Operational Medicine 2001
Low Back Pain

Initial evaluation requires:

• Differentiation of acute (6 wks or less) from chronic pain (>12 wks)

• Identification of neurologic deficit and radiculopathy.  

Chronic pain or pain that is refractory to conservative treatment requires a more thorough evaluation noting any changes in the history as to character, pattern and associated symptoms.

Differential Diagnosis of low back pain

• “Mechanical” low back pain

• Sciatica

• Herniated nucleus pulposus with/without nerve impingement

• Spondylolysis with or without Spondylolysthesis

• Scoliosis

• Sacroiliac joint (SI joint) dysfunction

• Rare causes: 

  • Infection

  • Connective tissue disease  (e.g. Ankylosing spondylitis)

  • Tumor

  • Referred pain – e.g. kidney stone, abdominal aortic aneurysm (AAA)

  • Spinal stenosis

History

Ask usual questions about the pain such as:

• Duration

• Character

• Radiation

• What makes it worse and better

• Associated symptoms

• Neurologic symptoms of numbness, tingling or weakness

• Any loss of bowel or bladder control

• Trauma

• Previous treatment

Physical Exam 

• Check for range of motion of the back in 

  • Flexion

  • Extension

  • Rotation to the right and left

  • Bending to the right and left.  

• Inspect the back for obvious signs of deformity.  

• While forward flexing, look for one shoulder higher than the other- this would suggest scoliosis.  

• Palpate the spinous processes and surrounding tissues for tenderness.  

• Note any paraspinal muscle spasm.  

• Perform a neurological exam as detailed below for a suspected herniated disk:

• Rectal tone if loss of bowel or bladder control (S2, 3,4)

• Straight leg raise – note the degree of flexion that reproduces the radiating symptoms

• Biomechanics should be evaluated as they may contribute to low back pain and may be corrected.  

  • Examine for tight hamstrings and hip flexors

  • Leg length discrepancy

  • Genu varum/valgum

  • Pes planus.

Additional tests:

• Stork – back extended while lifting one leg (pain in spine => R/O pars interarticularis defect; seen on oblique X-rays)

• Fabere– for hip and SI joint involvement.  Pt supine with involved side foot on opposite knee (flexed abducted, externally rotated hip) causes pain in hip; then to stress the SI joint, press down on flexed knee and the opposite anterior superior iliac spine

• Gaenslen’s sign (SI joint pain) – with both legs drawn onto chest, shift pt to side of table (one buttock over edge); the unsupported leg drops over the edge while the opposite leg remains flexed

• SI compression/distraction – compress or distract pelvis

Radiologic tests

• Plain radiographs are not recommended for routine evaluation of acute LBP within the first month unless a finding from the history and physical exam raises concern such as signs and symptoms of spondylolysis, scoliosis, cauda equina syndrome, tumor or infection.  Indications for further studies are reserved for patients whose symptoms continue despite conservative treatment. 

• X-rays (deformity of spine).  Check obliques if suspect spondylolysis

• MRI (tumors, infection, HNP, spinal stenosis)

• Bone scan if spondylolysis and can’t tell if new or old

Lab Tests

• CBC (infection, lymphoma)

• ESR (inflammatory process)

Waddell’s test is used to look for nonorganic back pain.  3 or more positive responses suggest psychosocial issues as cause of pain:

• Tenderness (superficial nonanatomic, tenderness to light touch)

• Simulation tests (axial loading – vertical loading on the skull; rotation – passive rotation of shoulders and pelvis in same plane causes pain)

• Distraction (discrepancy between sitting and supine straight leg raising tests)

• Regional disturbances (nonanatomic weakness or paresthesia)

• Overreaction (disproportionate facial expression, verbalization or tremor)

What should one look for to determine if there is a need for emergent referral/ Medevac:

• Cauda equina syndrome – pressure on the cauda equina/nerves in the spine from a herniated disk or other tissue that causes bladder/bowel incontinence, urinary retention, saddle anesthesia, loss of anal sphincter tone, neurological compromise or progressive major motor weakness of lower extremity.  If the pressure is not relieved in a timely fashion there may be permanent neurologic damage.

• Fracture – history of trauma, step off on exam, neurologic signs/symptoms

• Infection – fever, toxic appearing patient

• Tumor/malignancy - unexplained weight loss, night sweats, night pain, x-ray lesions

• AAA - Inability to find position of comfort, referred pain, pulsatile mass in belly – usually in elderly

Management of low back pain

• If there are no worrisome signs or symptoms, low back pain is usually managed conservatively very successfully – 80-90 percent will be recovered in 4-6 weeks.

• Radicular symptoms that are not progressing can be managed conservatively. 

• Reduce activity – relative rest.  Not bed rest – bed rest for longer than a day actually deconditions the body and may produce a prolonged time to recovery

• Pain management -NSAIDs, tylenol

• Modalities such as ice, heat, ultrasound may help

• Gentle flexibility exercises for back, hamstrings

• Strengthening of abdominal muscles/trunk support

• If signs and symptoms worsen or do not improve over 4 weeks, consider radiographic studies.

Sciatica

Sciatica refers to a form of low back pain where the sciatic nerve is irritated.  The sciatic nerve is the coalition of S2, 3, and 4.  There is often pain in the area of the sciatic notch and this may be where the nerve is irritated.  Treatment is the same as mechanical low back pain. 

Chris Polkoski, MS, PA-C and CDR Scott D. Flinn, MC, USN

For further information, read:

Low Back Pain, in the General Medical Officer Manual

Approved for public release; Distribution is unlimited.

The listing of any non-Federal product in this CD is not an endorsement of the product itself, but simply an acknowledgement of the source. 

Operational Medicine 2001
Health Care in Military Settings

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