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":
Scoliosis
Spondylolysis
Spondylolisthesis
Congenitally Small Spinal Canal
Congenital Poor Support
Tropism of the Facet Joints
Asymmetrical Vertebrae
Spina Bifida Occulta
Conjoined Nerve Roots
Intra-osseous Hemangiomas
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.