The Quantitative Assessment of Imaging Features for the Study of Hirayama Disease Progression

Objective. To evaluate the forward shifting of cervical spinal cords in different segments of patients with Hirayama disease to determine whether the disease is self-limiting. Methods. This study was performed on 11 healthy subjects and 64 patients. According to the duration, the patients were divided into 5 groups (≤1 year, 1-2 years, 2-3 years, 3-4 years, and ≥4 years). Cervical magnetic resonance imaging (MRI) of flexion and conventional position was performed. The distances between the posterior edge of the spinal cord and the cervical spinal canal (X), the anterior and posterior wall of the cervical spinal canal (Y), and the anterior-posterior (A) and the transverse diameter (B) of spinal cord cross sections were measured at different cervical spinal segments (C4 to T1). Results. In cervical flexion position, a significant increase in X/Y of C4-5 segments was found in groups 2–5, the C5-6 and C6-7 segments in groups 1–5, and the C7-T1 segments in group 5 (P < 0.05). The degree of the increased X/Y and cervical flexion X/Y of C5-6 segments were different among the 5 groups (P < 0.05), which was likely due to rapid increases in X/Y during the course of Hirayama's disease. Conclusion. The X/Y change progression indicates that Hirayama disease may not be self-limiting.