Hirayama Disease and Traumatic Myelopathy: Capabilities and the Role of MRI in Forensic Medicine

Objective: To determine key radiological features for differential diagnosis between traumatic myelopathy and Hirayama disease for the sake of forensic medical examination.

Materials and methods: The study included 17 patients (age, 17-26 years) with myelopathy at the C5-C7 level following traffic collisions. The patients were grouped into those with traumatic myelopathy (n=11) and those with signs of Hirayama disease on magnetic resonance imaging (MRI) (n=6). All the patients underwent cervical spine MRI in the T1- and T2-weighted, short tau inversion recovery, and diffusion-weighted imaging modes, as well as dynamic MRI in the neck flexion position. We analyzed the following: spinal cord compression, anterior horn atrophy, dynamic changes, lesion symmetry, and venous stasis.

Results: Traumatic myelopathy is characterized by focal T2-hyperintensities, soft tissue edema, impaired intervertebral disk integrity, and no changes in neck flexion. Hirayama disease is manifested by symmetrical atrophy of the anterior horns, ventral displacement of the posterior dural sac on flexion, hyperintensity of the epidural venous plexus on T2-weighted images, and no compression changes in the neutral position. The mean lesion area in traumatic myelopathy was 12.4±1.3 mm2, whereas in Hirayama disease, 8.2±0.9 mm2 (P =.03). The sensitivity and specificity of dynamic MRI in the diagnosis of Hirayama disease was 85% and 92%, respectively. Discussion: Differential diagnosis between traumatic myelopathy and Hirayama disease is critical for forensic medical examination due to similar radiological features. Dynamic MRI revealed key differences, allowing to accurately distinguish between these conditions. Hirayama disease occurs in young patients (≤25 years old), has characteristic changes in the neck flexion, and is not associated with traumatic effects.

Conclusions: Traumatic myelopathy and Hirayama disease have overlapping radiological findings but differ in some key features. Ventral displacement of the dural sac and venous stasis on dynamic MRI are specific markers of Hirayama disease. Hirayama disease is not linked to a traumatic episode, which should be taken into account during forensic assessment of the traumatic etiology. Dynamic MRI should be included in the standard for myelopathy diagnosis to improve the accuracy of differential diagnosis.

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