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, 10 (1), 63-68

MRI Radiological Predictors of Requiring Microscopic Lumbar Discectomy After Lumbar Disc Herniation


MRI Radiological Predictors of Requiring Microscopic Lumbar Discectomy After Lumbar Disc Herniation

Christopher G Varlotta et al. Global Spine J.


Study design: Retrospective cohort study.

Objective: To investigate radiological differences in lumbar disc herniations (herniated nucleus pulposus [HNP]) between patients receiving microscopic lumbar discectomy (MLD) and nonoperative patients.

Methods: Patients with primary treatment for an HNP at a single academic institution between November 2012 to March 2017 were divided into MLD and nonoperative treatment groups. Using magnetic resonance imaging (MRI), axial HNP area; axial canal area; HNP canal compromise; HNP cephalad/caudal migration and HNP MRI signal (black, gray, or mixed) were measured. T test and chi-square analyses compared differences in the groups, binary logistic regression analysis determined odds ratios (ORs), and decision tree analysis compared the cutoff values for risk factors.

Results: A total of 285 patients (78 MLD, 207 nonoperative) were included. Risk factors for MLD treatment included larger axial HNP area (P < .01, OR = 1.01), caudal migration, and migration magnitude (P < .05, OR = 1.90; P < .01, OR = 1.14), and gray HNP MRI signal (P < .01, OR = 5.42). Cutoff values for risks included axial HNP area (70.52 mm2, OR = 2.66, P < .01), HNP canal compromise (20.0%, OR = 3.29, P < .01), and cephalad/caudal migration (6.8 mm, OR = 2.43, P < .01). MLD risk for those with gray HNP MRI signal (67.6% alone) increased when combined with axial HNP area >70.52 mm2 (75.5%, P = .01) and HNP canal compromise >20.0% (71.1%, P = .05) cutoffs. MLD risk in patients with cephalad/caudal migration >6.8 mm (40.5% alone) increased when combined with axial HNP area and HNP canal compromise (52.4%, 50%; P < .01).

Conclusion: Patients who underwent MLD treatment had significantly different axial HNP area, frequency of caudal migration, magnitude of cephalad/caudal migration, and disc herniation MRI signal compared to patients with nonoperative treatment.

Keywords: MRI; herniated nucleus pulposus; lumbar spine; microscopic lumbar discectomy; surgery.

Conflict of interest statement

Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.


Figure 1.
Figure 1.
Axial diameter measurements of the herniation (vertical = A, horizontal = B) and the spinal canal (vertical = C, horizontal = D).
Figure 2.
Figure 2.
Sagittal canal migration in the cephalad or caudal direction. Cephalad herniations (line E) were measured using the inferior endplate of the upper vertebra as the starting point. Caudal herniations were measured using the superior endplate of lower vertebra as the starting point (line F).

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