Transitional Vertebrae

What Are Transitional Vertebrae?

Transitional vertebrae are abnormalities in our spine which, along with muscles, ligaments, and nerves, consists of 33 bones known as the vertebrae. The spine is a highly complex structure, and as most of us know, can be the subject of pain at times, mostly in the lower back, though sometimes in the neck.

The Sections Of The Spine - The spinal vertebrae are, for the purposes of easy identification, divided into three groups, the uppermost seven support the neck and are called the cervical vertebrae. The next twelve vertebrae are located in the upper and middle back and support the rib cage. These twelve vertebrae are called the thoracic vertebrae. The five lowest vertebrae, the lumbar vertebrae, are located in the lower back and sometimes can contribute to lower back pain, though there are other causes of this condition as well. Below the bottom lumbar vertebra, lumbar vertebra number 5, lies the sacrum, a large triangular shaped bone (actually five fused bones ), sometimes referred to as our seat bone, and beneath that is the coccyx, or tailbone, consisting of an additional four fused bones.

For the most part, the 33 vertebrae are fairly similar in appearance but by no means identical. The vertebrae in one of the sections of the spine, the cervical, thoracic, or lumbar section, are generally somewhat different in structure than the vertebrae in the other two sections, and the lumbar vertebrae are very different in structure than that of the adjoining sacrum bones. When one of the vertebrae takes on a structure which has the characteristics of both its neighboring vertebrae, it is called a transitional vertebra. This is almost always a congenital disorder, and in the majority of cases never presents a problem.

For example, in being attached to the ribs, the twelve thoracic vertebrae have a structure that differs from the cervical vertebrae, whose function is to support the neck. The junction of the cervical and thoracic parts of the spine is called the cervicothoracic region, other junctions are called the thoracolumbar, and the lumbosacral regions. If a transitional vertebrae exists it would, by definition, be located in one of these junctions.

Bertolotti's Syndrome - If the structural abnormality is not excessive transitional vertebrae will usually cause no problem and require no treatment. If the abnormality is such that pressure is placed on the nerve, or spinal motion is inhibited, transitional vertebrae can cause pain or other problems. The region in which most problems of this type are apt to be encountered is the lumbosacral region, the region where the lumbar vertebrae give way to the sacrum. What can happen is a situation known as Bertolotti's syndrome, in which the lowest lumbar vertebra, denoted as lumbar vertebra number 5, is elongated taking on the characteristics of both a lumbar vertebra and the sacrum. In some instances this fifth lumbar vertebra may actually fuse to the sacrum.

Transitional vertebrae problems in the lumbosacral region of the spine can be a source of lower back pain. There are of course other sources of lower back pain, and the presence of transitional vertebrae is by no means the most common cause. It is estimated that roughly 5 percent of adults have an abnormally formed 5th lumbar vertebra, but in the majority of cases the abnormality causes no problem. When it does cause a problem it is usually due to pressure being placed on the sciatic nerve. Bertolotti's syndrome is just one of several possible causes of what we call sciatica.

When treatment is required for transitional vertebrae, it usually consists of a combination of medications to ease pain and inflammation, and the use of a brace. Not too much is really known about this condition, and surgery on the spine is usually ruled out as an option due to the danger involved in possible damage being done to the nervous system.