Utility Of MRI In Guiding Surgical Decisions for
Sciatica Related To Disc Issues

The utilization of magnetic resonance imaging (MRI) is essential for diagnosing and formulating treatment plans for intervertebral disc herniations. It is the preferred imaging modality for suspected lumbar disc herniation and severe sciatica symptoms.

Qualitative MRI findings, including the identification of disc extrusion or nerve root compression, exhibit a significant association with sciatica. MRI enables precise measurements of disc herniation size, shape, and dimensions of the spinal canal.

However, the available data on the predictive value of MRI assessments in guiding decisions between surgical or nonsurgical management for sciatica is limited.

The findings from a randomized controlled trial comparing early surgery to prolonged conservative care for patients with sciatica lasting 6 to 12 weeks were previously reported.

While early surgery led to quicker relief of symptoms compared to conservative care, the outcomes were similar after 1 year of follow-up. Surprisingly, 39% of patients in the conservative care group still underwent surgery within the first year due to ongoing or worsening leg pain and progressive neurological issues.

Previous research indicated that patients with higher initial levels of leg pain intensity or disability scores had a greater likelihood of eventually requiring surgery.

The study reported by literature aimed to assess the predictive value of qualitative and quantitative MRI assessments for delayed surgery in patients with sciatica.

The researchers wanted to determine if early in the course of sciatica, specific MRI evaluations could accurately predict which patients would ultimately undergo surgery during follow-up.

Such predictive information could be valuable for patients and physicians, as it would allow for early consideration of surgery to minimize the duration of suffering and avoid unnecessary delays.

In the same study, out of 142 patients who received prolonged conservative care, 39% (55 patients) eventually opted for surgery. The average time until surgery was 18 weeks, with varying proportions of patients undergoing surgery within different time intervals.

The baseline characteristics, including age, sex, duration of sciatica, body mass index, and disc herniation level, were similar between the group that had delayed surgery and the group that did not undergo surgery.

The presence of nerve root compression and vertebral endplate signal changes showed no significant differences between the two groups. The distribution of large disc herniations and central/subarticular disc herniations was comparable among those who underwent surgery and those who did not.

However, extruded disc herniations were more frequently observed in the surgically treated group (59%) compared to the conservatively treated group (70%). The size of the herniation at baseline was similar between the surgical and nonsurgical groups, with no significant difference observed.

However, the size of the dural sac was smaller in the surgical group compared to the nonsurgical group. The ratio of the disc herniation size to the dural sac size did not significantly differ between the two groups.

The remaining spinal canal size was smaller in the surgical group compared to the nonsurgical group, and there was no significant difference in the ratio of the disc herniation size to the remaining spinal canal size between those who underwent surgery and those who did not.

In the surgical group, baseline scores for the RDQ (Roland-Morris Disability Questionnaire) and VAS (Visual Analog Scale) leg pain were higher compared to the nonsurgical group.

Upon conducting a subanalysis, significant differences were found in the baseline RDQ and VAS scores, as well as in the sizes of the dural sac and remaining spinal canal between patients who did not undergo surgery, those who underwent surgery within 6 months after conservative care assignment, and those who underwent surgery between 6 and 12 months after assignment.

The researchers evaluated the predictive value of different factors for surgery using the area under the ROC curve (AUC). The AUC values were calculated for the size of the dural sac, size of the spinal canal, VAS leg pain score, and RDQ score.

Combining the MRI variables resulted in a certain AUC value, and combining the RDQ score and VAS leg pain score yielded another AUC value. Finally, when all four variables were combined, a higher AUC value was obtained. These results suggest that these factors have some predictive value for the likelihood of undergoing surgery.

Clinical outcome scores did not show any significant differences between the surgical and nonsurgical groups after one year of randomization. However, the incidence of disc herniation was higher in the nonsurgical group.

Among the surgical patients, the presence or absence of nerve root compression at baseline did not have a notable impact on the perceived recovery at the one-year follow-up.

Baseline MRI assessments and the size of disc herniation were not successful in anticipating the necessity for surgery among sciatica patients following a conservative management approach.

Nonetheless, patients who ultimately underwent surgery displayed higher RDQ scores, more severe leg pain, and smaller dural sacs and spinal canals at baseline compared to those who did not require surgery.

Hence, MRI lacks reliability in differentiating between sciatica patients who will or will not undergo surgery.

Acute sciatica often resolves spontaneously within 18 weeks, and surgery is considered when conservative care fails. Absolute indications for surgery are rare, and clear clinical guidelines are lacking for other cases.

Retrospective studies suggest that patients undergoing surgery for sciatica tend to have larger disc herniations and smaller spinal canals, but these studies have limitations and potential biases.

Surgical treatment rates for lumbar discectomy vary widely, and there are no objective measures available to determine when to perform surgery for sciatica. Factors such as pain, disability, psychological aspects, and personal preferences play a role in the decision-making process.

The study found no significant predictive value of MRI for future surgery in patients with 6 to 12 weeks of sciatica. Reliable tools for patient selection in disc surgery are still needed.

At the one-year follow-up of the clinical trial, a significant proportion of patients still displayed visible disc herniation on MRI, regardless of their treatment. However, the presence of MRI abnormalities did not differentiate between patients experiencing persistent or recurrent sciatica symptoms and those without symptoms.

Other studies have reported similar findings, indicating a limited connection between MRI findings and clinical outcomes. Nonetheless, microsurgical discectomy has demonstrated effectiveness in treating sciatica patients

In discussions regarding the decision between surgery and a wait-and-see approach for sciatica, MRI should primarily be used to assess anatomical features and the level of a herniated disc for surgical planning.

However, MRI demonstrated limited ability to differentiate between patients who underwent delayed surgery and those who did not require surgery during the follow-up period.