Spinal (Lumbar) Fusion/Lumbar Spinal Stenosis – Pinched Nerves in the Back

The spine is divided into various regions, each characterized by its curvature and function. The lumbar spine, situated in the lower back, forms a curve beneath the waist and connects the upper body—comprising the head, trunk, and arms—to the lower body, including the pelvis and legs. The stability and movement of the spine are supported by ligaments and muscles.

The lumbar spine consists of five vertebrae, which form an arch at the back known as the lamina, creating a protective covering over the spinal canal. As the spinal cord narrows near the first lumbar vertebra, it branches out into a bundle of nerves known as the cauda equina, responsible for signaling between the brain and leg muscles, as well as regulating bowel and bladder functions.

Intervertebral discs are positioned between the lumbar vertebrae, consisting of durable connective tissue with a tough outer layer (annulus fibrosus) and a gel-like center (nucleus pulposus). These discs, along with small spinal facet joints, enable movement and provide stability, serving as shock-absorbers for the vertebrae.

Spinal stenosis occurs when one or more areas of the spine narrow, affecting the spinal canal and/or the nerve tunnels known as foramina. This condition is more common in individuals over 50 but can also occur in younger individuals born with a narrower spinal canal.

The primary cause of spinal stenosis is the gradual degeneration associated with aging. As intervertebral discs lose fluid and height over time, they may bulge into the spinal canal. Additionally, thickening of spinal facet joints and ligaments can further encroach upon the spinal canal. Arthritis is often the underlying cause of these degenerative changes.

Arthritis can lead to pain, swelling, and structural alterations in the lumbar spine due to various factors such as aging, injury, autoimmune diseases, or inflammatory conditions. There are over 100 types of arthritis, with osteoarthritis and rheumatoid arthritis being the most common in the spine.

Osteoarthritis, a chronic degenerative condition, typically develops with age, causing cartilage to deteriorate, leading to the overgrowth of bone (osteophytes). These bone spurs can intrude into the spinal canal, compressing the spinal cord and nerves. Spondylosis can occur when osteoarthritis affects the intervertebral discs and facet joints, leading to disc degeneration and narrowing of the spinal canal.

Acquired spinal stenosis can also result from spinal tumors, which may grow into the spinal canal or cause swelling, leading to shifts in the vertebrae. Another cause includes ossification of spinal ligaments, where calcium deposits transform a ligament into bone, potentially causing compression of the nerves.

Many individuals with spinal stenosis may not exhibit symptoms. However, if symptoms do arise, they may include pain or numbness in the legs, cramping, and weakness, which can fluctuate in intensity.

Symptoms may worsen with prolonged standing or walking but can be alleviated by bending forward or sitting, which increases the space in the spinal canal and reduces pressure on the spinal cord.

Severe compression of the spinal nerves can lead to cauda equina syndrome, a medical emergency characterized by loss of bowel and bladder control, low back pain, leg pain, sensory deficits in the lower body, and diminished leg reflexes.

Diagnosis of spinal stenosis involves a physical examination and imaging studies. Your doctor will assess your symptoms and medical history and may ask you to perform specific movements to evaluate muscle strength, joint motion, and spinal stability.

X-rays can reveal the condition of the vertebrae, identify narrowed discs, and highlight thickened facet joints. In some cases, a myelogram may be performed, where dye is injected into the spinal column to enhance X-ray images, helping to identify any pressure on the spinal cord or nerves.

A bone scan may also be utilized to detect fractures, tumors, infections, or arthritis. This procedure involves a harmless radioactive substance injected several hours before the test, highlighting areas of the bone that are undergoing changes.

CT scans or MRIs may be ordered for a more detailed view of the spinal structures, with MRIs providing the most sensitive images of the spinal cord, nerve roots, ligaments, and potential tumors. All imaging procedures are non-invasive and painless.

Non-surgical methods are effective for most cases of spinal stenosis. Over-the-counter or prescription medications can help manage pain. If symptoms persist, your doctor may recommend physical therapy or epidural steroid injections.

Epidural steroid injections, administered either by your doctor or a pain management specialist, deliver corticosteroids to the area surrounding the spinal cord and nerves, reducing inflammation and irritation. These injections are typically given in a series of three.

Physical therapy focuses on strengthening the back, abdominal, and leg muscles. Individuals with weakened core muscles or spinal degeneration may benefit from using a lumbar brace during activities for added support. Stretching and cardiovascular exercises can enhance flexibility and improve blood flow to the nerves, alleviating symptoms.

While non-surgical treatments aim to alleviate pain and restore function, they do not correct spinal canal narrowing. Surgery may be recommended when conservative treatments fail or if symptoms worsen, particularly if accompanied by bowel or bladder issues.

The most common surgical option is lumbar laminectomy, or lumbar decompression surgery, which aims to relieve pressure on the spinal cord and nerves by enlarging the narrowed spinal canal. The procedure involves making an incision along the lumbar spine, detaching muscles and tissues, and removing part or all of the lamina, along with any bone spurs or diseased tissue.

If instability occurs in the facet joints post-laminectomy, a lumbar spinal fusion may also be performed. This procedure fuses two or more vertebrae to prevent movement and reduce pain. Bone grafts are used to facilitate healing, with surgical hardware such as screws and rods securing the vertebrae.

After surgery, a drainage tube may be placed to remove fluid from the area and is typically removed within a couple of days. A rigid brace is often required during the healing process.

Post-operative recovery varies by individual and depends on the type of surgery performed. Most patients undergoing lumbar laminectomy stay in the hospital overnight, while those undergoing spinal fusion may require a longer hospital stay. Assistance may be necessary for the first few days or weeks at home, so discussing arrangements with your doctor is advisable.

The recovery period generally involves four weeks for resuming light activities after a lumbar laminectomy, with full recovery potentially taking several months. Recovery from lumbar spinal fusion is usually longer.

Physical therapy typically starts around six weeks after surgery, focusing initially on pain reduction followed by exercises to strengthen the lower back and improve endurance. Rehabilitation for spinal fusion patients may take more time due to the complexity of the procedure.