Overview

Low back pain is the fifth most common reason patients visit their physicians1. It is also responsible for direct health care expenditures of more than $20 billion annually2 here in the U.S. In the primary care practice, the specific anatomic cause of back pain is often impossible to define. Differential diagnoses can be varied and treatment options are not always obvious. However, distinguishing between a routine case and the more serious and immediately treatable case of back pain is essential.

A comprehensive history and physical examination can identify the small percentage of patients who require immediate evaluation. Urgent evaluation is indicated when patients report “red flag” symptoms, such as a low grade fever for more than 48 hours, severe pain at rest or pain that wakes the patient at night, weakness or numbness of the lower leg, loss of bowel or bladder function, and/or pain from trauma.

Most low back pain resolves itself within weeks with patients being able to return to work within three months. Conservative therapy, such as the use of analgesics, rest, mild exercise and rehabilitation are effective means in helping patients ease their pain.

A smaller population of patients may require interventional therapies, which may include epidural injections of local anesthetics, steroids, or narcotics into the affected soft tissues, joints, or nerve roots. If patients do not respond to these therapies and low back pain has significantly affected their lives, surgical intervention may be necessary. In this medical education piece, we will outline the importance of patient history and the examination process, briefly describe the investigation tools commonly ordered today, and review several surgical interventions, including minimally invasive therapies.


Importance of
Taking Patient History

Patient History
When a patient presents acute low back pain that has affected day-to-day activities, a thorough history should be elicited from the patient. Pertinent data should include, but are not limited to:

  • Type of occupation
  • Psychological profile
  • Family
  • Medical
  • Current medication profile

Pain is subjective. Differences occur in how people relate to their own pain experience. Because a patient’s memory of pain is unreliable, it is a good idea to get the patient to record the baseline symptoms on a standard pain chart. It is also useful to ask patients to visually point out the main areas of pain. This can be done by either providing the patient with a pain diagram, a body chart, or pointing to specific areas of the body. Further questioning would help identify if the pain goes beyond the buttock (radicular or somatic referred) or if located in multiple sites.


Onset of Pain
History taking helps build rapport with patients and enables clinicians to narrow down the possible causes as patients feel more comfortable releasing information. When questioning a patient, ask if the onset of pain was sudden, gradual, or was it precipitated by a traumatic event.

Duration and Pain Patterns
Most patients with acute low back pain are able to return to work within three months or less. Some may experience recurrence and/or functional limitations. As part of taking the patient history, it is important to ask the patient the duration and type of pain. The pattern of the patient’s pain over 24 hours and the patient’s response to various activities will indicate how it affects the patient and the level of severity.

The following demonstrates some typical pain patterns, but overlap may occur.

Mechanical Patterns:
  • Activities of Daily Living (ADL) aggravate pain at end of day. Question if this pattern only occurs during workday vs. weekend.
  • Mechanical pattern – stiffness and pain that often occurs in the morning for 30 minutes then easing with some aggravation throughout day.
  • Mechanical pattern – pain that is dependent on specific activities undertaken.


Physical
Examination

A traditional component of clinical examination is range of motion (ROM). It assists in developing and identifying baseline parameters for future reference. It should be noted that there is no direct evidence ROM assists in diagnosis. However, painful limitation-on-movement tests can be used to assist in the further development of a working diagnosis in individual cases. When performing ROM tests, the clinician should observe and record resting level of pain and pain reduction.

Following inspection of the back and assessment of lumbar motion, the lumbar spine should be carefully palpated and any tenderness or spasm of the lumbar para vertebral muscles be noted. Palpation of the lumbar spine should include both the bony processes and the soft tissues. The sciatic area, anterior abdominal wall, inguinal area, and lower extremities should also be palpated.

Investigations
In general, the ordering of investigations is controversial in low back pain. But as primary care physicians become more skilled in history taking and physical examination, the ordering of investigations is more specific and is conducted with some rationale, such as:

  • Elimination of red flags
  • Locating pathology for possibility of further specific intervention
  • Leading to therapeutic interventions, such as diagnostic blocks

There is no one test that can prove or disprove 100% that a specific structure is the source of pain. In any investigation, the quality of the imaging and the specificity of the imaging are important, as is the expertise of the radiologist. Some commonly used investigations include the following:

CT Scan — CT scans are very good at giving three-dimensional information about cortical bone. They are fine at giving information about disc position. In the absence of air in the disc, they are poor at giving information about disc health. In the absence of radicular pain and signs, a CT scan will give very little useful information.

Finding a disc bulge/prolapse on a CT in a patient with back pain does not indicate this is the diagnosis. However, with radicular pain and matching signs, finding appropriate changes on a CT or MRI helps confirm the diagnosis.

Bone Scan — Bone scans are rarely needed in the evaluation of acute low back pain. Asking for SPECT (single photon emission computer tomography) images will give dimensional images of the vertebra and posterior elements in great detail. A bone scan is useful if there is concern regarding infection (bone or disc), stress fracture, occult fracture or tumor.

Magnetic Resonance Imaging (MRI) — MRI has demonstrated excellent sensitivity in the diagnosis of lumbar disc herniation. MRI is good for detecting discitis, some tumors, disc health and bone stress. MR imaging is also excellent for identifying patients with progressive neurologic deficits or cauda equina syndrome. Its strength with radicular pain is in the quality of the sagital images, showing the nerve root foramen and being able to differentiate the disc from nerve root.

MRIs are not necessary in patients in non-red flag presentations. In fact, it should generally be reserved for those cases in which the imaging results are likely to guide treatment.

Plain Radiographs (X-rays) — X-rays are not usually necessary for most episodes of acute low back pain. Its main purpose is to detect serious underlying structural, pathologic conditions.

Neurological Tests — Neurological testing is conducted if the patient presents with radicular pain, pain below the buttock crease, or mentions other symptoms suggestive of neurological compromise, such as:
– Leg giving way
– Loss of balance-coordination
– Pins and needles
– Hot or cold sensations
– Numbness
– Bladder or bowel disturbances

Neurological testing is compared to the asymptomatic limb to assess the relevance of findings.


Clinical Syndrome

Reviewing the patient history and examination can help primary care physicians identify the patient with serious conditions requiring further evaluation and possible referral to a specialist. The following chart3 lists differential diagnoses for acute low back pain:


Click Figure to Enlarge

Treatment
Algorithms

The key point in following treatment algorithms is that, history and physical examination do not readily separate the major diagnoses in chronic low back pain and therefore a logical algorithmic approach is presented.

The following treatment algorithms for back4 and leg pain5 offer a procedural guidance for initial evaluation.





Surgical Interventions

Most patients with acute low back pain recover within weeks with return to modified and/or limited activities. Conservative therapies will not be discussed here since the topic has been covered extensively in various journals. Clinical practice guidelines produced by the Agency for Health Care Policy and Research, U.S. Department of Health and Human Services are also easily available online and in print6.

If symptoms persist or worsen, or new symptoms develop, diagnosis should be reevaluated with additional laboratory tests and procedures as indicated. Referral to a specialist may be necessary.

The nature of surgical interventions differs according to the presenting problem. Back and referred pain requires treatment directed at the particular structure causing the pain, such as facet joint or disc. Radicular pain requires removal of the structure that is compressing the nerve root. Pain and/or neurological deficit related to canal stenosis requires surgical excision of the structures causing the compression.

Surgical interventions are almost mandatory in the early presentation of cauda equina lesions. In the absence of cauda equina symptoms, it is essential that patients try conservative therapies prior to considering surgery.


Surgical Interventions
For Somatic Back and Referred Pain


Radiofrequency Neurotomy (RFN)
Radiofrequency neurotomy has a long history in the treatment of lumbar facet joints and is an emerging therapy for sacroiliac joint pain (Image A)7. At the sacroiliac joint level, the procedures are more complex by the variability in nerve supply.

RFN is performed in an operating setting using mild sedation and local anesthetics. Fluoroscopic x-ray guidance allows the operator to accurately position the radiofrequency probe adjacent to the medial branch nerves to be treated8,9. The nerve is then heated to 80° C using a radiofrequency generator10.

Nerve functions usually recover in 12 months. It has been demonstrated that muscles innervated by these medial branches undergo atrophy following successful denervation. However, patients never complain of weakness or instability following procedure.

A number of studies have been performed on the efficacy of RFN. For example, it has been shown that lumbar RFN is effective for facet joint pain. Dreyfuss et al, demonstrated that at 12 months, 60% of subjects had 90% relief, and 90% had 60% relief8.

Side effects of RFN9 potentially include:

  • Rare, but possible, is an allergic reaction to local anesthetic.
  • Bleeding and bruising, but the effects are minimal and should disappear within days.
  • Infection, but is unlikely.
  • Post procedure soreness is extremely variable and it is eased in a few days.


IDET (Intra-Discal Electro-Thermal Therapy)
The IDET procedure involves steering a catheter into the disc under x-ray control. IDET is a percutaneous procedure.

The disc itself is virtually avascular. Because of its avascularity, heat can be held into the tissue with relatively little fluctuation. Adjacent structures are protected from thermal injury by the vascular circulation outside the disc, which quickly dissipates any heat conducted beyond the disc.

Thermal therapies are well established in the surgical world11, used widely for ablation and desiccation. Heat is transferred by conduction from the catheter to the adjacent disc tissue. The intra-discal catheter delivers thermal energy directly to the annual wall and disc nucleus by a resistive heating coil. It is designed for creating temperature control coagulation and for shrinking collagenous tissue. Collagen is the basic strength structure in the disc. In discogenic pain, it is usually damaged. Thermal lesion shrinks the fibers of the disc annulus and nucleus, “de-bulking” the disc. Numerous studies on the effectiveness of the procedure have been performed. It seems that the results are similar to that of fusion, with about one in five patients receiving excellent pain relief.

Indication of IDET is a positive discogram. Discograms are performed in patients who have back pain with or without leg pain, who have not responded to other less invasive therapies, and who have severe pain12.


Surgical Interventions
For Radicular Pain

Percutaneous Disc Decompression
Disc decompression has been shown to treat symptomatic patients with contained herniated discs. Percutaneous disc decompression has been used in the treatment of herniated discs for more than 40 years. A variety of techniques have been used to decompress discs, including chemical, mechanical, and thermal/heat (radiofrequency and laser) methods. However, each of these methods has limitations.

DISC nucleoplasty is a relatively new procedure and utilizes radiofrequency energy for partial disc removal with minimal invasion and trauma (Image B)13. The radiofrequency energy excites the electrolytes to create a precisely focused plasma field. The energized particles in the plasma break the molecular bonds, dissolving soft tissue at relatively low temperatures (typically 40-70° C) and preserving the surrounding healthy tissue.

DISC nucleoplasty is performed on an outpatient basis (often in less than one hour); requires only local anesthesia and mild sedative; it is less invasive; recovery is rapid with no bracing needed; has a 79% success rate13; and demonstrates a 57% reduction in VAS pain scores13.

Biochemical analysis of degenerative discs demonstrated that DISC nucleoplasty produces significant changes in disc tissue14. Inclusion criteria for patients who might benefit from this procedure include:

Radicular/Axial Pain
- Leg pain > back pain
- MRI evidence of contained disc protusion
- Positive discography
- Failed conservative treatment
Axial Back Pain
- Central focal protusion
- Failed conservative therapy x 3 months
- Positive discography
- Disc height > 75%



The DISC nucleoplasty procedure is as follows:

  1. A 17 gauge needed is inserted into the disc under fluoroscopic guidance.
  2. A SpineWand is introduced through the access needle and channels are removed from within the nucleus of the disc using radiofrequency. Highly targeted plasma dissolves tissue. Procedure is thermally safe with no tissue necrosis15.
  3. Tissue removal relieves intradiscal pressure16 and reduces pressure applied by the disc to adjacent nerves.

Discectomy
In this procedure, the protruded part of a disc is removed either as an open operation, or done as a microdiscectomy. Discectomy typically restores function rapidly.

If radicular pain is due to a disc prolapse and not a component of canal stenosis, then it is sometimes possible to decompress the nerve root by removing the bone. Discectomy for radicular pain is a highly successful procedure. Patients are generally in the hospital between 2-5 days. Resolution of leg pain can be immediate.

Discectomy and Fusion
Various stabilizing procedures can be performed from posterior stabilization procedures to interbody fusions. These are considered necessary either if the surgeon considers the segment unstable or if it will become unstable as a result of surgery. Thus it is uncommon for fusion to be combined with a simple discectomy.

Laminectomy
This is the removal of the lamina. In radicular pain, however, it is usually possible to decompress a nerve root without total removal of the lamina. The more bone removed, the greater the chance of subsequent instability. Thus, the decision on whether or not to combine a fusion with a laminectomy depends on the surgeon’s views about the possibility of future instability (spondylolisthesis). More radical removal of the posterior elements is necessary in more severe cases of lateral canal stenosis.


Laminectomy and Fusion in Canal Stenosis
Non-operative treatment options for lumbar canal stenosis are aimed at removing pressure from the nerves to allow them to function more normally. Non-operative treatment options include physical therapy, medication, and pain therapy.

Laminectomy is used to treat patients who have progressive symptoms that could cause serious damage. Surgery may also be prescribed to treat people who have persistent symptoms, despite medical treatment. During a laminectomy, the central tunnels of the vertebrae are opened and nerve pressure is relieved. If the removal of the laminar is likely to lead to spinal segmental instability, the surgeon will consider stabilizing the segment by performing a fusion at the level of the laminectomy.

Vertebroplasty
This minimally invasive procedure uses image-guided, percutaneous injection of PPMA (poly-methylmethacrylate) bone cement into the fractured vertebral body. The purpose of the procedure is to achieve pain relief and restore strength to the damaged body.

During vertebroplasty, one or two bone biopsy needles are inserted into the collapsed vertebra through a small incision in the patient’s back; the stylet is removed and PMMA is injected through the cannula to stabilize the fracture. This procedure typically is outpatient and requires local anesthetic and mild sedation.

Vertebroplasty is indicated for vertebral compression fractures resulting from osteoporosis. Other indications for vertebroplasty include large vertebral hemangiomas and malignant spinal tumors, such as metastases, lymphomas, and myelomas.

The success rates for substantial reduction in pain of osteoporotic fractures and aggressive hemangiomas are approximately 90%17. In the case of tumors, it is reduced to 70-75%17. It has been demonstrated that 3ccs increases the strength by 150% and 6ccs by 190%, but there is no significant strength increase beyond an injection of 6ccs18.

Percutaneous vertebroplasty19,20 has many benefits:

  • Is minimally invasive and performed under fluoroscopic guidance.
  • Can be done as an outpatient using local anesthesia. Typically, patients who undergo vertebroplasty may go home the same day.
  • Prevents treated level from further collapsing
  • Provides significant pain relief within 24 hours19
  • Has a rapid recovery time, enabling patients to return to their daily activities quickly.


While complications for vertebroplasty is rare19,20, they do exist and should be mentioned. They include:

  • Fracture of the posterior elements of the spine during introduction of the needle in a transpedicular approach.
  • Leakage of cement into adjacent structures because of destruction or fracture of the bony margin due to the pre-existing condition or because of a fracture produced during the introduction of the needle. Leakage of the cement can lead to nerve root or spinal cord damage and potentially lead to paralysis. While a rare complication, neurosurgical intervention should be available quickly.
  • Injection into a vein could potentially lead to a pulmonary embolus.
  • Increased risk of fracture at the adjacent levels. The relative risk is 1.4 times without vertebroplasty21.
  • As with all spinal procedures, potential for infection and bleeding should be monitored.

Applying low-pressure injection; high viscosity of the PMMA mix; excellent fluoroscopic vision; and ability to adjust volume requirements easily further reduces the risks for these complications.


Spinal Cord Stimulators (SCS)

Spinal cord stimulation is a form of neuromodulation, which has been available to clinicians for decades. Recently, there have been significant developments, which have improved the quality of the spinal cord stimulation leads, its capacity to cover the patient’s areas of pain, and the long-term viability and reliability of the implants.

The goal of neurostimulation is to create a sensation of paraesthesia to cover the regular pain distribution. It has been demonstrated that this modality works best when treating sharp, naturopathic leg pain.

One of the difficulties in placing the spinal cord stimulator lead is potential side effects with abdominal cramping and other discomfort around the inferior costal margin and abdomen. However, new lead combinations and multi-system programs offer the clinician increasing capacity to try and cover both back and leg symptoms.

Spinal cord stimulation is a relatively simple surgical procedure and is non-destructive. Each patient has a trial of stimulation to determine if a more permanent system implantation is appropriate. The device can easily be removed should future tolerance to stimulation develop and/or some other issue with the device occur.

In a 15-year experience reported by Kumar22, 80% of patients reported satisfactory pain relief and therefore had permanent systems implanted. The major indications for spinal cord stimulation in this group were failed back surgery syndrome, peripheral vascular disease, peripheral neuropathy, multiple sclerosis, and complex regional pain syndrome (RSD).

For lower extremity pain with hip and back involvement, the usual lead tip level is in the T9-10 area. Initial trial stimulation is performed to confirm that the leads are well placed. Further fine-tuning of stimulation programs is then performed at post op and ensuing days.

Percutaneous leads are more common; however, laminectomy leads can be placed in certain circumstances requiring neurosurgical approach and insertion. The alternatives for running the spinal cord stimulator include an implanted battery (IPG), which is generally inserted into the upper outer buttock or upper outer abdomen. The alternative is an external power source using a radiofrequency generator. There are advantages in both systems and it is often the patient who determines which system will provide more comfort and compliance.

Complications are uncommon, but include displaced electrode, which can either be repositioned or removed and replaced; infection, which if not resolved, by antibiotic therapy requires removal of the implant; and fractured electrode subcutaneous hematoma or seroma around the implant.


Summary

As many primary care physicians know, approximately 90% of adults experience back pain at some point in their lives23. For the majority of these patients, conservative treatment, such as the use of analgesics, rest, modification of lifestyle, and exercise will help ease their acute low back pain. For a few, surgical interventions may be necessary.

It’s been noted that the United States has one of the highest rates of spinal surgery24. While some studies indicate no clear advantage for surgery, practicing physicians, however, know that select groups of patients should undergo immediate surgical evaluation. Patients with suspected cauda equina lesions or vertebral compression fractures, for example, may benefit from surgical intervention. Surgical evaluation is also indicated in patients with worsening of pain or pain that is resistant to conservative treatment.

Certain surgical procedures that are minimally invasive offer greater benefits for select patients because it reduces hospitalization costs, improves patient outcomes, decrease patient trauma, and expedites the patient’s ability to return to daily living.

References
1. Hart LG, Deyo RA, Cherkin DC. Physician office visits for low back pain. Frequency, clinical evaluation, and treatment patterns from a U.S. national survey. Spine 1995; 20:11-9.

2. Deyo RA, Cherkin D, Conrad D, Volinn E. Cost, controversy, crisis: low back pain and the health of the public. Annu Rev Public Health 1991;12:141-56.

3. Patel AT, Ogle Abna. Diagnosis and management of acute low back pain. Am Fam Physician 2000; 61:1779-86,
1789-90.

4. Interventional Management Algorithm for Back Pain from the Lowbackpain Cd-Rom: A Guide for the Treating Practitioner (2005) Clinica Media. Verrills P, Vivian D, and Mitchell B. Originally adapted from Verrills P and Vivian D: Interventions in Back Pain. Australian Fam Prac. June 2004 and International Spine Intervention Society (2004). Bogduk N (ed). Practice Guidelines for Spinal Diagnostic and Treatment Procedures. International Spinal Intervention Society, San Francisco (in press).

5. Interventional Management Algorithm for Leg Pain (USA): from the Lowbackpain Cd-Rom: A Guide for the Treating Practitioner (2005) Clinica Media. Authors: Verrills P, Vivian D, and Mitchell B. Originally adapted from Verrills P and Vivian D: Interventions in Back Pain. Australian Fam Prac. June 2004 and International Spine Intervention Society (2004). Bogduk N (ed). Practice Guidelines for Spinal Diagnostic and Treatment Procedures. International Spinal Intervention Society, San Francisco (in press).

6. Clinical Practice Guideline produced by the Agency for Health Care Policy and Research, U.S. Department of Health and Human Services, Dec 1994. Available at: http://www.chirobase.org/07Strategy/AHCPR/ahcprclinician.html Accessed January 6, 2006.

7. Yin W. Stereotactic Radiofrequency Neurotomy of the Sacroiliac Joint. Spine 2003; October.

8. Dreyfuss P, Halbrook B, Pauza K, et al. Efficacy and validity of radiofrequency neurotomy for chronic lumbar zygapophysical joint pain. Spine 2000:25; 1270-1277.

9. Baker R. Radiofrequency neurotomy for facet and sacroiliac joint pain. December 27, 2004. Accessed January 6, 2006. Spine-health.com/topics/conserv/radio/radio0l.html

10. Lord SM, Barnsley L, Wallis, BJ et al. Percutaneous radio-frequency neurotomy for chronic cervical zygapophyseal-joint pain. New Eng J Med 1996; 335:1721-1726.

11. Barna SA. Intradiscal electrothermal therapy. eMedicine. Last updated April 6, 2005. Available at: http://www.emedicine.com/NEURO/topic707.htm. Accessed January 6, 2006.

12. Sharps LS, Isacc Z. Percutaneous disc decompression using nucleoplasty. Pain Physician 2002; 5:121-126.

13. O’Neill C, Lotz J. Percutaneous plasma discectomy stimulates repair in injured porcine inter-vertebral discs. Presented at International Society for the Study of the Lumbar Spine annual meeting, May 2003, Vancouver, Canada.

14. Chen YC, Lee, SH. Saenz Y, Lehman NL. Histologic findings of disc, end plate and neural elements after coblation of the nucleus pulposus: an experiemental nucleoplasty study. Spine Journ 2003; 3: 466-480.

15. Chen YC, Lee S, and Chen D. Intradiscal pressure study of percutaneous disc decompression with nucleoplasty in human cadavers. Spine 2003; 28: 661-5.

16. Patel MD. Percutaneous vertebroplasty. eMedicine. Last updated March 4, 2005. Available at: http://www.emedicine.com/neuro/topic682.htm. Accessed December 6, 2005.

17. Liebschner, MAK, Rosenberg WS, Keaveny TM. Effects of bone cement volume and distribution on vertebral stiffness after vertebroplasty. Spine 2001; 26(14):1547-1554.

18. McGraw JK, Lippert JA, Minkus KD, Rami PM, Davis TM, Budzik RF. Prospective evaluation of pain relief in 100 patients undergoing percutaneous vertebroplasty: results and follow-up. J Vasc Interv Radiol. 2002; 13:883-886.

19. Zoarski GH, Snow P, Olan WJ, et al. Percutaneous vertebroplasty for osteoporotic compression fractures: quantitative prospective evaluation of long-term outcomes. J Vasc Interv Radiol 2002;13:139-148.

20. Diamond TH, Champion B, Willliam AC. Management of acute osteoporotic vertebral fractures: a nonrandomized trial comparing percutaneous vertebroplasty with conservative therapy. Am J Med 2003;114:257-265.

21. Kumar K, Toth C, Nath RK, Laing P. Epidural spinal cord stimulaton for treatment of chronic pain – some predictors of success. A 15-year experience. Surg Neurol 1998. Aug; 50(2); 110-20; discussion 120-1.

22. Frymoyer JD. Pack pain and sciatica. N Engl J Med 1988; 318: 291-300.

23. Taylor VM, Deyo RA, Cherkin DC, Kreuter W. Low back pain hospitalization. Recent United States trends and regional variations. Spine 1994; 19: 1207-12.