Nerve root sleeve diameters at normal segments and at segments with proximate disc disease: MRI evaluation
Tetyana A Gorbachova1, Michael R Terk
1LAC/USC Imaging Science Center, 1744 Zonal Avenue, Los Angeles, CA 90033, USA. tjester@hsc.usc.edu
Objective:
To compare MR morphologic parameters of spinal nerve roots and their range of variability in normal and abnormal spinal segments.
Design And Patients:
Ninety-six consecutive lumbar spine MRI examinations were segregated into three groups: group 1 was composed of 30 patients with disc bulge, protrusion or extrusion at the L5-S1 segment measuring 3 mm or more; group 2 consisted of 31 patients with no disc pathology; and group 3 was composed of 35 patients with no disc abnormality at the L5-S1 level but with coexisting spine pathology at other segments. Measurements of 192 S1 nerve root sleeves were performed at three consecutive levels on T1-weighted images. Differences between right and left nerve root sleeve diameters (delta value) at three slice levels were calculated in each group. Data were analyzed by ANOVA.
Results:
No significant differences between the mean values of traversing S1 nerve root sleeve diameter on three corresponding consecutive slices were found among groups ( P=0.733, P=0.824, P=0.365 respectively), nor were significant differences in delta values between groups found ( P=0.639, P=0.113, P=0.722).
Conclusions:
S1 nerve root sleeve diameter and the differences between right and left in the abnormal group were not significantly different from normal and therefore can not be used as an objective criterion of nerve root pathology.
Insights
Magnetic resonance imaging (MRI) measurements of S1 nerve root sleeve diameter showed no significant differences between normal and abnormal spinal segments. These findings suggest that nerve root sleeve diameter is not a reliable objective criterion for diagnosing nerve root pathology.
Area of Science:
- Radiology
- Neurosurgery
- Orthopedics
Background:
- Spinal nerve root morphology on MRI is crucial for diagnosing pathology.
- Variability in nerve root sleeve diameter can occur in normal and abnormal spinal segments.
Purpose of the Study:
- To compare MR morphologic parameters of spinal nerve roots.
- To assess the range of variability in normal and abnormal spinal segments.
Main Methods:
- Ninety-six lumbar spine MRI examinations were analyzed.
- S1 nerve root sleeves were measured at three consecutive levels on T1-weighted images.
- Differences between right and left nerve root sleeve diameters (delta value) were calculated and analyzed using ANOVA.
Main Results:
- No significant differences in mean S1 nerve root sleeve diameter were found among groups with normal, L5-S1, or other spinal pathologies.
- No significant differences in delta values (right vs. left diameter) were observed between the groups.
Conclusions:
- S1 nerve root sleeve diameter is not significantly different in abnormal spinal segments compared to normal.
- Differences between right and left S1 nerve root sleeve diameters do not reliably indicate nerve root pathology.
- MR morphologic parameters of S1 nerve root sleeve diameter cannot be used as an objective criterion for nerve root pathology.
