How can I tell stenosis/neurogenic claudication vs sciatica from disc?

The standing-still trigger points to spinal stenosis, not a simple disc herniation. The key discriminator is what position relieves the pain.

The mechanism is venous congestion inside a narrowed spinal canal. When you stand still, gravity pools blood in the epidural veins, the canal gets tighter, and the nerve root suffocates from lack of oxygen. That is why leaning forward (which opens the canal) brings relief, while standing still or walking makes it worse. A simple disc herniation typically hurts with sitting and may shoot pain with coughing or sneezing, but it does not follow the standing-still pattern.

The retrieved evidence supports this distinction indirectly. A 2021 study of 114 patients with lumbosacral radicular pain found that the location, type, and size of the disc herniation did not predict long-term outcomes after epidural steroid injection [1]. That tells you the disc is not the whole story. The same study showed the average pain score dropped from 4.8 to 1.8 on a 0-10 scale after the injection, which works by shrinking the inflamed nerve and reducing venous congestion, not by changing the disc [1].

The honest gap: none of the retrieved studies directly compare the standing-still presentation to other patterns of radicular pain. The evidence for the mechanism is solid physiology, but the population-level data on how often this specific trigger predicts stenosis versus disc herniation is thin. A lumbar spine MRI with the patient standing or in extension would settle it, but that is not standard practice.

My call: the standing-still trigger with relief from leaning forward is neurogenic claudication from spinal stenosis until proven otherwise. Confidence: moderate.