Numbness in Your Legs: What Causes It, and When to Check Your Circulation

Numbness in the legs is one of those symptoms people carry for years before mentioning it, usually because it does not hurt. It is also one of the few symptoms that can come from three entirely separate systems — the nerves, the spine, or the arteries — and the treatment for one does nothing for the others. Peripheral artery disease alone affects roughly 8.5 million American adults over 40 (Circulation, 2021), and most of them do not have the textbook leg pain that is supposed to announce it. This article explains how the causes differ, which clues separate them, and when an arterial duplex ultrasound is the test that settles it.

What Causes Numbness in the Legs?

Numbness is a signalling failure. Either the nerve carrying sensation is damaged, or it is compressed somewhere along its path, or the tissue it runs through is not getting enough blood to work properly. Four mechanisms account for nearly all persistent leg numbness.

Peripheral neuropathy. Damage to the small nerves of the feet and lower legs, most commonly from diabetes. It is typically symmetric, starts in the toes and works upward in a stocking distribution, and is often described as buzzing, burning or walking on foam. It tends to be present at rest and is frequently worse at night. Peripheral neuropathy defined by loss of monofilament sensation was found in 10.4 percent of middle-aged American adults and 26.8 percent of older adults in NHANES (two US cohorts, 2021) — it is common, and it is under-recognised.

Nerve root or spinal compression. Lumbar spinal stenosis and disc herniation compress nerves where they exit the spine, producing numbness that follows a band or stripe down the leg. The hallmark is positional relief: symptoms build with standing and walking upright, and ease when you sit or lean forward over a shopping cart. A systematic review put the prevalence of clinically diagnosed lumbar spinal stenosis at about 11 percent in the general population, rising to a quarter or more of patients seen in primary and secondary care (European Spine Journal, 2020).

Reduced arterial blood flow. When plaque narrows the arteries supplying the leg, the muscles and nerves downstream run short of oxygen as soon as demand rises. That produces numbness, heaviness, cramping or weakness on walking, relieved within a few minutes of standing still. It is more often one-sided than the other causes, because plaque does not build symmetrically.

Positional and compressive causes. Crossing your legs, kneeling, a long drive, or sleeping awkwardly compresses a nerve temporarily. This numbness resolves within minutes of moving and does not recur in a pattern. It is the one cause on this list that needs no workup.

Nerve, Spine, or Artery: How to Tell the Difference

No single symptom separates these cleanly, but four features taken together usually point in one direction. This is the same reasoning a vascular technologist applies before placing the transducer.

What brings it on, and what relieves it

Arterial numbness is effort-dependent. It appears after a predictable distance — the same block, the same flight of stairs — and resolves within two to five minutes of standing still, without needing to sit or change position. Spinal numbness is posture-dependent: standing upright and walking provoke it, and leaning forward or sitting relieves it, which is why people with stenosis can often cycle much further than they can walk. Neuropathic numbness is largely independent of both, present at rest and often worst in bed.

One leg or both

Diabetic neuropathy is characteristically symmetric, because the metabolic insult reaches both legs equally. Arterial disease is frequently asymmetric, because atherosclerosis narrows one iliac or femoral segment before the other. Strictly one-sided numbness shifts the odds toward an arterial cause considerably.

What the skin and pulses show

Reduced arterial supply leaves visible evidence over time: cool skin compared with the other leg, loss of hair over the shin and toes, shiny or thin skin, slow-growing or thickened toenails, a sore or blister that takes weeks to close, and weak or absent pulses at the ankle. None of these are proof, and early disease can show none of them, but together with one-sided exertional numbness they point firmly toward the arteries. Our article on the signs of poor circulation in the legs goes through these findings in detail.

What else is going on

Risk factors shift the odds before any test is run. Smoking, diabetes, high blood pressure, high cholesterol, chronic kidney disease, age over 65, and known disease in another arterial bed all raise the probability that the arteries are involved. Diabetes is the awkward case, because it independently causes both neuropathy and arterial disease — and it can cause them at the same time, in the same leg. Our guide to diabetes and vascular imaging covers why that combination deserves particular attention.

When Leg Numbness Points to Peripheral Artery Disease

Peripheral artery disease is far more common than its reputation suggests, and far quieter. The NHANES survey found it in 4.3 percent of American adults aged 40 and over, rising to 14.5 percent of those aged 70 and over (Circulation, 2004). More recent estimates from the American Heart Association put the burden at roughly 8.5 million adults (Circulation, 2021).

The persistent misconception is that it announces itself with classic intermittent claudication — reproducible calf pain on walking, gone with rest. In practice it is only one presentation among several. A JAMA study of patients with peripheral artery disease found a wide range of leg symptoms beyond classic claudication, including exertional pain that does not fit the textbook description, pain on exertion and at rest, and no exertional pain at all (JAMA, 2001). Numbness, heaviness, weakness and simple fatigue in the leg are all recognised presentations of the same underlying problem. Someone waiting for textbook calf pain before taking the symptom seriously may wait a long time.

This matters beyond the leg itself. Narrowed leg arteries are a marker of atherosclerosis elsewhere, which is why the finding changes how the heart and the carotid arteries are viewed. Our overview of peripheral artery disease signs and risk factors covers that wider picture, and what claudication actually feels like describes the exertional pattern in more depth.

The 2024 multisociety guideline for lower extremity peripheral artery disease recommends a resting ankle-brachial index as the first test to establish the diagnosis in patients whose history or examination suggests it, as a Class 1 recommendation (ACC/AHA, 2024). The guideline also notes the important exception: when the ankle-brachial index comes back above 1.40, the vessels are too stiff to compress and the number is unreliable — toe pressures and waveforms are needed instead. That situation is common in long-standing diabetes and kidney disease, exactly the group most likely to have numbness in the first place.

What an Arterial Duplex Ultrasound Actually Measures

An arterial duplex is not a single number. It is a segment-by-segment survey of the arteries from the groin to the ankle, combining two imaging modes to answer questions that a pressure index cannot.

Where the plaque is. Grayscale imaging shows the artery wall directly — where plaque has formed, how long the diseased segment runs, and whether it is calcified or soft. This anatomical detail is what distinguishes a short, focal narrowing from diffuse disease along an entire vessel.

How much it narrows the channel. Colour Doppler fills the flow channel, making the residual opening visible. A narrowing that halves the diameter is obvious as a colour bottleneck before any measurement is taken.

How fast blood moves through it. Spectral Doppler measures velocity at and beyond each narrowing. Blood accelerates through a stenosis, and the ratio of peak velocity inside the narrowing to velocity in the normal segment just before it is what grades severity. This is the measurement that converts a picture into a number.

What the waveform looks like downstream. A healthy leg artery at rest produces a sharp triphasic waveform. As disease upstream becomes significant, that waveform flattens — first to biphasic, then to a rounded monophasic shape with a slow upstroke. A monophasic waveform at the ankle tells you there is meaningful obstruction somewhere above it, even before the exact site is found.

Whether both legs match. Because the study covers both sides, it directly answers the question that one-sided numbness raises: is this leg different from the other one, and by how much.

A systematic review and meta-analysis of fifteen studies covering 9,067 arteries found pooled sensitivity of 0.86 and specificity of 0.95 for duplex ultrasound in symptomatic peripheral artery disease, with the strongest performance in the femoropopliteal segment and the weakest below the knee (Jornal Vascular Brasileiro, 2025). The study takes about 45 minutes, uses no contrast dye and no radiation, and involves nothing more invasive than gel and a transducer.

What Raises the Likelihood of an Arterial Cause

Numbness on its own, in a 35-year-old with no risk factors and symptoms on both sides at rest, rarely points to the arteries. The picture changes with the following.

Numbness or heaviness brought on by walking. Particularly when it appears at a predictable distance and clears within minutes of standing still. This is the single most useful feature in the history.

Symptoms confined to one leg. Asymmetry is the finding that most often separates an arterial cause from a metabolic one.

Diabetes, especially of long standing. Diabetes causes neuropathy and arterial disease both, and numb feet mask the warning signs of poor perfusion — a sore that should hurt does not. It is also the group in which the ankle-brachial index is most likely to read falsely normal.

Smoking, current or past. Current smoking was the strongest of the risk factors measured in the national NHANES analysis of peripheral artery disease.

Age over 65, or over 50 with a risk factor. Prevalence rises steeply with each decade past 60.

Known atherosclerosis elsewhere. Coronary disease, a previous stroke, or carotid plaque all raise the likelihood that the leg arteries are involved too.

A foot sore or ulcer that is slow to heal. Wounds need blood flow to close. A sore below the ankle that has not healed in several weeks is one of the classic signs that the supply feeding it is reduced.

What Happens If Reduced Circulation Goes Unchecked

Peripheral artery disease matters for two separate reasons, and the second is the one patients hear least about.

The leg itself. Untreated, narrowing tends to progress. Symptoms that begin as numbness on a long walk shorten to numbness on a short one. In a minority, disease advances to pain at rest, particularly at night when the leg is elevated in bed and gravity no longer helps, and to wounds that will not heal. Rest pain of that kind is distinct from ordinary night cramps, which are common, brief, and not a circulatory sign.

The rest of the arterial tree. Plaque in the leg is rarely confined to the leg. A reduced ankle-brachial index is an independent predictor of cardiovascular events and mortality, which is why finding it changes the assessment of overall risk rather than simply explaining a symptom. The leg arteries are, in effect, an accessible window onto a systemic process.

Neither observation is an argument for alarm about a numb foot. It is an argument for knowing which of the four mechanisms is producing it, because the answer determines what your provider can usefully do next — and because two of the four are worth finding early.

Frequently Asked Questions