Hirayama Disease: Neutral and Flexion Magnetic Resonance Imaging Manifestations and Single Tertiary Care Center Analysis on 3T Scanner.

Background: Hirayama disease (HD) is a rare benign type of cervical cord myelopathy occurring commonly in young males as unilateral or bilateral asymmetrical amyotrophy of the hand and forearm muscles in C8-T1 distribution. Magnetic resonance imaging (MRI) is the best technique for the evaluation and imaging of this entity.

Materials and methods: This is a retrospective review of cervical magnetic resonance images of patients that were taken for clinically suspected and diagnosed HD on 3T MRI in postcontrast neutral and flexion (30°-40°) positions from July 2019 to January 2024 at Shri Ram Murti Smarak Institute of Medical Sciences, Bareilly.

Results: Fourteen patients included in the study were males less than 34 years of age. MRI findings of cord atrophy in the lower cervical region/cervico-dorsal junction, abnormal cervical curvature, loss of attachment of the dorsal dural sac and subjacent laminae with anterior displacement, and a prominent intense enhancing posterior epidural space were observed in all 14 patients. The minimum anteroposterior cord diameters in the neutral and flexion positions were 2.9 and 2.8 mm, respectively (mean thickness of laminodural space on flexion - 5.2 mm). Other MRI findings showed variable representations.

Conclusions: Flexion-position MRI has emerged as the gold standard for establishing and validating the diagnosis of HD in clinically suspected cases and should be an essential part of the protocol for the screening of clinically suspected cases of HD to aid in early treatment and therapeutic intervention. Complimentary newer sequences such as the Three-dimensional (3D)-Constructive interference in Steady State (CISS)/Fast Imaging Employing Steady-state Acquisition Cycled Phases (FIESTA-C) may reinforce better appreciation of epidural flow voids.