Multimodal Management of Chronic Low Back Pain: An Interventionalist's Case-Based Perspective
by Douglas C. Schottenstein, MD
Patient J.L. presented to pain management/neurology with complaints of low back pain and radiating right greater than left buttocks pain. Patient also complained of radiating right antero-lateral thigh pain, which occasionally radiated to antero-lateral lower leg. Pain is a physiological consequence of injury to tissue, and it typically serves a protective function. However, pain itself can become a disease if it persistently occurs after normal healing time, the length of which varies substantially from patient to patient. Numerous studies have characterized the impairment, distress, and adverse impact of pain across multiple domains of function and quality of life. Timely diagnosis and targeted treatment strategies based on comprehensive, ongoing care are therefore critically important to achieving realistic treatment goals. On physical exam, the patient demonstrated normal neurologic function, including cranial nerves, muscle strength, sensation to pinprick and vibration, coordination and gait. Patient also had a relatively benign low back exam, including normal range of motion, negative straight leg raise test, and negative Patrick’s maneuver. A thorough physical exam should include a review of the anatomical and physiological basis that explains the significance of physical findings. Both neurologic and orthopedic components are vital, and typically only neurologically intact patients are candidates for pain interventions. On review of imaging studies, the patient had MRI L-spine showing L4-L5 disc herniation (Figure.). Typically, the L4-L5 disc, when herniated, irritates the L5 nerve. Traditional dermatome maps show L5 root distribution as antero-lateral thigh and lateral lower leg. This distribution of pain was consistent with the patient’s complaints. MRI is the modality of choice for imaging the lumbar spine. While it is estimated that nearly 30% of asymptomatic individuals have disc abnormalities on MRI, it is still the best noninvasive assessment of anatomy.1 MRI uses no radiation, and a typical magnet is sufficient for evaluation of anterior and posterior elements of the spine. Nerve integrity, including compression and irritation, is also well-visualized. Patient J.L was scheduled for transforaminal epidural steroid injection, in order to place potent anti-inflammatory steroid next to the presumably irritated nerves. Because the patient had components of both L4 and L5 nerve pain—specifically anterior and lateral thigh pain— either or both levels could be treated. Transforaminal epidural steroid injections, also known as selective nerve root blocks (SNRB), have both diagnostic and therapeutic potential. SNRB is most appropriately used in patients with radicular pain.2 The injection delivers a low volume of concentrated medication directly into the nerve root sleeve in question, while also dispersing medication into the adjacent epidural space. Delivering medications to both locations provides a diffuse epidural effect, while also typically covering an inflammatory nerve root. Used properly as a diagnostic tool, the SNRB will elicit pain in the distribution of the nerve root sheath that has been injected. If the needle contacts the nerve responsible for the pain, the patient will report that the pain is concordant with typical pain. In the majority of patients with radicular pain, a single-level SNRB is sufficient diagnostically and therapeutically. Patient J.L.’s transforaminal epidural steroid injection (SNRB) was delivered at L4 bilaterally, without complication. Please see procedure note below. Typically, epidural steroid injections of any nature, including the transforaminal type, realize complete benefit after several days.3 The preparation employed in most injectates is triamcinolone in a depot preparation, which tends to continually exert its effect over several days to weeks. Patient J.L returned to the office 2 weeks later, at which time he reported greater than 70% relief of lumbar and radicular pain. Because pain was still 3/10 on numeric rating scale, a second injection was undertaken. Patient received nearly total relief after the second injection, but was offered tramadol 50-100 q6 prn for residual pain. Analgesics are typically employed in conjunction with spine interventions and may provide additional pain relief. Although spine interventions are effective for many patients, patients may continue to experience pain to varying degrees. Patient J.L. returned 1 month following the second transforaminal injection, with sustained 70-80% relief. The patient, however, was occasionally experiencing both dull back ache and radiating lower extremity pain. Although tramadol was affording patient good relief, the radiating component of the pain was not completely controlled. Therefore, a trial of pregabalin (50 mg t.i.d), an α2δ ligand with documented efficacy for neuropathic pain, was begun. Low back pain, and radiating lower extremity pain, account for the second-largest group of patients seeking medical care in the United States, second only to headache.4 Patients like J.L. will typically need to be followed over a lifetime. While J.L has experienced one modality of interventional practice, dozens of other options are available should his pain return and continue to impair function. J.L. will be followed closely, likely every 8 weeks, to assess function and to treat any further exacerbations. 1. Carragee EJ. Persistent Low Back Pain. New Engl J Med. 2005;352:1891. Note: Some studies have identified herniated disc abnormalities in up to 50% of asymptomatic subjects, with extrusion of disk material observed in as many as 1 in 5 asymptomatic subjects. 2. Chou R, et al. Interventional therapies, surgery, and interdisciplinary rehabilitation for low back pain: an evidence-based clinical practice guideline from the American Pain Society. Spine (Phila Pa 1976). 2009;34(10):1066-77 3. Armon C, et al. Assessment: use of epidural steroid injections to treat radicular lumbosacral pain: report of the Therapeutics and Technology Assessment Subcommittee of the American Academy of Neurology. Neurology. 2007;68:723-729. 4. Deyo RA, et al. Back pain prevalence and visit rates. Spine. 2006;31:2724–7.
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Date of Operation: 11-6-08 Assessment: Technique:
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