Subarachnoid-pleural fistula: applied anatomy of the thoracic spinal nerve root

Abstract

Subarachnoid-pleural fistula (SPF) is a rare complication of chest or spine operations for neoplastic disease. Concomitant dural and parietal pleural defects permit flow of cerebrospinal fluid into the pleural cavity or intrapleural air into the subarachnoid space. Dural injury recognized intraoperatively permits immediate repair, but unnoticed damage may cause postoperative pleural effusion, intracranial hypotension, meningitis, or pneumocephalus. We review two cases of SPF following surgical intervention for chest wall metastatic disease to motivate a detailed review of the anatomy of neural, osseous, and ligamentous structures at the intervertebral foramen. We further provide recommendations for avoidance and detection of such complication.

Figure 1

Axial contrast-enhanced CT of a 17-year-old girl demonstrates a heterogeneous soft tissue mass in the right hemithorax (arrows) that abuts the costal and vertebral pleura, with no frank evidence of bony invasion. A small right pleural effusion is also present. There is no visible tumor invasion into the spinal canal. Biopsy of the lesion confirmed metastatic Wilm's tumor.

Figure 2

Supine portable chest radiograph obtained 12 hours after resection of the Wilm's metastasis shows the expected early postoperative appearance of the right pneumonectomy space, thoracotomy and bony resection of the 5th right posterior rib, midline position of the mediastinum, and predominantly air in the pneumonectomy space.

Figure 3

Upright portable chest radiograph obtained 9 days after surgery demonstrates rapid fluid accumulation in the right pneumonectomy space with contralateral shift of mediastinal structures to the left. Both findings are suggestive of excessive fluid volume in the pneumonectomy space.

Figure 4

Axial CT obtained after contrast myelogram demonstrates the subarachnoid-pleural fistula (thick black arrows) establishing communication between the spinal canal and the right pleural effusion. Contrast is observed to layer dependently in the right pleural space (white arrows). Note the adjacent surgical clips (thin black arrows).

Figure 5

Coronal reformatted CT after contrast myelogram shows the subarachnoid pleural fistula (arrows) connecting the radio-opaque subarachnoid space with the large area of dilute contrast in the right pleural space.

Figure 6

Axial T2-weighted MRI in a 66-year-old male through the upper right hemithorax demonstrates a soft tissue mass (white arrows) in the right pleural space. The lesion is observed to invade the chest wall and adjacent rib (black arrow). Note the proximity of the mass to the intervertebral foramen and spinal canal (thick white arrow).