All who deal with the problem of ruptured lumbar discs know that both false-negative and false-positive myelograms occur.
Many retrospective analysis have been made of the number of times myelograms agreed or disagreed with surgical findings, and an over all accuracy of lumbar myelography from 60% to 80% has been report
What the surgeon really needs to know for any given patient having certain signs and symptoms of a ruptured lumbar disc, is the likelihood that a positive myelogram truely predicts a ruptured dies or, if normal, that it truly predicts the absence of a ruptured disc.
To obtain the data necessary for such an analysis, a clinical study was done. The results of that study are reported here.
During January 1974 to September 1978, 134 lumbar intervertebral discs were revealed on 120 herniated lumbar intervertebral disc patients at the department of neurosurgery of Chungnam National University Hospital.
Myelography was done in all 120 patients. The myelographic study showed unilateral smooth round filling defect in 46 cases, unilateral wedge shaped defect in 44 cases, block type defect in 19 cases, bilateral wedge shaped defect in 12 cases and hourglass defect in 10 cases.
The operative finding revealed protruded disc in 70. 9%, bulging one in 14.2%, extru￢ded 11.2%, and migrated 3.7%.
The major discrepancies between myelographic and the operative finding were found in 10% while the minor discrepancies were 4. 2%.
In 103 patients of the present series of 120 cases the operative findings were in compl￢ete accord with the myelographic findings, giving an accuracy of 85.8 percent.
The myelographic finding of bulging type disc usually showed smooth round filling def￢ect while those of protruded was wedge shape filling defect, and the extruded type rev￢ealed smooth round and hourglass defect in the most of case, A positive myelogram is
more important than a negative myelogram.
A negative or normal myelogram in the face of clinical evidence of a ruptured disc so￢metimes will be wrong.
Myelography can be a valuable aid in accurately localizing herniated discs and showing multiple discs, and may be very helpful in borderline cases. now believe that myelogr￢aphy should routinely precede surgery for lumbar disc Lesions.
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