|
Spondylolisthesis is the Latin term for a slipped vertebral body, and
Isthmic refers to the fact that the slip is due to a stress fracture
through a piece of bone in the back (the pars interarticularis).
Approximately 5% of the population experiences a stress fracture in
the lowest lumbar vertebral segment (L5), usually between the ages
of five and seven. That segment then slides forward, encroaching on
the first sacral vertebral body (S1). This is almost never due to an
injury. The L5-S1 segment is the most likely to slip but it can also
occur at L4-L5 or L3-L4. This condition is the leading cause of
back pain in adolescents, though most adolescents that have the
condition will not experience any back pain because of it. It is not
a very dangerous condition as there are almost never any
neurological problems associated with it.
Symptoms
Probably 80% of people who have this condition never have any
symptoms, and therefore never even realize they have it. For those
who do develop low back pain, the cause may be from the vertebrae
sliding forward and compressing a nerve or from resulting disc
degeneration. With the bony segments of the spine not working
properly the disc has to work harder. The disc is designed to work
very well under normal compression, but the forward force applied to
the disc in the case of spondylolisthesis can cause the disc to
break down.
In addition to the low back pain, some patients also experience leg
and foot pain due to the nerve being pinched (almost always the L5
nerve). This leg pain will generally be worse when the patient
stands or walks. Pain can also come from the fracture, and the
tissue in that area may become irritated and painful. Within the
pars interarticularis the nerve endings (nociceptors) can become
sensitized and create pain. Most of the pain will be activity
related. Pain with rest is not typical.
Diagnosis
If, upon physical exam, symptoms indicate a possible isthmic
spondylolisthesis, an imaging study will be needed to confirm the
diagnosis. Isthmic spondylolisthesis can be seen on a regular X-ray,
and on a Magnetic Resonance Imaging (MRI) scan. As noted, the
spondylolisthesis will almost always occur at the juncture of the L5
and S1 vertebral segments, so that is where the most attention will
be focused on the images. The imaging study can also detect if there
is degenerative disc disease leading to a nerve root being pinched.
Treatment need only be considered if the pain limits the patient’s
pain to any great extent. It is not a dangerous situation, and the
pain is generally not progressive.
(Continued on next page.)
|
