Lumbar Disk Herniation with Mild Neurologic Deficit: Microdiskectomy Versus Conservative Treatment

Sciatica is one of the most common reasons patients seek medical attention in the United States and around the world. Sciatica, a radiculopathy arising when one or more lumbosacral nerve roots become compressed, can lead to radiating leg pain, as well as sensory and motor deficits in some cases. Sciatica is most commonly caused by disk herniation. L4-5 is the most frequently involved level, followed closely by L5-S1, then L3-4. Disk protrusion at other levels or at more than one level at any given time is rare. Other potential causes of sciatica include spondylosis, infection, neoplasm, and vascular disease. Although their clinical presentations may be similar, the management and prognosis of each of these conditions differs from that of a herniated disk and is not within the scope of this chapter.

To properly evaluate a patient presenting with a lumbosacral radiculopathy, it is important to understand the anatomy of the lumbar spine, with particular attention to the relationships of the lumbar intervertebral spaces and foramina, nerve roots, and pedicles. Each lumbosacral nerve root exits the spinal canal via the neural foramen at the disk space below its respective vertebral body and is typically compressed by a herniation of the disk immediately above this vertebral body. For example, the L5 nerve root exits through the neural foramen at the level of the L5-S1 disk space; L5 nerve root compression is generally caused by an L4-5 posterolateral disk herniation, although a large medial disk herniation at the level of L3-4 ( Figure 5-1 ) or a far-lateral L5-S1 herniated nucleus pulposus can also be responsible.

Although sciatica was initially described around 2000 bc , the relationship between lumbar disk disease and sciatica was not fully understood until the early part of the twentieth century. Once an effective surgical treatment of sciatica was described in 1934, surgery began to be offered routinely to a small subset of patients whose symptoms persisted after a period of nonsurgical management, since this treatment alone would lead to the resolution of symptoms in most patients. The ideal length of time that nonoperative treatment should be tried before surgery is considered is still under debate. Finding the optimal balance between conservative care and surgical treatment is critical, because sciatica can be completely debilitating to individuals and can negatively affect the economy through a combination of hospital costs, work absenteeism, and disability.

Case Presentation

A 29-year-old man had a 12-week history of progressively worsening lower back pain radiating down the lateral portion of his right leg into his foot. Complaints included an intermittent tingling sensation on the dorsal surface of his right foot. He reported no weakness, numbness, or change in bowel or bladder habits. The patient noted that the pain interfered with his job as a warehouse stocker, although he recalled no specific inciting event and had no history of trauma. He had tried both ibuprofen and tramadol for pain relief without success. He took no other medications. A complete review of symptoms yielded negative findings except for lower back pain rated 4 on a scale of 10 and right radicular leg pain rated 7 out of 10. The patient underwent a trial of physical therapy, which did not alleviate his pain.

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PMH: Hypertension and diabetes mellitus
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PSH: Unremarkable
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Exam: On neurologic examination, cranial nerves II through XII and cerebellar function were found to be intact. Results of the motor examination were 5/5 in bilateral upper and lower extremities, with very mild weakness of dorsiflexion on the right. His reflexes were normal. The patient had slightly decreased sensation to pinprick on the dorsum of his right foot; otherwise his sensation was intact. He was slightly tender to palpation of the lower lumbar spine and had a positive result on the straight leg raise test on the right. Gait was normal. No other abnormalities or deformities were noted.
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Imaging: Magnetic resonance imaging (MRI) of the lumbar spine showed a large lateral disk herniation at the level of L4-5 ( Figures 5-2 and 5-3 ). After discussion of all the therapeutic options, the patient selected surgery.

FIGURE 5-2

T2-weighted sagittal MRI scan showing L4-5 herniated disk.

FIGURE 5-3

T2-weighted axial MRI scan showing right-sided herniated disk with nerve root compression.

The patient underwent a standard L4 hemilaminectomy with L4-5 microdiskectomy. The patient did well postoperatively and was discharged on postoperative day 1. The patient was seen in the clinic for follow-up 2 weeks later and was doing well, with significant improvement in his lower back pain and right radicular leg pain. He has had moderate improvement of his right foot paresthesia.

Treatment Options

Any effective treatment plan should focus on alleviating pain, ameliorating symptoms, and improving the quality of the patient’s life. Since the natural history of sciatica secondary to disk herniation is favorable and typically self-limited, symptomatic therapy is usually used early on, with the goal of providing adequate pain relief while the underlying disease process resolves over time. The time it takes for symptoms to improve can vary, although most patients experience an improvement of leg pain within the first 7 to 10 days and a complete resolution of all symptoms within 8 weeks. Some patients will continue to have severe or intolerable, progressive symptoms (pain, weakness, or numbness) after several weeks or months. Once a course of conservative care has failed, surgery becomes a good option to adequately address the abnormality and improve both pain and/or neurologic symptoms in most patients requiring surgery. Although multiple studies have shown that the long-term outcomes of nonsurgical treatment and surgical management are comparable, surgery consistently provides the most effective, immediate relief for many patients.

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Multiple randomized trials have shown that patients with lumbar disk herniation and persistent radiculopathy who choose surgery experience a substantial improvement in their symptoms sooner than do patients undergoing nonsurgical treatment.

Conservative Treatment

The mainstay of conservative care includes a short-term (4-week) trial of nonnarcotic analgesics, such as nonsteroidal antiinflammatory drugs (NSAIDs) or acetaminophen, in addition to activity modification. Although NSAIDs are the analgesic of choice for most patients, acetaminophen can be used in patients who cannot tolerate NSAIDs. Although these medications are universally used as the initial nonsurgical management of sciatica, evidence supporting their effectiveness in sciatica is lacking.

Activity modification is a critical part of nonsurgical management, because it aims to minimize nerve root compression and avoid any activities that generate significant pain. Modification of activity does not equate to continual bed rest. As soon as acute symptoms lessen, which generally occurs within the first week, patients should resume modest physical activity, since multiple studies have shown that prolonged bed rest is of no benefit. Many patients with persistent symptoms also try physical therapy even though there is insufficient evidence evaluating this treatment. Additional studies are needed to assess the optimal timing and duration of visits, as well as the effectiveness of therapy in cases of lumbosacral radiculopathy. Given the favorable natural history of sciatica, it is currently recommended that physical therapy be delayed until symptoms have persisted for 3 weeks, since many patients will experience improvement on their own during this time.

Opioids and muscle relaxants are commonly used to treat patients with an acute radiculopathy when their pain is severe and insufficiently controlled by nonopioid analgesics. The use of opiates or muscle relaxants for acute radiculopathy is a matter of clinical judgment, due to the paucity of data regarding the efficacy of these medications. If prescribed, opioids should be used on a fixed schedule for a limited time and should not be combined with muscle relaxants due to the additive sedating effects. Systemic and epidural glucocorticoids are also treatment options for patients with persistent severe radicular pain refractory to NSAIDs, acetaminophen, and activity modification. The most recent American Pain Society practice guidelines concluded that systemic glucocorticoids are an ineffective treatment for low back pain with sciatica, whereas epidural steroid injections are moderately effective as a short-term treatment for persistent lumbosacral radiculopathy secondary to lumbar disk herniation, but are not indicated for use during the acute phase.

Although further randomized studies will be required to effectively evaluate all of the nonsurgical treatment options discussed here, the benign natural history of sciatica will continue to make accurate data collection and interpretation extremely difficult in future trials. Unfortunately, other confounders, such as the placebo effect and patient social issues, also interfere with study designs and subsequent result analysis, further hindering the selection of the most effective treatments for sciatica. Thus, it is critical to determine the optimal length of time that conservative management should be offered before surgery is considered.

Surgical Treatment

The main goal of surgery for symptomatic lumbar disk herniation is to alleviate unremitting radicular pain and/or persistent neurologic deficit caused by compression of lumbosacral nerve roots. This is done by removing either a portion of, or the entire, herniated disk. Although severe, progressive neurologic decline is an indication for urgent evaluation and potentially emergent surgical intervention, this is not commonly caused by a herniated lumbar disk. The most common indication for diskectomy is persistent or worsening radicular leg pain, but it is critical that the distribution of the radicular pain correspond to the nerve root compression seen on preoperative imaging for the operation to have the best outcome. Neurologic signs (slight weakness and/or pain on straight leg raise) are often more confirmatory of the level than the reason, per se, for surgery. Although lumbar microdiskectomy is a very successful procedure that relieves radicular leg pain in 85% to 90% of appropriately selected patients, the adequacy of relief of back pain after surgery is unpredictable. The importance of proper patient selection cannot be overemphasized, because complications and poor outcomes can arise when patients are not chosen carefully.

Early referral for surgery does not improve outcomes in patients with lumbar disk herniation and radiculopathy who do not have severe or progressive motor weakness, or symptoms of cauda equina syndrome. Referral for surgery should be an elective option for patients with persistent disabling symptoms after at least 4 to 6 weeks of standard nonsurgical management. Multiple studies have shown that these patients have a more favorable outcome after microdiskectomy than nonsurgically treated patients at short-term follow-up, but outcomes are equivalent at 1 to 2 years. The American Pain Society treatment guidelines currently recommend that physicians consider surgery in patients who have both persistent, disabling radiculopathy and a corresponding herniated lumbar disk on imaging. These patients generally experience a moderate improvement almost immediately after surgery, even though their total overall improvement at 1 to 2 years may be equivalent to that of patients managed conservatively.

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Surgery provides effective short-term relief in these patients, but this benefit lessens over time because both surgical and nonsurgical groups eventually report similar overall improvements.

There is no clear correlation between the size of the herniated disk or nerve compression and the amount of pain or nerve root injury. In fact, small compressive lesions can produce extensive, irreversible nerve damage if they affect the nerve’s arterial blood supply. Unfortunately, these ischemic nerve roots are not likely to improve after the compressive lesion is removed during surgery. Overall, microdiskectomy continues to be a reasonable option for patients with incessant disabling radicular symptoms lasting 4 to 6 weeks who are good surgical candidates and desire surgery.

Lumbar Diskectomy

A variety of diskectomy techniques are currently used by orthopedic and neurologic surgeons. The procedure chosen is typically based on the surgeon’s preference and experience. The conventional open diskectomy involves use of a standard surgical incision to obtain adequate visualization and illumination, then frequently performance of a hemilaminotomy to relieve pressure on the nerve roots and visualize the protruded disk, followed by a diskectomy to remove the herniated nuclear disk material. Microdiskectomy, the most common diskectomy procedure, is a modification of the open diskectomy technique that can be performed on an outpatient basis. A smaller incision is made in the back, visualization through loupes or an operating microscope is required, and a hemilaminectomy is performed with removal of the disk fragment compressing the affected nerve roots ( Figures 5-4 through 5-6 ).

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