Hirayama Disease: Best Depicted in the Prone Position with Full-Flexion Cervical MRI in A Serial Trial

The current case report presents a 17-year-old man newly diagnosed with Hirayama Disease (HD) with right-side upper limb weakness, which was best detected by full cervical flexion scan in the prone position, using a serial trial of flexion Magnetic Resonance Imaging (MRI). Using a neck coil resulted in inadequate flexion angle because of limited space and failed to demonstrate anterior dural displacement, which is known to be the most significant and important finding for the diagnosis of HD. By serial flexion scan, the researchers found that dural displacement may not be evident because of an insufficient flexion angle, and that as the flexion angle increases, the diameter and level of anterior dural displacement increases, emphasizing the necessity of full-flexion imaging in patients with clinically suspicious HD. In the present case, the prone position provided comfortable stabilization for ideal full-flexion position, resulting in optimized image quality.