A doctor explains how a pinched nerve in the back causes sciatica pain in the leg

Hi Dr. Lumbago,

I hope you have some answers for me. Sometimes I have pain in my lower back, and sometimes it goes down my butt and into the back part of my upper leg or thigh and ends about at the back of the knee.  When I get pain in the low back and leg pain it happens after I sit for a long time in a straight chair that has no padding. Once it starts up it might take a few hours for it to finally settle down. It seems like I get the most relief by putting some ice on my low back. But other times I get just leg pain alone when I go out for a long walk after dinner and my whole leg aches and throbs.  It seems like the whole leg gets tight and achy and hurts like crazy until I can rest for a few minutes and then the pain goes away until I walk again for a while. Isn’t this leg pain sciatica?  I always thought that sciatica was leg pain. Since I have back pain with the leg pain I thought this could not be connected to the sciatic nerve which is in the leg. Can you help me understand how this is connected and what is going on with me? I guess I should know all this but science was never easy for me.  What is sciatica?  And where is the sciatic nerve?

Thank you for your help.

Dennis Novak


Greetings Dennis,

If science was never easy for you, I understand because I had the same problem with math.  It is like the math part of my brain never developed. Science was always fun and naturally easy for me, but please keep me away from those numbers.  My brain just locks up. OK, now on to what is happening  with your legs.

To begin with, I believe you have two different problems possibly going on at the same time with your legs.  So, I will not be able to offer a simple or easy explanation since we will have two different issues to explain and discuss.  Based on what you have told me one problem is related to the sciatic nerve, and the other problem is actually a blood circulation problem and not related to the sciatic nerve at all.

The first leg pain issue you describe (low back pain and leg pain in the back part of the leg that starts after sitting and lasts a while) is probably related to sciatica (sciatic neuritis) that probably starts from some mechanical irritation in the lower back.  Sciatic is pain in the sciatic nerve due to inflammation.  The sciatic nerve starts from five different levels of the spinal cord and comes together to pass downward through the buttocks, the back portion of the thigh and calf muscle and ends at your big toe.  You have one sciatic nerve in each leg.  Any pressure or irritation along any part of the sciatic nerve can cause pain, numbness and weakness in any part of the leg that is supplied by that part of the nerve.  The place where the sciatic nerve is most vulnerable and likely to receive nerve pressure is at the spine, where it can be irritated by a swollen disc, arthritis spurs of the spine or spinal misalignment, to name a few.  I would suggest getting a doctor or a chiropractor to check these things out for you and correct what is causing this sciatic neuritis to be giving you leg pain.      

The second leg pain issue you describe (whole leg pain that comes on only after prolonged walking that quickly leaves with rest is probably a blood circulation, or vascular, problem with some type of circulation due to an issue with the health and integrity of the blood vessels themselves, called intermittent claudication.   If you have ever put a tourniquet on your arm or leg, or even put a rubber band tightly around a finger, you know how painful it can be to stop the blood flow into a part of your body.  Something similar happens if you have intermittent claudication going on in your leg.  I suggest you get yourself over to your family doctor to get your blood supply checked out in your legs; perhaps you will be referred to someone else if it is a major problem, but that would be unusual.  Your personal doctor can probably manage this aspect of your problem without much trouble.  

Keep in mind that not all leg pain is related to the sciatic nerve.  There are many ways pain can develop in the legs. You need a good nerve supply and a good blood supply in those legs to get you where you need to go.  

Good luck to you.  DL