Angiographic study of the effect of laminectomy in the presence of acute anterior epidural masses.

Laminectomies were performed in 16 monkeys to decompress simulated acute epidural masses in front of the spinal cord. When decompression restored normal arterial and venous hemodynamics, the monkeys were neurologically intact in spite of considerable mechanical distortion of the cord. When either the anterior spinal artery or the posterior spinal vein remained obstructed following laminectomy, the monkeys were paraplegic. Acute anterior epidural masses larger than 4 mm in diameter could not be adequately decompressed via the posterior approach. Only minor posterior displacement of the cord is observed following laminectomy in the presence of large anterior masses.