Lumbar Disc Disease 

Updated: Sep 25, 2018
Author: Kamran Sahrakar, MD, FACS; Chief Editor: Brian H Kopell, MD 

Overview

Practice Essentials

Lumbar disc disease accounts for a large amount of lost productivity in the workforce. Accurate diagnosis can be difficult and often requires interpretation. Treatment is controversial. Treatment failures are not uncommon, are often related to posttraumatic or work-related injuries, and may result in litigation. As a consequence, this disease can generate distrust of physicians on the part of patients and vice versa. Surgical treatment was not widespread until the 1950s. Today, lumbar discectomy is one of the most commonly performed elective operations in the United States.[1, 2, 3, 4, 5, 6]

Lumbar disc disease is a rather encompassing term. For example, some physicians include back pain alone as a symptom of disc disease. Others make the diagnosis without evidence of disc disease on MRI. The discussion of this article is limited to well-defined lumbar disc herniation. The pathophysiology, clinical presentation, radiographic diagnosis, treatment, and outcome are discussed.

A disc herniation (lumbar disc disease) most frequently irritates the displaced nerve root. One of the more difficult concepts for beginning medical students to grasp is the anatomic relationship of the fifth lumbar (L5) nerve root to the L4-5 disc herniation. Equally important to understand is the concept of the far lateral or foraminal disc herniation in which the root above the disc herniation is irritated.

With very large herniations, the entire cauda equina can be compressed and functionally compromised.[7] This causes saddle anesthesia and can cause urinary retention and incontinence.

A herniated disk fragment comes from the nucleus pulposus of the disc (a remnant of the embryonic notochord). In the normal condition, this nucleus is in the disk center securely contained by the annulus fibrosus. When a fragment of nucleus herniates, it irritates and/or compresses the adjacent nerve root. This can cause the pain syndrome known as sciatica and, in severe cases, dysfunction of the nerve. Although most people experience back pain during their lifetime, only a fraction experience lumbar radiculopathy or sciatica as a consequence of root compression or irritation. Almost 5% of males and 2.5% of females experience sciatica at some time in their lifetime.[8]

MRI is by far the most commonly ordered test to evaluate patients with sciatica. Often, MRI is performed prior to plain radiographs. MRI is very sensitive in delineating lumbar disc herniations. Far lateral discs are best evaluated with this test. In reoperations, MRI can delineate the full extent of scar tissue and, with moderate reliability, differentiate it from recurrent disc herniation.[2, 3, 9, 10, 11, 6]

Lumbar discectomy is the most common operation performed in the United States for lumbar-related symptoms. Almost all patients with sciatica and disc herniations deserve a trial of medical therapy. The one obvious exception is a patient presenting with cauda equina syndrome or profound motor deficits. a large multicenter trial found that surgical and nonsurgical outcomes at 2 years were similar, but that the surgical group experienced faster pain relief.[12, 13] The limitations of this study are outlined in an editorial.[14]

See the images below of herniated disc disease.

Degenerated lumbar disc disease. Degenerated lumbar disc disease.
Magnetic resonance image of a herniated nucleus pu Magnetic resonance image of a herniated nucleus pulposus of the lumbar spine.
Degenerative lumbar disc disease. The various forc Degenerative lumbar disc disease. The various forces placed upon the discs of the lumbar spine that can result in degenerative changes.

Epidemiology

The lifetime prevalence of low back pain is 80%, with disk disorders being the most common cause of adult low back pain. The most consistent risk factor for degeneration is increasing age.[15]

Correlations have been found with the following[15] :

  • Body mass index, mechanical loading, and genetic predisposition.
  • Genes coding for collagen, aggrecan, vitamin D receptors, matrix metalloproteinase, cartilage intermediate layer protein, and interleukins.
  • Smoking and increased rates of disk degeneration, with animal models showing increased proinflammatory markers, alterations to annular structure, vasoconstriction, and altered nutrient distribution to the disc.

The prevalence of a symptomatic herniated lumbar disc is about 1 to 3% in Finland and Italy, depending on age and sex. The highest prevalence is in persons 30 to 50 years of age, with a male-to-female ratio of 2:1. In persons 25 to 55 years of age, about 95% cases of herniated disc occur at the lower lumbar spine (L4–5 level); disc herniation above this level is more common in persons older than 55 years.[16]

Almost 5% of males and 2.5% of females experience sciatica at some time in their lifetime.[8]

Presentation

Most lumbar disc herniations (lumbar disc diseases) are preceded by bouts of varying degrees and duration of back pain. In many cases, an inciting event cannot be identified. Pain eventually may radiate into the leg. It may be characterized as less achy, burning, or similar to an electrical shock and is often described as a shooting or stabbing pain. The distribution of the leg pain is somewhat dependent on the level of nerve root irritation. Higher herniations (third or fourth lumbar levels) can radiate into the groin or anterior thigh. Lower radiculopathies (first sacral level) cause pain in the calf and bottom of the foot.

Fifth lumbar radiculopathy, which occurs most commonly, causes lateral and anterior thigh and leg pain. Often, accompanying numbness or tingling occurs with a distribution similar to the pain. Accompanying muscle weakness may be unrecognized if the pain is incapacitating. The pain usually improves when the patient is in the supine position with the legs slightly elevated. Patients are more comfortable when changing positions. Short walks can bring relief. Long walks or extended sitting (especially driving) can aggravate the pain.

On examination, patients may be neurologically normal, may have a profound radiculopathy, or may even demonstrate a cauda equina syndrome. A positive straight-leg raising sign is almost always present. However, a crossed straight-leg raising sign may be even more predictive of a lumbar disc herniation (lumbar disc disease). The back may appear scoliotic. Gait is often abnormal. Muscle weakness may be revealed particularly when testing walking on heels and toes.

Indications

The indications for surgical treatment of symptomatic lumbar disc disease are not clearly delineated. Nevertheless, situations exist in which most spine surgeons would probably agree on operative intervention. These situations include the following:

  • A patient with cauda equina syndrome

  • A patient demonstrating progressive neurologic deficit during a period of observation

  • A patient with persistent bothersome sciatic pain, despite conservative management, for a period of 6-12 weeks (a time period that varies from surgeon to surgeon)

Notably missing from this list is a patient presenting with a profound motor deficit of varying duration. In the absence of pain, whether such patients benefit from surgery is unclear. No consensus has been reached concerning how urgent surgery is for a patient who presents with a clinical picture of painful disc herniation. Unfortunately, the decision to operate emergently is often based on fear of legal repercussions rather than on scientific evidence of actual patient benefit.

Contraindications

Any claim of absolute contraindications for lumbar disc disease would invariably be challenged. Most spine surgeons adhere to some guidelines, including the following:

  • A patient with unrelenting back pain: Patients who have back pain after a bout of sciatica has resolved are not good candidates for operative treatment. Often, these patients are the most insistent and difficult to manage. Occasionally, these are patients whose back pain improved after discectomy for a large central disc herniation.

  • A patient with an incomplete workup: When diagnosis is uncertain, postpone surgery. Disc herniations are so ubiquitous that being cavalier in diagnosis is easy. Ensure the completeness of the workup prior to proceeding with the operation. All surgeons can recall several cases in which a diabetic plexopathy or an epidural metastasis was missed.

  • A patient not provided adequate conservative treatment: Spine surgeons rarely commit a patient with a short period of sciatica and without bedrest and a steroid trial to an operation that will permanently alter the patient's back mechanics and strength.

 

Workup

Imaging Studies

MRI is by far the most commonly ordered test to evaluate patients with sciatica. Often, MRI is performed prior to plain radiographs. MRI is very sensitive in delineating lumbar disc herniations. Far lateral discs are best evaluated with this test. In reoperations, MRI can delineate the full extent of scar tissue and, with moderate reliability, differentiate it from recurrent disc herniation.[9, 10, 11]

In an MRI study of 109 patients aged 17-80 years with lumbar disc degeneration, L4-L5 was the most common area involved. Decreased disc height was common at L5-S1. Most patients showed loss of lumbar lordosis. Annular disc tear, disc herniation, disc extrusion, narrowing of the spinal canal, narrowing of lateral recess, compression of neural foramen, ligamentum flavum thickening, and facet arthropathy were common at the L4 -L5 disc level. Disc bulge was common at L3-L4 and L4-L5. Posterior osteophytes were common at L3-L4 and L5-S1. L1-L2 disc involvement and spondylolisthesis were less common.[17]

In a meta-analysis of 20 studies evaluating MRI in asymptomatic individuals, the reported prevalence of disc abnormalities at any level were 20-83% for reduction in signal intensity, 10-81% for disc bulges, 3-63% for disc protrusion (versus 0 -24% for disc extrusion), 3-56% for disc narrowing, and 6-56% with annular tears.[2, 3]

CT scan myelography may be preferred by surgeons for evaluating patients before reoperation or for evaluating patients who have severely spondylotic changes. This is because CT scan myelography can delineate bony structures better than MRI.

Plain radiographs, especially with weight-bearing flexion and extension views, can be a useful adjunct to other radiographic evaluations. Some spine tumors, instabilities, malalignments, and congenital anomalies can be identified best with plain radiographs. Obtain plain films on all patients prior to surgery.

 

Treatment

Medical Therapy

Almost all patients with sciatica and disc herniations deserve a trial of medical therapy. The one obvious exception is a patient presenting with cauda equina syndrome or profound motor deficits.

Most practitioners are well versed in the initial management of cases of sciatica. Counseling and education about the disease help the patient commit to a successful trial of nonoperative management. Encourage bedrest and prescribe anti-inflammatory agents (steroidal and/or nonsteroidal) with analgesics that are sufficiently strong enough to relieve pain. Muscle relaxants aid in relieving associated muscle spasm. After 7-14 days, slow mobilization is started.[18]

Once the patient has recovered from the worst radicular pain, physical therapy can be instituted. Return to work (either limited or full) is important at this point. Stop steroidal medications. Reevaluate patients about a month after the onset of sciatica. At this time, studies can be ordered or a more intense back rehabilitation program can be designed, so appropriate referrals can be made.

The success of conservative management of lumbar disc herniations may depend on the type of herniation. A review of over 600 patients concluded that noncontained herniations may respond more successfully to nonsurgical treatment.[19]

Epidural steroid injections can be used at almost any time; however, the utility of this has been questioned.[20]

Surgical Therapy

What constitutes surgical therapy is open to discussion. The standard lumbar microdiscectomy has numerous variations, one of which is outlined below. Percutaneous discectomies are still performed frequently. Endoscopic techniques have gained in popularity. This method appears more applicable in small and contained disc herniations.[21] Chemonucleolysis, although in principle an excellent alternative, is no longer performed. Other procedures, such as thermal ablation, are also performed.[22, 23, 24, 25]

A complete workup is essential. Based on the patient's age group and comorbidities, perform the appropriate laboratory examinations, radiographic examinations, and further tests, as needed, to ensure a safe anesthetic period.

Intraoperative Details

In a standard lumbar microdiscectomy, the patient is anesthetized and placed in the prone position. Variations in technique exist depending on the institution, region, and surgeon.The hips are flexed to open the interlaminar spaces. A protuberant belly should hang as freely as possible to reduce venous hypertension. The ulnar nerves at the elbow are padded to prevent neuropathy. The legs cannot be overflexed. The back is parallel to the ground. A preoperative radiograph with a spinal needle is obtained to confirm localization. The back is shaved and prepared.

After injection of a long-acting local anesthetic agent, a 3-cm incision is made over the disc space (as determined by radiograph). Unipolar cautery is used to dissect down through midline subcutaneous fat. The lumbodorsal fascia is opened paramedially. Muscles are stripped from the lamina. Obtain a repeat radiograph to confirm the appropriate location.

A small laminotomy is created with a drill or rongeurs. The ligament is excised with rongeurs or a knife. An operating microscope is now used. The medial facet is partially resected in most patients. Some evidence indicates that joint angles smaller than 35° result in resection of larger portions of the medial facet and result in more immediate postoperative pain.[26] The root is then identified and retracted. The disc fragment is evident below the retracted root.

The annulus is incised and the disc removed with pituitary rongeurs. Loose fragments of the disc in the interspace are removed. The course of the nerve root is palpated with an angled instrument along its entirety to ensure adequate decompression. Significant controversy exists regarding the optimal extent of discectomy.[27] Bleeding is stopped, the wound is irrigated, and then it is closed in interrupted absorbable sutures layer by layer. A light dressing is applied.

Postoperative Details

The patient is treated with oral narcotics and IV supplementation for pain. Antiemetics are administered as needed. The patient is mobilized 4-6 hours after surgery and should be able to void without help. Once the patient tolerates fluids, he or she may leave the hospital with an ample supply of narcotics, antispasmodic agents, and stool softeners. Rarely, the patient may remain in the hospital 24 hours after the operation.

The patient is seen in follow-up one month after surgery. For uncomplicated cases, the patient is then released from the surgeon's care. The patient is usually released to work 6-10 weeks postoperatively, depending on the occupation.

Complications

The overall complication rate is 2-4% for the surgery.

Despite endless reports of misadventures, surgeons still sometimes operate on the wrong level. Therefore, reliance on intraoperative radiographic confirmation of the intended level is strongly encouraged.

Bleeding intraoperatively can be copious and is almost invariably due to malpositioning. Engorged venous epidural channels can make the operation more difficult and far more dangerous. Very rarely, the anterior annulus is violated and a retroperitoneal vessel is injured. Awareness of this complication is essential. Should this occur, the back is closed while a vascular surgeon prepares to repair the vessel via laparotomy.

Infections, usually skin infections, can occur. The authors' protocol is to administer one dose of a preoperative antibiotic within one hour of surgery. Very rarely, postoperative discitis can cripple a patient who is recovering. Suspect discitis in the setting of an increasing sedimentation rate, fevers, severe localized pain, and recurrent symptoms.

Increased neurologic deficit is usually mild and is due to excessive retraction of the root. If a nerve root is mistaken for a disc herniation and is removed, the resultant injury can be severe. If possible, identify the root and disc in the same field. On occasion, a conjoined root can add significant technical complexity to the case.

Outcome and Prognosis

Almost every study measures the outcome from lumbar disc surgery differently. A good outcome may be defined as the decreased use of narcotics, prompt return to work, or reported reduction in pain. Understandably, outcome studies can be misinterpreted or misrepresented.

Patients who experienced symptoms 6 months or more prior to treatment (both operative and nonoperative) had worse outcomes following their treatment. Surgery’s relative benefit over nonoperative treatment was not dependent on the symptom duration.[28]

Approximately 75% of patients who undergo a microdiscectomy have long-term reduction of sciatic pain and, thus, are considered cured. Reported results vary from 65-95%. Predominance of leg pain is the best determinant of good outcome from surgery for lumbar disc herniation.

Unfortunately, a rather large fraction of individuals who have had surgery for lumbar disc disease have recurrent or residual pain, which can be a significant challenge to treat. A methodical postoperative evaluation is necessary, focusing on symptom clarification, careful examination, and repeat radiographic examinations and MRI with contrast.

Interestingly, a large multicenter trial found that surgical and nonsurgical outcomes at 2 years were similar, but that the surgical group experienced faster pain relief.[12, 13] The limitations of this study are outlined in an editorial.[14]

Also, some patients who are surgically treated are more prone to further problems such as recurrent herniations, arachnoiditis, and vertebral instability.

A long-term follow-up study shows that frequent strenuous physical activity at work plays a prominent role in later hospitalization for herniated lumbar disc disease. Additionally, it has been found that while body height is also a significant predictor for herniated lumbar disc disease, body weight is only insignificantly associated with it.[29]

A study of long-term results for lumbar disc herniation operations in 39,048 patients compared microdiscectomy, endoscopic microdiscectomy, and the 'classic operation,' laminectomy/laminotomy with discectomy. Laminectomy/laminotomy with discectomy was performed on 34,547 patients (88.5%), with a mean follow-up of 6.3 years, and 27,050 (78.3%) patients had good/excellent results. Microdiscectomy was performed on 3,400 patients (8.7%); the mean follow-up was 4.1 years, with 2,866 patients (84.3%) reporting good/excellent results. Endoscopic microdiscectomy was performed on 1,101 patients (2.8%), with mean follow-up of 2.9 years and 845 (76.8%) reporting good/excellent results.[30]

Future and Controversies

Most areas of controversy are delineated within the above text. The major controversies are outlined in this section.

The duration of conservative management has been debated since the disease was identified. As surgical treatments become less invasive and medications change, the role and duration of conservative management will change as well.

Endoscopic operations are becoming safer and more prevalent. Although many microdiscectomies are now being performed in the outpatient setting, the impetus for even less invasive procedures continues. In fact, the endoscopic approach is even used in the traditionally more technically demanding recurrent cases.[31] The theoretical advantage of reduced muscle injury in the endoscopic approach is somewhat in question as CPK and multifidus muscle atrophy are not significantly different when compared to conventional microdiscectomy.[32]

The role of stabilization in lumbar disc surgery is very unclear. An increasing number of patients are having extensive fusions as the first-line management of lumbar radiculopathy secondary to disc herniations. However, the indications for stabilization need to be better established.

 

Guidelines

Guidelines Summary

The following guidelines were published by the North American Spine Society[33] :

Manual muscle testing, sensory testing, supine straight leg raise, Lasegue's sign, and crossed Lasegue's sign are recommended for use in diagnosing lumbar disc herniation with radiculopathy. The supine straight leg raise, as compared with the seated straight leg raise, is suggested for use in diagnosing lumbar disc herniation with radiculopathy.

In patients with a history and physical examination findings consistent with lumbar disc herniation with radiculopathy, MRI is considered as the most appropriate, noninvasive test to confirm the presence of lumbar disc herniation. If MRI is econtraindicated or inconclusive, CT or CT myelography is the next most appropriate test..

Contrast-enhanced fluoroscopy is recommended to guide epidural steroid injections to improve accuracy of medication delivery.

Transforaminal epidural steroid injection is recommended to provide short-term (2–4 wk) help provide pain relief in patients with lumbar disc herniations with radiculopathy.

Endoscopic percutaneous discectomy is suggested for carefully selected patients to reduce early postoperative disability and reduce opioid use, as compared with open discectomy in the treatment of patients with lumbar disc herniation with radiculopathy.

If surgery is indicated, sequestrectomy or aggressive discectomy is recommended for decompression in patients with lumbar disc herniation with radiculopathy because there is no difference in rates of reherniation.

 

Questions & Answers