Introduction: Surgical decision making in lumbar spinal stenosis
(LSS) takes into account primarily clinical symptoms as well as
concordant radiological findings. We hypothesized that a wide variation
of operative threshold would be found in particular as far as judgment
of severity of radiological stenosis is concerned.
Patients and methods: The number of surgeons who would proceed
to decompression was studied relative to the perceived severity of
radiological stenosis based either on measurements of dural sac cross
sectional area (DSCA) or on the recently described morphological
grading as seen on axial T2 MRI images. A link to an electronic survey
page with a set of ten axial T2 MRI images taken from ten patients
with either low back pain or LSS were sent to members of three
national or international spine societies. Those 10 images were
randomly presented initially and re-shuffled on a second page
including this time DSCA measurements in mm2, ranging from 14
to 226 mm2, giving a total of 20 images to appraise. Morphological
grades were ranging from grade A to D. Surgeons were asked if they
would consider decompression given the radiological appearance of
stenosis and that symptoms of neurological claudication were severe
in patients who were otherwise fit for surgery. Fisher's exact test was
performed following dichotomization of data when appropriate.
Results: A total of 142 spine surgeons (113 orthopedic spine
surgeons, 29 neurosurgeons) responded from 25 countries. A
substantial agreement was observed in operating patients with severe
(grade C) or extreme (grade D) stenosis as defined by the
morphological grade compared to lesser stenosis (A&B) grades
(p<0.0001). Decision to operate was not dependent on number of
years in practice, medical density in practicing country or specialty
although more neurosurgeons would operate on grade C stenosis
(p<0.005). Disclosing the DSCA measurement did not alter the
decision to operate. Although 20 surgeons only had prior knowledge
of the description of the morphological grading, their responses
showed no statistically significant difference with those of the
remaining 122 physicians.
Conclusions: This study showed that surgeons across borders are
less influenced by DSCA in their decision making than by the morphological
appearance of the dural sac. Classifying LSS according to
morphology rather than surface measurements appears to be consistent
with current clinical practice.