Causes And Risk Factors For Claudication

Definition and incidence of claudication

Claudication, also known as intermittent claudication, is a type of pain or cramping that occurs in your legs or less likely your arms. It happens as a result of insufficient blood supply to your leg muscles and is evident, especially after walking for a certain distance or after vigorous exercise. It indicates that you have a type of peripheral artery disease (PAD). Though some people report claudication discomfort as dull or painful, cramping is the most common description, while others report feeling weak, numb, or tingly.

Over 200 million individuals around the world are estimated to have PAD.¹ In the UK, 20% of people between the ages of 55 and 75 have PAD. It is uncommon in young people however its incidence increases by age. Moreover, asymptomatic PAD is more common than symptomatic intermittent claudication.² If PAD is not properly identified and treated, it can have an impact on life expectancy and quality of life. For at-risk patients to receive the best care possible to prevent complications and limit the development of their condition, a precise diagnosis is essential.³ 

Types of claudication

• Vascular claudication: this is the most common type of claudication. It often indicates a major blood flow issue, particularly peripheral artery disease. When arterial constriction occurs in vascular claudication, blood flow is reduced to a degree that is not adequate to meet the metabolic needs of the lower limb muscles.⁴
• Neurogenic claudication: Your spine and neural system are the root cause of it, lumbar spinal stenosis (LSS) results in intermittent neurogenic claudication. It occurs due to compression on the spinal cord where the nerves root from your legs, which supply your legs muscles.⁴

Causes of claudication

Vascular claudication

Your body's cells all need oxygen to function. Your muscles require extra oxygen for the cells to function when you exercise, even if it's only for a brief walk. Because their muscles require more oxygen than normal circulation can supply, people with circulation issues may feel discomfort when they exercise more. When they relax, the discomfort subsides because their circulation can once again meet the reduced oxygen need. Although it can also occur in your arms, this kind of discomfort is typically felt in your legs.

Claudication is a classic sign of atherosclerosis, or hardening of the arteries, and PAD. PAD is a narrowing of the blood vessels in your legs. Atherosclerosis and PAD both raise your risk of a heart attack or stroke.⁵

Neurogenic claudication

Spinal stenosis, a rare condition, is usually the cause of neurogenic claudication which is often referred to as pseudoclaudication. This happens when the area surrounding your lower spine constricts, potentially directly pressing on your spinal cord. Additionally, it may compress the blood arteries surrounding the spine, preventing blood that carries oxygen from reaching the tissues of the lower limbs. Either of these two scenarios may result in lower back discomfort radiating down your legs, as well as tingling, weakness, or numbness in your feet and legs. You may also lose control of your bladder or bowel movements.⁶

Risk factors for claudication

Risk factors for vascular claudication

They are the same risk factors for atherosclerosis (pipe arteries), and these are:

• Smoking: by far the most powerful risk factor for the development of intermittent claudication and peripheral atherosclerosis is cigarette smoking, which increases the risk at least twofold. The severity of the condition increases with the number of pack years smoked. Generally speaking, smoking leads to heart attack, stroke or failure of the heart.⁷
• Diabetes Mellitus: the main problem with uncontrolled sugar level is that it affects all the systems of your body, including your heart, vessels, and nerves. Diabetes mellitus ( Type-2 Diabetes), which is the most common type, can cause both vascular and neurogenic claudication as a complication of long-term uncontrolled blood glucose levels. Vascular claudication is due to atherosclerotic changes in the vessels supplying your leg, while neurogenic claudication is due to neuropathy of the nerves supplying the muscles of your legs. According to one study on Type-2 diabetics, having a haemoglobin A1C above 7% for a minimum of three years raises your chance of developing diabetic neuropathy.⁸
• Uncontrolled high lipids in the blood: high cholesterol and low density lipoproteins (LDL) raise the risk for peripheral artery disease as well as elevated blood pressure and stroke. The plaque that is deposited into your vessels leads to atherosclerosis. It becomes larger the longer you don't get therapy. You experience narrowing or blockage of your blood arteries as the plaque grows. You may have prolonged blood vessel function, similar to a partially clogged drain. However, they won't function as well as they ought to. You might start to feel claudication pain when a peripheral artery is at least 60% blocked.⁹
• Uncontrolled high blood pressure: untreated high blood pressure causes PAD as a complication. When the pressure inside your vessels increases for a long time, this changes the nature of these vessels where they become more rigid and not pliable with pressure, resulting in defects in the blood supply for your tissues and organs. Moreover, this eventually leads to atherosclerotic changes in the vessels, stroke and heart problems.
• Overweight/obesity: being overweight or obese means that a person is liable for all of the above risks, not only PAD.
• Sedentary lifestyle: exercise has lots of benefits and among these is improving and strengthening your circulatory system which includes your heart and blood vessels. Research indicates that engaging in regular exercise will reduce the frequency and intensity of PAD symptoms, as well as reduce your likelihood of getting another CVD. Therefore, supervised exercise is suggested by NICE as a starting point for controlling PAD.¹⁰
• Old age (over 55 years in men and 60 years in women): ageing increases the risk for PAD. When comparing low-income to high-income countries worldwide, the age range for PAD is younger (ages 45 to 49).¹¹ 
• Family history and genetics: Your risk of PAD is increased if there is a family history of heart disease, stroke, or blood vessel disease, including certain forms of vasculitis. Variations in some genes that appear to raise the incidence of PAD or may exacerbate the condition are being studied by researchers. According to some research, certain gene variants have been linked to several atherosclerotic illnesses, including coronary heart disease, PAD, and carotid artery disease. One of these gene mutations that increase the risk of blood clots is the gene variant associated with factor V Leiden condition, a specific gene mutation that leads to an increased risk of blood clots.¹¹

Risk factors for neurogenic claudication

Since spinal stenosis is the main cause of neurogenic claudication, the risk factors for it are the same. A family history of spinal stenosis or obesity are risk factor for this illness. Additional conditions that might cause the central spinal canal to become obstructed and get smaller include disc protrusion or bulging (due to increasing disc degeneration with ageing or trauma), as well as loss of disc height. Spondylolisthesis, a condition that means abnormal forward or backward movement of one of the vertebral bodies relative to the others can cause spinal stenosis.¹²

Other acquired causes of spinal stenosis include:

• Tumors of the spinal cord
• Fat sacs or lipoma
• Trauma
• Post-surgical conditions such as fibrous tissue formation
• Diseases of the bones such as ankylosing spondylitis, rheumatoid arthritis, or Paget disease.

Summary

Claudication, also known as intermittent claudication, manifests as leg (or occasionally arm) pain or cramping due to inadequate blood supply to the muscles, typically worsening after walking or vigorous activity. It's a sign of peripheral artery disease (PAD), with over 200 million worldwide estimated to have PAD, and in the UK, 20% of those aged 55 to 75 are affected. There are two main types: vascular, caused by arterial constriction leading to reduced blood flow, and neurogenic, resulting from spinal and neural issues like lumbar spinal stenosis (LSS). Risk factors for vascular claudication include smoking, diabetes, high cholesterol, hypertension, obesity, sedentary lifestyle, ageing, and genetics. Neurogenic claudication is mainly linked to spinal stenosis, with risk factors including family history, obesity, and certain spinal conditions or traumas. Treatment and prevention involve addressing underlying conditions, lifestyle changes, and sometimes surgical intervention.