The zebra has been chosen for this simile because one consistent characteristic of zebras is that they always travel in herds. The is also true for genomic spine disorders. The following represents a gallery of “zebras” seen in association with these disorders. The presence of a single zebra should start the alarm bells ringing in the mind of the astute clinician.
Some of the “zebras” are prominent and others are subtle. Examples of prominent “zebras” are”:
- Congenitally Small Spinal Canal
- Congenital Poor Support
- Tropism of the Facet Joints
- Asymmetrical Vertebrae
- Spina Bifida Occulta
- Conjoined Nerve Roots
- Intra-osseous Hemangiomas
- Multi-level Endplate Deformities
- Multi-level Vertebral Elongation Deformities
It has been the ability to pick up the more subtle “zebras” which has led to a higher incidence of appreciation of the incidence and prevalence of genomic spine disorders. Some of theses are seen below:
Diffuse genomic abnormalities are present throughout this spine. The red dot points to a “block vertebrae” in which the normal process of differentiation did not occur. Endplate abnormalities are present at each level and a high intensity zone annular tear is evident at the L5-S1 level.
This is another case of a lumbar “block vertebra” (shown with the green dot) in a young patient with diffuse degeneration, reversal of normal lordosis and advanced degeneration of the adjacent segments (red dots). This finding is similar to the post-rigid-fusion “transitional syndrome.” It simply is a poor idea to perform rigid stabilizations in patients with underlying multi-level degeneration due to genomic spine disorders. Non-rigid arthrodeses for stabilization are much more rational.
Occupying a good portion of the L2 vertebrae is a intraosseous hemangioma. These are benign tumors formed from aberrant clumps of vascular cells which should have disappeared prior to birth but apparently lost their way in the developmental
process. These benign tumors are often multiple in nature. They do not turn malignant but when large can weaken the vertebrae. They are frequently seen in association with genomic spine disorders (GSD).
In this patient with a diffuse genomic spine disorder there is a S1-S2 transitional vertebra. Associated “zebras” are an intra-osseous hemangioma in the body of L4 and a Grade 1 degenerative spondylolisthesis at the L4-% segmental level.
Congenital poor support refers to the relationship of the lower lumbar spine to the adjacent pelvis. A line drawn from the top of the iliac crests (lower line) in this patient crosses the base of the L5 vertebrae creating a shallow “valley” of support. The upper line shows where the intercristal line should be to afford the patient good ligamentous support of the lower spine. Patients with poor support sustain greater stress on the segments of the lower spine. This abnormality became a problem when homo sapiens assumed the upright position for ambulation.
This is a unique example of persistence of the primitive notochord into adult life. The notochord remains present with the L5 vertebral body alone. This is a liability for the patient as nutrition of the adjacent discs is impaired. There is also a very small chance that this remnant of the primordial notochord (which gave birth to the spine) could undergo malignant degeneration and become a chordoma.
The image to the left depicts a sacral bone tumor which could be a chordoma in a patient with a genomic spine disorder. This was picked up on a MRI performed for evaluation of back pain, leg numbness and weakness. Surgical removal was
recommended. Although rare, 50% of all chordomas are in the sacrum. This tumor can extend into adjacent tissues and has been known to metastasize.
Shown here is a small cyst diagnosed as a lipoma of the filum terminale of the cauda equina. Lipomas, which can be found in 3.8% of imaging studies for low back pain, are considered to be benign in nature. They need, however, to be differentiated from tumors such as ependymoma which can be quite malignant. These lipomas are sometimes associated with tethering of the spinal cord.
There are many more congenital spine abnormalities of development. The purpose of this page is to show some of the important, but often missed abnormalities which can then allow the radiologist or clinician to suspect a genomic spine disorder and allow the patient to be informed of this as well as the excellent conservative treatments available to them to treat their symptoms and prevent progression of the problem.