Myelographic versus clinical diagnostics in lumbar disc disease

Abstract

The series consisted of 200 patients on whom lumbar myelography was performed for sciatica. After myelography, a disc operation was carried out on 95 patients. The episode of sciatica was the first for 90 patients. Objective neurologic signs were present in 185 patients, while 15 had only subjective symptoms. Definite or possible disc herniation was revealed by myelography in 66%. Most positive findings were located at the L4-L5 interspace. The clinical diagnostic accuracy rate was assessed from the patients' histories. As confirmed by operation, the accuracy of the clinical diagnostics was 52%, and the accuracy rate of myelography was 90%. The rate of false positive findings in myelography was 4%, that of false negative findings 6%. When the clinical or myelographic diagnosis was definitive, a disc herniation or protrusion was always found at operation. Almost one fourth of the clinically diagnosed definite herniations were not treated surgically because myelography proved negative. One fifth of those patients in whom myelography revealed an unequivocal disc herniation were not operated on because these patients had clinically improved before being admitted to myelography. The results of this study justify the following conclusions: the clinical level diagnostics of a disc herniation is rather unreliable, and myelography is therefore always indicated before operation; myelography should only be performed in those cases in which there is a clear clinical indication for surgery; myelography ought to be performed within 1 week; an unequivocal positive finding in myelography predicts a good operative result.

Diagnostic accuracy of diagnostic imaging for lumbar disc herniation in adults with low back pain or sciatica is unknown; a systematic review

“…Of these, nine studies investigated CT [34–42], eight myelography [34, 37–39, 41, 43], six MRI [36, 39, 43–46], and none assessed X-ray. All studies were performed in secondary care settings, such as neurological clinics or pain clinics; three studies [41, 43, 47] were retrospective (Table 1). All but one study evaluated old imaging techniques as they were published between 1982 and 1994, one study evaluating MRI was published in 2006 [46].…”

“…The patients (14 to 82 years) all had clinical findings consistent with LDH. Seven studies ( n  = 288) [34, 37, 41, 42, 44, 46, 47] were analyzed on patient level; others analyzed disc levels (Table 1). …”

“…Seven studies were considered to have high RoB related to patient selection, as patients had not clearly been selected using consecutive or random sampling. Only two studies reported a time-interval between index test and reference standard, which were 3 months and 9 months, respectively [44, 47].

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“…Eight studies, with five studies with measurements on patient level (422 patients) [34, 37, 41, 42, 47] and a total 423 disc explorations [38, 39, 43], were included. The mean prior probability of LDH was 69.2% (range: 49.2–91.3%).…”

“…Not everyone is subjected to surgery but only those patients with a very strong suspicion based on clinical symptoms combined with the results of the diagnostic imaging of LDH which leads to (partial) verification bias. In this review, among 669 patients with suspected LDH, 349 (52.2%) patients did not undergo surgical treatment in seven studies [34, 36, 37, 43, 45–47]. Verification bias can lead to an increased diagnostic accuracy of the index test; i.e.…”