summary Spinal Tuberculosis, also known as Pott's Disease, is a spinal infection caused by tuberculosis that can lead to osteomyelitis, kyphotic deformity, and spinal mechanical instability. Diagnosis is made with a CT-guided biopsy sent for acid-fast bacilli. Treatment is usually bracing and anti-tuberculosis antibiotics in the absence of neurological defects or mechanical instability. Surgical management is indicated in the presence of neurological deficits, progressive kyphosis, and/or mechanical instability. Epidemiology Incidence increasing incidence of TB in United States due to increasing immunocompromised population Demographics HIV positive population (often seen in patients with CD4+ count of 50 to 200) Anatomic location 15% of patients with TB will have extrapulmonary involvement the spine, and specifically, the thoracic spine is the most common extrapulmonary site 5% of all TB patients have spine involvement Etiology Pathoanatomy early infection begins in the metaphysis of the vertebral body spreads under the anterior longitudinal ligament and leads to contiguous multilevel involvement skip lesion or noncontiguous segments (15%) paraspinal abscess formation (50%) usually anterior and can be quite large (much more common in TB than pyogenic infections) initially does not involve the disc space (distinguishes from pyogenic osteomyelitis, but can be misdiagnosed as a neoplastic lesion) chronic infection severe kyphosis mean deformity in nonoperative cases is 15° in 5% of patients, deformity is >60° higher rate of progression of kyphosis when involvement of the vertebral body and posterior elements infection is often diagnosed late, there is often much more severe kyphosis in granulomatous spinal infections compared to pyogenic infections in adults kyphosis stays static after healing of disease in children kyphosis progresses in 40% of cases because of growth spurt classification of progression (Rajasekaran) Type-I, increase in deformity until cessation of growth should be treated with surgery Type-II, decreasing progression with growth Type-III, minimal change during either active / healed phases. Presentation Symptoms onset of symptoms of tuberculous spondylitis is typically more insidious than pyogenic infection constitutional symptoms chronic illness malaise night sweats weight loss back pain often a late symptom that only occurs after significant boney destruction and deformity. Physical exam kyphotic deformity neurologic deficits (present in 10-47% of patients with Pott's Disease) mechanisms mechanical pressure on cord by abscess, granulation tissue, tubercular debris, caseous tissue mechanical instability from subluxation/dislocation paraplegia from healed disease can occur with severe deformity stenosis from ossification of ligamentum flavum adjacent to severe kyphosis Imaging CXR 66% will have an abnormal CXR should be ordered for any patients in which TB is a possibility Spine radiographs early infection shows involvement of anterior vertebral body with sparing of the disc space (this finding can differentiate from pyogenic infection) late infection shows disk space destruction, lucency and compression of adjacent vertebral bodies, and development of severe kyphosis risk factors for buckling collapse ("spine at risk signs") retropulsion subluxation lateral translation toppling MRI with gadolinium contrast indications remains preferred imaging study for diagnosis and treatment diagnose adjacent levels multiple levels involved in 16-70% findings low signal on T1-weighted images, bright signal on T2-weighted images presence of a septate pre-/ paravertebral / intra-osseous smooth walled abscess with a subligamentous extension and breaching of the epidural space end-plate disruption sensitivity 100%, specificity 81% paravertebral soft tissue shadow sensitivity 97%, specificity 85% high signal intensity of the disc on the T2-weighted image sensitivity 81%, specificity 82% spinal cord edema myelomalacia atrophy syringomyelia CT indications demonstrates lesions <1.5cm better than radiographs inaccurate for defining epidural extension findings types of destruction fragmentary osteolytic subperiosteal sclerotic Nuclear medicine studies obtain with combination of technetium and gallium shown to have highest sensitivity for detecting infection Studies CBC relative lymphocytosis low hemoglobin ESR usually elevated but may be normal in up to 25% PPD (purified protein derivative of tuberculin) positive in ~ 80% Diagnosis CT guided biopsy with cultures and staining effective at obtaining a diagnosis should be tested for acid-fast bacilli (AFB) mycobacteria (acid-fast bacilli) may take 10 weeks to grow in culture PCR allows for faster identification (95% sensitivity and 93% accuracy) smear positive in 52% culture positive in 83% Differential Other etiologies of granulomatous infection may have similar clinical picture as TB and include atypical bacteria Actinomyces israelii Nocardia asteroids Brucella fungi Coccidioides immitis Blastomyces dermatitidis Cryptococcus neoformans Aspergillosis spirochetes Treponema pallidum Treatment Nonoperative pharmacologic treatment +/- spinal orthosis indications no neurological deficit drugs are the mainstay of treatment in most cases pharmacologic agents isoniazid (H), rifampin (R), ethambutol (E) and pyrazanamide (Z) therapy regimen RHZE for 2 months, then RH for 9 to 18 months spinal orthosis indications may be used for pain control and prevention of deformity Operative anterior decompression/corpectomy, strut grafting ± posterior instrumented stabilization ± posterior column shortening indications neurologic deficit worsening neurological deficit acute severe paraplegia with panvertebral involvement with/without subluxation/dislocation spinal instability kyphosis correction > 60° in adult progressive kyphosis in child ≥3 vertebrae involved with loss of ≥1.5 vertebral bodies in thoracic spine children ≤ 7 years with ≥3 vertebral bodies affected in T/TL spine and ≥ 2 at risk signs are likely to have progression and should undergo correction late onset paraplegia (from kyphosis) cosmetic correction of kyphosis controversial advanced disease with caseation preventing access by antibiotics failure of nonoperative treatment after 3 to 6 months diagnosis uncertain panvertebral lesion advantages of surgical treatment less progressive kyphosis earlier healing decreased sinus formation in patients with neurologic deficits, early debridement and decompression led to improved neurologic recovery technical aspects autogenous and allograft strut grafts are acceptable with good results continue medical management with isoniazid, rifampin, and pyrazanamide chronic implant colonization is less common in TB and other granulomatous infections compared to more common pyogenic infections Halo traction, anterior decompression, bone grafting, anterior plating indications cervical kyphosis Pedicle subtraction osteotomy indications lumbar kyphosis Direct decompression / internal kyphectomy indications correction of healed thoracic/thoracolumbar kyphosis allows spinal cord to transpose anteriorly Technique Anterior decompression/corpectomy, strut grafting ± posterior instrumented stabilization ± posterior column shortening indications (see above) kyphosis active disease techniques single-stage transpedicular 2-stage anterior decompression with bone grafting posterior kyphosis correction and instrumentation single-stage extrapleural anterolateral Complications Deformity (kyphosis/gibbus) highest risk after anterior decompression and grafting alone slippage and breakage of graft (especially if ≥ 2 levels) lowest risk after both anterior and posterior fusion Retropharyngeal abscess affects swallowing/hoarseness TB arteritis and pseudoaneurysm Respiratory compromise if there is costopelvic impingement Sinus formation Pott's paraplegia spinal cord injury can be caused by abscess/bony sequestra or meningomyelitis abscess/bony sequestra has a better prognosis than meningomyelitis as the cause of spinal cord injury Atypical Spinal Tuberculosis definition compressive myelopathy without visible spinal deformity, without typical radiological appearance etiology intraspinal granuloma, neural arch involvement, concertina collapse of vertebra body , sclerotic vertebra with bridging of vertebral body treatment laminectomy indications extradural extraosseous granuloma subdural granuloma decompression and myelotomy indications intramedullary granuloma