What is spinal stenosis?
Spinal stenosis is the narrowing of one or more spaces within your spine. Less space within your spine reduces the amount of space available for your spinal cord and nerves that branch off your spinal cord. A tightened space can cause the spinal cord or nerves to become irritated, compressed or pinched, which can lead to back pain and sciatica.
Spinal stenosis usually develops slowly over time. It is most commonly caused by osteoarthritis or “wear-and-tear” changes that naturally occur in your spine as you age. For this reason, you may not have any symptoms for a long time even though some changes might be seen on X-rays or other imaging tests if taken for another reason. Depending on where and how severe your spinal stenosis is, you might feel pain, numbing, tingling and/or weakness in your neck, back, arms, legs, hands or feet.
Normal spine with no narrowing of the space around the spinal cord or nerve roots exiting the spinal column.
Where does spinal stenosis occur?
Spinal stenosis can occur anywhere along the spine but most commonly occurs in two areas:
- Lower back (lumbar canal stenosis).
- Neck (cervical spinal stenosis).
What is lumbar canal stenosis?
Lumbar canal stenosis is the narrowing of the spinal canal or the tunnels through which nerves and other structures communicate with that canal. Narrowing of the spinal canal usually occurs due to changes associated with aging that decrease the size of the canal, including the movement of one of the vertebrae out of alignment.
The narrowing of the spinal canal or the side canals that protect the nerves often results in a pinching of the nerve root of the spinal cord. The nerves become increasingly irritated as the diameter of the canal becomes narrower.
Symptoms of lumbar canal stenosis include pain, numbness or weakness in the legs, groin, hips, buttocks, and lower back. Symptoms usually worsen when walking or standing and might decrease when lying down, sitting, or leaning slightly forward.
Who gets spinal stenosis?
Spinal stenosis can develop in anyone but is most common in men and women over the age of 50. Younger people who are born with a narrow spinal canal can also have spinal stenosis. Other conditions that affect the spine, such as scoliosis, or injury to the spine can put you at risk for developing spinal stenosis.
What are the parts of the spine?
Your spine (or backbone) is a stack or column of 24 bones (vertebrae) plus the fused bones of the sacrum and coccyx. It begins at the base of your skull and ends at your pelvis. Your spine supports your body’s weight and protects your spinal cord. Each vertebrae has a round front portion (the body), a central ring-shaped opening (the spinal canal), flat bony areas (facet joints) where one vertebrae comes into contact with others above and below it, and bone sections along the sides (transverse processes) and back (laminae). Part of the lamina called the spinous process is the ridge you feel when you run your hand down your back. Between each vertebrae body is a flat, round pad called an intervertebral disk that serves as a cushion or shock absorber. Ligaments are strong fiber bands that hold the vertebrae together, keep the spine stable and protect the disks.
The spinal cord – the body’s “master cable cord” that sends and receives messages between the body (including muscles and organs) and the brain – runs through the center of the spinal canal. It is completely surrounded by the bony parts of the spine. Nerves roots are the initial segment of a bundle of nerve fibers that come off the spinal cord and exit the spinal column through side spaces between the vertebrae called the neural foramen. The nerve fibers or “nerves” (the “mini cable network”) then go out to all parts of the body.
What causes spinal stenosis?
Spinal stenosis has many causes. What they share in common is that they change the structure of the spine, causing a narrowing of the space around your spinal cord and nerves roots that exit through the spine. The spinal cord and/or nerve roots become compressed or pinched, which causes symptoms, such as low back pain and sciatica.
The causes of spinal stenosis include:
- Bone overgrowth/arthritic spurs: Osteoarthritis is the “wear and tear” condition that breaks down cartilage in your joints, including your spine. Cartilage is the protective covering of joints. As cartilage wears away, the bones begin to rub against each other. Your body responds by growing new bone. Bone spurs, or an overgrowth of bone, commonly occurs. Bone spurs on the vertebrae extend into the spinal canal, narrowing the space and pinching nerves in the spine. Paget’s disease of the bone also can also cause on overgrowth of bone in the spine, compressing the nerves.
- Bulging disks/herniated disk: Between each vertebrae is a flat, round cushioning pad (vertebral disk) that acts as shock absorbers along the spine. Age-related drying out and flattening of vertebral disks and cracking in the outer edge of the disks cause the gel-like center of these disks to break through a weak or torn outer layer. The bulging disk then press on the nerves near the disk.
Herniated disks and bone spurs are two common causes of spinal stenosis.
- Thickened ligaments: Ligaments are the fiber bands that hold the spine together. Arthritis can cause ligaments to thicken over time and bulge into the spinal canal space.
- Spinal fractures and injuries: Broken or dislocated bones and inflammation from damage occurring near the spine can narrow the canal space and/or put pressure on spinal nerves.
- Spinal cord cysts or tumors: Growths within the spinal cord or between the spinal cord and vertebrae can narrow the space and put pressure on the spinal cord and its nerves.
- Congenital spinal stenosis: This is a condition in which a person is born with a small spinal canal. Another congenital spinal deformity that can put a person at risk for spinal stenosis is scoliosis (an abnormally shaped spine).
What are the symptoms of spinal stenosis?
You may or may not have symptoms when spinal stenosis first develops. The narrowing of the spinal canal is usually a slow process and worsens over time. Although spinal stenosis can happen anywhere along the spinal column, the lower back (number one most common area) and neck are common areas. Symptoms vary from person to person and may come and go.
Symptoms of lower back (lumbar) spinal stenosis include:
- Pain in the lower back. Pain is sometimes described as dull ache or tenderness to electric-like or burning sensation. Pain can come and go.
- Sciatica. This is pain that begins in the buttocks and extends down the leg and may continue into your foot.
- A heavy feeling in the legs, which may lead to cramping in one or both legs.
- Numbness or tingling (“pins and needles”) in the buttocks, leg or foot.
- Weakness in the leg or foot (as the stenosis worsens).
- Pain that worsens when standing for long periods of time, walking or walking downhill.
- Pain that lessens when leaning, bending slightly forward, walking uphill or sitting.
- Loss of bladder or bowel control (in severe cases).
Symptoms of neck (cervical) spinal stenosis include:
- Neck pain.
- Numbness or tingling in the arm, hand, leg or foot. (Symptoms can be felt anywhere below the point of the nerve compression.)
- Weakness or clumsiness in the arm, hand, leg or foot.
- Problems with balance.
- Loss of function in hands, like having problems writing or buttoning shirts.
- Loss of bladder or bowel control (in severe cases).
Symptoms of abdomen (thoracic) spinal stenosis include:
- Pain, numbness, tingling and or weakness at or below the level of the abdomen.
- Problems with balance.
Can spinal stenosis cause permanent paralysis?
While the narrowing of the spine can cause pain, it usually doesn’t cause paralysis. However, if a spinal nerve or the spinal cord is compressed for a long period of time, permanent numbness and/or paralysis is possible. This is why it is especially important to see your healthcare provider right away if you experience numbness or weakness in your arms or legs.