What is Lumbar Degenerative Disk Disease?
In simple terms, the spine is cushioned by small, spongy pads known as intervertebral discs. These discs are made of a type of material called fibrocartilage and they allow your spine to be flexible, while also carrying some of the body’s weight. There are two parts to these discs – the soft, jelly-like inner part called the nucleus pulposus, and the harder external part known as the annulus fibrosus.
Sometimes, these discs can get damaged, causing the soft inner part of the disc to push out or “herniate”. This can result in pressure on the spinal cord or nerves that stem from the spine. If this happens, it can lead to pain and weakness that spreads or ‘radiates’ from the affected area. The most common places for this to happen are in the lower back, affecting either the L4-L5 or L5-S1 disc space. This can cause discomfort in the back of the leg and top of the foot.
If the damage to the disc is severe enough to impact normal activities or affect the nervous system, surgery may be needed to relieve pressure and stabilize the damaged area of the spine. However, when there’s not a risk of lasting nerve damage, non-surgical treatments like pain relievers, changes to daily activities, and injections may be successfully used for several months instead of surgery.
For the most part, surgery to treat pain in the sciatic nerve (which runs from the lower back down the back of each leg) that hasn’t improved with other treatments is usually successful and has a favorable outcome.
What Causes Lumbar Degenerative Disk Disease?
As people age, they are more likely to experience disc degeneration, a condition where the discs in the spine wear down. Men tend to start this condition almost ten years earlier than women. However, women with this condition could be more affected by it, experiencing issues like misalignment and instability in the spine.
In the past, especially around the 1990s, it was widely believed that environmental exposures like smoking, vibrations from vehicles, and certain jobs, could cause disc degeneration. However, recent research has shifted this belief. Studies now show that genetic factors play a big role in disc degeneration.
Modern consensus focuses highly on these genetic factors as the key causes for disc degeneration. Environmental factors are still believed to play a role, but these are considered as minor contributors to the disease. Furthermore, the effect of smoking on disc degeneration has been questioned, with recent studies finding only a weak link between smoking and the disease. Similarly, while jobs involving heavy lifting or forceful bending might contribute a bit to disc degeneration, recent understanding suggests that factors such as a person’s social and economic conditions could be making these jobs seem like bigger contributors than they really are.
Risk Factors and Frequency for Lumbar Degenerative Disk Disease
Intervertebral disc degenerations, which are often painless, can be difficult to fully understand because of their symptoms, or lack of them. The way these disc issues are defined can vary, making it challenging to accurately estimate how often they occur. The results of a detailed review of 20 studies shed some light on the issue. They used magnetic resonance imaging (MRI) to examine people with no symptoms and found that:
- 20% to 83% had a decrease in signal intensity
- 10% to 81% had disc bulges
- 3% to 63% had disc protrusions, while 0% to 24% had disc extrusions
- 3% to 56% had narrowing of the disc
- 6% to 56% had annular tears (rips in the outer layer of the disc)
From this study, we can gather that incidental findings of disc disease are common. However, it is not always necessary for a specialist to evaluate these findings unless the person is experiencing pain or has physical limitations.
Signs and Symptoms of Lumbar Degenerative Disk Disease
Patient evaluation for lower back pain should study the pain’s timeline, its spread, and what might have caused it. Previous incidents of trauma should also be noted. Patients generally describe pain radiating down the buttocks and lower legs. It’s useful to know whether the pain is focused on the lower back or if it extends to the legs. This type of radiating pain can indicate canal stenosis. Radiating pain alone tends to have a more predictable surgery outcome as opposed to nonspecific lower back pain that could be related to muscle fatigue or strain. Pain that only occurs with certain movements might point to instability or a degenerative pars fracture. As part of the assessment, the patient’s blood circulation should also be evaluated because vascular claudication can mimic or mirror nerve-related issues.
Observing how the patient walks is an essential part of the assessment as it reveals the daily impact of the pain or deficit. The patient should be asked to get up from a chair, walk on heels and toes, and then sit on the examination table for further tests like testing strength, reflex, and straight leg testing. This assessment could also rule out a Trendelenburg gait, which indicates weakness in the gluteus medius, a muscle controlled by the L5 nerve root.
Every physical exam should evaluate the functioning of the arms, legs, bladder, and bowels. It’s not just strength that needs evaluating, but sensation and reflexes too. The skin on the back should also be inspected, and any tenderness to pressure or past surgical scars recorded.
The Straight Leg Raise (SLR) test involves stretching the patient’s fully extended leg from 0 to about 80 degrees while they lie down. If this causes back pain to spread to either leg, it can suggest a stenotic canal. Symptoms of a herniation pressing the L5 nerve root include weakness of ankle dorsiflexion and an extension of the great toe. This deficit may also reduce the Achilles tendon reflex. Weakness in the quadriceps and a decreased patellar tendon reflex may signal an L4 radiculopathy.
It is crucial to note that recording these initial findings is vital, as they will be used as a baseline for future evaluations.
An in-depth examination should also rule out non-organic causes of low back pain/symptoms. If the healthcare provider suspects psychological causes, the following should be considered:
- Non-specific or inconsistent symptoms, or tenderness at superficial/non-anatomic sites
- Pain with axial load/rotational movements
- Negative Straight Leg Raise test with patient distraction (one method involves having the patient sit in a chair and reproducing the Straight Leg Raise “environment”)
- Non-dermatomal patterns of symptom distribution
- Disproportionate pain during the examination
Testing for Lumbar Degenerative Disk Disease
When a patient complains of lower back pain, usually the doctor orders what we call anterior-posterior (front-to-back) and lateral (side) X-rays of the affected area. Sometimes, X-rays of the entire spine may be taken. However, a more detailed imaging test, called a magnetic resonance imaging (MRI), is not immediately done if the doctor suspects a condition called acute disc herniation, unless there are severe symptoms (red flags).
Acute disc herniation is a condition where one of the discs – these are cushions between the bones of your spine – slips out of place. But why don’t they order an MRI at the first sign of this condition? It’s because it’s common for these patients to undergo 6 weeks of physical therapy and often show significant improvement. An immediate MRI at the initial stage puts an extra financial burden on the patient and often isn’t necessary.
If after physical therapy, the symptoms are still there, then an MRI can be done. The main focus in the MRI scan is directed towards the T2-weighted sagittal (side view) and axial (top-down view) images. These pictures help indicate if the disc has pressed on to any nerve structures.
Interestingly, over time, MRI scans show that a slipped disc (whether it causes symptoms or not) will reduce in size. This is why an MRI finding of disc disease (either from wearing out or a slipped disc) doesn’t necessarily mean that the patient will have a lifetime of pain or that they’ll definitely need future surgery.
Treatment Options for Lumbar Degenerative Disk Disease
If you’re dealing with “red flags,” it might be time to think about serious diagnostic measures, and even possibly surgery. Red flags can include things like cauda equina syndrome (problems with bowel or bladder control, difficulty starting to urinate), suspected infection (especially in those who use intravenous drugs, or if you have a history of fever and nighttime chills), suspected tumor (a known history of cancer or recent, unexplained weight loss), or trauma (from a fall, assault, or physical collision).
Luckily, most people start to feel better without needing to go under the knife. Trying at least 6 weeks of physical therapy, with a focus on strengthening the core and stretching, can be a good start. Along with physical therapy, other non-surgical options to consider include cognitive therapy, lifestyle changes, avoiding activities that make the pain worse, taking non-steroidal anti-inflammatory drugs, and receiving epidural injections. Epidural injections might offer moderate, temporary relief from disc herniation pain, but their effectiveness for long-term, non-radiating back pain isn’t as clear. That being said, the existing medical literature does not tell us not to try injections as a treatment option.
Sadly, not all patients see improvement from these conservative treatment approaches. If you find that these treatments aren’t working for you, you have a few options: 1) deal with the ongoing pain, 2) completely avoid any activities that cause pain, or 3) consider surgery. Surgical options for conditions like disc herniations or spinal stenosis should be considered for those with neurologic deficits, degenerative spondylolisthesis, or pain that limits daily activities.
Surgical options could include:
- Lumbar discectomy with fusion: There’s evidence from the Swedish Lumbar Spine Study Group showing that fusion surgery can offer better outcomes for degenerative lumbar disc disease than non-surgical treatment. Fusion has long been seen as the gold standard approach to managing this condition.
- Lumbar total disc replacement: This option is mostly chosen when a person has a single-level disc disease, but disease-free facet joints. While this method generally offers better results and lower chances of disease in the surrounding segments in comparison to fusion, post-surgery, patients may complain of ongoing back pain, which could be a result of slight instability of the prosthesis. Additionally, troubles with the polyethylene inlay may occur and could be treated by either revision arthroplasty or conversion to arthrodesis, which involves the fusion of the joints.
The Spine Patient Outcomes Research Trial (SPORT), a widely cited study, reported that patients who opted for surgery generally had better outcomes at 3 months, 1 year, and 4 years, compared to those who did not have surgery. Regarding which surgical procedure, or approach is best, the literature continues to grow and expand. It appears that old-fashioned open surgery and microdiscectomy are both effective, with similar outcomes overall. While a “limited” discectomy might provide better pain relief and patient satisfaction than a subtotal discectomy, it does come with a higher risk of re-herniations. However, for repeat or revision microdiscectomies, patient outcomes and satisfaction appear to be as good as their initial discectomy. Depending on the extent of your surgery, you might need to stay in the hospital overnight, although many of these procedures can be done on an outpatient basis.
It’s important to understand that, while surgical intervention can often relieve pain shooting down the leg, the results for treating non-radiating lower back pain are less predictable.
What else can Lumbar Degenerative Disk Disease be?
When trying to identify the cause of certain back or spinal issues, doctors may consider a variety of conditions which can cause similar symptoms. These potential conditions include:
- Cauda equina syndrome
- Muscle spasm
- Spinal cord tumor
- Spinal infection
- Spondylolisthesis (a condition where a vertebra slips forward onto the bone below it)
- Spondylolysis (a defect in the spine that can lead to pain).
It’s crucial for doctors to evaluate these possibilities accurately so they can recommend the most effective treatment.
Possible Complications When Diagnosed with Lumbar Degenerative Disk Disease
Possible Side Effects:
- Bleeding
- Return of disease or symptoms
- Infection
- Worsening loss of nerve function
- Unsuccessful surgery
Recovery from Lumbar Degenerative Disk Disease
It’s crucial to start moving around and getting back into your exercise routine as part of your recovery. Managing your pain effectively is also a very important step. Lastly, maintaining a healthy weight can assist in both recovery and general health.
