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Pott's Disease:Tuberculous Spondylitis
Medicine Morning ReportMarch 30, 2009Michael Craig
Introduction
HistoryEpidemiologyPathophysiologyClincal FindingsDifferential DiagnosisRadiologic and Diagnostic StudiesTreatment
History
Classic description first in 1779 by Percival Pott, an English surgeon. Other notable achievements:
First to link cancer to environmental carcinogens (scrotal cancer in chimney sweeps)Pott's fracture - bimalleolar ankle fracturePott's puffy tumor - subperiosteal abcess and osteomyelitis of the frontal bone, serous complication of sinusitis
One of oldest diseases of which we have evidence
4000 BC Egyptian mummies noted with typical featuresDNA from vertebral lesion in 12-year-old from 1000 AD identified M. tuberculosis
Epidemiology
20% of TB patients in the US have extrapulmonary TBPott's diseease occurs in 5% of those with extrapulmonary tuberculosis45% with spinal involvement have associated neurological deficits1-2% of overall tuberculosis cases
Much more common in the undeveloped world
Endemic areas - tends to occur about 1 year after primary infection and more common in children & young adultsDeveloped nations - more often late reactivation disease and occurs more in adults
PathophysiologyUsually occurs via hematongenous spread
Vertebral bodies vulnerable due to high blood flow
Lumbar and lower thoracic involvement more common, although can involve cervical vertebrae
Usually begins in anterior vertebral body
Neurological symptoms and cord compression from abcesses, dural involvement or scarring tissue
Kyphosis develops from collapse of anterior spine (mainly amongst thoracic vertebrae)
Clinical FindingsUsual presents as local pain
Can be indolent in onset with gradually worsening over weeks to monthsAs worsens usually severe muscle spasm and rigidity
Systemic symptoms (fever, weight loss, etc.) present <40% of patients
60-90% with no evidence of extraspinal tuberculosis
Many (~50% in endemic areas) present with neurologic symptoms
Kyphosis may be seen on presentation in advanced disease
Gibbious Deformity
Anterior wedging leads to focal kyphosisthis is the angular gibbious deformity, or "humpbacked" appearance
Differential DiagnosisInfection
Staph aureus vertebral osteomyelitisBrucellosisActinomycesCandidaHistoplasmosisBlastomycosisOther mycobacterium
Cancer
Metastatic lesionsSpinal tumors
Radiologic Studies - X-RayLikely normal in early diseaseFirst changes in anterior part of vertebral body with demineralization of endplateNext the opposite vertebral endplate will become involvedWith progression, anterior wedging develops50% cases spare the disk spaceMay also show evidence of abcess
Radiologic Studies - MRI
Show the anterior endplate involvement and relative sparing of the disk and posterior vertebral body in more detailCan better demonstrate abcess formationBest method for demonstrating nerve root and spinal cord compression
Diagnostic Studies
PPD - 90% will have positive PPD May be negative in some immunocompetent and many immunosuppressed patientNot helpful in endemic areas
Biopsy and culture (with AFB smear) essential to confirm diagnosis and rule-out other causes
If surgical stabilization done may be done interoperativelyOtherwise, CT-guided needle biopsy is most common
Treatment
AntibioticsFour-drug therapy (isoniazid, rifampin, pyrazinamide & ethambutol)May be more complicated if concerns of multi-drug resistant TB or if associated with septicemiaAt least six months of therapyUsually responds well (even in severe cases)
Surgery
May play role in spinal stabilization or abcess drainage/debridementMore role if advanced neurologic deficits, worsening deficits on medical therapy or severe kyphosisUsually two-procedure process - first anterior decompression and reconstruction then posterior fusion
Take-Home Points
Pott's disease can be a indolent cause of back pain without necessarily any systemic symptoms of tuberculosis
Progression can lead to major deformity or neurologic consequences
Tuberculosis should be considered in any case of vertebral osteomyelitis or diskitis
Most patients do well with prolonged 4-drug anti-TB therapy
References
http://www.surgical-tutor.org.uk/default-home.htm?surgeons/pott.htm~right McLain R and Isada C. Spinal tuberculosis deserves a place on the radar screen. Cleveland Clinic Journal of Medicine 2004; 71(7):537-549.http://www.ccjm.org/content/71/7/537.full.pdf Wikipedia.org Emedicine.com Uptodate.com