Pott's Disease

Pott’s disease Definition Pott’s disease is a presentation of extrapulmonary tuberculosis that affects the spine, a kind of tuberculous arthritis of the intervertebral joints. It is named after Percivall Pott (1714-1788), a London surgeon who trained at Barts. Scientifically, it is called tuberculous spondylitis and it is most commonly localized in the thoracic portion of the spine. AKA: Pott's syndrome, Pott's caries, Pott's curvature, angular kyphosis, kyphosis secondary to tuberculosis, tuberculosis of the spine, tuberculous spondylitis and David's disease Incidence United States • • • •

Although the incidence of tuberculosis increased in the late 1980s to early 1990s, the total number of cases has decreased in recent years. The frequency of extrapulmonary tuberculosis has remained stable. Bone and soft-tissue tuberculosis accounts for approximately 10% of extrapulmonary tuberculosis cases and between 1% and 2% of total cases. Tuberculous spondylitis is the most common manifestation of musculoskeletal tuberculosis, accounting for approximately 40-50% of cases.4

International Approximately 1-2% of total tuberculosis cases are attributable to Pott disease. In the Netherlands between 1993 and 2001, tuberculosis of the bone and joints accounted for 3.5% of all tuberculosis cases (0.2-1.1% in patients of European origin and 2.3-6.3% in patients of non-European origin). Mortality/Morbidity • •

Pott disease is the most dangerous form of musculoskeletal tuberculosis because it can cause bone destruction, deformity, and paraplegia. Pott disease most commonly involves the thoracic and lumbosacral spine. However, published series have show some variation. Lower thoracic vertebrae is the most common area of involvement (40-50%), followed closely by the lumbar spine (35-45%). In other series, proportions are similar but favor lumbar spine involvement.

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Approximately 10% of Pott disease cases involve the cervical spine.

Risk/ Predisposing factors • • • • • •

Manifestation: back pain fever night sweating anorexia weight loss Spinal mass, sometimes associated with numbness, tingling, or muscle weakness of the legs

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Data from Los Angeles and New York show that musculoskeletal tuberculosis primarily affects African Americans, Hispanic Americans, Asian Americans, and foreign-born individuals. As with other forms of tuberculosis, the frequency of Pott Disease is related to socioeconomic factors and historical exposure to the infection.

Sex •

Although some series have found that Pott disease does not have a sexual predilection, the disease is more common in males (male-to-female ratio of 1.52:1).

Age • •

In the United States and other developed countries, Pott disease occurs primarily in adults. In countries with higher rates of Pott disease, involvement in young adults and older children predominates.

Type/ Stage/ Classification • •

Bone/Spinal Disease Non-Communicable Disease

Pathophysiology Pott’s disease is usually secondary to an extraspinal source of infection. The basic lesion involved in Pott’s disease is a combination of osteomyelitis and arthritis that usually involves more than one vertebra. The anterior aspect of the vertebral body adjacent to the subchondral plate is area usually affected. Tuberculosis may spread from that area to adjacent intervertebral disks. In adults, disk disease is secondary to the spread of infection from the vertebral body. In children, because the disk is vascularized, it can be a primary site. Progressive bone destruction leads to vertebral collapse and kyphosis. The spinal canal can be narrowed by abscesses, granulation tissue, or direct dural invasion, leading to spinal cord compression and neurologic deficits. The kyphotic deformity is caused by collapse in the anterior spine. Lesions in the thoracic spine are more likely to lead to kyphosis than those in the lumbar spine. A cold abscess can occur if the infection extends to adjacent ligaments and soft tissues. Abscesses in the lumbar region may descend down the sheath of the psoas to the femoral trigone region and eventually erode into the skin.

Pulmonary tuberculosis

Spread of mycobacterium tuberculosis from other Extrapulmomary tuberculosis The infection spreads from two adjacent vertebrae into the adjoining disc space

Back pain, Fever, Night sweats, Anorexia, Weight loss, and easy One vertebra is affected, the disc is normal Two are involved; the avascular intervertebral disc cannot receive nutrients and collapse Disk tissue dies and broken down by caseation

Vertebral narrowing

Vertebral collapse

Spinal damage POTT’S DISEASE Kyphosis, paraplegia, bowel and urinary incontinenece Surgery: evacuation of pus, Anterior decompression spinal fusion

Diagnostic Studies

Laboratory Studies • • •

Tuberculin skin test (purified protein derivative [PPD]) results are positive in 8495% of patients with Pott disease who are not infected with HIV. The erythrocyte sedimentation rate (ESR) may be markedly elevated (>100 mm/h). Microbiology studies are used to confirm diagnosis. Bone tissue or abscess samples are obtained to stain for acid-fast bacilli (AFB), and organisms are isolated for culture and susceptibility. CT-guided procedures can be used to guide percutaneous sampling of affected bone or soft-tissue structures. These study findings are positive in only about 50% of the cases.

Imaging Studies •

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Radiography • Radiographic changes associated with Pott disease present relatively late. The following are radiographic changes characteristic of spinal tuberculosis on plain radiography:13 • Lytic destruction of anterior portion of vertebral body • Increased anterior wedging • Collapse of vertebral body • Reactive sclerosis on a progressive lytic process • Enlarged psoas shadow with or without calcification • Additional radiographic findings may include the following: • Vertebral end plates are osteoporotic. • Intervertebral disks may be shrunk or destroyed. • Vertebral bodies show variable degrees of destruction. • Fusiform paravertebral shadows suggest abscess formation. • Bone lesions may occur at more than one level. CT scanning14 ο ο ο ο

CT scanning provides much better bony detail of irregular lytic lesions, sclerosis, disk collapse, and disruption of bone circumference. Low-contrast resolution provides a better assessment of soft tissue, particularly in epidural and paraspinal areas. CT scanning reveals early lesions and is more effective for defining the shape and calcification of soft-tissue abscesses. In contrast to pyogenic disease, calcification is common in tuberculous lesions.

MRI

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MRI is the criterion standard for evaluating disk-space infection and osteomyelitis of the spine and is most effective for demonstrating the extension of disease into soft tissues and the spread of tuberculous debris under the anterior and posterior longitudinal ligaments. MRI is also the most effective imaging study for demonstrating neural compression. MRI findings useful to differentiate tuberculous spondylitis from pyogenic spondylitis include thin and smooth enhancement of the abscess wall and well-defined paraspinal abnormal signal, whereas thick and irregular enhancement of abscess wall and ill-defined paraspinal abnormal signal suggest pyogenic spondylitis. Thus, contrast-enhanced MRI appears to be important in the differentiation of these two types of spondylitis.

Other Tests • •

Radionuclide scanning findings are not specific for Pott disease. Gallium and Tc-bone scans yield high false-negative rates (70% and up to 35%, respectively).

Management Medical Care •

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Before the advent of effective antituberculosis chemotherapy, Pott disease was treated with immobilization using prolonged bed rest or a body cast. At the time, Pott disease carried a mortality rate of 20%, and relapse was common (30%). The duration of treatment, surgical indications, and inpatient care have since evolved. Studies performed by the British Medical Research Council indicate that tuberculous spondylitis of the thoracolumbar spine should be treated with combination chemotherapy for 6-9 months. According to the most recent recommendations issued in 2003 by the US Centers for Disease Control and Prevention, the Infectious Diseases Society of America, and the American Thoracic Society, a 4-drug regimen should be used empirically to treat Pott disease. Isoniazid and rifampin should be administered during the whole course of therapy. Additional drugs are administered during the first 2 months of therapy. 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. Regarding the duration of therapy, the British Medical Research Council studies did not include patients with multiple vertebral involvement, cervical lesions, or major neurologic involvement. Because of these limitations, many experts still recommend chemotherapy for 9-12 months. Opinions differ regarding whether the treatment of choice should be conservative chemotherapy or a combination of chemotherapy and surgery. The treatment

decision should be individualized for each patient. Routine surgery does not to seem to be indicated. Most common indications for surgical procedures are discussed below. Surgical Care •

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Indications for surgical treatment of Pott disease generally include the following: o Neurologic deficit (acute neurologic deterioration, paraparesis, paraplegia) o Spinal deformity with instability or pain o No response to medical therapy (continuing progression of kyphosis or instability) o Large paraspinal abscess o Nondiagnostic percutaneous needle biopsy sample Resources and experience are key factors in the decision to use a surgical approach. The lesion site, extent of vertebral destruction, and presence of cord compression or spinal deformity determine the specific operative approach (kyphosis, paraplegia, tuberculous abscess). Vertebral damage is considered significant if more than 50% of the vertebral body is collapsed or destroyed or a spinal deformity of more than 5° exists. The most conventional approaches include anterior radical focal debridement and posterior stabilization with instrumentation. In Pott disease that involves the cervical spine, the following factors justify early surgical intervention: o High frequency and severity of neurologic deficits o Severe abscess compression that may induce dysphagia or asphyxia o Instability of the cervical spine Contraindications: Vertebral collapse of a lesser magnitude is not considered an indication for surgery because, with appropriate treatment and therapy compliance, it is less likely to progress to a severe deformity.

Nursing Diagnosis •

Acute pain related to inflammatory process

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Disturbed body image related to trauma/injury to spinal cord

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Self – bathing hygiene deficit related to musculoskeletal impairment

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Impaired physical mobility related to therapeutic restriction of movement

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Imbalance nutrition related to inadequate food intake

Nursing Responsibilities

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Drug treatment is generally sufficient for Pott’s disease, with spinal immobilization if required. Surgery is required if there is spinal deformity or neurological signs of spinal cord compression. Standard antituberculosis treatment is required. Duration of antituberculosis treatment: If debridement and fusion with bone grafting are performed, treatment can be for six months. If debridement and fusion with bone grafting are NOT performed a minimum of 12 months’ treatment is required. It may also be necessary to immobilize the area of the spine affected by the disease, or the person may need to undergo surgery in order to drain any abscesses that may have formed or to stabilize the spine. Other interventions include application of knight/ taylor brace, head halter traction. Surgery includes ADSF (Anterior decompression Spinal fusion).

Illustration: Internet http://www.patient.co.uk/showdoc/40001278/ http://emedicine.medscape.com/article/226141 http://www.pdfcoke.com Book Medical Surgical Nursing by Suzanne Smeltzer and Brenda Bare, 10th Edition, Chapter 68-Musculoskeletal Medical Surgical Nursing by Joyce Black