Should Cervical Disc Arthroplasty Be Done on Patients with Increased Intramedullary Signal Intensity on Magnetic Resonance Imaging?

OBJECTIVE: Several trials from the U.S. Food and Drug Administration have demonstrated the success of cervical disc arthroplasty (CDA) in patients with degenerative disc disease causing radiculopathy, myelopathy, or both. For patients who had increased intramedullary signal intensity (IISI) on magnetic resonance image (MRI), however, the effectiveness and safety of CDA was unclear. This study aimed to evaluate the outcomes of CDA for patients with IISI on preoperative MRI. METHODS: Consecutive patients who received 1-level CDA for symptomatic degenerative disc disease were reviewed retrospectively. Patients with IISI on preoperative T2-weighted MRI were compared to those without IISI (non-IISI). Clinical outcome parameters including visual analog scale, Neck Disability Index, Japanese Orthopedic Association (JOA), and Nurick scores were analyzed. Radiographic studies included dynamic lateral radiography and MRI. RESULTS: A total of 91 patients were analyzed (22 in the IISI group and 69 in the non-IISI group). The mean follow-up was 30.0 months. The demographic data were mostly similar between the 2 groups. All clinical outcomes, including visual analog scale, Neck Disability Index, JOA, and Nurick scores in the IISI group demonstrated significant improvement after operation. The IISI group had similar clinical outcomes to the non-IISI group, except that the JOA scores were generally worse. Follow-up MRI demonstrated significant regression of the length of IISI (P = 0.009). Both groups had preserved motion after CDA. CONCLUSIONS: Both clinical and radiological outcomes improved (the average length of IISI in the cervical spinal cord became shorter) after CDA. Therefore, CDA is a safe and effective option for patients even when there is IISI on the preoperative T2-weighted MRI.