Clinical StudyPreoperative MRI predictors of health-related quality of life improvement after microscopic lumbar discectomy
Introduction
Lumbar herniated nucleus pulposus (HNP) is considered to be one of the most prevalent spinal degenerative disorders, often leading to lower back pain and radiculopathy [1,2]. Disc degeneration and herniation vary in severity, as a small protrusion or a complete annular fibrous tear can both contribute to inflammation, nerve root compression, and impending lower back pain [3], [4], [5], [6]. Although there exists a complexity in determining how HNP morphology directly contributes to symptom presentation, it is useful for physicians to visualize this morphology using magnetic resonance imaging (MRI) when determining the optimal treatment for pain relief [7], [8], [9].
Operative treatment, in the form of microlumbar discectomy (MLD), is commonly utilized to treat HNPs. For patients suffering from back pain and sciatica, MLD is the most common surgical procedure performed in the United States, as over 300,000 discectomy procedures are conducted annually [8,10]. There are also a multitude of patients who opt to receive nonoperative HNP treatment, such as epidural steroid injections or physical therapy, as it serves as a low risk and low cost option [11], [12], [13], [14]. MLD itself is a proven cost-effective treatment option that provides rapid relief of pain, improved quality of life [15], [16], [17], [18], [19], [20]. It remains to be determined which radiological characteristics of HNP indicate that patients are more likely to have a favorable short-term outcome after MLD.
With the goal of providing value-based care for patients, surgeons utilize health-related quality of life (HRQoL) metrics to quantify patient reported improvement from surgical intervention. The advent of computer adaptive Patient-Reported Outcome Measurement Information System (PROMIS) allows for standardized assessment across health conditions and provides the ability to calculate patient improvement after procedures. Previous studies have explored the benefits of surgical treatment for HNP through the comparison of preoperative and postoperative HRQoL scores including Oswestry disability index, EQ-5D, and SF-12 Physical Component Scores (PCS) [21,22]. Additionally, the high validity that PROMIS carries when measuring patient-reported improvement after HNP surgical treatment has been reported [23]. However, prior reports have not investigated specific preoperative MRI parameters that may contribute to clinically meaningful HRQoL improvement following MLD treatment. Minimal clinical important difference (MCID) values for MLD derived in the literature help quantify significant clinical improvement in patients with surgical HNP [24]. Consequently, using MCID values, this study aimed to meticulously analyze the ability of MRI morphologic characteristics in HNP patients to predict meaningful short-term clinical improvement after MLD using preoperative and postoperative HRQoL metrics.
Section snippets
Study design
This study was an institutional review board-approved retrospective review of consecutive patients presenting to a single academic center from March 2017 to August 2018.
Patient population
Inclusion criteria consisted of patients older than 18 years old presenting symptoms, examination, and imaging consistent with primary lumbar disc herniation (HNP) treated through MLD, along with baseline and 3-month HRQoL scores of PROMIS (Physical Function, Pain Interference, and Pain Intensity), ODI, VAS Back, and VAS Leg.
Demographic assessment
The patient cohort contained 88 patients who received MLD treatment. The mean age of the cohort was 44.6 years old, the mean BMI of the cohort was 28.5. The cohort was 38.6% female. The only demographic variable that was significantly different between the MCID+ and MCID– groups was age within the Physical Function comparison, as MCID+ patients were significantly younger than MCID– patients (41.0±13.7 years vs 47.9±15.3 years, p=.028).
Linear regression and overall radiographic analyses
Linear regression analysis demonstrated a strong correlation
Discussion
This study systematically analyzed the MRI morphologic characteristics of lumbar HNP to determine the likelihood of achieving MCID following MLD. These radiological characteristics were compared in patients who met and did not meet MCID for MLD reported in recent literature. The results suggest that these radiological characteristics do in fact have clinical significance in patient improvement following MLD. More specifically, patients with large, gray signal HNP with larger percentage of canal
Conclusions
This study investigated the MRI morphologic characteristics in HNP patients that may predict meaningful clinical improvement after MLD, measured by HRQoL metrics. MLD patients who met MCID for the respective HRQoL tests had larger total HNP areas and larger Hemi-HNP Areas than those who did not meet MCID. These patients were also 2.7× more likely to have a gray HNP signal as opposed to having a mixed or black HNP signal. MRI morphologic parameters can aid in predicting the likelihood of
Acknowledgments
There was no source of study funding for the manuscript submitted.
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Author disclosures: CGV: Nothing to disclose. JHM: Nothing to disclose. EWA: Nothing to disclose. EW: Nothing to disclose. DW: Nothing to disclose. DV-M: Nothing to disclose. HA: Nothing to disclose. AB: Nothing to disclose. ME: Nothing to disclose. YK: Royalties: Biomet (Money paid to you); Consulting: Biomet (Money paid to you). JAB: Nothing to disclose. CRF: Consulting: Stryker (amount undisclosed); Speaking and/or Teaching Arrangements: Expert Connect (amount undisclosed). TSP: Stock Ownership: Torus Medical (amount undisclosed); Consulting: Globus Medical (D), Innovasis (B), K2M (B), Medicrea International (B), Nuvasive (B); Research Support (Investigator Salary, Staff/Materials): Cervical Spine Research Society (amount undisclosed). JRS: Consulting: Speaking and/or Teaching Arrangements: Stryker (C); Research Support (Investigator Salary, Staff/Materials): Intrinsic Therapeutics (C). AJB: Consulting: EOS Imaging (B), K2M (B), Medtronic (B), Nuvasive (E); Research Support (Staff and/or materials): Nuvasive (E); Royalties: Altus Spine (B).