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Lower Back Pain - 10/5/2012

posted Oct 5, 2012, 1:04 PM by Monique Tanna   [ updated Dec 27, 2012, 6:45 AM by Purnema Madahar ]

Firm II has finally hit the NW wards this month!  We had our first CRS today, a very interesting case of a young man who presented with back pain.  The patient had been experiencing back pain for the past few months, and had attributed it to musculoskeletal pain.  His pain acutely worsened over 1-2 weeks which is when he presented to us.  After a great discussion on the pertinent history and differential diagnosis, the Residents successfully narrowed their differential to malignancy secondary to myeloma or metastases and put 90% of their money on this diagnosis.

I’d like to take a moment to discuss the presentation of back pain, an exceedingly common entity and one that causes frustration among many clinicians due to the limited therapeutic options for chronic musculoskeletal pain.  As we learned today, there are some features of back pain that should raise some flags, and some questions that we should be sure to ask every patient presenting to us with back pain in the outpatient setting.

Low back pain is the second most common symptom-related reason for a physician visit (second to upper respiratory complaints) (1).  The attached article reviews the common complaint of back pain, including causes, diagnostic evaluation, and natural history of mechanical back pain.  Important questions to ask to differentiate mechanical back pain from nonmechanical spinal conditions and visceral disease and identify emergencies are:

  1. Is systemic disease causing the pain?
    Think about: patient’s age (age>65 increases likelihood of malignancy, compression fractures, spinal stenosis, aortic aneurysms), h/o cancer, weight loss, IVDU, chronic infection, duration, nighttime pain, response to therapy, characteristics of sciatica or pseudoclaudication.

  2. Is there social or psychological distress that may amplify or prolong the pain?

  3. Is there neurologic compromise that may require surgical evaluation?

Associations of specific etiologies of back pain with history/physical (i.e. things to ask and look for!):

  • malignancy: nighttime pain, not relieved by lying down, weight loss, night sweats
  • infection: pain not relieved by lying down, fever, vertebral tenderness (sensitive but not specific)
  • ankylosing spondylitits: may have concurrent arthritides of knees or hips, chest expansion of
    < 2.5 cm (specific but not sensitive)
  • spinal stenosis: pseudoclaudication
  • sciatica due to disc herniation: increases with cough and Valsalva, positive straight leg raise
  • cauda equine syndrome: bowel or bladder dysfunction; may be due to malignancy or a massive herniation; may also see overflow incontinence, saddle anesthesia, bilateral sciatica and weakness
  • persistent unexplained symptoms: may be due to depression, somatization, psychosocial stressors

Straight Leg Raise: we do it all the time, but can you define it?  An abnormal test is one that reproduces symptoms of sciatica at less than 60 degrees.  The pain radiates below the knee, not just in the back or hamstring.  An ipsilateral SLR test is sensitive but not specific for a herniated disc.  Crossed SLR (symptoms reproduced in the opposite leg) is specific but not sensitive (1). 

When to Image: some guidelines recommend plain radiography in the presence of trauma or findings suggesting systemic disease such as fever, weight loss, focal neurologic deficits, IVDU, age above 50, and persistent symptoms for more than 4-6 weeks, while others argue for more stringent criteria.  An ESR and CBC may be helpful in cases of a strong suspicion of systemic disease.  CT or MRI should be reserved for when there is a strong suspicion of an underlying infection, malignancy or neurologic deficits, as incidental findings can lead to overdiagnosis, anxiety, and unnecessary testing and treatment.

Our patient was 44 years old, had constant lower back pain for months with acute worsening for one week.  There was no radiation, and the pain was worse with movement.  He had a 30-lb weight loss over 3 years but was also on a diet for his DM.  No fever, h/o IVDU, incontinence, sciatica symptoms, or weakness, but he had impaired mobility due to pain without focal deficits on exam.  He had a nontender soft tissue mass below the right posterior rib, as well as a soft tissue mass in the left upper quadrant of his abdomen.  Labs revealed mild hypercalcemia, mild renal insufficiency, no protein gap, elevated alkaline phosphatase, and imaging revealed innumerable lucencies in the pelvis and spine.  Further workup and biopsy led to the diagnosis of kappa light chain myeloma.  Dr. Fries gave us an excellent review of multiple myeloma, and I am also attaching a recent NEJM article that reviews the biology, clinical presentation, diagnosis, staging, and treatment of multiple myeloma.  Enjoy!

1. Low Back Pain Review
Deyo RA, Weinstein JN. Low back pain. N Engl J Med 2001;344:363-370

2. Multiple Myeloma Review
Palumbo A, Anderson K. Multiple Myeloma. N Engl J Med 2011;364:1046-1060

3. Multiple Myeloma, Images in Clinical Medicine
Green WH, Schosser RH. Dermatologic Signs of Multiple Myeloma. N Engl J Med 2011;365:71