Does the Size of Cervical Disc Herniation Affect Clinical Parameters in Cervical Radiculopathy?

Background/Objectives: The extent to which compression or inflammation contribute to the development of cervical radiculopathy and its associated symptoms remains unclear. This study aimed to evaluate whether herniated disc size correlates with baseline symptom severity and/or clinical outcome in patients with cervical radiculopathy, treated surgically or conservatively. Methods: This multi-centre retrospective cohort study included 206 patients with cervical radiculopathy due to a herniated disc. MRI scans from 108 patients in the NECK trial (surgical treatment, evaluating disc replacement) and 98 from the CASINO trial (surgical versus conservative treatment), were used to classify herniation size. Clinical outcome was assessed using the Visual Analogue Scale for arm and neck pain, the Neck Disability Index and the EuroQol VAS at baseline and one year after treatment. Binary logistic regression models were used to evaluate associations between herniation size and clinical outcome, adjusting for treatment type, gender, Body Mass Index and age. Results: A total of 107 patients presented with a small herniation, and 99 had a large herniation. Baseline mean NDI scores were 39.1 ± 15 (surgical group, n = 165) and 32.9 ± 16 (conservative group, n = 41). No association was observed between herniation size and clinical condition (OR 1.010, p = 0.323). After one year, mean NDI scores were 16.2 ± 15 (surgical group) versus 19.6 ± 22 (conservative group), with no significant associations between herniation size and outcome in either group. Similar findings were found for VAS arm and neck pain and EQ-VAS. Conclusions: Disc herniation size on baseline MRI showed no correlation with symptom severity or one-year clinical outcomes, suggesting that inflammatory mechanisms, rather than mechanical compression alone, play a key role in cervical radiculopathy.