Which nerve root is affected by lumbar disc herniation, IVF stenosis, or degenerative spondylolisthesis?

It is important to know which spinal pathology can create which radicular symptoms. Often one must correlate imaging with the patient’s symptoms, in order to determine if imaging findings are responsible for symptoms or if they are merely incidental findings. Knowing which nerve roots are affected by which spinal conditions also helps formulate a differential diagnosis and helps with treatment approaches. To help with this, I created a summary table of common conditions, intervertebral foramen stenosis (IVF), lumbar disc herniation (LDH), and degenerative spondylolisthesis (DSPL).

	L4	L5	S1	Ref.
L4-5 IVF	100%	--	--
L4-5 LDH	7%	94%	10%	1
L4-5 DSPL	sometimes	Uni/bi	--
L5-S1 IVF	--	100%	--
L5-S1 LDH	--	29%	81%	1
L5-S1 DSPL	--	sometimes	Uni/bi

Lower lumbar disc herniations affect a single nerve root in 60% of cases and two nerve roots in 40% of cases (considering that radiculopathy is present).2 Degenerative lumbar spondylolisthesis affects a single nerve root in only 10% of cases, two nerve roots in 19% of cases, and three or more nerve roots in 71% of cases, being bilateral in the same percentage of cases.3 Intervertebral foraminal stenosis affects the exiting nerve root and thus usually only affects one nerve root4, except for cases with conjoined nerve roots, which is rare.5

1. Janardhana, A. P., Rajagopal, S. R. & Kamath, A. Correlation between clinical features and magnetic resonance imaging findings in lumbar disc prolapse. Indian J. Orthop. 44, 263 (2010).

2. Kortelainen, P., Puranen, J., Koivisto, E., Lähde, S. & others. Symptoms and signs of sciatica and their relation to the localization of the lumbar disc herniation. Spine 10, 88 (1985).

3. Epstein, N. E., Epstein, J. A., Carras, R. & Lavine, L. S. Degenerative spondylolisthesis with an intact neural arch: a review of 60 cases with an analysis of clinical findings and the development of surgical management. Neurosurgery 13, 555–561 (1983).

4. Jenis, L. G. & An, H. S. Spine update: lumbar foraminal stenosis. Spine 25, 389–394 (2000).

5. Taghipour, M., Razmkon, A. & Hosseini, K. Conjoined Lumbosacral Nerve Roots: Analysis of Cases Diagnosed Intraoperatively. J. Spinal Disord. 22, 413–416 (2009).