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Chapter 7 covered a general approach to and a detailed examination of the patient with back or neck pain. In this chapter, a more extensive discussion of specific conditions of the spine is presented. For a review of seronegative spondyloarthropathy (e.g., ankylosing spondylitis), the reader is referred to Chapter 3, “Rheumatology.” Fractures of the spine are addressed in Chapters 9 and 10.
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It should be noted that in an unselected emergency department (ED) population presenting with back pain, between 1 and 5 will have a specific diagnosis and approximately 1 in 200 will need surgery. The challenge for the clinician is to identify these small patient populations from amongst the larger group with a complaint of “back pain.” The clinician, armed with a history and physical examination, must frequently decide who needs further emergent workup and who can be safely observed. Further challenging the clinician is that spinal syndromes can present in a subtle fashion, and there is a great deal of clinical overlap between many of the pathophysiologic processes.
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The imaging of most patients presenting with spinal disorders is driven by the search for “red flags” in the history or physical examination. Generally, there is higher concern and hence a lower threshold to image those aged younger than 18 and those with age above 50. Also included in this group are those with immunocompromise, IV drug use, those with histories of primary cancers that are known to metastasize to the spine, those with recurrent infections (e.g., GU infections), those with significant trauma, and those exhibiting neurologic dysfunction. In the absence of “red flags,” it is generally recommended that imaging be avoided in the first 4 to 6 weeks of the back pain syndrome, as the vast majority of patients will resolve within this time frame.
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Cauda Equina Syndrome
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Cauda equina syndrome refers to nerve compression within the spinal canal that occurs below the L1–2 interspace after the termination of the spinal cord. The clinical picture is that of a lower motor neuron lesion with weakness or paralysis, loss of rectal tone, sensory loss in a dermatomal pattern, decreased deep tendon reflexes, and bladder dysfunction. The classic sensory description is “saddle” anesthesia, with loss of sensation in the buttocks and perineal areas. It should be noted that within the first few days, a complete cord syndrome may present similarly until upper motor neuron symptoms develop.
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The most common cause of cauda equina syndrome is a large midline disk herniation, usually at the L4–5 or L5-S1 interspaces. Other causes include spinal metastases, spinal hematoma, epidural abscess, vertebral fracture, or transverse myelitis.1,2 Although anal sphincter tone is decreased in up to 80% of patients, an elevated postvoid residual is the most consistent finding to make the diagnosis.3 A postvoid residual of more than 100 to 200 mL of urine is ...