Spontaneous regression of extruded lumbar disc herniation: Correlation with clinical outcome

OBJECTIVE: To evaluate the natural history of lumbar extruded disc with conservative treatment on MRI and to assess relation between the radiologic changes and clinical outcome. METHODS: This prospective observational study was conducted at University of Health Sciences, Diskapi Yildirim Beyazit Training and Research Hospital between May 2015-June 2018. It included consecutive patients who were diagnosed as having lumbar symptomatic extruded disc as shown in MRI. After an average period of 17.0±7.2 months, repeat MRI was taken in 40 patients who received only conservative care during follow-up. Changes in the volume of herniated disc was measured. The patients were assigned into 3 groups as follow: (1) non-regression, (2) partial-regression, and (3) complete resolution. Numeric Rating Scale (NRS) pain score, the Oswestry Low Back Pain Disability Index (ODI) and muscle weakness were evaluated. RESULTS: Based on disc volume of the T2-weighted MR images; four patients (10%) did not show any regression, six patients (15%) had a partial regression, and 30 patients (75%) had a complete resolution. Patients with complete resolution showed a significant improvement in the NRS pain score and the ODI score (p<0,001) over time. In patients with partial regression, only the ODI score improved significantly (p=0,043). Non-regression group did not show any improvement in any clinical outcome measure (p>0,05). Changes in the NRS scores over time were significantly higher in complete resolution group compared to non-regression group (p=0.016). CONCLUSION: The majority of the patients with extruded lumbar disc herniation might have reduction in size of herniated disc in the long run along with improvement in symptoms and function with conservative care.