Diagnosing generalized back pain
What should you do with patients presenting with generalized low back pain? Generalized back pain refers to pain centered in the back that doesn’t fit the classical pattern of radiculopathy or neurogenic claudication.
The back is a complex machine consisting of an array of components that serve multiple functions and withstand various external demands and forces. At each spinal level, there is an intricate arrangement involving numerous muscles and their attachments, ligaments, facet joints, vertebral bodies, discs, fascial plains, boney processes, spinal cords, nerve roots, and vasculature.
On top of this, the human spine undergoes relentless degeneration through the years, starting at 16 years old. Essentially, any component of the back is susceptible to pathological and inflammatory conditions that may cause direct pain or affect other components of the back.
What is the pattern of disease for generalized low back pain?
The pain-spasm-pain cycle of low back pain
The back tends to act stereotypically when it senses irritation, inflammation, or instability. It tends to tighten up the supporting muscles to act as an internal brace against movement in the region. These chronically contracting muscles start to ache and generate their own pain, setting up a pain-spasm-pain cycle. It can be rather difficult to break out of this cycle without addressing or eliminating the original source of irritation and pain (e.g., the pain generator).
Identifying the origins of generalized low back pain
The back can become painful for any number of reasons. Yet, the pain principally manifests as generalized muscular pain. This pain can run up and down the spine, radiate into the buttocks and legs (as far as the knees), or can be localized into regions (e.g., sacroiliac region) of intense muscular spasms.
The original cause of low back pain can be almost impossible to identify. Furthermore, imaging generally reveals a host of degenerative abnormalities. All of these abnormalities (or possibly none of them) can be acting as the primary pain generators or contributing to the pain syndrome.
Ladled on top of this is the fact that a straightforward assessment of low back pain can be hampered by psychosocial and legal factors such as workman’s compensation, litigation, drug dependency, narcotic abuse or sales, depression, secondary gain, malingering, and conversion disorder (a psychosomatic disorder).
When you are confronted with a patient with acute generalized back pain, you have quite a challenge on your hands. Most of the time, a definitive cause will never be determined. However, the good news is that most acute low back pain syndromes are self-limited and will go away—or at least improve—with time and conservative management.
What to do if you suspect generalized low back pain as a possible diagnosis?
Obtain a good history on the low back pain
When assessing a patient with generalized low back pain, start with a good history. Ask about precipitating factors and alleviating factors. In other words, which factors make the pain worse, and which factors make it better?
Ask about the symptom onset, duration, and attempted treatments, including any history of spinal surgery. You'll be amazed at how many patients forget to tell you that they’ve had major spinal surgery in the past!
Next, grade the patient’s pain for future reference. It's important to follow the trajectory of the syndrome. There are multiple pain scales available, such as the Oswestry Disability Index. Some clinicians employ a simple pain rating scale of one to ten. Or, you can use the patient's own words to denote the degree of pain.
Ask about associated neurological symptoms such as leg weakness, paresthesia, imbalance, bowel dysfunctions, and bladder dysfunctions. Always keep in mind the possibility of myelopathy or cauda equina syndrome.
Also, ask about daily activities and occupational demands. For example, it should not come as a surprise that a coal miner or a paratrooper would develop back pain. Also, consider that psychological factors may be contributing to the symptoms.
Remember to ask low back pain patients about red flags (indicators of more serious and urgent conditions), since definitive red flags necessitate early radiographic evaluation:
- History of cancer and related symptoms
- Recent trauma
- High-risk behavior
- Steroid use
- Progressive weakness
- Severe intractable pain
- Gait dysfunction
- Bowel and bladder dysfunction
Perform physical and neurological exams for low back pain
It's important to perform good physical and neurological exams for patients with generalized low back pain. You don't want to miss clues for what could be a pain generator for your patient. As well, you want to evaluate for the possibility of serious differential pathologies.
In your physical examination of the patient, start by examining their back. Look for localized tenderness in the spinous processes or in the adjacent muscles of the spine. Does palpation reproduce the pain? Are the muscles tight? Next, look at the skin of the back. Check for signs of spina bifida such as hemangiomas, lumps, tracts, or hairy patches.
Note that patients with severe persistent back pain often have burns on their back from overuse of various heating pads and devices.
Also, try to gauge how deconditioned the patient is. How strong are the patient’s truncal support muscles?
Next, have the patient go through a range of motion for their spine, including flexion, extension, rotation, and lateral bending. How limited is the patient? Do any of these movements exacerbate the pain?
Consider diagnostic imaging for low back pain
Do not feel that you have to order magnetic resonance imaging (MRI) right away. Remember, most lower back pain flair-ups will be self-limited.
Although discouraged by some experts, if you are evaluating a patient in an acute care setting, an anteroposterior (AP) and lateral flexion-extension x-ray can help assess obvious boney lesions, evidence of trauma, severe spinal deformity, and abnormal movement in the spine. It also can be somewhat reassuring for the patient.
On the other hand, electromyogram (EMG) and nerve conduction velocity (NCV) studies are seldom of use and can be very confusing.
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