Lumbar spinal stenosis
It is the reason many people over sixty stop walking any distance. Almost half the people of that age have a narrowed canal on imaging and most of them have no symptoms at all, so the MRI on its own is never enough to decide anything.
If you have arrived here, you have probably read the word "stenosis" in an MRI report, perhaps followed by "moderate" or "severe", and you are trying to translate it. Or you may not even have a report yet, and you are looking for why your legs hurt when you walk two blocks and settle the moment you sit down.
Both routes lead to the same place.
What it actually is
The spinal cord and the nerve roots travel through a tunnel formed by the vertebrae. Over the years that tunnel narrows: the ligament lining it thickens, the joints at the back enlarge with arthritis, the discs bulge, sometimes one vertebra slips slightly over another. None of that is a disease: it is the normal wear of a spine that has worked for decades.
The problem appears when the narrowing goes far enough to compress the roots. And it appears above all on walking, because standing upright closes the canal a little further; sitting down or leaning forward opens it.
That is the key to the whole picture. It is also why stenosis and a herniated disc are not the same thing, although they are confused all the time: a herniated disc is an event, it usually involves one root, and it happens to people between thirty and fifty. Stenosis is a process, it usually involves several roots, and it happens to people over sixty.
How it feels
There is one symptom that almost defines the condition and has a name of its own: neurogenic claudication. You walk a certain distance — one that everyone knows precisely: "to the corner", "half a block", "as far as the shop" — and the legs start to feel heavy, to cramp, to go numb. You have to stop. And after sitting for a while, or simply leaning forward, it passes.
Two very characteristic signs follow from this:
The supermarket trolley. Many people find they can walk without trouble while pushing the trolley, because they are leaning forward. With their hands free, they cannot.
The bicycle. You can pedal for kilometres without any trouble and not manage three blocks on foot. Seated and bent forward, the canal is open.
It is also typical that walking up a hill is better tolerated than walking down it, for the same postural reason. And that the back pain, if there is any, is the least of it: what limits life is the legs.
The numbers worth knowing
- In the Framingham community study, 47 per cent of people aged 60 to 69 had stenosis on imaging, and 19 per cent had it to an absolute degree. These are people from the community, not patients. Most of them never seek care for it.
- The association between stenosis on imaging and symptoms is real, but weak. Having a narrowed canal raises the probability of low back pain about threefold. It does not determine it.
- Symptomatic stenosis, by contrast, is far less common: around 5 in every 1,000 people over 50 and 1 in every 1,000 over 65.
- The natural history is not a relentless decline. It fluctuates: worse periods and better periods, with a slow tendency to worsen over years, not months.
Out of those numbers comes the most useful sentence on this page: the word "severe" in an MRI report describes a measurement in millimetres, not a prognosis. There are people with severe stenosis on imaging who walk forty blocks and people with moderate stenosis who cannot reach the corner. What is treated is the limitation, not the number.
When not to wait
- Difficulty passing urine, difficulty emptying the bladder, or loss of bladder or bowel control.
- Numbness in the groin, the genitals or around the anus.
- Weakness that progresses over days: the foot that catches, the knee that gives way, difficulty getting up from a chair.
- Severe pain in both legs coming on suddenly.
Outside these situations, lumbar stenosis is not an emergency and there is no hurry to decide. It is one of the few spinal conditions where taking your time is explicitly the right thing to do.
What you will hear that is not true
"Stenosis is the same as a herniated disc." No. You can have both, but they are different conditions, with different ages, symptoms and treatments.
"It says severe, so it has to be operated on now." Radiological severity and clinical severity run in separate lanes. The decision is made by looking at how far you can walk, not at how many millimetres the canal measures.
"If I do not have surgery, I will end up in a wheelchair." That is not what the natural history of the condition shows. Degenerative stenosis limits the distance you can walk; it does not typically lead to paralysis. That sentence is used to rush decisions and it is not supported by the evidence.
"At my age there is nothing to be done." The opposite extreme, and just as false. Stenosis surgery in older people, when well selected, is one of the operations that gives the best results in terms of regaining independence. Age on its own rules nothing out; what matters is general health.
What will happen at the appointment
You will be asked about distance. How many blocks you can walk today, how many you could walk a year ago, what you do when you have to stop, whether the trolley or the bicycle changes things. That history is worth more than the MRI, and it is the one that will be used to measure whether anything improves or worsens.
Then the examination: strength, reflexes, sensation, pulses in the legs. The pulses matter because there is a condition that looks very similar — claudication from poor arterial supply — and that is precisely where it is told apart: in the vascular kind, the pain settles as soon as you stop, whatever your posture; in the neurogenic kind, you need to bend forward.
And if the limitation is tolerable, the sensible course is to start with targeted physiotherapy, adapted physical activity and weight control, and to measure again in a few months. Surgery is a good tool once the distance you can walk is shaping your life.
Questions worth writing down before you go
- Does my limitation on walking match the level seen on the MRI?
- What is my maximum distance today, so that it can be compared in six months?
- If we wait, what is the worst that can happen in that time?
- If I have surgery, is the operation decompression alone or does it include fixation with screws? Why?
- Which of my symptoms do you expect to improve, and which probably will not?
The questions people ask most
Does lumbar spinal stenosis heal on its own?
It does not reverse: the canal does not widen again. But the symptoms do fluctuate, and many people manage well for years with non-surgical treatment. "It does not heal" and "you cannot live well with it" are two different things.
When does lumbar spinal stenosis need surgery?
When the distance you can walk genuinely limits everyday life and properly delivered non-surgical treatment is no longer enough. Or sooner, if progressive weakness or loss of bladder or bowel control appears. The figure in the report is not the criterion.
What happens if I do not have surgery?
The most likely thing is that you carry on as you are, with ups and downs, and that the distance slowly shortens over the years. It is not a condition that suddenly accelerates. That is why putting the decision off is a legitimate option if you are reasonably well.
Why can I ride a bike but not walk?
Because on a bicycle you are sitting with your trunk leaning forward, and in that position the canal is more open. It is one of the most helpful pieces of information for the diagnosis, and it is worth mentioning at the appointment even if nobody asks.
What does moderate or severe stenosis on an MRI report mean?
It describes how much the canal has narrowed, in millimetres. That is useful information for the surgeon, but it does not predict how much it will hurt, or how far you will be able to walk, or whether surgery is needed. Almost half of all people in their sixties have stenosis on imaging with no symptoms at all.
What is the best way to sleep?
Almost always better on your side with your knees drawn up, or on your back with pillows under your knees: these are flexed positions, and they open the canal. Sleeping stretched out face down is usually the least well tolerated.
What is a laminectomy and what is a spinal fusion?
A laminectomy — or decompression — removes the bone and thickened ligament pressing on the roots, and leaves the spine as it is. A fusion, in addition, fixes two or more vertebrae together with screws. The second is a major operation and is reserved for cases with instability or slippage. If fusion is proposed, it is entirely reasonable to ask why decompression alone is not enough in your case.