MECHANICAL ASPECTS OF SUBARACHNOID SPACE PUNCTURE IN THE DOG

Lumbar subarachnoid space puncture using two different techniques was performed repeatedly on a dog following injection of metrizamide into the subarachnoid space at the cervical cistern. The lumbar needle punctures were observed fluoroscopically and recorded on 100-mm spot films at a rate of 2/sec. The needle tip indented the dura, depressing it several millimeters before penetration. A hemilaminectomy was performed on a cadaver, to expose the cord and intact meninges for confirmation of this compression. Cord compression and penetration during subarachnoid space puncture may contribute to the exacerbation or aggravation of neurologic signs that sometimes follows myelography.