Magnetic resonance imaging findings of the lumbar root pathway in patients over 50 years old.

In patients with degenerative disease of the lumbar spine, stenosis not only in the entrance zone but also in the mid- and exit zones of the nerve root pathway can occur. With the development of magnetic resonance imaging (MRI), it has become easier to assess stenosis of the root pathway, especially in the mid- and exit zones. T1-weighted sagittal images in the lateral facet plane show the state of the exit zone. I studied the incidence of severe exit-zone stenosis of L3-5 roots in 45 patients aged over 50 years 15 in their fifties, 15 in their sixties, and 15 in their seventies) by MRI and assessed the results on the basis of age, intervertebral disc degeneration, and disc height. I also studied the relationship between clinical symptoms and severe stenosis in both entrance and exit zones of the L4 and L5 roots. The incidence of severe exit-zone stenosis at the L3 root was < 20% at all ages. On the other hand, L4 and L5 nerve root stenosis increased with age and severe stenosis affected 70% of L4 roots and 80% of L5 roots in patients in their seventies. The incidence of deformation or disappearance of the dorsal root ganglion (DRG) was 10% or less at L3 and L5 roots, while it was 10% at L4 root.(ABSTRACT TRUNCATED AT 250 WORDS)