Spinal cord intramedullary pressure: direct cord traction test.

Spinal cord intramedullary pressure was measured in eight mongrel dogs using a balloon method. The neck of the animals was maintained in the neutral position. Following cervical laminectomy, the cervical spinal cord was drawn dorsally using a small plastic saddle inserted ventral to the spinal cord at the C-5 level. The cord pressure at C-5 increased with traction load. The cord pressure at C-6 not in direct contact with the plastic saddle also increased to about one third the increase at C-5. These findings indicate that spinal cord intramedullary pressure is increased by mechanical compression on the anterior structure of the spinal canal and stretching of the cord to some extent. This phenomenon might be important in cord insult in patients with spinal column lesions located anterior to the spinal cord and presenting with neurological signs extending over several segments.