Lumbar Degenerative Disc Disease

Lumbar degenerative disc disease refers to a condition in which a compromised or degenerative disc in lumbar spine causes low back pain.

Lumbar degenerative disc disease is quite common. At least 30% of people aged 30-50 years old are estimated to have some degree of disc space degeneration. All patients with the degenerated disc are not necessarily symptomatic.

Lumbar degenerative disc disease is a common cause of low back pain. In fact, most of the episodes of low back pain are as a consequence of disc injury, rather than strain on muscles and ligaments.

Pain due to lumbar degenerative disc disease affects men and women equally. The usual affected group is middle-aged persons with a peak incidence at approximately 40 years.

The cause of lumbar degenerative disc disease is not known. Acute annular tear is thought to be the inciting event. Causes appear to be multifactorial.

Surgeries like lumbar arthrodesis, lumbar discectomy, or lumbar laminectomy alter the biomechanics of lumbar spine resulting in increased susceptibility to discogenic pain.

Pathophysiology

Degenerative cascade was described by Kirkaldy-Willis. It is a widely accepted pathophysiologic model describing the degenerative process that occurs in 3 phases

The typical initiating event in the degenerative cascade is the loss of internal disc integrity. This could be due to congenital reasons or acquired insult and injury.

In congenital or genomic situations such as juvenile discogenic disease, disc nutrition may be poor because of the existing endplate abnormalities and premature disc collagen deterioration.

The collagen itself may have not formed normally at birth due to congenital enzymatic deficiencies.

In normal disc, progressively destruction may occur by acquired insult and/ or injury.

Following factors adversely affect the process

Cigarette smoking
Environmental pollutants
Lack of exercise.

The disc becomes incompetent for segmental support [dysfunction] and progress to the point of true segmental instability

The process itself can cause discogenic pain or tears can coalesce and form a causing a herniated disc by protrusion of annulus.

Facet joints gets involved with instability and first react by effusion and become pain generator as the nerves get irritated by abnormal movement and inflammation.

With continued degeneration, facets become markedly degenerated, eroded and contain fluid.

Pain originating from facets as pain generator is referred to as facet syndrome [as opposed to a discogenic pain syndrome]

Degenerative cascade is discussed in detail below.

Phase I- Dysfunction

Repetitive trauma
- Circumferential tears or fissures in the outer annulus
  - Circumferential tears may coalesce to form radial tears.
- Endplate separation or failure
  - Due to the interrupted blood supply to the disc
  - This affects nutrition and waste removal.
Nucleus pulposus
- Loss of normal water-imbibing abilities due to
  - Biochemical changes in aggregating proteoglycans
  - Proteoglycan destruction
Loss of nuclear hydrostatic pressure results in buckling of the annular lamellae.
Increased focal segmental mobility and shear stress to the annular wall.
Delamination and fissuring within the annulus

MRI at this stage may reveal

Disc desiccation
Disc bulging without herniation
High-intensity zone in the annulus
Facet joints during the dysfunctional phase may include synovitis and hypomobility.

Tears or fissures in this area may be painful as outer part of the annulus is innervated. Moreover, muscles undergo spasm, contributing further to pain.

The facet joint may serve as a pain generator.

Phase II – Instability

Progressive loss of mechanical integrity of the disc and facet joints.
Multiple annular tears (eg, radial, circumferential)
Internal disc disruption and resorption, leading to loss of disc-space height.
Facet joint cartilage degeneration, capsular laxity, and subluxation.

The biomechanical result of these alterations leads to segmental instability. This phase of the cascade in clinical situations is diagnosed as segmental instability, internal disc disruption, and herniated disc.

Phase III- Restabilization

Further disc resorption
Disc-space narrowing
Endplate destruction
Disc fibrosis
Osteophyte formation

Clinical Presentation

The patient may present with back pain that could be related to a traumatic event that caused forced flexion and/or rotation. Spontaneous onset of symptoms could be also a presenting feature.

The pain is usually low lumbar region and buttocks. It can radiate to upper spinal regions, abdomen, flanks, groin, genitals and varying distances in lower limb [ thighs, knees, calves, ankles, feet, and toes]. Usually, the involvement is unilateral.

The pain can range from aching to the stabbing.

Typically, the pain is exacerbated by activities which load the disc

Sitting
Arising from a seated position
Getting up in the morning
Awaking in the morning
Lumbar flexion with and without rotation/twisting
Lifting
Vibration (as in riding in a car)
Coughing
Sneezing
Laughing

Symptoms get better by lying on the side with hips and knees flexed or by changing positions frequently, and/or by engaging in the activity.

On physical examination, inspection may reveal kyphotic or scoliotic deformity. Paraspinal muscles are tight and may be tender.

A step deformity may be present in spondylolisthesis.

Stress maneuvers

These maneuvers reproduce symptoms

Pelvic Rocking

Flex both hips of the patient in supine position till the flexed knees approximate to the chest. Then, rotate the lower extremities from one side to the other.

Leg Extension

Raise the patient’s extended lower extremities to approximately 60° and ask the patient to hold there.

Note if pain occurs in the low lumbar buttock region.

Now lower the successively approximately 15°, and, at each point, note the reproduction and intensity of pain.

Differential Diagnoses

Soft tissue trauma to back
Sacroiliac joint syndrome
Lower lumbar zygapophyseal joint [facet joint] syndrome
Compression fracture
Stress fracture
Spondylolysis
Spondyloarthropathy
Myofascial pain syndrome
Malignancy
Discitis
Fibromyalgia
Spinal Stenosis

Lab Studies

Generally not required for diagnosis. CBC, ESR, CRP, RF may be done to rule out infective or inflammatory processes.

Imaging

X-rays

X-rays help in finding gross anatomic changes. Standing anteroposterior and lateral views are the standard x-rays. Lateral views provide the best information on intervertebral discs are visualized.

Signs of degeneration on x-ray

Loss of disc height revealed by a decrease in disc space
Endplate sclerosis
Osteophytes
Spondylolisthesis changes can be seen.
Flexion/extension view for assessing relative motion between two vertebral bodies.

Magnetic resonance imaging

MRI is the gold standard imaging modality for detecting disc condition. It can tell about disc height, hydration status of nucleus and intensity changes in annulus fibrosus, any protrusion and impingement of the nerve, presence or absence of nerve edema and status of the end plate.

High-intensity zones visible on MRI is considered to a marker for a painful disc.

CT

CT can be used to identify diffuse annular disc bulge, loss of disc height, endplate degenerative changes, including sclerosis and cortical irregularity with erosions.

But CT is not as detailed as MRI.

Discography

Discography is a provocative test where the disc is injected with contrast material and if the pain is produced similar to symptoms, the disc being investigated is a source of pain.

It is especially useful in cases with multiple levels of disc involvement on MRI.

It is the only available diagnostic intervention that identifies a symptomatic disc though some spinal physicians do not acknowledge its reliability or validity

Treatment of Lumbar Degenerative Disc Disease

The approach to treatment involves pain control and once the pain is controlled, the patient is put on exercises and rehabilitation.

Most of the pain control measures are nonoperative, surgery is required in very few patients.

Exercise is best done under professional supervision.

Medication

Medications are an integral part of the treatment of lumbar degenerative disc disease. Following medications are used

Analgesics
- NSAIDs or Nonsteroidal anti-inflammatory drugs like ibuprofen, ketorolac etc.
Acetaminophen
Duloxetine – An anti-depressant and potent inhibitor of neuronal serotonin and norepinephrine reuptake.
Skeletal muscle relaxants
- Modest short-term benefit
- Thiocolchicoside
- Cyclobenzaprine

Relative Rest

Initial rest from all activities occupational or avocational should be carried for up to two days. In some cases, a slight extension of the rest may be done but rest for longer periods has not been shown to be beneficial. Patient, in fact, should be made independent as early as possible.

Epidural Injections

Conservative measures are tried first before epidural steroid injections are considered. But undue delay should not be made because the ongoing inflammatory process to result in fibrosis and possibly permanent damage.

After first injections, two weeks should be given for assessing response to injection and for possible reinjection.

The transforaminal route is considered best for injection as placing medication as close to the site of pathology provides the best results.

Contraindications to epidural steroid injections

- Pregnancy (because of the adverse effects of fluoroscopy on the fetus),
- Hypersensitivity to injection
- Sepsis
- Bleeding diathesis.
- Diabetic with elevated serum glucose levels
- Elevated blood pressure
- Congestive heart failure with fluid retention

Epidural steroid injection has an unfavorable response in following conditions.

Long duration of symptoms
Nonradicular pain
Smoking
Pain not relieved by medication
Pain not increased by activity.

Patient Education, Exercises and Rehabilitation

The patient should be explained about the natural history of the disease, body mechanics and lumbar ergonomics during activities. The patients who are young fear that the disease might progress with age and stress them unnecessarily. They should be explained that it is not so.

Manual techniques may be applied in case of myofascial tightness.

In case, the above measures are completed, dynamic rehabilitation may be started on an outpatient basis.

Dynamic lumbar-spine stabilization [DLSS] programs

This is aimed at maintaining a neutral spine position throughout various daily activities allowing for balanced segmental force distribution between the disc and facet joints. It is also called core strengthening or muscular fusion and aims at strengthening the core muscle which provides functional stability with axial

Cardiovascular training is an important adjunct training to prevent fatigue of the muscles.

Exercises should work on strength, endurance, and flexibility.

Workplaces should have proper ergonomics at the work site, which might be as simple as changing chair and desk arrangement or be more complex.

The patient should continue through these exercises to reduce the risk of further injury

Physical modalities

Ice packs, heating pads, electrical stimulation, phonophoresis, iontophoresis, relaxation, and biofeedback.

Lifestyle Changes

Lifestyle changes aim at avoiding stress on the spine and inculcate habits of right posture and ergonomics.

The patient should avoid nicotine, excess alcohol, avoid staying in position for too long. It is better to stand up and stretch and walk around every 20 to 30 minutes instead of sitting for a prolonged period.

The patient should also maintain proper hydration.

The goal is to teach patients how to help themselves manage their back pain.

Patients should be taught about

Basic body mechanics
- Correct posture for standing, standing at a desk or drawing board, sitting, brushing teeth, washing the face
Pushing and pulling a weight
Lifting a weight
Getting in and out of bed
Sleeping
Getting in and out of a car, and sitting in a car.

[Also read: Tips for managing Back Pain]

Exercises

Different types of exercises are prescribed

Floor exercises
- Abdominal bracing
- Modified sit-ups
- Double-knee-to-chest or low back stretches
- Seat lifts
- Mountain and sag exercises
- Knee-to-elbow exercises
- Hamstring stretches
- Extension exercises
- Extension flexibility exercises.
Swimming exercises
Aerobic exercises
Relaxation exercises are good for relieving muscular tension that may aggravate back pain.

Surgery for Lumbar Degenerative Disc Disease

Surgical treatment is used in about 5% of patients and includes lumbar surgeries and cervical surgeries.

Surgeries for degenerative disc need to decompress the nerve root by either removing the offending structure [disc] or create more space so that the disc does not impinge on the nerve root.

The second part of the surgery is fusion which aims at removal of motion between two vertebrae and thus decreasing the pain generated from the joint. This involves using a bone graft to fuse one or more vertebrae and stop motion at a painful vertebral segment.

Fusion is almost always accompanied by fixation surgery. In fact, the actual procedure includes fixation first and fusion later.

The fixation is required to hold the vertebrae in immobilized position till they fuse.

Various implants used for fixation are pedicle screws, anterior and posterior body cages.

Usually, the fusion and decompression are done in the same sitting, using the same approach.

Decompression Surgeries

Lumbar Discectomy

It involves removal of the affected disc through a posterior approach. The offending structure is removed which relieves the nerve of the pressure.

Lumbar Laminotomy

It is done for central and lateral stenosis at one level and involves minimal removal of lamina for enlarging the canal.

Lumbar Laminectomy

This is done in cases of for central and lateral stenosis at several levels and involves removal of lamina at the desired levels.

Fusion Surgeries

Lumbar spinal posterolateral gutter fusion

This type of spinal fusion involves placing bone graft material in the posterolateral portion of the spine. Bone graft is harvested from the posterior iliac crest.

For better chances of fusion, immobilization is done and smoking should be stopped.

Posterior lumbar interbody fusion [PLIF]

Posterior lumbar interbody fusion achieves spinal fusion by inserting a bone graft directly into the disc space through posterior approach after removal of the disc.

Anterior lumbar interbody fusion [ALIF]

Anterior lumbar interbody fusion is similar to posterior lumbar interbody fusion except that approach is anterior.

Transforaminal lumbar interbody fusion

Transforaminal lumbar interbody fusion (TLIF) has become an increasingly popular treatment for lumbar degenerative disk disease, spondylolisthesis, degenerative adult scoliosis, spinal stenosis, and recurrent disk herniation.

The approach to the spine is posterior.

TLIF is a modification of PLIF .

Total Disk Arthroplasty

This procedure has been used for lumbar discogenic pain, with and without radicular symptoms.

Artificial disk replacement has shown results similar to fusion in the short term, but long-term results are not known.

Intradiscal electrothermal therapy

Intradiscal electrothermal therapy (IDET) or intradiscal electrothermal annuloplasty (IDEA) is a minimally invasive form of annuloplasty (repair of annulus fibrosus) that includes the use of heat to seal any ruptures in the disc wall and probably burn nerve endings making the area less sensitive to pain.