MSU classification for herniated lumbar discs on MRI: toward developing objective criteria for surgical selection

Area of Science:

• Neurosurgery
• Radiology
• Orthopedic Surgery

Background:

• Over 300,000 lumbar discectomies occur annually in the US.
• Patient selection lacks objective MRI-based standards, leading to ambiguity.
• Developing objective criteria is crucial for optimizing surgical outcomes.

Purpose of the Study:

• To develop and validate an objective MRI-based classification scheme for lumbar disc herniation.
• To establish reliable criteria for selecting patients for lumbar microdiscectomy.
• To correlate the classification with clinical outcomes.

Main Methods:

• A prospective study of 200 lumbar microdiscectomy cases with 5-year follow-up.
• Development of the MSU Classification based on herniation size (1-3) and location (A-C).
• Validation of the classification in a second series of 100 patients, excluding size-1 lesions.

Main Results:

• The MSU Classification demonstrated 98% inter-examiner reliability.
• Patients selected using the MSU Classification achieved 80-84% good to excellent outcomes at 5 years.
• Herniation types 2-B and 2-AB were most frequently selected, highlighting size and location importance.

Conclusions:

• The MSU Classification offers a simple, reliable, and objective method for measuring lumbar disc herniation on MRI.
• Objective criteria derived from the MSU Classification, combined with clinical findings, can enhance surgical decision-making.
• This approach may lead to a higher percentage of successful surgical outcomes in lumbar discectomy procedures.