A 39-Year-Old Man With Debilitating Back Pain

Tami O. Tiamfook-Morgan, MD; Daniel M. Lindberg, MD

Disclosures

April 27, 2016

Tuberculous spondylitis typically presents with a 3- to 4-month history of achy back pain that gradually intensifies and is sometimes associated with muscle spasm or radicular pain. Fever, weight loss, and elevated white blood cell counts are not typical, presenting in less than 40% of cases.[4] Neurologic abnormalities occur in 50% of patients and may include nerve root pain, cauda equina syndrome, sensory loss, or paresis. The most serious complication of tuberculous spondylitis is spinal cord compression that causes paraplegia; this condition is also known as "Pott paraplegia."

Diagnosis of Pott disease can be challenging because of the indolent nature of the disease and the extensive differential diagnosis. A comprehensive history that includes questions about the patient's country of origin, history of tuberculosis exposure, and family history of tuberculosis must be performed. A complete physical examination should also be performed, with careful assessment of the spine, skin, abdomen (looking for a flank mass), and lungs. A complete neurologic examination, including assessment of strength, rectal tone, perineal sensation, and lower-extremity reflexes, is vital. A chest radiograph can be obtained to visualize apical scarring, cavitary disease, or infiltrates; however, the diagnosis should still be investigated despite a negative chest radiograph, especially if clinical suspicion is strong.

Tuberculin skin testing (purified protein derivative [PPD]) should be performed because it is positive in 90% of immunocompetent patients with skeletal tuberculosis. Nonetheless, a negative tuberculin skin test does not exclude a diagnosis of tuberculosis. In particular, patients who are immunocompromised are more likely to have a false-negative PPD test; such patients are the most susceptible to Pott disease.[5] The erythrocyte sedimentation rate should also be checked, because it is frequently elevated (> 100 mm/h) in patients with Pott disease.

A biopsy of the affected area with positive acid-fast bacillus stain or cultures is diagnostic. Unfortunately, the tubercle bacillus is notably difficult to isolate, with only 50% of biopsies yielding positive cultures.

MRI and CT are both excellent studies for visualizing the typical findings of Pott disease. Plain radiographs can also show evidence of tuberculous spondylitis, including osteolytic destruction of the vertebral body, collapse of the vertebral body, increased anterior wedging, and reactive sclerosis. CT can reveal the bony detail of irregular osteolytic lesions, disk collapse, sclerosis, or disruption of bone circumference.

MRI is effective at demonstrating neural compression and the presence of epidural abscesses, and differentiating tuberculous spondylitis from pyogenic spondylitis; the latter condition is characterized by a thick and irregular enhancement of the abscess wall, whereas enhancement is typically smooth and thin in tuberculous spondylitis.[6] In addition, tuberculous spondylitis differs radiologically from pyogenic spondylitis in that the disk space is usually secondarily involved or not involved at all; vertebral body involvement with disk-space sparing may be seen. As a result of this pattern of involvement, tuberculous spondylitis may exhibit skip lesions from subligamentous extension, whereas pyogenic spondylitis almost always involves a disk and adjacent vertebral bodies.

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