is subject to restenosis. Stents are tubes placed in the veins that spring outward to keep the veins open. Stents are more durable and less likely to re-stenose but pose more problems due to clots. In cases such as the one above it is a tough choice, but if the structural problem causing the impingement is permanent then durability may become more of a factor to consider in choosing procedures.
If you look closely at the above image to the right and follow the contour of the spine you will notice that it arches backwards slightly. As mentioned at the start, the neck or cervical spine should arch gently forward toward the chin. In this particular case the cervical spine is kyphotic or going in the opposite direction that it should.
The internal jugular veins exit the skull through the jugular foramen on the floor of the skull just in front of the transverse process of the C1 vertebra of the upper cervical spine called atlas. After exiting the skull the internal jugular veins join the external jugular veins and follow the curve of the cervical spine on their way down from the head and back to the heart. In the case above, the internal jugulars like the cervical spine bend backward due to the cervical kyphosis. This causes a sharp change in the course of the normal direction of blood flow out of the brain as the internal jugular veins bend around the upper cervical spine. In addition to possibly impinging the internal jugular veins where they exit the skull in front of the transverse process of C1 (atlas), kyphosis most likely compresses the vertebral veins on the inside curve of the cervical spine similar to what scoliosis does in the rest of the spine. Kyphosis and scoliosis most likely play a significant role in CCSVI and CCVBP.
The angle of the upper cervical spine to the base of the skull is important to blood and CSF flow going into and out of the brain and cord. Likewise, the relationship of the base of the skull and upper cervical spine to the curve in the lower cervical spine is important to blood and CSF flow. Inherited and acquired misalignments and disorders of the upper cervical spine, as well as spondylosis (degeneration), scoliosis and other abnormal curves including kyphosis affect blood and CSF flow to the brain and cord. They also cause malpositioning and thus mechanical stress and strain of the brainstem and cord within the skull and spinal canal.
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