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20 Articles in Volume 20, Issue #2
20/20 with Peter Staats, MD: The Future of Pain Medicine
Ask the APP: How useful and practical are pain assessment tools?
Ask the PharmD: What are the recommendations for preventing and treating pediatric migraine?
Axial Spondyloarthritis: Updated Medication and Imaging Recommendations
CGRP Monoclonal Antibodies for Chronic Migraine Prevention: Evaluation of Adverse Effects Using A Checklist
Chronic Low Back Pain: Can We Find a Treatment Consensus?
Chronic Pain and Coronavirus
Correspondence: Are ESIs Still Worth It? Benzocaine for Orofacial Pain.
Could Pulsed RF Provide Lasting Chronic Headache Relief in Refractory Patients?
Diagnosis Is Everything: Low Back Pain As a Symptom of an Underlying Condition or Conditions
Editorial: From Just Say No, to Say Now and Say Know
Erenumab and Onabotulinumtoxin A Show Additive Effect in Refractory Chronic Migraine
Experts Roundtable: Finding a Bottom Line in Back Pain Care
Inside the Potential of RNAi to Target the Etiology of hATTR Neuropathy
Muscle Dysfunction in Head and Neck: Pain Causes, Osteopathic Options
New Migraine Medications: Oral Gepants, Ditan Tablet, and More
Root Cause of Sacroiliac Joint Dysfunction: Four-Step Exercise Protocol
The Emotional Impact of Chronic Low Back Pain
The Rise in Tianeptine Abuse: Our Next Kratom Problem?
The Sensory Component of Pain: Modifying Its Emotional and Cognitive Meaning

Diagnosis Is Everything: Low Back Pain As a Symptom of an Underlying Condition or Conditions

A pain-fellowship trained neurologist shares tips from the field for addressing chronic lumbar pain.
Pages 35-37

As part of this special report, PPM addresses the common and confounding problem of low back pain. We asked clinicians across disciplines to share their approach to a hypothetical case of non-specific back pain and to discuss why they think there is a standstill on treating this extremely prevalent condition. Here, one of our roundtable discussants, John A. Campa III, MD, imparts additional tips from the field based on his career as a pain-fellowship trained neurologist.

Pattern recognition as part of diagnosis should be secondary, due to the multitude of nociceptive structures that refer to and are otherwise encompassed in the lumbar region. (Image: iStock).

Overview

Keep in mind that low back pain is a symptom of an underlying condition or conditions. Hence, the success of any treatment approach or consensus must rely upon a well-established diagnosis, which can be developed from:

  • performing a directed history, including
    mechanism of onset or injury as well as physical
    and neurological examinations
  • formulating a cogent assessment, differential diagnosis, and plan (diagnostic, treatment, education).

Although a diagnosis ultimately rests upon a clinician’s experience and knowledge base, there are several key points that any provider can relate to which will assist in arriving at an initial or provisional diagnosis. In neurology training, we are taught to always ask, “Where’s the lesion?” be it the neuraxis (brain and spinal cord) or periphery. Pattern recognition, while helpful, should be secondary, due to the multitude of nociceptive structures that refer to and are otherwise encompassed in the lumbar region.

At the initial patient visit, a comprehensive diagnosis may be lacking, as you will need a good history and physical to guide you as to what further ancillary studies and consultations are required to refine your initial impressions.

Assessment should be based on a list, starting with the most likely of at least three diagnoses that could explain or contribute to the symptoms and physical findings, that is, your differential diagnosis. An initial diagnostic plan should be guided by the first item in your differential diagnosis, wherein you may order electrodiagnostics (eg, electromyography and nerve conduction studies, x-rays, MRI, CT, bone scan, CT-myelography) and laboratory tests to include inflammatory markers (eg, CBC, Sed Rate, CRP, RF, ANA).

Treatment may, if necessary, be limited to symptom management until further information is known. It should also be guided by what the patient has tried in the past and what they may want to avoid. Typically, treatment may include: analgesics (eg, acetaminophen, NSAIDs, a mild opioid such as tramadol), muscle relaxants, antispasmodics (eg, methocarbamol, tizanidine), and gabapentin if nerve pain is present. Go slowly with careful dose escalation, as these agents may impair cognition if an initial dose is too high. Allow at least five half-lives before increasing dose. A firm lumbar brace is often helpful, as well as local heat, ice, and muscle rubs. Consider recommending to the patient medical leave from work, and physical therapy to tolerance. All of these modalities may be indicated early on as you refine the diagnosis.

Perhaps the most important caveat is to not miss a problem that may require a prompt surgical remedy or consultation, or perhaps a metastatic lesion to the spine (eg, rectal or prostatic cancer). Also, keep in mind that primary neuropathic pain (ie, sharp, shooting, tight, squeezing) from direct injury to a specific neural structure is notoriously difficult to treat and only minimally responsive (if at all) to the above modalities. In these cases, it is imperative to isolate the offending structural lesion or disease, such as diabetes, and correct promptly, lest a chronic neuropathic pain state supervenes. The use of tricyclic antidepressants (TCAs), pregabalin, and duloxetine, may also be helpful but should be limited due to impaired cognition at higher doses which also makes weaning patients off these agents exceptionally difficult.

History Taking

Before developing the patient’s relevant history, confirm with the patient the various marks and text indicated on a symptom body figure (SBF). These markings are very important as, often, the patient may misunderstand the form or anatomy or left and right sides, and the markings will be either higher or lower, or on the opposite sides. With the most severe region indicated, use this as your focal point to continue the history. Commonly, radicular radiating symptoms can help to localize the spinal segmental level(s) to guide x-ray and imaging. With a recent injury indicative of significant axial loading of the spine, a disc or facet lesion may be likely. Alternatively, if the axial loading is less so but the SBF is clearly radicular, then an underlying lesion may have previously compromised the lumbar spinal segment, making it more susceptible to minor injury (eg, insidious lung metastases to the pedicles).

When interpreting “radicular” patterns on the SBF, inquire if the direction is proximal to distal. If not, then the source may be outside the spinal axis. When the SBF is localized to a spinal segment or two, consider focal pathology such as a fracture, neoplasm, or tear in the underlying disc. Of course, all of this must be interpreted with the patient’s prior medical and surgical history (eg, remote injury) or potentially relevant medical disorders (eg, diabetes mellitus-related polyradiculoneuropathy, lumbo-sacral plexopathy). Gradual onset with pain worsening over time suggests an enlarging neoplasm. Whatever the complaint, always consider its natural history, that is, without any treatment or intervention, what would be its natural course or endpoint?

Examination

The physical exam on the lumbar spine should begin with an assessment of the gait, limping, favoring one side (ie, the natural tendency of a person to ambulate in such a way to avoid pain – an antalgic gait). Seated behind the patient, have the patient “point” with one finger to the area of greatest pain, mark the skin, and correlate with anatomical landmarks (eg, tops of the iliac crests are at the L4-5 spinal segmental level). Is the pain only right-sided, bilateral, one-sided more than the other, midline? Then using your thumbs, walk them down from the thoraco-lumbar level, pressing with force, and note/mark areas of greatest pain. If doubt remains, percuss the spine with your dominant fist. There also may be focal paravertebral muscle spasm.

Test for a disc lesion by performing the anterior loading maneuver (ALM) having the patient stand and gradually flex the trunk forward but stop and put one finger on the spot where increased pain is noted. Mark this area and correlate to the particular spinal segment, that is, L4-5 or L5-S1. In the author’s experience, ALM is preferred as the term disc maneuver indicates pre-judgment, when other lesions can induce a positive ALM, such as a pathological fracture. Similarly, a posterior loading maneuver (PLM) should be performed to isolate a spinal segmental posterior element lesion of the facets (eg, facet arthropathy related neural foraminal stenosis or metastatic spread to the facets). If both the ALM and PLM are negative, a rent in the disc may be present on MRI.

Regarding the neurological exam, significant nerve root impingement can be detected on exam by simply performing the knee jerk (L2, L3, L4) and ankle jerk (S1, S2). The former suggests a problem of the L3 root (or L2, L4) and the latter assesses impairment of the S1 root (or S2). Hyperreflexia may indicate a problem of the motor components of the brain or spinal cord (ie, the central nervous system, CNS). Note, in most adults, the cord ends in the conus medullaris at about the L2 level. With a CNS lesion, an up-going toe and/or ankle clonus will be present as well. Also keep in mind that an SSRI may induce these same findings due to its stimulatory and/or toxic effect on the CNS.

Often, with significant nerve root impairment, the affected dermatome may be cooler than the surrounding dermatomes. Scan the sensory dermatomes with either light touch or a safety pin and assess as follows: L2-proximal antero-medial, thigh; L3-medial, knee; L4-medial, mid leg; L5-lateral, mid leg; and S1 lateral, foot. Assess motor function: L2, L3, hip flexors; L3, L4, knee extensors; L4, L5, foot dorsi-flexors; and S1, S2, foot plantar flexors.

Note any atrophy of the affected muscle as well. Referred pain to thoraco-lumbar region can be caused by a lesion in the prostrate or uterus. Always look for sidedness, asymmetry. Rectal tone may be impaired in a lesion of the S2, S3, S4 roots. Romberg’s sign (patient standing, eyes open, steady, then falling with eyes closed), when positive indicates a proprioceptive problem, either in the periphery (eg, olyneuropathy) or centrally (eg, spinal cord dorsal columns).

Once the exam is completed, there should be a concordance of the deep tendon reflexes, sensory, and motor findings. The exam findings should enable you to find a structural lesion and direct imaging and/or electrodiagnostic workup to a specific spinal segmental level.

Treatment Plan

Involve the patient in the planning by informing them of your current assessment and how you intend to refine your impressions. Explain what your initial treatment and expectations are. The patient may realize they have forgotten to mention helpful symptoms and/or failure of a particular intolerance to prior types of treatment. They may even now reluctantly reveal what they introspectively fear is really wrong. If your exam has suggested a specific spinal segmental level(s), this must be clarified, x-rayed, and imaged post-haste. To treat it conservatively as a lumbar strain may only waste valuable time and expose the patient to further pain, injury, and disability as the lesion progresses and deteriorates.

In my clinical experience, I typically order a lumbar spine x-ray series, including flexion, extension, and oblique views. The revelation of an unstable spinal segment may push your treatment plan early to surgical considerations and consultation, as physical therapy may be intolerable and injections and medications may needlessly delay a more corrective approach. I will usually order an L-spine MRI as well. I find that x-rays (including of the sacrum, coccyx, and pelvis as indicated) offer an excellent assessment of the osseous structure integrity (ie, segmental instability and any spinal metastases that may be present).

EMG-NCVs may reveal exam concordant radiculopathy and an underlying polyneuropathy. Order a Technetium-99 bone scan if you suspect metastatic spread. CT-myelography can be very valuable when surgery is considered or when faced with multilevel disc lesions by MRI, perhaps isolating the most likely cause of back pain. In the end, remember to treat the patient and not the image result. Imaging must be concordant with the history and physical findings. Surgery may not be required and may actually worsen the patient’s condition. I have often been impressed with the degree of spinal pathology uncovered by imaging when the patient has no complaints relevant to these findings.

Once you have reached the end of your particular diagnostic plan and are confronted with a variety of possibilities, consider the problem-solving principles of Occam’s Razor to pare down the surrounding diagnostic noise and arrive at the most likely cause. If a particular nerve root(s) or facet level(s) is isolated, consider translaminar or transforaminal epidural steroid injection or radio-frequency ablation. When the proper levels are treated, these methods can be very effective to ameliorate the pain and permit natural healing to progress. Once steroid thresholds have been reached, one may continue with neural blockade of the dorsal rami, sensory, cutaneous nerves, at the level of the transverse processes of the affected spinal segments. I have found that a 1-2 cc dose of a mixture of 2cc 2% plain lidocaine and 4cc 0.25% plain bupivacaine often makes for an effective injectate. Further, I have found success injecting high density (20 mg/mL; gel particles/mL: 100K; particle size: 0.28 to 0.50 mm), cross-linked hyaluronic acid at the same level, resulting in cross-linked neural matrix antinociception.

Summary

Diagnosis, diagnosis, diagnosis. Most therapies and treatments are reliable and will render the expected results. But as presented, a firm diagnosis can be the sine qua non of successful treatment of low back pain – and above all, always remember, Primum Non Nocere

Last updated on: April 2, 2020
Continue Reading:
Chronic Low Back Pain: Can We Find a Treatment Consensus?
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