Tuberculosis (TB) of the spine, or Pott's disease, represents only 1% of all TB cases, but it is one of the most dangerous forms of osteoarticular TB, because of the risk of bone destruction, deformity, paraplegia and involvement of adjacent structures.1 Airway obstruction associated with Pott's disease has been described with retropharyngeal abscesses with TB of the cervical spine but not with mediastinal abscesses.2,3 We present a case of severe airway obstruction secondary to a mediastinal abscess in a child with TB of the thoracic spine.
A 3-year-old boy was admitted with a 3-month history of sporadic fever, progressive back pain and a hump in the middle of his back. Two weeks before admission, he developed difficulty walking, daily fevers and cough. He was admitted with a generalized seizure and respiratory arrest. The medical history was remarkable for having received 3 months of isoniazid prophylaxis when the patient was 3 months of age because the mother had pulmonary TB. When the patient was 2 years old, another family member had pulmonary TB, but the patient was not screened or treated. At the time of admission, the patient had severe respiratory distress with diffuse bilateral crackles, a kyphotic malformation in the upper thoracic spine and a mild left hemiparesis. His hematocrit was 27%, white blood cell count 8800 per μL (8% bands) and platelets 510,000 μL; electrolytes and liver function tests were normal. The lumbar puncture was normal (white blood cells 0, red blood counts 4, glucose 120, protein 40); cerebrospinal fluid and blood cultures were negative for common bacteria and Mycobacterium tuberculosis. Multiple tracheal aspirates and gastric aspirate smears were negative for TB, but his purified protein derivative was 7 mm (induration >5 mm is positive in contacts to active TB). The chest radiograph showed a diffuse micronodular/miliary pattern and the spine film showed collapse and destruction of vertebral bodies T4–5, with kyphosis and a paravertebral fusiform lesion in the spine (Fig. 1). The head computed tomography scan showed a mild diffuse cerebral edema. Because of severe respiratory distress, the patient received mechanical ventilation. He was treated with isoniazid, rifampin, pyrazinamide and streptomycin with dexamethasone, assuming the diagnosis of miliary TB and Pott's disease. Three weeks after initiation of therapy, there was neurologic and pulmonary improvement, but he failed extubation on 4 occasions, requiring synchronized intermittent mandatory ventilation with positive pressure ventilatory support (PPV) and later continuous positive airway pressure + PPV. A computed tomography scan of the spine and mediastinum showed spondylitis involving 5 vertebral bodies (from T4 to T8) and an extensive paravertebral abscess in the posterior mediastinum with compression of the main bronchi and forward displacement of the trachea and bronchi (Fig. 1). To decompress the airway, the patient underwent CT-guided percutaneous needle aspiration of the mediastinal abscess; 8 mL of a dense purulent secretion was aspirated. The routine culture was negative (4 weeks after initiation of therapy), but the smear showed acid-fast bacilli (AFB). After the procedure, he did not improve and required open thoracotomy. Caseum, cellular detritus and 30 mL of pus were drained, which was AFB smear-positive and culture-negative (5 weeks after initiation of therapy). The patient tolerated surgery adequately and 1 week later was extubated. He completed 12 months of anti-TB therapy and had a good clinical condition with no sequelae, except for the gibbus deformity.
Airway obstruction in patients with TB can be related to laryngotracheal, endobronchial and primary mediastinal TB with compression of the bronchi by mediastinal lymph nodes and abscesses.4–7 Although paravertebral abscesses secondary to TB can be found anywhere along the spine, usually only cervical abscesses are associated with airway obstruction and respiratory distress, because of their anatomic localization in the retropharyngeal area.2,3 These patients typically present with chronic cervical pain, dysphagia, dyspnea, hoarse voice and foreign body sensation, and require endoscope-guided intubation to ensure the airway and posterior surgical drainage of the abscess.
Mediastinal abscesses secondary to TB of the thoracic spine are frequent. There are some case reports of paravertebral abscesses with extrapleural extension and mediastinal masses secondary to osteomyelitis of the spine after bacille Calmette-Guerin vaccination.8 To our knowledge, this is the first report of tracheal and bronchial obstruction resulting from a mediastinal TB mass in a patient with Pott's disease. In the literature, there is a similar case of an infant with severe airway obstruction secondary to a mediastinal mass associated with a spinal osteomyelitis caused by Staphylococcus aureus.9 In general, mediastinal tumors in infants (neuroblastoma, neuroenteric cysts, dorsal enteric cysts, abscesses and so on) can produce severe airway obstruction because of the relative easy compression of the tracheal rings in small children.9 Our patient required prolonged positive pressure ventilatory support and his condition did not improve with medical treatment. Surgical drainage was required. The cultures from the paravertebral abscess were obtained 4 and 5 weeks after starting anti-TB therapy; both were negative for M. tuberculosis. Like in this case, many children are treated for pulmonary and extrapulmonary TB based on clinical diagnosis criteria.
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