Pott's Disease

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Original Editors - David Pieschel & Craig Satterley from Bellarmine University's Pathophysiology of Complex Patient Problems project.

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Definition/Description

Pott’s Disease, also known as tuberculosis spondylitis, is a rare infectious disease of the spine which is typically caused by an extraspinal infection. Pott’s Disease is a combination of osteomyelitis and arthritis which involves multiple vertebrae. (3) The typical site of involvement is the anterior aspect of the vertebral body adjacent to the subchondral plate and occurs most frequently in the lower thoracic vertebrae. A possible effect of this disease is vertebral collapse and when this occurs in this aspect of the vertebrae, anterior wedging results leading to kyphotic deformity of the spine. (2,3) Other possible effects can include compression fractures, spinal deformities and neurological insults, including paraplegia. (3,4)

Prevalence

Incidence
In 2005, there were 8.8 million new patients with tuberculosis (TB) all over the world, and of these, there were 7.4 million in Asia and sub-Saharan Africa (5). Involvement of the spine reportedly occurs in less than 1-2% of patients who contracted TB. Although the incidence of tuberculosis increased in the late 1980’s to early 1990’s, the total number of cases has decreased in recent years. In the United States, bone and soft tissue tuberculosis accounts for approximately 10% of extrapulmonary TB cases and between 1% and 2% of total cases. Of these cases, Pott’s disease is the most common manifestation of musculoskeletal TB, accounting for approximately 40-50% (3).Internationally, approximately 1-2% of total tuberculosis cases are attributable to Pott’s disease.

Ethnicity
Data from the United States show that musculoskeletal tuberculosis primarily affects African Americans, Hispanic Americans, Asian Americans, and foreign-born individuals (3). The number of patients with TB spondylitis in Japan also declined to 233 in 2005 from 734 in 1978 and 276 in 2001 [10, 21].

Gender
Although some series have found that Pott’s disease does not have sexual predilection, the disease is more common in males. The male to female ratio is reportedly 1.5-2:1.

Age
In the United States and other developed countries, Pott’s disease occurs primarily in adults. In underdeveloped countries which have higher rates of Pott’s disease, involvement in young adults and older children predominates (3).

Characteristics/Clinical Presentation

Signs and Symptoms

• Back Pain: Back pain is the earliest and most common symptom. Patients with Pott’s disease usually experience back pain for weeks before seeking treatment and the pain caused by spinal TB can present as spinal or radicular. Although both the thoracic and lumbar spinal segments are nearly equally affected, the thoracic spine is frequently reported as the most common site of involvement. Together, thoracic and lumbar involvement comprise of 80-90% of spinal TB sites(3).
• Neurological signs: Neurologic abnormalities occur in 50% of cases and can include spinal cord compression with paraplegia, paresis, impaired sensation, nerve root pain and/or cauda equina syndrome(3).

• Spinal Deformities: Almost all patients with Pott’s disease have some degree of spine deformity with thoracic kyphosis being the most common (3).
• Constitutional Symptoms: Potential constitutional symptoms include fever, weight loss and malaise(7).
• Cervical Spinal TB: Cervical spine TB is a less common presentation occurring in approximately 10% of cases, but is potentially more serious because severe neurological complications are more likely. This condition is characterized by cervical pain and stiffness and symptoms can also include torticollis, hoarseness, and neurological deficits. Upper cervical spine involvement can cause rapidly progressive symptoms and neurologic manifestations occur early and range from a single nerve palsy to hemiparesis or quadriplegia. Retropharyngeal abscesses occur in almost all cases. In lower cervical spine insults, the patient can present with dysphagia or stridor(3).
• Presentation in People Infected with HIV: The clinical presentation of spinal tuberculosis in patients infected with the human immunodeficiency virus (HIV) is similar to that of patients who are HIV negative; however, spinal TB seems to be more common in persons infected with HIV(3).
• Asymptomatic Presentation: Many persons with Pott’s disease (62-90%) of patients reported series have no evidence of extraspinal tuberculosis, further complicating a timely diagnosis.(3)
  

Associated Co-morbidities

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Medications

The duration of treatment is somewhat controversial. Although some studies favor 6 to 9 month course, traditional courses range from 9 months to longer than 1 year. The duration of therapy should be individualized and based on the resolution of active symptoms and the clinical stability of the patient.
The main drug class consists of agents that inhibit growth and proliferation of the causative bacteria. Isoniazid and rifampin should be administered during the whole course of therapy. Additional drugs are administered during the first two months of therapy and these are generally chosen among the first-line drugs which include pyrazinamide, ethambutol, and streptomycin. The use of second-line drugs is indicated in cases of drug resistance.

Isoniazid (Laniazid, Nydrazid)
View full drug information: http://reference.medscape.com/drug/isoniazid-342564
Highly active against Mycobacterium tuberculosis. Has good GI absorption and penetrates well into all body fluids and cavities.

Rifampin (Rifadin, Rimactane)
View full drug information: http://reference.medscape.com/drug/rifadin-rimactane-rifampin-342570
For use in combination with at least one other antituberculous drug; inhibits DNA-dependent bacterial but not mammalian RNA polymerase. Cross-resistance may occur.

Pyrazinamide
View full drug information: http://reference.medscape.com/drug/pyrazinamide-342678
Bactericidal against M tuberculosis in an acid environment (macrophages). Has good absorption from the GI tract and penetrates well into most tissues, including CSF.

Ethambutol (Myambutol)
View full drug information: http://reference.medscape.com/drug/myambutol-ethambutol-342677
Has bacteriostatic activity against M tuberculosis. Has good GI absorption. CSF concentrations remain low, even in the presence of meningeal inflammation.

Streptomycin
View full drug information: http://reference.medscape.com/drug/streptomycin-342682
Bactericidal in an alkaline environment. Because it is not absorbed from the GI tract, must be administered parenterally. Exerts action mainly on extracellular tubercle bacilli. Only about 10% of the drug penetrates cells that harbor organisms. Enters the CSF only in the presence of meningeal inflammation. Excretion is almost entirely renal. (3)

Diagnostic Tests/Lab Tests/Lab Values

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Etiology/Causes

The organism that has been identified as causing Pott’s disease is mycobacterium tuberculosis. The bacteria’s primary mode of transmission to the spine is through the blood most often originating in the lungs. (8, 9) The infection has also been found to spread through the lymphatic system. (6) Once being spread, the infection can target vertebrae, intervertebral discs, the epidural or intradural space within the spinal canal and adjacent soft tissue. (7)

If a single vertebra is affected, the surrounding intervertebral discs will remain normal. However, if two adjacent vertebrae are affected, the intervertebral disc between them will also collapse and become avascular. (8) Due to the vascularity of intervertebral discs in children, the discs can become a primary site of infection rather than spreading from the vertebrae. (3)

Spinal cord compression in Pott’s disease is usually caused by paravertebral abscesses which can also develop calcifications or sequestra within them. (2) If the infection reaches adjacent ligaments and soft tissues, a cold abscess can also form. Abscesses in the lumbar region may descend down the sheath of the psoas to the femoral trigone region and eventually erode into the skin. (3) Other causes of neurological involvement include dural invasion from granulation tissue, sequestrated bone, intervertebral disc collapse or a dislocated vertebra. (2,3,8) Neurological symptoms can occur at any point, including years later as a result of stretching of the spinal cord within the vertebral foramen of the deformed spine. (2)

Systemic Involvement

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Medical Management (current best evidence)

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Physical Therapy Management (current best evidence)

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Alternative/Holistic Management (current best evidence)

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Differential Diagnosis

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Case Reports/ Case Studies

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Resources

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Recent Related Research (from Pubmed)

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References

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