The problem of subdural placement in myelography.

Subdural placement of contrast medium is anathema to the myelographer. It immediately compromises the diagnostic accuracy of the procedure and jeopardizes the success of future examination of the spinal subarachnoid space (1–6). In the literature, allusions to extra-arachnoidal injection of radiopaque oil are invariably coupled to warnings that in such instances interpretation of findings is difficult and often erroneous. The purpose of this paper is to consider the cause, appearance, effect, and possible prevention of subdural placement of contrast medium. Material A total of 140 myelographic examinations via lumbar puncture were attempted or performed between January 1959 and April 1961 at the University of Florida Teaching Hospital and Clinics. In 9 instances, the test dose was completely subdural in position, and in most of these the procedure was discontinued. In 10 cases, the instillation was in part subdural, sufficient in amount to interfere with radiologic study. In several instances, no test dos...