Pyogenic abscess of the filum terminale. Case report.

Intradural spinal abscesses are rare. They are predominantly encountered as intramedullary abscesses of the spinal cord and infrequently as subdural lesions. To their knowledge, the authors report the first case of a chronic pyogenic abscess of the terminal filum in an adult woman with kyphoscoliosis who presented with lumbar radiculopathies. Magnetic resonance imaging revealed a partly cystic intradural L3-4 mass that markedly enhanced after contrast administration. Laboratory signs of infection were absent. Intraoperatively a lobulated lesion observed within the terminal filum was tightly attached to neighboring nerve roots by fibrosis. On opening the cyst wall pus was revealed. Histological examination confirmed the diagnosis of a chronic abscess. Microbiological culture detected Staphylococcus aureus. Antibiotic therapy resulted in an uneventful postoperative course, with complete resolution of symptoms and radiologically demonstrated disappearance of the lesion. The pathogenesis and radiological features of the lesion are discussed. Although extremely rare, a pyogenic abscess should be considered in the differential diagnosis of mass lesions of the cauda equina, especially in patients with preexisting spinal abnormalities. Surgical exposure, including drainage and biopsy sampling to rule out underlying tumor, combined with antibiotic treatment result in a favorable outcome.