Pitfalls of Myelography

Abstract

Myelography is rapidly becoming one of the more important radiological procedures. Within the past nine years at the Mary Hitchcock Memorial Hospital (Hanover, N. H.) there has been a sevenfold increase in the number of these examinations, as compared with a two- or threefold increase in other examinations, such as cholecystography, gastrointestinal series, or intravenous pyelography. This may be due in part to an increasing number of patients referred to the Clinic as the size and reputation of the Neurosurgical Service have grown. Chiefly, however, myelography's increased importance seems to stem from the realization on the part of the medical profession that it is a safe procedure, does not usually upset the patient, and is invaluable with regard to diagnosis and precise localization of intraspinal lesions. Review of 400 Myelograms In order to evaluate our accuracy in this important procedure, it was decided to review 400 consecutive cases in which Pantopaque myelography had been done. Of these patients, we were most interested in 223 who were operated upon, since they afforded an accurate anatomic diagnosis for comparison with the myelographic findings. All roentgenograms were reviewed by the Radiology Department without knowledge of the clinical or operative findings, and the myelographic diagnoses were compared with the observations at surgery. If there was a marked discrepancy such as a normal interpretation in the presence of tumor or ruptured intervertebral disk, the error was classed as a major one. Minor errors were those of localization, differentiation between single and double disks, and technic. Scoville, Moretz and Hankins (1) carried on a similar survey at the Cushing General Hospital in 1948, which showed overall errors in 33 per cent of the cases and revealed that clinical evidence of a ruptured disk is more important than myelographic evidence. Our series is more closely in accord with that of Ramsey, French and Strain (2), who state that the accuracy of myelography in the diagnosis of intraspinal lesions should approximate 95 per cent, which must compare favorably with operative exploration. The 223 patients who were explored had the following findings at operation. Ruptured intervertebral disk was by far the most common pathological condition, being present in 181 cases (81.2 per cent). Tumor of the spinal cord, meninges, or extradural tissues was present in 19 (8.5 per cent). Six patients (2.7 per cent) had only hypertrophic changes causing myelographic abnormalities. Such ridging was present in much higher percentage in conjunction with other pathological changes, but at operation the ridging was not considered responsible for the disabilities in these patients. The same may be said of the vascular anomalies which were present in 8 cases (3.6 per cent).